A bio-based flame retardant and degradable composition and preparation method thereof

Abstract

The present invention relates to the flame retardant and degradable field, and particularly to a bio-based flame retardant and degradable composition and a preparation method thereof. Wherein, the bio-based flame retardant and degradable composition includes the following raw materials for preparation: PCL resin, PLA resin, modified starch, bio-based flame retardant, compatibilizer, toughening agent, antioxidant, compared with the prior art, the present invention uses the unique rod-shaped nanomaterials of bamboo cellulose microcrystals, and combines surface modification and loading to prepare bamboo cellulose microcrystals loaded with phenyl phospho-taurine (PHPA-PA), forming an efficient flame retardant acid source, and at the same time, by modifying starch, the shortcomings of traditional starch such as high viscosity, strong hydrophilicity, and easy gelatinization are solved, modified starch is used as a carbon source, bamboo cellulose microcrystals loaded with phenyl phospho-taurine (PHPA-PA) are used as an acid source, PCL, PLA resin and other processing aids are compounded, and a bio-based flame retardant and degradable composition is developed, which solves the poor flame retardancy of traditional bio-based materials, and the contradiction between non-renewable and non-degradable flame retardants, and broadens the application field of degradable materials.

Description

Technical Field

[0001] The invention relates to the field of flame retardant and degradable materials, and in particular to a bio-based flame retardant and degradable composition and a preparation method thereof. Background Art

[0002] In daily life, plastics exist in all aspects of our lives, bringing us various conveniences. Due to the depletion of petroleum resources and the biodegradation problem of petroleum-based polymers in recent years, the demand for bio-based materials as degradable and renewable materials is increasing.

[0003] Bio-based polymer materials are renewable and degradable polymer materials. They have good biocompatibility and processing properties, and are widely used in the automotive industry, electronic products and other fields. They are ideal substitutes for petroleum-based polymers. However, bio-based polymer materials are also very easy to burn, just like traditional petroleum-based polymer materials, which greatly limits their application areas. Therefore, flame retardants need to be added to improve flame retardant properties. Currently, most flame retardants are non-renewable and non-degradable, which contradicts the renewable and degradable advantages of bio-based polymer materials. Summary of the invention

[0004] In order to solve the contradiction between flame retardancy and biodegradability mentioned in the above background technology, the purpose of the present invention is to develop a bio-based flame retardant and biodegradable composition, including the following preparation raw materials: PCL resin, PLA resin, modified starch, bio-based flame retardant, compatibilizer, toughening agent, antioxidant. While improving the flame retardancy of the material, the flame retardant maintains the advantages of renewable and biodegradable materials, and broadens the application field.

[0005] On the basis of the above scheme, further, the following raw materials are included in parts by weight:

[0006]

[0007] On the basis of the above scheme, further, the preparation method of the bio-based flame retardant is:

[0008] (1) preparing a 1-2 mol / L phenylphospho-taurine (PHPA-PA) solution, adding an alkaline regulator to adjust the pH value of the solution to about 7-7.5, and obtaining a solution A;

[0009] (2) adding surface-modified bamboo cellulose microcrystals to solution A, heating to 50-70° C. while stirring, allowing the solution to fully react for 12-24 h, and obtaining product B after the reaction is completed;

[0010] (3) The product B is centrifuged, dried, and ground to obtain a bio-based flame retardant.

[0011] On the basis of the above scheme, further, the preparation method of the phenylphosphoric acid-taurine (PHPA-PA) solution is:

[0012] (1) adding 20 g of 60% phenylphosphoric acid solution into a flask containing 100 mL of deionized water, and adding ammonia water to adjust the pH value of the solution to 4-5 to obtain solution A;

[0013] (2) Weigh 3 g of taurine and add it to solution A, heat it to 80-100° C., stir it thoroughly and react for 6-12 hours to obtain reaction liquid B;

[0014] (3) The reaction liquid was subjected to a rotary evaporator to remove deionized water at 80-100° C. After the concentrated reaction liquid was cooled to room temperature, it was added to 300-500 mL of ethanol, and the product was precipitated in the ethanol. After filtering and washing with ethanol for 3-5 times, it was placed in a vacuum oven at 60-80° C. and dried for 24-48 hours to obtain a phenylphosphoric acid-taurine (PHPA-PA) solution with a yield of 78.2%.

[0015] On the basis of the above scheme, further, the preparation method of the surface modified bamboo cellulose microcrystals is:

[0016] (1) Prepare an ethanol solution with a ratio of ethanol to purified water of 70 / 30 (mass fraction) in a beaker, add a coupling agent to the ethanol aqueous solution, and slowly add acetic acid to adjust the pH value of the solution to 4-6 to obtain solution A;

[0017] (2) adding bamboo cellulose microcrystals to solution A, reacting at a temperature of 50 to 65° C. for 1 to 5 hours, and centrifuging for 20 to 60 minutes at a centrifugal speed of 2000 to 4000 r / min to obtain a primary product of surface-modified bamboo cellulose microcrystals;

[0018] (3) The surface-modified bamboo cellulose microcrystals are dried, washed with deionized water and anhydrous ethanol for 3 to 5 times, and finally vacuum-dried to obtain surface-modified bamboo cellulose microcrystals.

[0019] On the basis of the above scheme, further, in the step (2), the coupling agent is at least one of the silane coupling agents KH-550, KH-560 and KH-570.

[0020] On the basis of the above scheme, further, the PCL resin is polycaprolactone resin, and the melt flow rate (160°C / 2.16kg) is 5-7g / 10min; the PLA resin is polylactic acid resin, and the melt flow rate (190°C / 2.16kg) is 15-30g / 10min.

[0021] On the basis of the above scheme, further, the modified starch preparation method is: weigh a certain amount of starch and water, add them into a reaction container and stir, heat to 40-60°C while stirring, then add acetic anhydride and toluene-4-sulfonic acid in sequence to react, add pH adjusting solution to adjust the pH value to 7-8, finally add a cross-linking agent to react and adjust the pH to neutral, and obtain the modified starch after washing, drying and crushing.

[0022] On the basis of the above scheme, further, the compatibilizer is at least one of POE-g-MAH, EAA-g-MAH and EVA-g-MAH; the toughening agent is at least one of POE, EVA and EAA; the weight ratio of the antioxidants 168 and 1010 is 1:(1~5).

[0023] The present invention provides a method for preparing the bio-based flame retardant and degradable composition, comprising the following steps:

[0024] Step 1: Mix PCL resin, PLA resin, modified starch, bio-based flame retardant, compatibilizer, toughening agent and antioxidant and discharge the mixture to obtain a bio-based flame retardant and degradable composite mixture;

[0025] Step 2: melt-extrude the bio-based flame retardant and degradable composition mixture through a twin-screw extruder to obtain a bio-based flame retardant and degradable composition modified material.

[0026] On the basis of the above scheme, further, in the step 2, the operating parameters of the twin-screw extruder are: the temperature of zone 1 is 45-60°C, the temperature of zone 2 is 110-150°C, the temperature of zone 3 is 150-170°C, the temperature of zone 4 is 170-190°C, the temperature of zone 5 is 160-180°C, the die head temperature is 110-130°C, the feeding speed is 100-200r / min, and the screw speed is 200-300r / min.

[0027] The bio-based flame retardant and degradable composition and preparation method thereof provided by the present invention have the following technical principles and beneficial effects compared with the prior art:

[0028] Traditional flame retardants are mostly made from chemical raw materials through complex reactions. Although they have good flame retardant effects, this preparation process often involves a large amount of non-renewable chemical raw materials and even a large amount of organic solvents. They are not completely renewable and degradable biomass, and cannot truly achieve sustainable development of renewable and degradable biomass. Currently, most bio-based flame retardants come from nature, but require complex post-processing, purification and other processing processes. They have high production costs and generally have poor thermal stability. They are prone to degradation and blackening during polymer processing, which affects their actual application value.

[0029] The invention utilizes the unique rod-shaped nanomaterial of bamboo cellulose microcrystals, which has the characteristics of high specific surface area, strong adsorption capacity, high reaction activity, large Young's modulus and the like. The bamboo cellulose microcrystals loaded with phenylphospho-taurine (PHPA-PA) are prepared by a surface modification and loading combined treatment method to form a high-efficiency flame retardant acid source. At the same time, starch is denatured and acetic anhydride is used to replace starch hydroxyl groups to weaken the hydrogen bonding effect between starch molecules, thereby reducing the melting temperature of starch, improving the thermoplasticity, hydrophobicity and hot melt processing performance of starch, solving the shortcomings of traditional starch such as high viscosity, strong hydrophilicity and easy gelatinization. The denatured starch is used as a carbon source, and PCL, PLA resin and other processing aids are compounded to develop a bio-based flame retardant and degradable composition, solving the contradictory problems that traditional bio-based materials have poor flame retardant properties and flame retardants are non-renewable and non-degradable, and broadening the application field of degradable materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0031] Figure 1 This is a SEM image of a bio-based flame retardant provided by the present invention;

[0032] Figure 2 A TEM image of a bio-based flame retardant provided by the present invention;

[0033] Figure 3 This is a SEM image of a burning char layer of a bio-based flame retardant and degradable composition provided by the present invention;

[0034] Figure 4 This is the SEM image of the char layer of the degradable composition burned without adding bio-based flame retardant. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The present invention also provides the following embodiments:

[0037] In the following examples and comparative examples, each raw material was prepared using the following raw materials:

[0038] PCL resin; polycaprolactone resin, model: 6500, melt flow rate (160℃ / 2.16kg): 5-7g / 10min, selected from Sweden Ingevity;

[0039] PLA resin: polylactic acid resin, model: LX575, melt flow rate (190℃ / 2.16kg), 15-30g / 10Min, selected from Total of Thailand;

[0040] Modified starch: Model: BEST-2, water content ≤10%, selected from Sanming Besta Starch Co., Ltd.;

[0041] Compatibilizer: POE-g-MAH, EAA-g-MAH, and EVA-g-MAH are all commercially available products;

[0042] Toughening agent: POE, EVA, and EAA are all commercially available products;

[0043] Antioxidant: a mixture of antioxidants 168 and 1010, both of which are commercially available products selected from Guangzhou Yantai Chemical Co., Ltd.

[0044] Examples 1-5 and Comparative Examples 1-4:

[0045] Table 1 Components and ratios of Examples 1-5 and Comparative Examples 1-4

[0046]

[0047] The specific preparation method is as follows:

[0048] The preparation method of the bio-based flame retardant is:

[0049] (1) preparing a 1.5 mol / L phenylphospho-taurine (PHPA-PA) solution, adding an alkaline regulator to adjust the pH value of the solution to about 7.5, and obtaining a solution A;

[0050] (2) adding surface-modified bamboo cellulose microcrystals to solution A, heating to 60° C. while stirring to allow the solution to react fully for 18 h, and obtaining product B after the reaction is completed;

[0051] (3) The product B is centrifuged, dried, and ground to obtain a bio-based flame retardant. The SEM and TEM images of the obtained bio-based flame retardant are as follows: Figure 1 shown.

[0052] In the above scheme, the preparation method of phenylphosphoric acid-taurine (PHPA-PA) solution is:

[0053] (1) adding 20 g of 60% phenylphosphoric acid solution into a flask containing 100 mL of deionized water, and adding ammonia water to adjust the pH value of the solution to 5 to obtain solution A;

[0054] (2) Weigh 3 g of taurine and add it to solution A, heat it to 80° C., and stir it thoroughly for 10 h to obtain reaction liquid B;

[0055] (3) The reaction liquid was subjected to a rotary evaporator at 90°C to remove deionized water. After the concentrated reaction liquid was cooled to room temperature, it was added to 350 mL of ethanol. The product was precipitated in the ethanol. After filtering and washing with ethanol for 5 times, it was placed in a vacuum oven at 70°C and dried for 30 hours to obtain a phenylphosphoric acid-taurine (PHPA-PA) solution with a yield of 78.2%.

[0056] In the above scheme, the preparation method of surface modified bamboo cellulose microcrystals is:

[0057] (1) Prepare an ethanol solution with an ethanol / purified water ratio of 70 / 30 (mass fraction) in a beaker, add a coupling agent to the ethanol aqueous solution, and slowly add acetic acid to adjust the pH value of the solution to 6 to obtain solution A;

[0058] (2) adding bamboo cellulose microcrystals to solution A, reacting at 60° C. for 4 h, and centrifuging for 50 min at a centrifugal speed of 3500 r / min to obtain a primary product of surface-modified bamboo cellulose microcrystals;

[0059] (3) The surface-modified bamboo cellulose microcrystals were dried, washed with deionized water and anhydrous ethanol for four times, and finally vacuum-dried to obtain surface-modified bamboo cellulose microcrystals.

[0060] In the above scheme, the modified starch preparation method is: weigh a certain amount of starch and water, add them into a reaction container and stir, heat to 50°C while stirring, then add acetic anhydride and toluene-4-sulfonic acid in sequence to react, add pH adjusting liquid to adjust the pH value to 7.5, finally add a cross-linking agent to react and adjust the pH to neutral, and obtain the modified starch after washing, drying and pulverizing.

[0061] The method for preparing a bio-based flame retardant and degradable composition comprises the following steps:

[0062] Step 1: Mix PCL resin, PLA resin, modified starch, bio-based flame retardant, compatibilizer, toughening agent and antioxidant and discharge the mixture to obtain a bio-based flame retardant and degradable composite mixture;

[0063] Step 2: melt-extrude the bio-based flame retardant and degradable composition mixture through a twin-screw extruder to obtain a bio-based flame retardant and degradable composition modified material. The working parameters of the twin-screw extruder are: the temperature of zone 1 is 55°C, the temperature of zone 2 is 115°C, the temperature of zone 3 is 155°C, the temperature of zone 4 is 180°C, the temperature of zone 5 is 175°C, the die temperature is 125°C, the feed speed is 150r / min, and the screw speed is 250r / min. The SEM image of the combustion charcoal layer of the obtained bio-based flame retardant and degradable composition is as follows: Figure 2 As shown, the SEM image of the char layer of the biodegradable composition without adding bio-based flame retardant is as shown Figure 3 As shown, through the comparison of SEM images, it can be clearly seen that the charcoal layer of the bio-based flame retardant and degradable composition prepared by the present invention is more compact than the charcoal layer of the degradable composition without adding bio-based flame retardant, and the flame retardant effect is better.

[0064] The specific performance tests and evaluation results are as follows:

[0065] The samples obtained from the above Examples 1-5 and Comparative Examples 1-4 were subjected to vertical burning grade test in accordance with GB / T 2408-2021 “Horizontal and vertical methods for determination of combustion performance of plastics”, the limiting oxygen index test was carried out in accordance with “Determination of combustion behavior of plastics by oxygen index method - Part 2: Room temperature test”, and the 180d biodegradation rate was tested in accordance with ISO14855-1-2012; the test results are shown in Table 2.

[0066] Table 2 Test results of Examples 1-5 and Comparative Examples 1-4

[0067]

[0068] As can be seen from the results in Table 2, in Examples 1-5 and Comparative Examples 1-4, regardless of the examples or the comparative examples, the addition of bio-based flame retardants can effectively improve the flame retardant properties of degradable materials. Comparative Example 1 does not add bio-based flame retardants, and its material basically does not have flame retardant properties; Comparative Example 2 uses ordinary starch instead of modified starch to compound bio-based flame retardants, and its flame retardant effect is obviously not as good as the modified flame retardant, indicating that bio-based flame retardants and modified starch have good synergistic effects. Comparative Examples 3-4 are respectively not adding bio-based flame retardants and modified starch, and adding bio-based flame retardants alone without adding starch, and their flame retardant effects are far less than the flame retardant effect of bio-based flame retardants compounded with modified starch on the material. It can be seen that the use of bio-based flame retardants compounded with modified starch can effectively improve the flame retardant properties of PCL / PLA biodegradable materials, and bio-based flame retardants are green and degradable. This technical solution utilizes the unique rod-shaped nanomaterials of bamboo cellulose microcrystals, and prepares bamboo cellulose microcrystals loaded with phenylphospho-taurine (PHPA-PA) as an acid source through a combination of surface modification and loading treatment. At the same time, starch is denatured as a carbon source, and PCL, PLA resin and other processing aids are compounded to develop a bio-based flame retardant and degradable composition, which solves the contradictory problem that traditional bio-based materials have poor flame retardant properties and flame retardants are non-renewable and non-degradable, and broadens the application field of degradable materials.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bio-based flame retardant and degradable composition, characterized in that: It includes the following components by weight: 20-30 parts of PCL resin; 20-35 parts of PLA resin; 5-15 parts of modified starch; 5-10 parts of bio-based flame retardant; Compatibilizer 2~6 parts; 5-15 parts of toughening agent; 0.2~1 part of antioxidant; The preparation method of the bio-based flame retardant is: (1) preparing a 1-2 mol / L phenylphospho-taurine PHPA-PA solution, adding an alkaline regulator to adjust the pH value of the solution to about 7-7.5, and obtaining solution A; (2) Add surface-modified bamboo cellulose microcrystals to solution A, heat to 50-70°C while stirring, and allow the solution to fully react for 12-24 hours. After the reaction is complete, product B is obtained. (3) centrifuging, drying, and grinding the product B to obtain a bio-based flame retardant; The preparation method of the phenylphosphoric acid-taurine PHPA-PA solution is: (1) Add 20 g of 60% phenylphosphoric acid solution into a flask containing 100 mL of deionized water, and add aqueous ammonia to adjust the pH value of the solution to 4-5 to obtain solution C; (2) Weigh 3 g of taurine and add it to solution C, heat it to 80-100 °C, stir it thoroughly and react for 6-12 h to obtain reaction liquid D; (3) The reaction liquid D was subjected to a rotary evaporator to remove deionized water at 80-100°C. After the concentrated reaction liquid was cooled to room temperature, it was added to 300-500 mL of ethanol. The product was precipitated in the ethanol, filtered, washed with ethanol 3-5 times, and dried in a vacuum oven at 60-80°C for 24-48 h to obtain a phenylphospho-taurine PHPA-PA solution with a yield of 78.2%; The modified starch preparation method comprises the following steps: weighing a certain amount of starch and water, adding them into a reaction container and stirring, heating to 40-60° C. while stirring, then sequentially adding acetic anhydride and toluene-4-sulfonic acid to react, adding a pH adjusting liquid to adjust the pH value to 7-8, finally adding a cross-linking agent to react, adjusting the pH value to neutral, and washing, drying, and pulverizing to obtain the modified starch.

2. The bio-based flame retardant and degradable composition according to claim 1, characterized in that: The preparation method of the surface modified bamboo cellulose microcrystals is: (1) Prepare an ethanol solution with a mass fraction ratio of ethanol to pure water of 70 / 30 in a beaker, add a coupling agent to the ethanol aqueous solution, and slowly add acetic acid to adjust the pH value of the solution to 4-6 to obtain solution E; (2) adding bamboo cellulose microcrystals to solution E, reacting at a temperature of 50-65°C for 1-5 hours, and centrifuging the solution for 20-60 minutes at a centrifuge speed of 2000-4000 r / min to obtain a primary product of surface-modified bamboo cellulose microcrystals; (3) drying the surface-modified bamboo cellulose microcrystals, washing them with deionized water and anhydrous ethanol for 3 to 5 times, and finally vacuum drying them to obtain surface-modified bamboo cellulose microcrystals; The coupling agent in step (1) is at least one of the silane coupling agents KH-550, KH-560 and KH-570.

3. The bio-based flame retardant and degradable composition according to claim 1, characterized in that: The compatibilizer is at least one of POE-g-MAH, EAA-g-MAH and EVA-g-MAH; the toughening agent is at least one of POE, EVA and EAA; the weight ratio of the antioxidants 168 and 1010 is 1: (1-5).

4. The method for preparing the bio-based flame retardant and degradable composition according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: Mix PCL resin, PLA resin, modified starch, bio-based flame retardant, compatibilizer, toughening agent and antioxidant and discharge the mixture to obtain a bio-based flame retardant and degradable composite mixture; Step 2: melt-extrude the bio-based flame retardant and degradable composition mixture through a twin-screw extruder to obtain a bio-based flame retardant and degradable composition.

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