Hydrophobic, antibacterial, flame-retardant copolyesters and methods for making the same

Abstract

The application provides a hydrophobic, antibacterial and flame-retardant copolyester and a preparation method thereof, and the method comprises the following steps: dissolving benzimidazole and bromine long-chain alkane in acetonitrile, and refluxing to obtain an alkane substitution product; dissolving the alkane substitution product and bromine ethanol in acetonitrile to prepare a first functional monomer; dissolving o-phenylenediamine, EDCI, HOBt and triethylamine in a DMF solution, adding long-chain fatty carboxylic acid, refluxing to obtain a substitution product, and dissolving the substitution product and bromine ethanol in acetonitrile to prepare a second functional monomer; adding a dibasic acid, a dibasic alcohol and the functional monomers into a reaction kettle to perform esterification and polycondensation, discharging the material from the bottom of the reaction kettle after the reaction is completed, and performing granulation to obtain the hydrophobic, antibacterial and flame-retardant copolyester. The copolyester has the properties of hydrophobicity, antibacterial property and flame retardancy, matches the traditional polyester production process, has a simple preparation process, and has the potential for industrial production. The designed and synthesized functional monomers can simultaneously endow the copolyester with multiple functions, and expand the application field of the polyester.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyester materials, in particular to a hydrophobic, antibacterial and flame-retardant copolyester and a preparation method thereof. BACKGROUND

[0002] Polyester materials, with their excellent mechanical properties, chemical stability and easy processability, play an important role in many fields. Currently, polyester materials achieved by copolymerizing functional monomers can only provide one specific function, such as hydrophobicity, antibacterial property or flame retardancy. In the medical field, hydrophobicity can reduce the wettability of the material surface, reduce the adhesion of bacteria on the surface, antibacterial property can help reduce the risk of hospital infection, and flame retardancy can ensure that the material will not help the fire in an emergency; in outdoor clothing and equipment, hydrophobicity can prevent water penetration, keeping the wearer dry and comfortable, antibacterial property can help control odor and bacterial growth, and flame retardancy can provide additional safety in the event of a fire during outdoor activities. However, with the advancement of technology and the increasing demand of consumers, traditional single-function polyester materials have gradually failed to meet the complex needs of specific applications, and the single-function characteristics have limited the application potential of polyester materials in a wider range. In order to break through this limitation, molecular design has become a key way to realize the multifunctionalization of polyester materials.

[0003] Therefore, it is necessary to design an improved hydrophobic, antibacterial and flame-retardant copolyester and a preparation method thereof to solve the above problems. SUMMARY

[0004] In view of the defects of the prior art, the purpose of the present application is to provide a hydrophobic, antibacterial and flame-retardant copolyester and a preparation method thereof, which can impart multiple properties to the material by precisely controlling the molecular structure of the polymer and introducing diversified functional groups.

[0005] To achieve the above purpose, the present application provides a preparation method of a hydrophobic, antibacterial and flame-retardant copolyester, comprising the following steps:

[0006] S1. Dissolve benzimidazole and brominated long-chain alkane in acetonitrile, add sodium hydroxide, and reflux at 55-65℃ for 5-8h to obtain an alkane-substituted product by column chromatography; dissolve the alkane-substituted product and bromoethanol in acetonitrile, and reflux at 55-65℃ for 8-12h to obtain a first functional monomer;

[0007] S2. Dissolve o-phenylenediamine, EDCI (1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride), HOBt (1-hydroxybenzotriazole) and triethylamine in DMF (N,N-dimethylformamide) solution, stir at room temperature for 12-24 h, remove the solvent by distillation under reduced pressure to obtain an oily intermediate product, add long-chain fatty carboxylic acid, reflux for 8-10 h, dissolve the obtained substituted product and bromoethanol in acetonitrile, add sodium hydroxide, reflux at 55-65℃ for 8-12 h to obtain a second functional monomer;

[0008] S3. Add diacid, diol and functional monomer into a reaction kettle, the functional monomer is the first functional monomer or the second functional monomer, add Sb2O3 as a catalyst to perform esterification reaction, then perform polycondensation reaction after the esterification reaction is completed, discharge the material from the bottom of the reaction kettle after the polycondensation reaction is completed and perform pelletizing to obtain a hydrophobic, antibacterial and flame-retardant copolyester.

[0009] As a further improvement of the present application, in step S1, the structural formula of the brominated long-chain alkane is wherein p is 6-15; the molar ratio of the benzimidazole, brominated long-chain alkane and sodium hydroxide is 1:(1-1.5):(4-5); the molar ratio of the alkane substituted product and bromoethanol is 1:(1.1-1.5).

[0010] As a further improvement of the present application, in step S2, the molar ratio of the o-phenylenediamine, EDCI, HOBt and triethylamine is 1:(1-2):(1-2):(2-3).

[0011] The structural formula of the long-chain fatty carboxylic acid is wherein q is 6-15; the molar ratio of the o-phenylenediamine and long-chain fatty carboxylic acid is 1:(1-1.5).

[0012] The molar ratio of the substituted product, bromoethanol and sodium hydroxide is 1:(2-3):(4-5).

[0013] As a further improvement of the present application, in step S3, the diacid is one of terephthalic acid, adipic acid, 2,5-furan dicarboxylic acid and 2,6-naphthalene dicarboxylic acid, the diol is one of ethylene glycol, propylene glycol and butanediol; the molar ratio of the diacid, diol and functional monomer is 1:1.3:(0.01-0.1).

[0014] The temperature of the esterification reaction is 240-260℃; the specific reaction conditions of the polycondensation reaction are: slowly vacuumize to 80-100 pa within 1-2 h, increase the temperature of the system to 270-280℃, and react for 1-2 h.

[0015] The addition amount of the catalyst is 400-600 ppm.

[0016] The present invention also provides a hydrophobic, antibacterial, and flame-retardant copolyester, which is prepared by the above-described method for preparing the hydrophobic, antibacterial, and flame-retardant copolyester.

[0017] The beneficial effects of this invention are:

[0018] This invention provides a hydrophobic, antibacterial, and flame-retardant copolyester and its preparation method. The method involves dissolving benzimidazole and a long-chain brominated alkane in acetonitrile and refluxing to obtain an alkane-substituted product. The alkane-substituted product and bromoethanol are then dissolved in acetonitrile to prepare a first functional monomer. o-Phenylenediamine, EDCI, HOBt, and triethylamine are dissolved in DMF solution, and a long-chain aliphatic carboxylic acid is added. The resulting substituted product is then dissolved in acetonitrile along with bromoethanol to prepare a second functional monomer. A diacid, a diol, and the functional monomer are added to a reaction vessel for esterification and polycondensation reactions to obtain the hydrophobic, antibacterial, and flame-retardant copolyester. The copolyester of this invention possesses hydrophobic, antibacterial, and flame-retardant properties, is compatible with traditional polyester production processes, has a simple preparation process, and has potential for industrial production.

[0019] The functional monomers synthesized in this invention can simultaneously endow copolyesters with multiple functions, expanding the application fields of polyesters and enhancing the application value of polymer materials in industry, agriculture, and medicine. Simultaneously, this copolyester possesses good processability and physical properties, and can be made into various forms of products such as films and fibers, showing broad application prospects. Furthermore, the preparation method of this invention is simple, with low emissions of waste gas and wastewater, making it environmentally friendly and in line with the requirements of sustainable development. Attached Figure Description

[0020] Figure 1 This is a synthetic route diagram for the first functional monomer in this invention.

[0021] Figure 2 This is a synthetic route diagram for the second functional monomer in this invention.

[0022] Figure 3 This is a roadmap for synthesizing copolyesters using the first functional monomer in this invention.

[0023] Figure 4 This is a roadmap for synthesizing copolyesters using a second functional monomer, as described in this invention.

[0024] Figure 5 The hydrophobic test results of the hydrophobic, antibacterial, and flame-retardant copolyester provided by this invention.

[0025] Figure 6 The antibacterial test results of the hydrophobic, antibacterial, and flame-retardant copolyester provided by this invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0028] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0029] This invention provides a method for preparing a hydrophobic, antibacterial, and flame-retardant copolyester, such as... Figures 1 to 4 As shown, it includes the following steps:

[0030] S1. Dissolve benzimidazole and bromo-substituted long-chain alkanes in acetonitrile, add sodium hydroxide, and reflux at 55-65°C for 5-8 h. Obtain the alkane-substituted product by column chromatography. Dissolve the alkane-substituted product and bromoethanol in acetonitrile, and reflux at 55-65°C for 8-12 h to obtain the first functional monomer.

[0031] Specifically, the structural formula of brominated long-chain alkanes is: Where p is 6–15; the molar ratio of benzimidazole, bromo-substituted long-chain alkane, and sodium hydroxide is 1:(1–1.5):(4–5); the preferred molar ratio of the obtained alkane substitution product to bromoethanol is 1:(1–1.5), and the synthetic route is as follows: Figure 1 As shown, p ranges from 6 to 15.

[0032] S2. Dissolve o-phenylenediamine, EDCI, HOBt and triethylamine in DMF solution, stir at room temperature for 12-24 h, remove solvent by vacuum distillation to obtain an oily intermediate product, add long-chain fatty carboxylic acid, reflux for 8-10 h, dissolve the obtained substituted product and bromoethanol in acetonitrile, add sodium hydroxide, reflux at 55-65 °C for 8-12 h to obtain the second functional monomer.

[0033] Specifically, the molar ratio of o-phenylenediamine, EDCI, HOBt, and triethylamine is 1:(1-2):(1-2):(2-3). The structural formula of the long-chain aliphatic carboxylic acid is... Where q is 6–15; the molar ratio of o-phenylenediamine to long-chain aliphatic carboxylic acid is 1:(1–1.5). The preferred molar ratio of the obtained substituted product, bromoethanol, and sodium hydroxide is 1:(2–3):(4–5). The synthetic route is as follows:Figure 2 as shown in the formula, wherein q is 6-15.

[0034] S3. Binary acid, dihydric alcohol and functional monomer are added into the reaction kettle, the functional monomer is the first functional monomer or the second functional monomer, Sb2O3 is added as a catalyst to perform esterification reaction, after the reaction is completed, polycondensation reaction is performed, after the reaction is completed, the material is discharged from the bottom of the reaction kettle and is cut into particles to obtain the hydrophobic, antibacterial and flame-retardant copolyester.

[0035] Specifically, the binary acid is preferably one of terephthalic acid, adipic acid, 2,5-furan dicarboxylic acid and 2,6-naphthalene dicarboxylic acid, the dihydric alcohol is preferably one of ethylene glycol, propylene glycol and butanediol; the molar ratio of the binary acid, dihydric alcohol and functional monomer is preferably 1:1.3:(0.01-0.1); the temperature of the esterification reaction is preferably 240-260°C, the addition amount of the catalyst is preferably 400-600 ppm, the esterification reaction is stopped when the water output of the esterification reaction reaches 90% of the theoretical water output; the specific reaction conditions of the polycondensation reaction are: the system is slowly vacuumed to 80-100 pa within 1-2 h, the system is heated to 270-280°C, and the reaction is performed for 1-2 h. The synthesis route is as shown in the formula Figure 3 or Figure 4 as shown in the formula, wherein n and m are the number of repeating units. represents a hydrocarbon group in the general formula of the molecular structure of the binary acid and dihydric alcohol.

[0036] The preparation method of the hydrophobic, antibacterial and flame-retardant copolyester provided by the present application will be described below in combination with specific examples.

[0037] Example 1

[0038] Example 1 provides a preparation method of a hydrophobic, antibacterial and flame-retardant copolyester, which comprises the following steps:

[0039] S1. Benzimidazole and 1-bromotetradecane are dissolved in acetonitrile at a molar ratio of 1:1, 4 times the molar amount of sodium hydroxide of benzimidazole is added, reflux reaction is performed at 60°C for 7 h, column chromatography is performed to obtain the alkane substitution product; then the alkane substitution product and bromoethanol are dissolved in acetonitrile at a molar ratio of 1:1.1, reflux reaction is performed at 60°C for 10 h to obtain the first functional monomer;

[0040] S2. Terephthalic acid, ethylene glycol and the first functional monomer are mixed in the reaction kettle at a molar ratio of 1:1.3:0.01, 500 ppm of Sb2O3 is added as a catalyst to perform esterification reaction, the reaction temperature is 240°C, the esterification reaction is stopped when the water output of the esterification reaction reaches 90% of the theoretical water output; next, the polycondensation stage is entered; first, pre-polycondensation treatment is performed, the system is slowly vacuumed to 100 pa within 1.5 h, then the system is heated to 270°C, and the reaction is continuously performed for 2 h, the material is discharged from the bottom of the reaction kettle and is cut into particles.

[0041] Example 2

[0042] Example 2 provides a method for preparing a hydrophobic, antibacterial, flame-retardant copolyester, comprising the following steps:

[0043] S1. Dissolve o-phenylenediamine, EDCI, HOBt and triethylamine in a DMF solution at a molar ratio of 1:1:1:2, stir overnight at room temperature, and remove the solvent by distillation under reduced pressure to obtain an oily intermediate product. Then add hexadecanoic acid, reflux for 8 h to obtain a substitution product, dissolve the substitution product and bromoethanol in acetonitrile at a molar ratio of 1:2, add 4 times the molar amount of sodium hydroxide of the substitution product, and reflux at 60°C for 10 h to obtain a second functional monomer;

[0044] S2. Mix terephthalic acid, ethylene glycol, and the second functional monomer in a reaction kettle at a molar ratio of 1:1.3:0.01, add 500 ppm Sb2O3 as a catalyst for esterification, the reaction temperature is 240°C, and the esterification reaction is stopped when the water output reaches 90% of the theoretical water output; Next, enter the polycondensation stage; First, perform pre-polycondensation treatment, slowly vacuum to 100 pa within 1.5 h, then, raise the system temperature to 270°C and continue to react for 2 h, discharge the material from the bottom of the reaction kettle and cut it into particles.

[0045] Example 3

[0046] Example 3 provides a method for preparing a hydrophobic, antibacterial, flame-retardant copolyester, which differs from Example 1 only in that the molar ratio of diacid, diol, and first functional monomer is 1:1.3:0.1, and the other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0047] Comparative Example 1

[0048] Comparative Example 1 provides a method for preparing a hydrophobic, antibacterial, flame-retardant copolyester, which differs from Example 1 only in that no first functional monomer is added, and the obtained polymer is PET.

[0049] Comparative Example 2

[0050] Comparative Example 2 provides a method for preparing a hydrophobic, antibacterial, flame-retardant copolyester, which differs from Example 1 only in that the molar ratio of terephthalic acid, ethylene glycol, and first functional monomer is 1:1.3:0.15, and the other experimental parameters and conditions are basically the same as those of Example 1, which will not be repeated here.

[0051] Comparative Example 3

[0052] Comparative Example 3 provides a method for preparing a hydrophobic, antibacterial, flame-retardant copolyester, which is different from Example 2 only in that the molar ratio of terephthalic acid, ethylene glycol, and the second functional monomer is 1:1.3:0.15, and other experimental parameters and conditions are substantially the same as in Example 2, which will not be repeated here.

[0053] The prepared copolyester was subjected to hydrophobic, antibacterial, and flame-retardant tests, as shown in Figure 5 The hydrophobic experiment from the water contact angle of the sample shows that, compared with the results of the original PET, the introduction of the functional monomer has a great effect on the contact angle of the polyester. Because long-chain alkanes have strong hydrophobicity, their introduction will reduce the surface tension of the polyester, making it more inclined to repel water molecules. However, the addition of excess functional monomers does not completely participate in the reaction, but forms some isolated chains or aggregates, resulting in a decrease in the contact area of the polyester surface with water and a decrease in the surface tension. Therefore, the excessive introduction of functional monomers will reduce the contact angle of the polyester surface, thereby reducing its hydrophobicity.

[0054] The antibacterial results are shown in Figure 6 Compared with PET polyester, the introduction of functional monomers has a significant effect on the antibacterial effect of the polyester. First, the hydrophobic effect of long-chain alkanes in the functional monomer also enhances the antibacterial effect of the polyester, because many microbial cell membranes are mainly composed of hydrophilic phospholipids, and a hydrophobic environment may be detrimental to the growth of microorganisms. Second, the functional monomer interferes with the structure of the bacterial cell membrane, affecting the fluidity and integrity of the cell membrane, thereby inhibiting the growth and reproduction of bacteria. Excessive functional monomers may cause cross-linking or aggregation, affecting their solubility and morphological structure, resulting in a decrease or even disappearance of the antibacterial effect. Therefore, during the addition of functional monomers, the amount of addition needs to be reasonably controlled to avoid the negative effects of excessive introduction of functional monomers on the antibacterial effect.

[0055] The flame retardant experiment results are shown in Table 1. The introduction of the functional monomer can significantly increase the flame retardant effect of the polyester. Compared with the limiting oxygen index of the PET polyester, the limiting oxygen index value of the polyester with the functional monomer has a significant upward trend. The main reason is that the functional monomer has a benzimidazole structure, which can form a carbon ash effect during the combustion of the polyester, so that the surface of the polyester is covered with a dense carbon layer. The carbon layer can effectively isolate heat and flammable gas products during combustion. However, adding an excessive amount of functional monomers can reduce the flame retardant effect. This is because the excessive functional monomers can form isolated chains or aggregates in the polyester, thereby affecting the molecular structure and morphology of the polyester, resulting in higher energy release during the decomposition and combustion process, thereby reducing the flame resistance. In addition, the excessive introduction of functional monomers can also change the physical and chemical properties and processing performance of the polyester, such as making the polyester more brittle, viscous, and difficult to process, which can affect the actual application effect of the polyester. Therefore, under the premise of achieving the flame retardant effect, the amount of the functional monomer needs to be controlled within a suitable range to improve the fire resistance and processability of the polyester.

[0056] Table 1 Flame retardant test results of copolyesters provided by Example 1 and Comparative Examples 1-3

[0057] Item Limiting oxygen index LOI (vol. %) Example 1 29.0 Comparative Example 1 22.0 Comparative Example 2 26.0 Comparative Example 3 28.0

[0058] In summary, the copolyester provided by the present application has hydrophobic, antibacterial, and flame retardant properties, matches the traditional polyester production process, has a simple preparation process, and has industrial production potential.

[0059] The above examples are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing a hydrophobic, antibacterial, and flame-retardant copolyester, characterized in that, Includes the following steps: S1. Dissolve benzimidazole and bromo-substituted long-chain alkanes in acetonitrile, add sodium hydroxide, and reflux at 55-65℃ for 5-8 h. Obtain the alkane-substituted product by column chromatography. Dissolve the alkane-substituted product and bromoethanol in acetonitrile, and reflux at 55-65℃ for 8-12 h to obtain the first functional monomer. The structural formula of the brominated long-chain alkane is: Where p is 6~15; the molar ratio of benzimidazole, long-chain brominated alkanes and sodium hydroxide is 1:(1~1.5):(4~5); S2. Dissolve o-phenylenediamine, EDCI, HOBt and triethylamine in DMF solution, stir at room temperature for 12-24 h, remove solvent by vacuum distillation to obtain an oily intermediate product, add long-chain fatty carboxylic acid, reflux for 8-10 h, dissolve the obtained substituted product and bromoethanol in acetonitrile, add sodium hydroxide, reflux at 55-65 °C for 8-12 h to obtain the second functional monomer; The structural formula of the long-chain fatty carboxylic acid is as follows: Where q is 6~15; the molar ratio of o-phenylenediamine to long-chain aliphatic carboxylic acid is 1:(1~1.5). S3. Add the diacid, diol and functional monomer to the reactor, wherein the functional monomer is a first functional monomer or a second functional monomer. Add Sb2O3 as a catalyst to carry out the esterification reaction. After the reaction is completed, carry out the polycondensation reaction. After the reaction is completed, release the material from the bottom of the reactor and granulate it to obtain a hydrophobic, antibacterial and flame-retardant copolyester. The dicarboxylic acid is one of terephthalic acid, adipic acid, 2,5-furandicarboxylic acid and 2,6-naphthalenedicarboxylic acid, and the diol is one of ethylene glycol, propylene glycol and butanediol; the molar ratio of the dicarboxylic acid, diol and functional monomer is 1:1.3:(0.01~0.1).

2. The method for preparing the hydrophobic, antibacterial, and flame-retardant copolyester according to claim 1, characterized in that, In step S1, the molar ratio of the alkane substitution product to bromoethanol is 1:(1.1~1.5).

3. The method for preparing the hydrophobic, antibacterial, and flame-retardant copolyester according to claim 1, characterized in that, In step S2, the molar ratio of o-phenylenediamine, EDCI, HOBt and triethylamine is 1:(1~2):(1~2):(2~3).

4. The method for preparing the hydrophobic, antibacterial, and flame-retardant copolyester according to claim 1, characterized in that, In step S2, the molar ratio of the substitution product, bromoethanol and sodium hydroxide is 1:(2~3):(4~5).

5. The method for preparing the hydrophobic, antibacterial, and flame-retardant copolyester according to claim 1, characterized in that, In step S3, the temperature of the esterification reaction is 240~260℃; the specific reaction conditions of the polycondensation reaction are: slowly evacuate to 80~100 Pa within 1~2 hours, raise the system temperature to 270~280℃, and react for 1~2 hours.

6. The method for preparing the hydrophobic, antibacterial, and flame-retardant copolyester according to claim 1, characterized in that, The catalyst is added in an amount of 400-600 ppm.

7. A hydrophobic, antibacterial, and flame-retardant copolyester, characterized in that, It is prepared by the method of any one of claims 1-6 for the preparation of hydrophobic, antibacterial, and flame-retardant copolyester.

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