Bio-based flame-retardant polyester material and preparation method thereof

Abstract

The invention belongs to the technical field of polyester materials, and particularly provides a bio-based flame-retardant polyester material and a preparation method thereof.The preparation method comprises the following steps that S1, bio-based dibasic acid, dihydric alcohol, a flame-retardant modifier and a first catalyst react for 3-5 h at the temperature of 180-250 DEG C, and a first product is obtained; s2, the first product obtained in the step S1 and a second catalyst react for 3-10 h at the temperature of 200-300 DEG C under the pressure of 20-50 Pa, and the bio-based flame-retardant polyester material is obtained. According to the polyester material, biomass raw materials are preferably selected, and the polyester material has excellent flame retardant property and mechanical property.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polyester materials, and particularly relates to a bio-based flame-retardant polyester material and a preparation method thereof. BACKGROUND

[0002] Traditional polyester materials, such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), have become indispensable basic materials in the fields of electronic appliances, automobiles, textiles, and home building materials, due to their excellent mechanical properties, processing properties, and cost advantages. However, with the deepening of the global sustainable development strategy and the increasing strictness of environmental protection regulations, traditional polyester materials face two major challenges. First, their raw materials are highly dependent on non-renewable petroleum resources, and a large amount of carbon emissions is generated in the production process, which is contrary to the global goal of carbon neutrality. Second, most polyester materials are flammable high polymer materials, with an ultimate oxygen index (LOI) of about 21%, close to the concentration of oxygen in the air, which means that they can continue to burn after ignition in the air and are accompanied by melt dripping, which can easily cause fire spread and cause huge life and property losses.

[0003] On the one hand, seeking green alternatives from the source of materials has also become an important trend. Using biomass resources to prepare bio-based chemicals and then synthesizing polyester materials is an effective way to reduce fossil energy consumption and achieve carbon cycling. On the other hand, in order to endow polyester materials with flame retardancy, halogen-based flame retardants have been widely used in industry. This type of flame retardant interrupts the combustion chain reaction by capturing free radicals in the gas phase, has high flame retardant efficiency, requires a small amount of addition, and has relatively small impact on the mechanical properties of the base material. However, in-depth studies have revealed that halogen-based flame retardants release a large amount of toxic, corrosive smoke and halogen-containing dioxins and other persistent organic pollutants during combustion, posing a serious threat to the environment and human health.

[0004] Under this background, halogen-free flame retardant systems such as phosphorus-based, nitrogen-based, inorganic hydroxides (such as magnesium hydroxide and aluminum hydroxide), and intumescent flame retardants have received widespread attention. However, the current mainstream additive-type halogen-free flame retardant technology still has many bottlenecks. For example, in order to achieve an ideal flame retardant grade (such as UL-94 V-0), a high addition amount (sometimes as high as 20% or more) is often required, which can severely damage the molecular chain regularity of the polyester, resulting in a significant decrease in its mechanical strength, toughness, and heat distortion temperature, and causing difficulties in melt processing. More critically, small molecule additive-type flame retardants have poor compatibility with the polyester matrix and can easily migrate from the interior of the material to the surface under the action of heat and stress, causing "precipitation" phenomenon. This not only deteriorates the surface of the material, affects the appearance and electrical properties, but also causes the flame retardant performance to decay over time, which cannot meet the requirements of durability for high-end applications.

[0005] The invention patent CN106543473B discloses a phosphazene / triazine double-base molecular flame retardant based on in-situ doping nanoscale metal compound, and a preparation method thereof. The preparation method comprises the following steps: substituting six chlorine atoms in hexachlorocyclotriphosphazene with ethylenediamine, introducing a triazine group having a charring effect into each side chain to obtain a double-base molecule containing phosphazene and triazine groups, introducing aminopropyl triethoxysilane (KH550) into the side chain of the double-base molecule, and further adding a nanoscale metal compound Me into a reaction system to perform a silanization reaction, so as to obtain the flame retardant. The flame retardant can be widely applied to the flame-retardant modification of various high polymer materials including polyester materials. However, the direct addition of the flame retardant will cause the mechanical properties of the material to decrease.

[0006] Therefore, there is an urgent need for a bio-based flame-retardant polyester material based on renewable resources, which can introduce efficient and long-lasting flame-retardant components and has excellent mechanical properties. SUMMARY

[0007] In view of the existing technical problems, the purpose of the present application is to provide a bio-based flame-retardant polyester material and a preparation method thereof. The polyester material of the present application preferably uses biomass raw materials and has excellent flame-retardant properties and mechanical properties.

[0008] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: In one aspect, the present application provides a preparation method of a bio-based flame-retardant polyester material, comprising the following steps: S1: reacting bio-based dibasic acid, dibasic alcohol, flame-retardant modifier and first catalyst at 180-250℃ for 3-5h to obtain a first product; S2: reacting the first product of step S1 and second catalyst at 20-50Pa at 200-300℃ for 3-10h to obtain the bio-based flame-retardant polyester material.

[0009] In some embodiments of the present application, the bio-based dibasic acid is 2,5-furandicarboxylic acid.

[0010] In some embodiments of the present application, the dibasic alcohol is ethylene glycol.

[0011] In some embodiments of the present application, the preparation steps of the flame-retardant modifier are as follows: (1) mixing 2-allyl-3-hydroxybenzaldehyde, triethylamine and dichloromethane, adding diphenyl chlorophosphate dropwise under an inert atmosphere, stirring at 0-3℃ for 3-5h, and post-processing to obtain an intermediate 1; ​(2) mixing the intermediate 1 and toluene, heating to 45-55°C under inert atmosphere, adding Kast catalyst and stirring for 0.5-1h, then adding triethoxysilane dropwise, reacting at 70-75°C for 22-24h, and post-treating to obtain the intermediate 2; (3) mixing the intermediate 2 and N,N-dimethylformamide, adding sodium persulfate, and adding a 4,5-diaminobenzene-1,2-diol N,N-dimethylformamide solution dropwise at 25-30°C, reacting for 5-6h, and post-treating to obtain the intermediate 3; (4) mixing the intermediate 3, ethylene carbonate and potassium carbonate, heating to 180-200°C, and reacting for 1-3h to obtain the flame-retardant modifier.

[0012] In some embodiments of the present application, in step (1), the molar ratio of the 2-allyl-3-hydroxybenzaldehyde and the diphenyl chlorophosphate is (1-1.2):1.

[0013] Preferably, in step (1), the 2-allyl-3-hydroxybenzaldehyde, triethylamine and dichloromethane are used in a proportion of 1g:1.5-2mL:5-10mL.

[0014] Preferably, in step (1), after the reaction is completed, the post-treatment is washing with 5wt% sodium hydroxide solution and deionized water ≥2 times respectively, taking the organic phase, and then drying and rotary evaporation to obtain the product.

[0015] In some embodiments of the present application, in step (2), the molar ratio of the intermediate 1 and triethoxysilane is 1:(1-1.2).

[0016] Preferably, in step (2), the intermediate 1, toluene and Kast catalyst are used in a proportion of 1g:30-50mL:0.05-0.08g.

[0017] Preferably, in step (2), after the reaction is completed, the post-treatment is cooling to room temperature, followed by reduced pressure distillation and ethanol recrystallization to obtain the product.

[0018] In some embodiments of the present application, in step (3), the molar ratio of the intermediate 2 and 4,5-diaminobenzene-1,2-diol is 1:(1-1.1).

[0019] Preferably, in step (3), the intermediate 2, N,N-dimethylformamide and sodium persulfate are used in a proportion of 1g:10-15mL:0.3-0.6g.

[0020] Preferably, in step (3), after the reaction is completed, the post-treatment is adding dichloromethane and purified water at 25 30°C, stirring for 15 25 min, separate, the organic phase is washed with deionized water ≥ 2 times, and then dried, distilled under reduced pressure until no liquid is discharged, to obtain.

[0021] In some embodiments of the present application, in step (4), the molar ratio of the intermediate 3 and ethylene carbonate is 1: (2.01-2.1).

[0022] Preferably, in step (4), the amount of the intermediate 3 and potassium carbonate is 1g: 0.01-0.02g.

[0023] In some embodiments of the present application, the molar ratio of the bio-based diacid, dihydric alcohol and flame-retardant modifier is 1: (1-1.5): (0.5-1).

[0024] In the prior art, phosphorus-containing flame-retardant components are often introduced into polyester systems, which can play a certain flame-retardant effect, but often have poor compatibility with the polyester matrix, easily form interface defects of stress concentration points, and also face technical problems such as easy migration affecting the flame-retardant effect, large addition amount seriously damaging mechanical properties, etc.

[0025] The present application realizes the balanced improvement of flame-retardant performance and mechanical properties by preparing a flame-retardant modifier. On the one hand, the reaction-type flame-retardant modifier is fixed in the molecular chain of the polyester material, solving the interface compatibility problem of traditional additive flame-retardant agents and not easily migrating out, and realizing P-N-Si triple synergistic flame-retardation, P catalyzing carbonization, N gas expansion, and Si reinforcing the carbon layer, thereby forming a dense, tough, heat-insulating protective layer, having permanent flame-retardant property, and good flame-retardant effect, and high oxygen index. On the other hand, the flame-retardant modifier has more benzene rings in the molecular structure, which can reduce the internal free rotation and vibration of the molecule, making the molecular structure more stable and the flame-retardant effect more durable. Further, the applicant has found that the presence of the Si-O bond-containing segment can promote the balance between flame-retardant property and mechanical property, and at the same time improve the processing fluidity of the polyester material and broaden the application field of the polyester material.

[0026] In some embodiments of the present application, the first catalyst is any one or more of a zinc-based catalyst, a manganese-based catalyst, a titanium-based catalyst, and an antimony-based catalyst.

[0027] Preferably, the first catalyst is an antimony-based catalyst, and further preferably antimony acetate.

[0028] Preferably, the amount of the first catalyst added is 0.5-1.5‰ of the molar amount of the bio-based diacid.

[0029] In some embodiments of the present application, the second catalyst is any one or more of a titanium-based catalyst, a tin-based catalyst, an antimony-based catalyst, a germanium-based catalyst.

[0030] Preferably, the second catalyst is an antimony-based catalyst, further preferably diantimony trioxide.

[0031] Preferably, the second catalyst is added in an amount of 0.5-1 ‰ of the molar amount of the bio-based diacid.

[0032] The second aspect of the present application also provides a bio-based flame-retardant polyester material prepared by the above preparation method.

[0033] Compared with the prior art, the present application has the following advantages: 1. The polyester material of the present application preferably uses biomass raw materials, and has excellent flame-retardant properties and mechanical properties.

[0034] 2. The present application prepares a new flame-retardant modifier, which has the following main advantages: effectively improves the flame-retardant ability of the polyester material, enhances the stability, ensures the mechanical strength, and meets the needs of various flame-retardant polyester application fields. DETAILED DESCRIPTION

[0035] The present application will be described below in conjunction with specific embodiments. It should be noted that the following examples are examples of the present application and are only used to illustrate the present application, but not to limit the present application. Other combinations and various modifications within the concept of the present application can be made without departing from the spirit or scope of the present application.

[0036] The polyester material is prepared according to the ratio of each raw material and the preparation method specified in the following examples and comparative examples.

[0037] In order to facilitate the implementation of the present application by those skilled in the art, unless otherwise specified, the raw materials appearing in the following detailed description are not specially specified and can be purchased from the market.

[0038] Unless otherwise specified, the post-treatment steps such as "drying", "rotary evaporation", "washing", "recrystallization", "reduced pressure distillation" and the like appearing in the following detailed description are routine operations for those skilled in the art, which are selected by the actual operation.

[0039] Preparation Example 1 The preparation steps of the flame-retardant modifier are as follows: (1) 1 g of 2-allyl-3-hydroxybenzaldehyde, 1.8 g of triethylamine and 8 mL of dichloromethane were mixed, 1.67 g of diphenyl chlorophosphate was added dropwise under a nitrogen atmosphere, and the reaction was stirred at 0°C for 4 h. After the reaction was completed, the organic phase was washed with 5 wt% sodium hydroxide solution and deionized water twice, respectively, and then dried and rotary evaporated to obtain intermediate 1; The structure of the intermediate 1 is shown in formula I: (I); The nuclear magnetic data of the intermediate 1 is tested as follows: 1 H-NMR (400MHz, DMSO): δ 3.40 (2H, d), 4.76-4.91 (2H, 4.83 (dd), 4.83 (dd)), 5.70 (1H, ddt), 6.89-7.04 (5H, 6.96 (dd), 6.98 (dddd)), 7.13 (1H, dd), 7.30 (2H, tt), 7.41-7.63 (5H, 7.48 (dddd), 7.57 (dd)), 10.04 (1H, s); (2) 1 g of the intermediate 1 and 12 mL of toluene are mixed, and the mixture is heated to 50°C under a nitrogen atmosphere, 0.06 g of a Karstedt catalyst is added, and stirred for 0.8 h, then 0.46 g of triethoxysilane is added dropwise, and the reaction is carried out at 72°C for 23 h, after the reaction is completed, the mixture is cooled to room temperature, and then subjected to reduced pressure distillation and ethanol recrystallization to obtain the intermediate 2; The structure of the intermediate 2 is shown in formula II: (II); The nuclear magnetic data of the intermediate 2 is tested as follows: 1 H-NMR (400MHz, DMSO): δ 1.26-1.40 (11H, 1.32 (t), 1.33 (t)), 2.94 (2H, t), 3.40 (6H, q), 6.89-7.04 (5H, 6.95 (dd), 6.98 (dddd)), 7.13 (1H, dd), 7.30 (2H, tt), 7.40-7.61 (5H, 7.48 (dddd), 7.55 (dd)), 10.04 (1H, s); (3) 1 g of the intermediate 2 and 12 mL of N,N-dimethylformamide are mixed, then 0.5 g of sodium persulfate is added, and 0.8 mL of an N,N-dimethylformamide solution containing 0.27 g of 4,5-diaminobenzene-1,2-diol is added dropwise at 28°C, and the reaction is carried out for 5.5 h, after the reaction is completed, 1.5 times the volume of dichloromethane and 1 times the volume of purified water are added at 28°C, and stirred for 20 min, and then the mixture is separated, the organic phase is washed with deionized water for 2 times, and then subjected to drying, reduced pressure distillation until no liquid is discharged, to obtain the intermediate 3; The structure of the intermediate 3 is shown in formula III: (III); The nuclear magnetic data of the intermediate 3 is tested as follows: 1H-NMR (400 MHz, DMSO): δ 1.26-1.48 (11H, 1.33(t), 1.42(t)), 2.61 (2H, t), 3.40 (6H, q), 6.91-7.40 (10H, 6.98(dddd), 7.05(d), 7.16(dd), 7.19(d), 7.30(ddt), 7.33(dd)), 7.48 (4H, dddd), 7.84 (1H, dd); (4) 1 g of intermediate 3, 0.27 g of ethylene carbonate and 0.015 g of potassium carbonate were mixed, and the mixture was heated to 190°C for 2.5 h to obtain the flame-retardant modifier; The structure of the flame-retardant modifier is shown in formula IV: (IV); The test results of the flame-retardant modifier are as follows: 1 H-NMR (400 MHz, DMSO): δ 1.26-1.48 (11H, 1.33(t), 1.42(t)), 2.61 (2H, t), 3.40 (6H, q), 6.91-7.40 (10H, 6.98(dddd), 7.05(d), 7.16(dd), 7.19(d), 7.30(ddt), 7.33(dd)), 7.48 (4H, dddd), 7.84 (1H, dd);

[0040] Preparation Example 2 The specific preparation steps of the flame-retardant modifier are the same as those in Preparation Example 1, except that 2-allyl-3-hydroxybenzaldehyde is replaced by m-hydroxybenzaldehyde in step (1) in an equimolar ratio.

[0041] Preparation Example 3 The specific preparation steps of the flame-retardant modifier are the same as those in Preparation Example 1, except that triethoxysilane is replaced by trimethoxysilane in step (2) in an equimolar ratio.

[0042] Example 1 A preparation method of a bio-based flame-retardant polyester material, comprising the following steps: S1: 1 mol of 2,5-furan dicarboxylic acid, 1.3 mol of ethylene glycol, 0.75 mol of the flame-retardant modifier and 0.001 mol of antimony acetate were reacted at 200°C for 4 h to obtain a first product; S2: The first product of step S1 and 0.0008 mol of antimony trioxide were reacted at 250°C for 6 h under 40 Pa to obtain the bio-based flame-retardant polyester material.

[0043] The flame-retardant modifier was obtained from Preparation Example 1.

[0044] Example 2 A preparation method of a bio-based flame-retardant polyester material, comprising the following steps: S1: reacting 1 mol of 2,5-furan dicarboxylic acid, 1 mol of ethylene glycol, 0.5 mol of a flame-retardant modifier, and 0.001 mol of antimony acetate at 200℃ for 4h to obtain a first product; S2: reacting the first product of step S1 and 0.0008 mol of antimony trioxide at 250℃ for 6h under 40Pa to obtain the bio-based flame-retardant polyester material.

[0045] The flame-retardant modifier is obtained from Preparation Example 1.

[0046] Example 3 A preparation method of a bio-based flame-retardant polyester material, comprising the following steps: S1: reacting 1 mol of 2,5-furan dicarboxylic acid, 1.5 mol of ethylene glycol, 1 mol of a flame-retardant modifier, and 0.001 mol of antimony acetate at 200℃ for 4h to obtain a first product; S2: reacting the first product of step S1 and 0.0008 mol of antimony trioxide at 250℃ for 6h under 40Pa to obtain the bio-based flame-retardant polyester material.

[0047] The flame-retardant modifier is obtained from Preparation Example 1.

[0048] Example 4 A preparation method of a bio-based flame-retardant polyester material, the specific implementation manner is the same as that of Example 1, except that the flame-retardant modifier is obtained from Preparation Example 2.

[0049] Example 5 A preparation method of a bio-based flame-retardant polyester material, the specific implementation manner is the same as that of Example 1, except that the flame-retardant modifier is obtained from Preparation Example 3.

[0050] Example 6 A preparation method of a bio-based flame-retardant polyester material, the specific implementation manner is the same as that of Example 1, except that the amount of the flame-retardant modifier added is 1.2 mol.

[0051] Comparative Example 1 A preparation method of a bio-based flame-retardant polyester material, the specific implementation manner is the same as that of Example 1, except that no flame-retardant modifier is added.

[0052] Comparative Example 2 A preparation method of a bio-based flame-retardant polyester material, the specific implementation manner is the same as that of Example 1, except that a commercially available flame retardant TPP is used to replace the flame-retardant modifier.

[0053] Performance test: The polyester materials prepared in the above Examples 1-6 and Comparative Examples 1-2 were subjected to the following performance tests, and the specific results are shown in Table 1.

[0054] (1) Flame-retardant performance: The standard samples of the polyester materials prepared in the above Examples 1-6 and Comparative Examples 1-2 were subjected to the limiting oxygen index and vertical burning tests according to the standards GB2406-2009 and GB / T2408-2008, respectively. (2) Mechanical performance: The standard samples of the polyester materials prepared in the above Examples 1-6 and Comparative Examples 1-2 were subjected to the tensile strength test.

[0055] Table 1

[0056] In the above, NR represents No Result.

[0057] As can be seen from the results in Table 1, the polyester material prepared in Example 1-3 has better flame-retardant performance and mechanical performance. Compared with Example 1, in the preparation of the flame-retardant modifier, the isomolar ratio of m-hydroxybenzaldehyde is used to replace 2-allyl-3-hydroxybenzaldehyde, the mechanical performance is affected, and the flame-retardant effect also decreases due to the lack of the synergistic effect between silicon and P-N. In Example 5, compared with Example 1, the isomolar ratio of trimethoxysilane is used to replace triethoxysilane in the preparation of the flame-retardant modifier, which still has good flame-retardant performance, but the balance between the flame-retardant performance and the mechanical performance of the polyester material is adversely affected due to the change in the length of the side chain and the steric hindrance effect, and the tensile strength decreases. In Example 6, compared with Example 1, the amount of the flame-retardant modifier is changed, and the excessive large rigid side group seriously destroys the regularity of the polyester main chain, resulting in a great loss of mechanical performance. In Comparative Example 1, compared with Example 1, no flame-retardant modifier is added, although the mechanical performance of the polyester material is stable, the flame-retardant performance is greatly lost. In Comparative Example 2, compared with Example 1, the commercial flame retardant is used to replace the flame-retardant modifier of the present application in the same amount, and the application effect in the present system is obviously insufficient.

[0058] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application is disclosed as above, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and the equivalent embodiments are also equivalent. Any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application are still within the scope of the technical solution.

Claims

1. A method for the preparation of a bio-based flame retardant polyester material, characterized in that, The preparation method comprises the following steps: S1: reacting bio-based dibasic acid, dibasic alcohol, flame-retardant modifier and first catalyst at 180-250 ℃ for 3-5 h to obtain first product; S2: reacting the first product of step S1 and second catalyst at 20-50 Pa at 200-300 ℃ for 3-10 h to obtain the bio-based flame-retardant polyester material.

2. A process for the preparation of a bio-based flame retardant polyester material according to claim 1, characterized in that, The bio-based dibasic acid is 2,5-furan dicarboxylic acid.

3. A process for the preparation of a bio-based flame retardant polyester material according to claim 1, characterized in that, The dibasic alcohol is ethylene glycol.

4. The method of making a bio-based flame retardant polyester material according to claim 1, wherein, The preparation steps of the flame-retardant modifier are as follows: (1) mixing 2-allyl-3-hydroxybenzaldehyde, triethylamine and dichloromethane, adding diphenyl chlorophosphate dropwise under inert atmosphere, stirring at 0-3 ℃ for 3-5 h, and post-treating to obtain intermediate 1; (2) mixing intermediate 1 and toluene, heating to 45-55 ℃ under inert atmosphere, adding Karstedt catalyst and stirring for 0.5-1 h, then adding triethoxysilane dropwise, and reacting at 70-75 ℃ for 22-24 h, and post-treating to obtain intermediate 2; (3) mixing intermediate 2 and N,N-dimethylformamide, adding sodium persulfate, adding 4,5-diaminobenzene-1,2-diol N,N-dimethylformamide solution dropwise at 25-30 ℃, and reacting for 5-6 h, and post-treating to obtain intermediate 3; (4) mixing intermediate 3, ethylene carbonate and potassium carbonate, heating to 180-200 ℃, and reacting for 1-3 h to obtain the flame-retardant modifier.

5. A process for the preparation of a bio-based flame retardant polyester material according to claim 4, characterized in that, In step (1), the molar ratio of 2-allyl-3-hydroxybenzaldehyde to diphenyl chlorophosphate is (1-1.2):

1.

6. A process for the preparation of a bio-based flame retardant polyester material according to claim 4, characterized in that, In step (2), the molar ratio of intermediate 1 to triethoxysilane is 1:(1-1.2).

7. A process for the preparation of a bio-based flame retardant polyester material according to claim 4, characterized in that, In step (3), the molar ratio of intermediate 2 to 4,5-diaminobenzene-1,2-diol is 1:(1-1.1).

8. A process for preparing a bio-based flame retardant polyester material according to claim 4, characterized in that, In step (4), the molar ratio of intermediate 3 to ethylene carbonate is 1:(2.01-2.1).

9. The method of making a bio-based flame retardant polyester material according to claim 1, wherein, The molar ratio of the bio-based dibasic acid, dibasic alcohol and flame-retardant modifier is 1:(1-1.5):(0.5-1).

10. A bio-based flame-retardant polyester material prepared by the preparation method of any one of claims 1-9.

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