Flame-retardant plasticizer, its preparation method and application

Abstract

The application discloses a kind of flame-retardant plasticizers, such as formula (I) shows.The application also discloses the preparation method of the flame-retardant plasticizer, comprising: 9,10-dihydro-10-(2,3-dicarboxypropyl)-9-oxo-10-phosphaphenanthrene-10-oxide and n-octanol are esterified under the action of catalyst and water-carrying agent;The product after esterification is washed and separated, to obtain the flame-retardant plasticizer.The application uses DDP derived from renewable resources as raw material, preparation method is simple, easy to operate and environmental protection, and the comprehensive performance of the flame-retardant plasticizer prepared is excellent, can be used for the plasticizing and flame-retardant of polylactic acid resin, and the application prospect is very broad.

Description

Technical Field

[0001] This invention relates to the field of plastic additives, specifically to a flame-retardant plasticizer, its preparation method, and its application. Background Technology

[0002] While traditional plastics have brought great convenience to people's lives, the resulting "white pollution" has also caused serious harm to the natural environment and human health. With increasing environmental awareness, biodegradable polymer materials are gradually gaining attention, and related products are appearing in our daily lives.

[0003] Polylactic acid (PLA) is a biodegradable polyester synthesized 100% from renewable plant resources. PLA possesses excellent mechanical properties, processing performance, and biocompatibility. Furthermore, its degradation by microorganisms and the environment produces only water and carbon dioxide, causing no pollution. It is an ideal alternative to traditional plastics and is widely used in disposable tableware, packaging materials, and pharmaceuticals. However, PLA is relatively brittle, has a very low elongation at break (<10%), and is flammable and prone to dripping. These drawbacks severely limit its application range.

[0004] Patent document CN116253762A discloses a flame retardant, its preparation method, and its application. The method involves preparing 6,6'-dihydroxy-p-benzimidazole using 3,4-diaminophenol and hexachloroacetone as raw materials, and reacting 6,6'-dihydroxy-p-benzimidazole with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) to prepare a DOPO-type flame retardant containing a p-benzimidazole structure. This flame retardant, when used in polylactic acid (PLA), can improve the poor compatibility between the flame retardant and the PLA matrix, thereby increasing the flame retardant efficiency of PLA.

[0005] Patent document CN116284713A discloses an acetylated lactic acid ester flame-retardant plasticizer containing phosphorophenanthrene groups, its preparation method, and its application. The method uses L-lactic acid, monobasic fatty acid, epichlorohydrin, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and acetic anhydride as raw materials, and proceeds through a series of reactions including esterification, epoxidation, ring-opening, and acylation to obtain the acetylated lactic acid ester plasticizer containing phosphorophenanthrene groups. The plasticizer prepared by this method not only possesses excellent plasticizing properties but also excellent flame-retardant properties and good compatibility with polylactic acid resins.

[0006] Although existing technologies have researched flame-retardant plasticizers for PLA modification, the preparation methods of these plasticizers are relatively complex, and the raw materials are not environmentally friendly. Therefore, developing a flame-retardant plasticizer with a simple preparation method, environmentally friendly raw materials, and the ability to simultaneously improve the flexibility and flame retardancy of PLA is of great practical significance. Summary of the Invention

[0007] To address the issues of PLA's brittleness and flammability, this invention provides a flame-retardant plasticizer. This flame-retardant plasticizer uses 9,10-dihydro-10-(2,3-dicarboxypropyl)-9-oxy-10-phosphaphenanthrene-10-oxide (DDP) as a raw material, is environmentally friendly, and exhibits excellent overall performance. It can be used to simultaneously improve the toughness and flame-retardant properties of PLA.

[0008] A flame-retardant plasticizer, the chemical structure of which is shown in formula (Ⅰ):

[0009]

[0010] The present invention also provides a method for preparing the above-mentioned flame-retardant plasticizer. The method uses DDP as raw material and reacts it with n-octanol in the presence of a catalyst and a dehydrating agent to prepare the flame-retardant plasticizer. The synthesis process of this method is simple and convenient to operate.

[0011] A method for preparing a flame-retardant plasticizer includes the following steps:

[0012] (1) 9,10-dihydro-10-(2,3-dicarboxypropyl)-9-oxy-10-phosphaphenanthrene-10-oxide (DDP) was esterified with n-octanol in the presence of a catalyst and a dehydrating agent.

[0013] (2) The product after esterification reaction is washed and separated to obtain a flame-retardant plasticizer with the chemical structure shown in formula (I).

[0014] Preferably, in step (1), the molar ratio of DDP to n-octanol is 1:3 to 30. Since this esterification reaction is reversible, an excess of n-octanol will greatly promote the reaction in the forward direction. However, if too much n-octanol is added, it will not only cause waste and increase costs, but also make subsequent purification more difficult.

[0015] More preferably, the molar ratio of DDP to n-octanol is 1:5 to 20.

[0016] Preferably, in step (1), the catalyst is any one of concentrated sulfuric acid, p-toluenesulfonic acid, or zinc oxide.

[0017] Preferably, the amount of catalyst used is 0.2-5% of the mass of DDP.

[0018] To save costs, more preferably, the amount of catalyst used is 0.3 to 3% of the mass of DDP.

[0019] Preferably, in step (1), the dehydrating agent is one of toluene or cyclohexane.

[0020] Preferably, the amount of the dehydrating agent is 30-80% of the total volume of the raw materials. More preferably, to save costs, the amount of the dehydrating agent is 30-70% of the total volume of the raw materials.

[0021] Preferably, in step (1), the reaction conditions for the esterification reaction are heating under reflux for 3 to 8 hours.

[0022] To save costs, more preferably, the esterification reaction is carried out under reflux conditions for 3 to 6 hours.

[0023] In step (1), the equation for the esterification reaction is:

[0024]

[0025] The present invention also provides the application of the flame-retardant plasticizer in flame retardancy and plasticization of plastics.

[0026] Preferably, the plastic is polylactic acid resin (PLA). The flame-retardant plasticizer prepared in this invention has a similar chemical structure to traditional phthalates, exhibits good compatibility with PLA resin, and has a good plasticizing effect on PLA. Furthermore, the flame-retardant plasticizer contains a high content of phosphorus, which can improve the flame-retardant properties of PLA.

[0027] Preferably, the mass ratio of the flame-retardant plasticizer to polylactic acid resin is 5-30:100.

[0028] More preferably, the mass ratio of the flame-retardant plasticizer to polylactic acid resin is 10-30:100. Within this mass ratio range, the flame-retardant plasticizer exhibits good flame-retardant and plasticizing effects, and the prepared composite PLA sample has a high limiting oxygen index, a low elastic modulus, and a high elongation at break.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] (1) The present invention uses DDP as raw material to prepare flame retardant plasticizer. The synthesis process is simple and easy to operate, and it can be used for large-scale industrial production.

[0031] (2) The DDP of the present invention can be obtained from itaconic acid derived from renewable resources. Therefore, the flame retardant plasticizer of the present invention is also a green and environmentally friendly plastic additive.

[0032] (3) The flame-retardant plasticizer of the present invention can improve the flame-retardant properties of PLA while making PLA have better toughness. Its plasticizing properties are comparable to those of phthalate plasticizers, and it has a very broad development prospect in the flame retardant and plasticizing of plastics. Attached Figure Description

[0033] Figure 1 The 1H NMR spectrum of the flame-retardant plasticizer prepared in Example 1. Detailed Implementation

[0034] To further understand the present invention, the preparation method of a flame-retardant plasticizer provided by the present invention is described in detail below with reference to embodiments. However, the present invention is not limited to these embodiments. Non-essential improvements and adjustments to the raw materials and processes made by those skilled in the art based on the above-described invention are still within the scope of protection of the present invention.

[0035] Example 1

[0036] 17.7 g (0.05 mol) of DDP and 79.1 mL (0.5 mol) of n-octanol were added to a single-necked flask equipped with a water separator and a reflux condenser. Then, 0.5 g of p-toluenesulfonic acid and 50 mL of cyclohexane were added. The mixture was stirred and heated until the first drop of cyclohexane began to reflux, and this process was continued for 6 h. The reaction was then stopped, and the system was allowed to cool to room temperature. The reaction product was washed with deionized water until neutral. Cyclohexane and excess n-octanol were then removed by vacuum distillation at 90 °C. The product was then dissolved in ethyl acetate and centrifuged. The supernatant was distilled under reduced pressure at 70 °C to obtain 27.1 g of a colorless, transparent liquid. The proton NMR spectrum of the obtained product is shown below. Figure 1 As shown, it can be proven to be a flame-retardant plasticizer (DODP) of formula (Ⅰ).

[0037] Example 2

[0038] 17.7 g (0.05 mol) of DDP and 158.2 mL (1 mol) of n-octanol were added to a single-necked flask equipped with a water separator and a reflux condenser. Then, 0.5 g of p-toluenesulfonic acid and 80 mL of toluene were added. The mixture was stirred and heated until the first drop of toluene began to reflux, and this process was continued for 6 hours. The reaction was then stopped, and the system was allowed to cool to room temperature. The reaction product was washed with deionized water until neutral. Cyclohexane and excess n-octanol were then removed by vacuum distillation at 90 °C. The product was then dissolved in ethyl acetate and centrifuged. The supernatant was distilled under reduced pressure at 70 °C to obtain 27.8 g of a colorless, transparent liquid, which was the flame-retardant plasticizer DODP.

[0039] Example 3

[0040] 17.7 g (0.05 mol) of DDP and 79.1 mL (0.5 mol) of n-octanol were added to a single-necked flask equipped with a water separator and a reflux condenser. Then, 0.3 g of concentrated sulfuric acid and 50 mL of cyclohexane were added. The mixture was stirred and heated until the first drop of cyclohexane began to reflux, and this process was continued for 5 hours. The reaction was then stopped, and the system was allowed to cool to room temperature. The reaction product was washed with deionized water until neutral. Cyclohexane and excess n-octanol were then removed by vacuum distillation at 90 °C. The product was then dissolved in ethyl acetate and centrifuged. The supernatant was distilled under reduced pressure at 70 °C to obtain 26.5 g of a colorless, transparent liquid, which is the flame-retardant plasticizer DODP.

[0041] Application Example 1

[0042] The flame-retardant plasticizer DODP prepared in Example 1 was added to PLA at mass ratios of 5:95, 10:90, 15:85, and 20:80 in an internal mixer and melt-blended at 180°C. Then, the PLA / DODP blends were hot-pressed into samples of the required size and thickness using a flat vulcanizing machine at 185°C and 10 MPa. Finally, all samples were cut into the desired shapes and subjected to tensile and flame-retardant property tests. The test results are shown in Tables 1 and 2, respectively.

[0043] Comparative Example 1

[0044] Dioctyl phthalate (DOP) and PLA were added to a mixer at a mass ratio of 20:80 and melt-blended at 180°C. Then, the PLA / DOP blend was hot-pressed into samples of the required size and thickness using a flat vulcanizing machine at 185°C and 10 MPa. Finally, all samples were cut into the required shapes and subjected to tensile and flame retardant property tests. The test results are shown in Tables 1 and 2, respectively.

[0045] Table 1 Mechanical properties of plasticized PLA blends

[0046]

[0047] Table 1 shows the tensile test results of the plasticized PLA blends. The results indicate that the flame-retardant plasticizer DODP has a good plasticizing effect on PLA. With increasing DODP content, the tensile modulus and yield strength of the plasticized PLA samples decrease, while the elongation at break increases. Compared to PLA / DOP20, PLA / DODP20 has a lower tensile modulus and a higher elongation at break, indicating that the flame-retardant plasticizer DODP prepared in Example 1 of this invention has a better plasticizing effect on PLA than DOP.

[0048] Table 2 shows the flame retardant test results of the plasticized PLA blends. The test results show that the flame-retardant plasticizer DODP has a good flame-retardant effect on PLA. The flame retardant properties of the PLA / DODP blends increase with increasing DODP content. When the DODP content is 20 wt%, the molten droplets produced during combustion do not ignite cotton. The PLA / DODP20 sample has a limiting oxygen index of 26.0% and a UL-94 flammability rating of V1. In contrast, adding the same amount of DOP has no flame-retardant effect on PLA.

[0049] Table 2 Flame retardant properties of plasticized PLA blends

[0050]

Claims

1. Use of a flame-retardant plasticizer in the flame-retardation and plasticization of plastics, characterized in that, The plastic is polylactic acid resin, and the mass ratio of the flame-retardant plasticizer to the polylactic acid resin is 20:

80. The chemical structure of the flame-retardant plasticizer is shown in formula (Ⅰ): （Ⅰ）； The preparation method of the flame-retardant plasticizer includes the following steps: (1) 9,10-dihydro-10-(2,3-dicarboxypropyl)-9-oxy-10-phosphaphenanthrene-10-oxide is subjected to an esterification reaction with n-octanol in the presence of a catalyst and a dehydrating agent; the molar ratio of 9,10-dihydro-10-(2,3-dicarboxypropyl)-9-oxy-10-phosphaphenanthrene-10-oxide to n-octanol is 1:3~30; the catalyst is one of concentrated sulfuric acid, p-toluenesulfonic acid or zinc oxide, and the amount of catalyst used is 0.2~5% of the mass of 9,10-dihydro-10-(2,3-dicarboxypropyl)-9-oxy-10-phosphaphenanthrene-10-oxide; (2) The product after esterification reaction is washed and separated to obtain a flame-retardant plasticizer with the chemical structure shown in formula (I).

2. The application of the flame-retardant plasticizer according to claim 1 in flame retardancy and plasticization of plastics, characterized in that, In step (1), the dehydrating agent is one of toluene or cyclohexane, and the amount of the dehydrating agent is 30-80% of the total volume of the raw materials.

3. The application of the flame-retardant plasticizer according to claim 1 in flame retardancy and plasticization of plastics, characterized in that, In step (1), the reaction conditions for the esterification reaction are heating under reflux for 3-8 h.

4. The application of the flame-retardant plasticizer according to claim 3 in flame retardancy and plasticization of plastics, characterized in that, In step (1), the reaction conditions for the esterification reaction are heating under reflux for 3 to 6 hours.

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