A fluorinated polyether cationic surfactant and its preparation method

Abstract

This invention discloses a method for preparing a fluorinated polyether cationic surfactant, relating to the field of fluorinated polyether cationic surfactant preparation technology, comprising the following steps: S1, methanol is first added to a reaction apparatus, and under stirring conditions, the temperature is raised, then perfluoropolyether carboxylic acid is added, the reaction is maintained at the temperature, and the mixture is allowed to stand and separate into layers to obtain product one; S2, product one is added to a reaction apparatus, and under stirring conditions, the reaction temperature is controlled at 0~30℃, then an amidation reagent is added, and the reaction is carried out to obtain product two; S3, product two is added to a reaction apparatus, and under stirring conditions, the temperature is controlled, a halogenation reagent is added in a certain proportion, and the reaction is carried out at room temperature for 2~5 hours to obtain a crude product; S4, the crude product in step S3 is then filtered and purified to obtain a fluorinated polyether cationic surfactant. This product has the advantages of fluorinated surfactants and can also handle the excess perfluoropolyether carboxylic acid generated during the production of perfluoropolyether carboxylic acid anionic surfactants and other products.

Description

Technical Field

[0001] This invention relates to the field of fluorinated polyether cationic surfactant preparation technology, specifically to a fluorinated polyether cationic surfactant and its preparation method. Background Technology

[0002] Fluorinated acrylates, due to their combination of the excellent water and oil repellency of organofluorine substances and the excellent film-forming properties of acrylates, have outstanding performance advantages over other types of surface treatment agents in the surface treatment of leather and fabrics. They are widely favored and have become the mainstream products for water and oil repellency treatment in the textile industry and other industries.

[0003] Fluorinated fabric finishing agents exhibit significant advantages over traditional silicone, nitrogen-based, and paraffin-based finishing agents in terms of water and oil repellency, stain resistance, wash resistance, abrasion resistance, and corrosion resistance. This is fundamentally due to fluorine's high electronegativity and the high bond energy of the carbon-fluorine (CF) bond. Furthermore, the covalently bonded fluorine atom has a larger atomic radius than hydrogen, effectively protecting the perfluorinated C-F bond. The low concentration and high effectiveness of fluorinated fabric finishing agents are also due to the extremely low surface energy of the fluorocarbon chain, making it difficult for liquids to spread on its surface. When water or oil droplets come into contact with the treated surface, they do not penetrate into the fabric, forming droplets that roll off.

[0004] Perfluoroalkyl and polyfluoroalkyl (PFAS) surfactants are hazardous "permanent chemicals." These substances are highly resistant to both chemical and biodegradation and are frequently used as lubricants in manufacturing processes. Some PFAS often remain on or within consumer products because they do not decompose naturally, hence the term "permanent chemicals." They are linked to cancer, fetal complications, liver disease, kidney disease, autoimmune diseases, and other serious health problems. The potential environmental and human health impacts of these substances have garnered significant attention both domestically and internationally as awareness of perfluorooctanoic acid (PFOA) has deepened, leading governments and businesses to place increasing emphasis on PFOA substitution efforts. In 2017, several fluorochemical companies began PFOA substitution work. In May 2019, following the Geneva Conference, the European Union officially included PFOA and its salts in the Stockholm Convention, banning its use globally with some exemptions. Research indicates that PFOS / PFOA fluorosurfactants are among the most difficult substances to degrade, exhibiting persistence, bioaccumulation, and even the potential for long-distance environmental migration. Once ingested, PFOS / PFOA fluorinated surfactants are distributed in the blood and liver. Due to their inherent stability, they are difficult to break down through human metabolism. Perfluorooctane sulfonic acid (PFOS / PFOA) has a "half-expellable time" of up to 8.7 years in the human body. This means that PFOS / PFOA fluorinated surfactants have high bioaccumulation and various toxicities in the human body, causing damage to the respiratory system and even posing a risk of death to newborns. The United Nations Environment Programme's Organic Pollutant Review Committee has determined that it meets the criteria for persistent organic pollutants.

[0005] On February 2, 2021, the European Commission approved and published Authorizing Regulation (EU) 2021 / 115, revising Annex I of the Persistent Organic Pollutants (POPs) Regulation (EU) 2019 / 1021 regarding restrictions on perfluorooctanoic acid (PFOA), its salts, and related compounds. The revisions entered into force on February 22, 2021. On September 20, 2024, the Official Journal of the European Union (OJEU) published (EU) 2024 / 2462, revising Annex XVI of the REACH Regulation, adding Article 79 to control perfluorooctanoic acid (PFHXA), its salts, and related substances. These restrictions will enter into force on October 10, 2024.

[0006] Patent application No. 202211234461.6, published on January 31, 2023, discloses an ionic ammonium salt short-chain fluorocarbon surfactant and its synthesis method. This method uses short-chain perfluoropentanoyl fluoride and dipentaerythritol as raw materials, and generates a fluorocarbon-based cationic surfactant through diisocyanate linkage. This solves the problem of insufficient surface activity due to the short fluorocarbon chain segments. This diisocyanate-crosslinked fluorocarbon cationic surfactant, when used as an anti-fogging agent, improves the anti-fogging performance of resin lenses. However, this reaction route is complex and involves the use of multiple solvents, posing significant difficulties for industrial application. Another example is patent application No. 201210321443.1, published on December 12, 2012, which discloses an environmentally friendly cationic fluorosurfactant based on short fluorocarbon chains, including amine salt-type cationic fluorosurfactants or quaternary ammonium salt-type cationic fluorosurfactants. This method uses inexpensive amines as raw materials, and through a ring-opening reaction with 3-perfluorohexyl-1,2-epoxypropane, prepares a fluorinated intermediate that is easy to introduce various hydrophilic groups. This intermediate is then reacted with hydrochloric acid or iodomethane to obtain the corresponding amine salt or quaternary ammonium salt cationic fluorinated surfactants, including two ionic liquids. However, with updated environmental policies, these substances are now classified as perfluorohexyl substances and are prohibited from use. Summary of the Invention

[0007] The purpose of this invention is to provide a method for preparing a fluorinated polyether cationic surfactant, and to propose a new fluorinated polyether cationic surfactant that meets environmental protection requirements. In addition to having the advantages of fluorinated surfactants, it can also deal with the excess perfluoropolyether carboxylic acid generated during the production of perfluoropolyether carboxylic acid anionic surfactants, nonionic surfactants and other products.

[0008] This invention is achieved through the following technical solution: A method for preparing a fluorinated polyether cationic surfactant includes the following steps: S1. Take the raw materials by mixing perfluoropolyether carboxylic acid and methanol in a molar ratio of 1.0:1.0~1.5. First, add methanol to the reaction device, and under stirring, heat to 40~63℃. Then add perfluoropolyether carboxylic acid, keep the reaction at the temperature for 1~3 hours, let stand, separate the layers, and separate the lower liquid to obtain product one. S2. Add product one to the reaction apparatus. Under stirring conditions, control the reaction temperature at 0~30℃. Then add the amidating reagent at a uniform rate with a molar ratio of lower liquid to amidating reagent of 1.0:1.0~2.0. Keep the reaction at the temperature for 0.5~2h to obtain product two. S3. Add product 2 to the reaction apparatus, and under stirring, control the temperature to 10~45℃. Take the halogenated reagent according to the molar ratio of product 2 to halogenated reagent 1.0:1.0~1.5, and then add the halogenated reagent dropwise to the reaction apparatus. React at room temperature for 2~5 hours to obtain the crude product. S4. The crude product from step S3 is then filtered and purified to obtain a fluorinated polyether cationic surfactant.

[0009] Furthermore, in step S1, the perfluoropolyether carboxylic acid is an intermediate for the production of perfluoropolyether anionic surfactants, and the molecular weight of the perfluoropolyether carboxylic acid is 400~1200.

[0010] Furthermore, the general structural formula of perfluoropolyether carboxylic acid is as follows: CF3-O-(-CF3CF-CF2-O-) m -(-CF2-O-) n -COOH, Where m is 1~10, n / m is 0.01~0.05, and the perfluoropolyether carboxylic acid satisfies: Acid value: 33~100mg / g; Peroxide value: 0.01~0.3%; Boiling point: 120~260℃.

[0011] Furthermore, in step S2, the amidation reagent includes one of triethylamine, 3-methylaminopropylamine, 3-ethylaminopropylamine, 3-diethylaminopropylamine, 3-dimethylaminopropylamine, dimethylamine, etc.

[0012] Furthermore, in step S3, the halogenating agent is one or a mixture of several of bromoethane, chloroethane, iodomethane, and bromododecane.

[0013] Furthermore, in step S4, the purification method is as follows: the crude product is purified by vacuum distillation, and the fluorinated polyether cationic surfactant is separated at 80~100℃.

[0014] A fluorinated polyether cationic surfactant prepared by any of the aforementioned methods.

[0015] Furthermore, fluorinated polyether cationic surfactants meet the following criteria: Appearance: Pale yellow liquid; Specific gravity: 1.700~2.300; Dynamic viscosity at 20℃: 8000~20000 mPa·s; Critical micelle concentration: 0.30~1.20%; Surface tension at 1% concentration: 18.00~40.00 mN / m.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: I. In this invention, the method for synthesizing perfluoropolyether carboxylic acid is an existing, mature production process that can be used directly. This method is safe and simple, with a wide range of reaction types applicable. By controlling the selection of reactants, reactants of specific molecular weights can be used to prepare quaternary ammonium salt-type cationic fluorocarbon surfactants of different molecular weights, which can then be used to prepare surface treatment agents with various properties.

[0017] Second, in the preparation of quaternary ammonium salt cationic fluorocarbon surfactants, no other solvents are used, the reaction conditions are mild and controllable, and the forward reaction is promoted by means of temperature and reaction rate. The production process is easy to control, with few by-products, which makes it easy to promote to industrial and large-scale production.

[0018] Third, in the preparation of quaternary ammonium salt cationic fluorocarbon surfactants, the purification methods in the post-treatment process are all physical methods, such as drying and filtration, which effectively avoids the addition of chemical reagents, simplifies the operation process, and reduces production costs.

[0019] IV. This invention can process a large amount of intermediate product—perfluoropolyether carboxylic acid—generated from the company's perfluoropolyether anionic surfactant production line and its production line for fluorinated surfactants (disclosed in the process described in patent "CN201510635260.0"), thus solving the problem of large-scale stockpiling of perfluoropolyether carboxylic acid within the company. This solution utilizes the perfluoropolyether group portion of the perfluoropolyether carboxylic acid to synthesize a green and environmentally friendly quaternary ammonium salt-type cationic fluorocarbon surfactant that does not contain PFOS / PFOA, while maintaining the excellent performance of fluorinated surfactants.

[0020] V. In this invention, the quaternary ammonium salt cationic fluorocarbon surfactant of this solution is used to replace the original perfluoroalkyl substance quaternary ammonium salt fluorocarbon surfactant, thereby solving the environmental protection problem in this field.

[0021] VI. In this invention, one of the reactants, perfluoropolyether carboxylic acid, has a variety of molecular weights to choose from, and the prepared quaternary ammonium salt fluorocarbon surfactant system is large and can meet the performance requirements of a variety of surface treatment agents. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0023] In the following examples, the perfluoropolyether carboxylic acid used is an acyl fluoride-terminated product generated from the production of perfluoropolyether carboxylic acid anionic surfactants, nonionic surfactants, and other products by our company, and a perfluoropolyether carboxylic acid intermediate obtained by hydrolysis. For example, the perfluoropolyether carboxylic acid generated in the surfactant preparation process disclosed in patent application No. 201510635307.3, "A Fluorinated Surfactant Without Perfluorooctanoic Acid and Its Preparation Method and Process System," etc.

[0024] The main steps involved include: Ⅰ. Take a perfluoroolefin and control its temperature at -20~-25℃. Pass a mixed gas consisting of oxygen and a third monomer containing at least one non-fluorine atom of olefin or alkyne into the perfluoroolefin. After maintaining the ultraviolet light irradiation and gas passage time for 2~12h, recover the unreacted perfluoroolefin by evaporation at room temperature to obtain a product containing acyl fluoride end groups. The third monomer includes one or more of the following: bromotrifluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, and dichlorofluoroethylene.

[0025] II. After mixing deionized water and the acyl fluoride-containing end-group product, the temperature of the liquid phase fluid in the material prepared in step I is controlled by stirring at 30~50℃. Continue to add the acyl fluoride-containing end-group product to the material at a rate of 10~60L / h, and control the stirring time at 1~5h. Ⅲ. The crude product obtained in step Ⅱ is allowed to stand and separate into layers. After removing the supernatant, a fluorinated oligomer with a carboxyl group at one end is obtained. IV. After pyrolysis stabilization of the fluorinated oligomers, they are distilled and divided according to usage requirements to obtain fluorinated carboxylic acid components with different molecular weight distributions; V. Select perfluoropolyether carboxylic acid with a molecular weight of 400~1200 for later use.

[0026] The examples below all use perfluoropolyether carboxylic acids with a molecular weight of 400-1200, which are intermediate products of perfluoropolyether anionic surfactants and nonionic surfactants produced by our company. The general structural formula of perfluoropolyether carboxylic acids is as follows: CF3-O-(-CF3CF-CF2-O-) m -(-CF2-O-) n -COOH, Where m is 1~10, n / m is 0.01~0.05, and the perfluoropolyether carboxylic acid satisfies: Acid value: 33~100mg / g; Peroxide value: 0.01~0.3%; Boiling point: 120~260℃.

[0027] Example 1 A method for preparing a fluorinated polyether cationic surfactant includes the following steps: S1. Take the raw materials by mixing perfluoropolyether carboxylic acid and methanol in a molar ratio of 1.0:1.0~1.5. First, add methanol to the reaction device, and under stirring, heat to 40~63℃. Then add perfluoropolyether carboxylic acid, keep the reaction at the temperature for 1~3 hours, let stand, separate the layers, and separate the lower liquid to obtain product one. S2. Add product one to the reaction apparatus. Under stirring conditions, control the reaction temperature at 0~30℃. Then add the amidating reagent at a uniform rate with a molar ratio of lower liquid to amidating reagent of 1.0:1.0~2.0. After keeping the reaction at the temperature for 0.5~2h, product two is obtained. S3. Add product 2 to the reaction apparatus, and under stirring, control the temperature to 10~45℃. Take the halogenated reagent according to the molar ratio of product 2 to halogenated reagent 1.0:1.0~1.5, and then add the halogenated reagent dropwise to the reaction apparatus. React at room temperature for 2~5 hours to obtain the crude product. S4. The crude product from step S3 is then filtered and purified by vacuum distillation. The purified fluorinated polyether cationic surfactant is separated at 80-100℃.

[0028] In this embodiment, all fluorinated polyether cationic surfactants were prepared in the laboratory. The process conditions for each experimental group are shown in Table 1.

[0029] Table 1 By comparing the preparation process, the yield of the product in each step of each group was statistically analyzed, and the results are shown in Table 2.

[0030] Table 2 As shown in Tables 1 and 2, and considering the actual production situation, step S2 is one of the key steps. Controlling the temperature at a lower level is beneficial for promoting the forward reaction. In addition, compared with steps S2 and S3, the reaction product is more viscous. The small-scale experimental quantity was small, and the material residue resulted in a slightly lower product yield in steps S2 and S3 than in actual production.

[0031] The properties of the prepared fluorinated polyether cationic surfactant were then tested. The test results are shown in Table 3.

[0032] The testing method is: ASTM D1331-11 Standard Test Methods for Surface and Interfacial Tension of Solutions of Surface-Active Agents.

[0033] Table 3 As is known from existing technology, the viscosity of a surfactant affects its processing difficulty during application, thus limiting its application areas. Table 3 shows that the molecular weight of the perfluoropolyether carboxylic acid raw material has a significant impact on the dynamic viscosity of the final product—the fluorinated polyether cationic surfactant. The fluorinated polyether cationic surfactants obtained using the method described in this scheme are all pale yellow liquids and meet the following specifications: specific gravity: 1.700~2.300; dynamic viscosity at 20℃: 8000~20000 mPa·s; critical micelle concentration: 0.30~1.20%; surface tension at 1% concentration: 18.00~40.00 mN / m. This indicates that the obtained fluorinated polyether cationic surfactants possess high surface activity and a low critical micelle concentration, allowing them to function effectively even at low concentrations. They are particularly suitable for textile finishing, surface treatment, and other fields.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a fluorinated polyether cationic surfactant, characterized in that, Includes the following steps: S1. Take the raw materials by mixing perfluoropolyether carboxylic acid and methanol in a molar ratio of 1.0:1.0~1.

5. First, add methanol to the reaction device, and under stirring, heat to 40~63℃. Then add perfluoropolyether carboxylic acid, keep the reaction at the temperature for 1~3 hours, let stand, separate the layers, and separate the lower liquid to obtain product one. S2. Add product one to the reaction apparatus. Under stirring conditions, control the reaction temperature at 0~30℃. Then add the amidating reagent at a uniform rate with a molar ratio of lower liquid to amidating reagent of 1.0:1.0~2.

0. Keep the reaction at the temperature for 0.5~2h to obtain product two. S3. Add product 2 to the reaction apparatus, and under stirring, control the temperature to 10~45℃. Take the halogenated reagent according to the molar ratio of product 2 to halogenated reagent 1.0:1.0~1.5, and then add the halogenated reagent dropwise to the reaction apparatus. React at room temperature for 2~5 hours to obtain the crude product. S4. The crude product from step S3 is then filtered and purified to obtain a fluorinated polyether cationic surfactant.

2. The method for preparing a fluorinated polyether cationic surfactant according to claim 1, characterized in that: In step S1, the perfluoropolyether carboxylic acid is an intermediate for the production of perfluoropolyether anionic surfactants, and the molecular weight of the perfluoropolyether carboxylic acid is 400~1200.

3. The method for preparing a fluorinated polyether cationic surfactant according to claim 2, characterized in that: The general structural formula of perfluoropolyether carboxylic acid is as follows: CF3-O-(-CF3CF-CF2-O-) m -(-CF2-O-) n -COOH, Where m is 1~10, n / m is 0.01~0.05, and the perfluoropolyether carboxylic acid satisfies: Acid value: 33~100mg / g; Peroxide value: 0.01~0.3%; Boiling point: 120~260℃.

4. The method for preparing a fluorinated polyether cationic surfactant according to claim 1, characterized in that: In step S2, the amidation reagent includes one of triethylamine, 3-methylaminopropylamine, 3-ethylaminopropylamine, 3-diethylaminopropylamine, 3-dimethylaminopropylamine, dimethylamine, etc.

5. The method for preparing a fluorinated polyether cationic surfactant according to claim 1, characterized in that: In step S3, the halogenating agent is one or a mixture of several of the following: bromoethane, chloroethane, iodomethane, and bromododecane.

6. The method for preparing a fluorinated polyether cationic surfactant according to claim 1, characterized in that: In step S4, the purification method is as follows: the crude product is purified by vacuum distillation, and the fluorinated polyether cationic surfactant is separated at 80~100℃.

7. A fluorinated polyether cationic surfactant obtained by the preparation method according to any one of claims 1 to 6.

8. The fluorinated polyether cationic surfactant as described in claim 6, characterized in that, Meet the following criteria: Appearance: Pale yellow liquid; Specific gravity: 1.700~2.300; Dynamic viscosity at 20℃: 8000~20000 mPa·s; Critical micelle concentration: 0.30~1.20%; Surface tension at 1% concentration: 18.00~40.00 mN / m.

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