Fluorine-containing end-functionalized liquid rubber and method of making the same

Abstract

This invention discloses a fluorine-containing end-functionalized liquid rubber and its preparation method. The structure of the fluorine-containing end-functionalized liquid rubber is as follows: where R1 is -OH, C (2+a) H (1+2a) O4 (a=1~6), C (4+b) H (6+2b) N1O1 (b=0~5), C (4+c) H (4+2c) One of N1O2 (c=0~5); R2 is -H or -CH3; R3 is one or more of -CN, -C6H5, and -C8H7; R f R4 is independently selected from -H, -F, and -CF3, and not all of them are -H; R4 is -OH or C. (2+a) H (1+2a) O4 (a=1~6), C (4+b) H (6+2b) N1O1 (b=0~5), C (4+c) H (4+2c) One of N1O2 (c=0~5); m=0~200, n=0~200, x=0~100, y=1~100, and m, n, and x are not simultaneously 0. This invention uses fluorinated olefins and one or more conjugated olefins as raw materials, and directly prepares fluorinated hydroxyl-terminated or carboxyl-terminated liquid rubbers through free radical solution polymerization under the combined action of two initiators. The fluorinated end-functionalized liquid rubber and its preparation method provided by this invention do not require prior polymerization followed by modification, do not introduce side chain structures, and have the advantages of fewer synthesis steps, milder reaction conditions, and lower production costs. It can be widely used as a reactive liquid rubber raw material in the fields of specialty coatings, adhesives, and polyurethanes.

Description

Technical Field

[0001] This invention relates to the technical field of liquid rubber and polymers, and in particular to fluorine-containing end-functionalized liquid rubber and its preparation method. Background Technology

[0002] Fluorine is the most electronegative element, forming carbon-fluorine bonds with high bond energy and low polarizability. Therefore, fluoropolymers typically possess excellent heat resistance, corrosion resistance, weather resistance, solvent resistance, low hygroscopicity, and oxidation resistance, making them widely used as resins, adhesives, and coatings in the automotive, electronics, and aerospace industries. Furthermore, when fluoropolymers are used in metal-based solid fuels, they can reduce sintering, increase heat transfer and combustion rate, improve calorific value, and ensure more complete combustion.

[0003] Since the last century, end-functionalized liquid rubbers, represented by carboxyl-terminated butadiene-acrylonitrile copolymers and hydroxyl-terminated polybutadiene, have been widely used in polyurethane materials, adhesives, coatings, and other fields. One of the important applications of end-functionalized liquid rubbers is as a matrix to bind oxidants, metal fuels, catalysts, stabilizers, and other additives. Chinese patent CN115141293A describes the preparation of a series of fluorinated hydroxyl-terminated polybutadiene liquid rubbers by chemically linking fluorinated small molecule compounds to hydroxyl-terminated polybutadiene as side chains. In addition, fluorine can also be introduced into prepolymers prepared from end-functionalized liquid rubbers by grafting fluorinated side chains (CN104892850A), or by using fluorinated chain extenders, fluorinated polyols, fluorinated monomers, etc., to prepare fluorinated elastomers (CN101177476A, CN100500724C). However, these schemes have significantly altered the chemical structure of end-functionalized liquid rubbers, severely affecting the mechanical properties of the corresponding elastomers, such as elongation at break, tensile strength, and elastic modulus, and reducing important characteristics such as compatibility and stability. Summary of the Invention

[0004] The first objective of this invention is to disclose a type of fluorine-containing end-functionalized liquid rubber. This product can improve the stability of end-functionalized liquid rubber, especially its combustion-promoting effect on metal fuels. Compared with existing fluorine-containing end-functionalized liquid rubbers, this invention does not change the main structure of the end-functionalized liquid rubber; the fluorine element exists in the main chain in the form of carbon-fluorine bonds; and the preparation process is simple, the preparation cost is low, and it can be directly synthesized through monomer polymerization.

[0005] To achieve the above objectives, the present invention provides a fluorinated end-functionalized liquid rubber with the following structure: , Where R1 is -OH, C (2+a) H (1+2a)O4 (a=1~6), C (4+b) H (6+2b) N1O1 (b=0~5), C (4+c) H (4+2c) One of N1O2 (c=0~5); R2 is -H or -CH3; R3 is one or more of -CN, -C6H5, and -C8H7; R f R4 is independently selected from -H, -F, and -CF3, and not all of them are -H; R4 is -OH or C. (2+a) H (1+2a) O4 (a=1~6), C (4+b) H (6+2b) N1O1 (b=0~5), C (4+c) H (4+2c) One of N1O2 (c=0~5); m=0~200, n=0~200, x=0~100, y=1~100, and m, n, and x are not all 0 at the same time.

[0006] The second objective of this invention is to disclose a method for preparing fluorine-containing end-functionalized liquid rubber, wherein a free radical initiator is used to initiate the polymerization of conjugated olefin monomers and fluorine-containing olefin monomers in a solvent to obtain fluorine-containing end-functionalized liquid rubber.

[0007] To achieve the above objectives, the present invention provides a method for preparing the fluorinated end-functionalized liquid rubber, comprising the following steps: (1) Under nitrogen protection, add conjugated olefin monomer, fluorinated olefin monomer and solvent to the reaction vessel, stir evenly and heat to the reaction temperature; (2) Free radical polymerization is carried out by adding an initiator solution at the reaction temperature; (3) After the polymerization is completed, the reaction is terminated and the fluorinated end-functionalized liquid rubber is obtained after treatment.

[0008] The conjugated olefin monomer is one or a mixture of butadiene, isoprene, styrene, divinylbenzene, and acrylonitrile, preferably one or a mixture of butadiene, styrene, and acrylonitrile.

[0009] The fluorinated olefin monomer is one or a mixture of several of vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, trifluoropropylene, hexafluoropropylene, hexafluoroisobutylene, and octafluoroisobutylene, preferably one or a mixture of several of vinyl fluoride, vinylidene fluoride, and trifluoropropylene.

[0010] The initiator is a mixture of peroxide initiators and azo initiators. The peroxide initiator is one or more of hydrogen peroxide, malonic acid peroxide, succinic acid peroxide, glutaric acid peroxide, adipic acid peroxide, pimelic acid peroxide, and octanoic acid peroxide, preferably one or more of hydrogen peroxide, succinic acid peroxide, and glutaric acid peroxide. The amount used is 0.1-20% of the total amount of the conjugated olefin monomer and the fluorinated olefin monomer. mol%; the azo initiator is one or more of azodicyanopropanol, azodicyanobutanol, azodicyanopentanol, azodicyanohexanol, azodicyanoheptanol, azodicyanooctanol, azodicyanopropionic acid, azodicyanobutyric acid, azodicyanopentanol, azodicyanohexanoic acid, azodicyanoheptanol, and azodicyanooctanoic acid, preferably one or a mixture of several of azodicyanobutanol, azodicyanopentanol, azodicyanobutyric acid, and azodicyanopentanol, and the amount used is 0.1~20 mol of the total amount of conjugated olefin monomer and fluorinated olefin monomer.

[0011] The solvent is one or more of water, methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, tert-butanol, mixed alcohols, diethyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, anisole, dichloromethane, chloroform, tetrachloromethane, dichloroethane, acetonitrile, ethyl acetate, trimethyl phosphate, dimethyl carbonate, diethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propylene carbonate, preferably a mixture of one or more of ethanol, tert-butanol, tetrahydrofuran, and dimethyl carbonate, and is used in an amount of 50-300 w of the total amount of conjugated olefin monomers and fluorinated olefin monomers.

[0012] The polymerization reaction temperature is 50~150 ℃, preferably 80~130 ℃; the polymerization reaction time is 1~12 h, preferably 2~6 h.

[0013] Step (3) involves cooling and depressurizing to remove unreacted monomers after polymerization. The remaining reaction solution is then washed with water and dried to obtain the corresponding fluorinated end-functionalized liquid rubber.

[0014] Compared with existing fluorinated end-functionalized liquid rubbers and their preparation methods, the advantages of this invention are that it eliminates the need for pre-preparing end-functionalized liquid rubbers followed by fluorination modification, avoids altering the main structure of the end-functionalized liquid rubber, and does not add side chains. Fluorinated end-functionalized liquid rubbers can be directly obtained through one-step polymerization. The preparation process is simple, low-cost, and suitable for industrial production. Introducing fluorine into the main chain can improve product stability, increase the combustion-promoting ability of metal fuels, and enhance the product's application performance, especially in the fields of specialty coatings, adhesives, and polyurethanes. Attached Figure Description

[0015] Figure 1 Hydroxyl-terminated butadiene-vinyl fluoride copolymer1 H NMR spectrum; Figure 2 Hydroxyl-terminated butadiene-vinyl fluoride copolymer 19 F NMR spectrum; Figure 3 This is a gel permeation chromatogram of a hydroxyl-terminated butadiene-vinyl fluoride copolymer. Detailed Implementation

[0016] The present invention will be further illustrated by specific embodiments below.

[0017] Example 1

[0018] Under a nitrogen atmosphere, 1 kg of ethanol, 1 kg of butadiene, and 50 g of vinyl fluoride were added sequentially to a dry, sealed 10 L polymerization reactor. The mixture was stirred and heated to 130 °C. Using a plunger pump, 30 g of a 50 w% aqueous solution of hydrogen peroxide and 12 g of a 50 w% ethanol solution of azodicyanopentanol were added, respectively. After reacting for 4 h, the mixture was cooled to room temperature, and unreacted butadiene and vinyl fluoride monomers were removed under reduced pressure. The resulting reaction mixture was washed with water and dried to obtain 510 g of hydroxyl-terminated butadiene-vinyl fluoride copolymer with a number-average molecular weight of 4050, a hydroxyl value of 0.52 mmol / g, and a vinyl fluoride content of 6 mol.

[0019]

[0020] Figure 1 The hydroxyl-terminated butadiene-vinyl fluoride copolymer prepared in Example 1 1 The 1H NMR spectrum shows the characteristic peaks of the [-CH2-CFH-CH2-] structural fragment. Figure 2 The hydroxyl-terminated butadiene-vinyl fluoride copolymer prepared in Example 1 19 The fluorine NMR spectrum shows the characteristic peaks of the [-CH2-CFH-CH2-] structural fragment. Figure 3 The image shows a gel permeation chromatogram of the hydroxyl-terminated butadiene-fluorinated vinyl copolymer prepared in Example 1. The chromatogram shows that the hydroxyl-terminated butadiene-fluorinated vinyl copolymer is a homogeneous polymer.

[0021] Example 2 Under a nitrogen atmosphere, 1 kg of ethanol, 700 g of butadiene, 300 g of styrene, and 50 g of vinyl fluoride were added sequentially to a dry, sealed 10 L polymerization reactor. The mixture was stirred and heated to 130 °C. Using a plunger pump, 30 g of a 50 w% aqueous solution of hydrogen peroxide and 11 g of a 50 w% ethanol solution of azodicyanobutanol were added, respectively. After reacting for 4 h, the mixture was cooled to room temperature, and unreacted butadiene, styrene, and vinyl fluoride monomers were removed under reduced pressure. The resulting reaction mixture was washed with water and dried to obtain 530 g of hydroxyl-terminated butadiene-styrene-vinyl fluoride copolymer with a number average molecular weight of 4200, a hydroxyl value of 0.50 mmol / g, and a vinyl fluoride content of 5 mol.

[0022]

[0023] Example 3 Under a nitrogen atmosphere, 1 kg of tetrahydrofuran, 700 g of butadiene, 300 g of acrylonitrile, and 100 g of vinylidene fluoride were added sequentially to a dry, sealed 10 L polymerization reactor. The mixture was stirred and heated to 120 °C. Using a plunger pump, 40 g of a 50 w% aqueous solution of hydrogen peroxide and 20 g of a 50 w% tetrahydrofuran solution of azodicyanobutanol were added, respectively. After reacting for 3 h, the mixture was cooled to room temperature, and unreacted butadiene, acrylonitrile, and vinylidene fluoride monomers were removed under reduced pressure. The resulting reaction mixture was washed with water and dried to obtain 540 g of hydroxyl-terminated butadiene-acrylonitrile-vinylidene fluoride copolymer with a number average molecular weight of 3500, a hydroxyl value of 0.63 mmol / g, and a vinylidene fluoride content of 9 mol.

[0024]

[0025] Example 4 Under a nitrogen atmosphere, 1 kg of ethanol, 1 kg of butadiene, and 50 g of vinyl fluoride were added sequentially to a dry, sealed 10 L polymerization reactor. The mixture was stirred and heated to 130 °C. Using a plunger pump, 200 g of a 50 w% ethanol solution of glutaric acid peroxide and 20 g of a 50 w% ethanol solution of azodicyanovalerate were added separately. After reacting for 4 h, the mixture was cooled to room temperature, and unreacted butadiene and vinyl fluoride monomers were removed under reduced pressure. The resulting reaction mixture was washed with water and dried to obtain 450 g of carboxyl-terminated butadiene-vinyl fluoride copolymer with a number average molecular weight of 4500, a carboxyl value of 0.51 mmol / g, and a vinyl fluoride content of 7 mol.

[0026]

[0027] Example 5 Under a nitrogen atmosphere, 1 kg of dimethyl carbonate, 700 g of butadiene, 300 g of acrylonitrile, and 100 g of vinylidene fluoride were added sequentially to a dry and sealed 10 L polymerization reactor. The mixture was stirred and heated to 120 °C. Using a plunger pump, 200 g of a 50 w% dimethyl carbonate solution of succinic acid peroxide and 20 g of a 50 w% dimethyl carbonate solution of azodicyanovalerate were added, respectively. After reacting for 6 h, the mixture was cooled to room temperature, and unreacted butadiene, acrylonitrile, and vinylidene fluoride monomers were removed under reduced pressure. The resulting reaction mixture was washed with water and dried to obtain 580 g of carboxyl-terminated butadiene-acrylonitrile-vinylidene fluoride copolymer with a number average molecular weight of 4800, a carboxyl value of 0.51 mmol / g, and a vinylidene fluoride content of 9 mol.

[0028]

[0029] Comparative Example 1 Under a nitrogen atmosphere, 1 kg of ethanol, 1 kg of butadiene, and 50 g of vinyl fluoride were sequentially added to a dry, sealed 10 L polymerization reactor. The mixture was stirred and heated to 130 °C. Then, 30 g of a 50 w% aqueous solution of hydrogen peroxide was added using a plunger pump. After reacting for 4 h, the mixture was cooled to room temperature, and unreacted butadiene and vinyl fluoride monomers were removed under reduced pressure. The resulting reaction mixture, after washing with water and drying, yielded 480 g of hydroxyl-terminated polybutadiene with a number-average molecular weight of 4000 and a hydroxyl value of 0.52 mmol / g. 19 F-NMR analysis showed no fluorine was detected.

[0030] Comparative Example 2 Under a nitrogen atmosphere, 1 kg of ethanol, 1 kg of butadiene, and 50 g of vinyl fluoride were sequentially added to a dry, sealed 10 L polymerization reactor. The mixture was stirred and heated to 130 °C. Then, 12 g of a 50 w% ethanol solution of azodicyanopentanol was added using a plunger pump. After reacting for 4 h, the mixture was cooled to room temperature, and unreacted butadiene and vinyl fluoride monomers were removed under reduced pressure. The resulting reaction mixture, after washing with water and drying, yielded 50 g of hydroxyl-terminated polybutadiene with a number-average molecular weight of 7300 and a hydroxyl value of 0.26 mmol / g. 19 F-NMR analysis showed no fluorine was detected.

[0031] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. Fluorine-containing end-functionalized liquid rubber, with the following structure: ， in, R1 is -OH, C (2+a) H (1+2a) O4 (a=1~6), C (4+b) H (6+2b) N1O1 (b=0~5), C (4+c) H (4+2c) One of N1O2 (c=0~5); R2 is -H or -CH3; R3 is one or more of -CN, -C6H5, and -C8H7; R f R4 is independently selected from -H, -F, and -CF3, and not all of them are -H; R4 is -OH or C. (2+a) H (1+2a) O4 (a=1~6), C (4+b) H (6+2b) N1O1 (b=0~5), C (4+c) H (4+2c) One of N1O2 (c=0~5); m=0~200, n=0~200, x=0~100, y=1~100, and m, n, and x are not all 0 at the same time.

2. The method for preparing the fluorine-containing end-functionalized liquid rubber according to claim 1, comprising the following steps: (1) Under nitrogen protection, add conjugated olefin monomer, fluorinated olefin monomer and solvent to the reaction vessel, stir evenly and heat to the reaction temperature; (2) Free radical polymerization is carried out by adding an initiator solution at the reaction temperature; (3) After the polymerization is completed, the reaction is terminated and the fluorinated end-functionalized liquid rubber is obtained after treatment.

3. The preparation method according to claim 2, characterized in that, The conjugated olefin monomer is one or a mixture of butadiene, isoprene, styrene, divinylbenzene, and acrylonitrile, preferably one or a mixture of butadiene, styrene, and acrylonitrile.

4. The preparation method according to claim 2, characterized in that, The fluorinated olefin monomer is one or a mixture of several of vinyl fluoride, vinylidene fluoride, tetrafluoroethylene, trifluoropropylene, hexafluoropropylene, hexafluoroisobutylene, and octafluoroisobutylene, preferably one or a mixture of several of vinyl fluoride, vinylidene fluoride, and trifluoropropylene.

5. The preparation method according to claim 2, characterized in that, The initiator is a mixture of peroxide initiators and azo initiators.

6. The preparation method according to claim 5, characterized in that, The initiator is a peroxide-based initiator, which is one or more of hydrogen peroxide, malonic acid peroxide, succinic acid peroxide, glutaric acid peroxide, adipic acid peroxide, pimelic acid peroxide, and octanoic acid peroxide, preferably a mixture of one or more of hydrogen peroxide, succinic acid peroxide, and glutaric acid peroxide; the azo-based initiator is one or more of azodicyanopropanol, azodicyanobutanol, azodicyanopentanol, azodicyanohexanol, azodicyanoheptanol, azodicyanooctanol, azodicyanopropionic acid, azodicyanobutanol, azodicyanopentanol, azodicyanohexanoic acid, azodicyanoheptanol, and azodicyanooctanoic acid, preferably a mixture of one or more of azodicyanobutanol, azodicyanopentanol, and azodicyanobutanol.

7. The preparation method according to claim 5, characterized in that, The amount of peroxide initiator is 0.1~20 mol of the total amount of conjugated olefin monomers and fluorinated olefin monomers; the amount of azo initiator is 0.1~20 mol of the total amount of conjugated olefin monomers and fluorinated olefin monomers.

8. The preparation method according to claim 2, characterized in that, The solvent is one or more of water, methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, tert-butanol, mixed alcohols, diethyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, anisole, dichloromethane, chloroform, tetrachloromethane, dichloroethane, acetonitrile, ethyl acetate, trimethyl phosphate, dimethyl carbonate, diethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, and propylene carbonate, preferably a mixture of one or more of ethanol, tert-butanol, tetrahydrofuran, and dimethyl carbonate, and is used in an amount of 50-300 w of the total olefin monomer.

9. The preparation method according to claim 2, characterized in that, The polymerization reaction temperature is 50~150 ℃, preferably 80~130 ℃; the polymerization reaction time is 1~12 h, preferably 2~6 h.

10. The preparation method according to claim 2, characterized in that, Step (3) involves cooling and depressurizing to remove unreacted monomers after polymerization. The remaining reaction solution is then washed with water and dried to obtain the corresponding fluorinated end-functionalized liquid rubber.

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