Self-crosslinking oil-resistant fluorosilicone gel, preparation method and application thereof

Abstract

This invention discloses a self-crosslinking oil-resistant fluorosilicone gel, its preparation method, and its applications, belonging to the field of special polymer materials technology. The preparation method of the gel includes: ring-opening copolymerization of trifluoropropylmethylcyclotrisiloxane and octylmethylcyclotetrasiloxane under alkaline catalysis to obtain a prepolymer; then reacting it with 3-(methacryloyloxy)propyltrimethoxysilane to introduce self-crosslinking groups, followed by post-treatment to obtain a self-crosslinkable prepolymer; finally, adding an organotin catalyst allows for rapid curing at room temperature to form a three-dimensional network structure. This invention imparts extremely low oil swelling rate to the material by introducing fluorinated segments, while achieving rapid self-crosslinking curing under mild conditions through molecular design. The resulting material possesses excellent oil resistance, ease of application, and good interfacial adhesion, making it suitable for sealing and plugging in harsh oil environments in aerospace, petrochemical, and other fields.

Description

Technical Field

[0001] This invention belongs to the field of special polymer materials technology, specifically relating to a self-crosslinking oil-resistant fluorosilicone gel, its preparation method, and its application. Background Technology

[0002] In high-end equipment and harsh industrial environments, sealing and plugging materials capable of withstanding long-term immersion in non-polar solvents such as fuel oil, lubricating oil, and hydraulic oil are crucial for ensuring equipment reliability and safety. Traditional silicone materials have been widely used in sealing applications due to their excellent hydrophobicity, resistance to high and low temperatures, flexibility, and biocompatibility. However, their low molecular chain polarity and solubility parameters similar to non-polar solvents make them prone to severe swelling and structural deformation in such media, significantly limiting their application in critical oil-resistant scenarios such as fuel tank sealing and oilfield plugging. Furthermore, the curing process of existing silicone materials typically requires heating, the addition of curing agents, or reliance on ultraviolet light irradiation, which is not only complex and energy-intensive but can also lead to internal stress concentration or weak bonding with the substrate, affecting the long-term reliability of the seal.

[0003] Self-crosslinking technology, as a method for material curing under mild conditions without the need for external curing agents, has received widespread attention in recent years. Self-crosslinking gels can form a three-dimensional network structure through the reaction of their own functional groups at room temperature or lower temperatures, thereby significantly improving the material's mechanical strength, resistance to media, and interfacial adhesion. However, existing self-crosslinking systems are mostly concentrated on general-purpose polymers, and their long-term stability in oil-resistant environments remains insufficient, making it difficult to meet the sealing requirements under harsh working conditions. Fluorosilicone gels combine the high oil and solvent resistance of fluorine materials with the flexibility and thermal stability of silicon materials, and are considered highly promising high-performance sealing materials. In particular, through rational molecular design, they can possess self-crosslinking properties, enabling rapid and mild curing during construction, avoiding substrate damage or performance degradation caused by high temperatures or ultraviolet radiation. For example, existing research shows that fluorosiloxane prepolymers can undergo condensation crosslinking at room temperature under the action of a catalyst to form transparent, strongly adhesive, and aging-resistant gel materials, providing an important approach for developing novel oil-resistant self-crosslinking sealing systems.

[0004] Nevertheless, existing technologies still lack a self-crosslinking oil-resistant fluorosilicone gel that combines excellent oil resistance, ease of application, and high reliability. Especially in long-term plugging applications in complex oily environments, the material's impermeability, interfacial bonding strength, and anti-aging properties still need further improvement. Summary of the Invention

[0005] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0006] In view of the problems existing in the above and / or prior art, the present invention is proposed.

[0007] Therefore, the purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing a self-crosslinking oil-resistant fluorosilicone gel.

[0008] To solve the above-mentioned technical problems, the present invention provides the following technical solution: including, Trifluoropropylmethylcyclotrisiloxane and tetramethylammonium hydroxide were mixed and reacted under nitrogen atmosphere at 40-60℃ for 1 hour with continuous stirring to obtain mixture I; Add octylmethylcyclotetrasiloxane to mixture I, stir for 2-4 hours, and then add trifluoropropylmethylcyclotrisiloxane in an equal amount to mixture I at 40-60°C. Quench the reaction after 1-2 hours to obtain mixture II. Mixture II was dissolved in tetrahydrofuran, and 3-(methacryloyloxy)propyltrimethoxysilane was added to it. The mixture was stirred at 60-80℃ for 1-2 hours to carry out the reaction. Ethanol was added to stop the reaction. Tetrahydrofuran and ethanol were removed to obtain a colorless viscous liquid fluoropropylmethylsiloxane-dimethylsiloxane multiblock polymer. A self-crosslinking, oil-resistant fluorosilicone gel is obtained by reacting a fluoropropylmethylsiloxane-dimethylsiloxane multiblock polymer with an organotin catalyst at room temperature for 15-30 minutes.

[0009] In a preferred embodiment of the preparation method of the self-crosslinking oil-resistant fluorosilicone gel of the present invention, the mixture II raw material comprises, by mass fraction, 600-800 parts of trifluoropropylmethylcyclotrisiloxane; 3-3.5 parts tetramethylammonium hydroxide; 200-300 parts of octylmethylcyclotetrasiloxane.

[0010] In a preferred embodiment of the preparation method of the self-crosslinking oil-resistant fluorosilicone gel of the present invention, the ratio of the amount of mixture II to trifluoropropylmethylcyclotrisiloxane is 100:3.50-4.

[0011] As a preferred embodiment of the preparation method of the self-crosslinking oil-resistant fluorosilicone gel of the present invention, wherein: The ratio of the fluoropropylmethylsiloxane-dimethylsiloxane multiblock polymer to the organotin catalyst is 1:0.1-0.2.

[0012] In a preferred embodiment of the preparation method of the self-crosslinking oil-resistant fluorosilicone gel of the present invention, the organotin catalyst includes one or more of dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetate, and stannous octoate.

[0013] In a preferred embodiment of the preparation method of the self-crosslinking oil-resistant fluorosilicone gel of the present invention, the quenching is achieved by adding ethanol to the reaction system.

[0014] In a preferred embodiment of the preparation method of the self-crosslinking oil-resistant fluorosilicone gel of the present invention, the method for removing THF and ethanol includes using a vacuum pump.

[0015] Another object of the present invention is to provide a self-crosslinking oil-resistant fluorosilicone gel.

[0016] Another object of the present invention is to provide a self-crosslinking oil-resistant fluorosilicone gel for sealing applications in complex oily media environments.

[0017] Beneficial effects of this invention: (1) This application provides a self-crosslinking oil-resistant fluorosilicone gel preparation and its sealing application. By optimizing the molecular structure and crosslinking process, it achieves efficient and long-lasting sealing effect in oily environments, meeting the urgent needs of the industrial field for high-performance sealing materials.

[0018] (2) By introducing the fluorinated segment F3 (trifluoropropylmethylcyclotrisiloxane), the solubility parameter matching degree between the silica gel and the non-polar oil medium is significantly reduced, thus exhibiting extremely low swelling rate and deformation in environments such as fuel oil and lubricating oil, ensuring dimensional stability and sealing reliability under long-term oil immersion conditions.

[0019] (3) The introduced active functional group MPS (3-(methacryloyloxy)propyltrimethoxysilane) enables it to undergo self-crosslinking reaction under mild conditions, without the need for external curing agents, high temperature or ultraviolet irradiation. This simplifies the construction process, reduces energy consumption, and improves the applicability and operational safety of the sealing process.

[0020] (4) The preparation process of this application is simple, easy to scale up, the synthesis route is concise, the reaction conditions are mild, the raw materials are readily available, and the post-processing is convenient. It is suitable for continuous and large-scale preparation and has high industrial application prospects. Detailed Implementation

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.

[0022] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0023] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0024] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.

[0025] The abbreviations and corresponding relationships of the raw materials used in this application are as follows: F3: Trifluoropropylmethylcyclotrisiloxane / 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane; TMAH: Tetramethylammonium hydroxide; D4: Octamethylcyclotetrasiloxane / Octomethylcyclotetrasiloxane; MPS: 3-(methacryloyloxy)propyltrimethoxysilane; F3 was purchased from Tokyo Chemical Industry Co., Ltd.; TMAH, D4, and MPS, analytical grade, were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The organotin catalyst was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. This invention standardizes the oil resistance of gels by measuring swelling ratio and gel content. The gels prepared in the embodiments / comparative examples of the present invention were placed in seawater and insulating oil for 90°C thermo-oxidative aging treatment. The swelling ratio of each sample at different time periods was measured in accordance with standard GB / T 7763-1987. The gels prepared in the embodiments / comparative examples of the present invention were soaked in xylene solution at 130°C for 12 hours, and their gel content was measured in accordance with the standard GB / T27843-2011.

[0026] Example 1 This embodiment provides a method for preparing a self-crosslinking, oil-resistant fluorosilicone gel. Specifically: 1) Mix 37g F3 and 0.37g TMAH, and react continuously with stirring in a dry flask at 40°C for 1 hour under a nitrogen atmosphere to obtain mixture I; 2) Add 24g of D4 to mixture I, stir for 2 hours, then add 37g of F3 to the mixture at 40℃. After the polymerization reaction lasts for 2 hours, quench with 0.5ml of ethanol to obtain mixture II; 3) Dissolve 10g of mixture II in 5ml of THF (tetrahydrofuran), add 0.37g of MPS, and stir the mixture at 60℃ for 1h. Add ethanol to stop the reaction. Remove THF and ethanol by vacuum pump to obtain a colorless viscous liquid fluoropropylmethylsiloxane-dimethylsiloxane multiblock polymer. 4) Take 1.5g of colorless viscous liquid fluoropropylmethylsiloxane-dimethylsiloxane multiblock polymer, add 15mg of catalyst dibutyltin dilaurate, and cure at room temperature for 30min to obtain crosslinked fluoropropylmethylsiloxane-dimethylsiloxane multiblock gel, which is the oil-resistant fluorosilicone gel of this embodiment.

[0027] Example 2 The difference between this embodiment and Example 1 is that the amount of dibutyltin dilaurate catalyst in step 4) is adjusted to 30 mg, that is, the ratio of fluoropropylmethylsiloxane-dimethylsiloxane multiblock polymer to organotin catalyst is 1:0.2. The formulation and process of the remaining components are the same as in Example 1, and the oil-resistant fluorosilicone gel of this embodiment is obtained.

[0028] Example 3 The difference between this embodiment and Example 1 is that the catalyst in step 4) is changed from dibutyltin dilaurate to dibutyltin diacetate. The formulations and processes of the remaining components are the same as in Example 1, and the oil-resistant fluorosilicone gel of this embodiment is obtained.

[0029] Example 4 The difference between this embodiment and Example 1 is that the catalyst in step 4) is changed from dibutyltin dilaurate to stannous octoate. The formulations and processes of the remaining components are the same as in Example 1, and the oil-resistant fluorosilicone gel of this embodiment is obtained.

[0030] The oil resistance of the gels prepared in Examples 1 to 4 was determined, and the results are shown in Table 1.

[0031] Table 1 As shown in Table 1, different types of organotin catalysts selected in this application can effectively promote the self-crosslinking reaction of the colorless viscous liquid fluoropropylmethylsiloxane-dimethylsiloxane multiblock polymer. With the increase of the amount of organotin catalyst, the self-crosslinking reaction rate is significantly improved, thereby obtaining a cured self-crosslinking oil-resistant fluorosilicone gel in a shorter time.

[0032] Comparative Example 1 The difference between this comparative example and Example 1 is that F3 is replaced with an equimolar amount of the common cyclosiloxane monomer decamethylcyclopentasiloxane, while the formulations and processes of the remaining components are the same as in Example 1, and the non-fluorinated silica gel of this comparative example is prepared.

[0033] Comparative Example 2 The difference between this comparative example and Example 1 is that F3 was replaced with an equimolar amount of ordinary poly(3,3,3-trifluoropropylmethylsiloxane) (PTFPMS), while the formulations and processes of the remaining components were the same as in Example 1, and the fluorinated silicone gel of this comparative example was prepared.

[0034] Comparative Example 3 The difference between this comparative example and Example 1 is that the content of F3 was reduced to 20 grams, while the formulation and process of the remaining components were the same as in Example 1. As a result, the fluorinated silicone gel in this comparative example failed to form.

[0035] The oil resistance of the gels prepared in Comparative Examples 1 and 2 was measured and compared with that in Example 1. The results are shown in Table 2.

[0036] Table 2 As shown in Table 2, the introduction of the fluorinated monomer (1,3,5-trichloropropylmethyl(3,3,3-trifluoropropyl)cyclotrisiloxane) in this application is a key factor in significantly improving the oil resistance of the material. Fluorine atoms possess extremely high electronegativity and low polarity; their introduction effectively reduces the solubility parameter of the silica gel molecular chain, significantly decreasing its chemical affinity for non-polar oil media such as fuel oil and lubricating oil. This fundamental structural change results in the material exhibiting extremely low swelling tendency in oily environments. Specifically, the swelling ratio of the fluorinated examples after oil immersion is far lower than that of the non-fluorinated Comparative Example 1, demonstrating the core anti-swelling role of fluorine atoms, which is the basis for the material of this invention to maintain long-term structural integrity and functional reliability in harsh oil media. Furthermore, the selection of the fluorinated monomer is crucial for the self-crosslinking process; a lower F3 content results in the material not curing, and F3 exhibits better oil resistance compared to PTFPMS.

[0037] Comparative Example 3 The difference between this comparative example and Example 1 is that MPS is omitted, while the formulations and processes of the remaining components are the same as in Example 1. As a result, the system in this comparative example has no self-crosslinking ability.

[0038] This comparative example demonstrates that the self-crosslinking monomer 3-(methacryloxy)propyltrimethoxysilane plays a crucial role in achieving efficient curing under mild conditions. The hydrolyzable alkoxy groups provided by this monomer can undergo hydrolytic condensation in the presence of trace amounts of moisture and a catalyst, forming a stable siloxane (Si-O-Si) crosslinking network between polymer chains. This mechanism allows the material to transform from a prepolymer to an elastomer without relying on external curing agents, high temperatures, or UV irradiation. This not only simplifies the construction process and avoids substrate damage or internal stress caused by complex curing conditions, but also helps to form a dense and uniform three-dimensional network structure, thereby endowing the cured material with higher mechanical strength, better interfacial adhesion, and superior long-term durability.

[0039] Comparative Example 4 The difference between this comparative example and Example 1 is that the catalyst in step 4) is adjusted to be a platinum catalyst (Karstedt catalyst), while the formulations and processes of the other components are the same as in Example 1. As a result, the system in this comparative example cannot achieve curing.

[0040] This comparative example demonstrates that the choice of catalyst type is crucial to the self-crosslinking process, and that platinum catalysts do not cause material curing.

[0041] In summary, this application provides a method for preparing a self-crosslinking, oil-resistant fluorosilicone gel and its sealing application. By optimizing the molecular structure and crosslinking process, it achieves efficient and durable sealing in oily environments, meeting the urgent industrial demand for high-performance sealing materials. The introduction of the fluorinated F3 segment significantly reduces the solubility parameter matching between the silicone gel and non-polar oil media, resulting in extremely low swelling and deformation in environments such as fuel oil and lubricating oil, ensuring dimensional stability and sealing reliability under long-term oil immersion conditions. The introduced active functional group (MPS) enables self-crosslinking under mild conditions, eliminating the need for external curing agents, high temperatures, or ultraviolet irradiation. This simplifies the construction process, reduces energy consumption, and improves the applicability and operational safety of sealing. The preparation process of this application is simple, easy to scale up, with a concise synthetic route, mild reaction conditions, readily available raw materials, and convenient post-processing, making it suitable for continuous and large-scale preparation and possessing high industrial application prospects.

[0042] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a self-crosslinking oil-resistant fluorosilicone gel, characterized in that: include, Trifluoropropylmethylcyclotrisiloxane and tetramethylammonium hydroxide were mixed and reacted under nitrogen atmosphere at 40-60℃ for 1 hour with continuous stirring to obtain mixture I; Add octylmethylcyclotetrasiloxane to mixture I, stir for 2-4 hours, and then add trifluoropropylmethylcyclotrisiloxane in an equal amount to mixture I at 40-60°C. Quench the reaction after 1-2 hours to obtain mixture II. Mixture II was dissolved in tetrahydrofuran, and 3-(methacryloyloxy)propyltrimethoxysilane was added to it. The mixture was stirred at 60-80℃ for 1-2 hours to carry out the reaction. Ethanol was added to stop the reaction. Tetrahydrofuran and ethanol were removed to obtain a colorless viscous liquid fluoropropylmethylsiloxane-dimethylsiloxane multiblock polymer. A self-crosslinking, oil-resistant fluorosilicone gel is obtained by reacting a fluoropropylmethylsiloxane-dimethylsiloxane multiblock polymer with an organotin catalyst at room temperature for 15-30 minutes.

2. The preparation method of the self-crosslinking oil-resistant fluorosilicone gel as described in claim 1, characterized in that: Based on the mass parts of the raw materials in mixture II, it includes, 600-800 parts of trifluoropropylmethylcyclotrisiloxane; 3-3.5 parts tetramethylammonium hydroxide; 200-300 parts of octylmethylcyclotetrasiloxane.

3. The preparation method of the self-crosslinking oil-resistant fluorosilicone gel as described in claim 2, characterized in that: The ratio of mixture II to trifluoropropylmethylcyclotrisiloxane is 100:3.50-4.

4. The method for preparing the self-crosslinking oil-resistant fluorosilicone gel as described in claim 1, characterized in that: The ratio of the fluoropropylmethylsiloxane-dimethylsiloxane multiblock polymer to the organotin catalyst is 1:0.1-0.

2.

5. The preparation method of the self-crosslinking oil-resistant fluorosilicone gel as described in claim 4, characterized in that: The organotin catalyst includes one or more of dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetate, and stannous octoate.

6. The method for preparing the self-crosslinking oil-resistant fluorosilicone gel as described in claim 1, characterized in that: The quenching is achieved by adding ethanol to the reaction system.

7. The method for preparing the self-crosslinking oil-resistant fluorosilicone gel as described in claim 1, characterized in that: The method for removing tetrahydrofuran and ethanol includes using a vacuum pump.

8. The self-crosslinking oil-resistant fluorosilicone gel prepared by any one of the preparation methods described in claims 1 to 7.

9. The sealing application of the self-crosslinking oil-resistant fluorosilicone gel as described in claim 8 in complex oil media environments.

Images