A core-shell structure flame-retardant POE compatibilizer and application thereof

Abstract

The application discloses a kind of core-shell structure flame-retardant POE compatibilizer and application thereof, belong to plastic compatibilizer technical field, the preparation method of the flame-retardant POE compatibilizer includes the following steps: octavinyl-POSS is reacted with cysteine mercapto-alkene click chemistry, obtain octa (cysteine) substituted POSS;Octa (cysteine) substituted POSS and 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene occur nucleophilic substitution reaction, obtain POSS-x (Cys-DOPO) -COOH;POSS-x (Cys-DOPO) -COOH and POE-g-GMA are reacted with carboxyl-epoxy ring-opening esterification, obtain flame-retardant POE compatibilizer.The application is connected with cysteine as linker, and POSS and phosphaphenanthrene are connected with covalent bond into POE-g-GMA polymer, and flame-retardant POE compatibilizer is prepared.

Description

Technical Field

[0001] This invention relates to the field of plastic compatibilizer technology, specifically to a core-shell structured flame-retardant POE compatibilizer and its application. Background Technology

[0002] Compatibilizers are additives that promote compatibility between different polymers. In the blending or compounding of polymer materials, compatibility issues often arise due to differences in chemical structure, polarity, molecular weight, etc., leading to a decline in the performance of the blend. Copolymer compatibilizers, through their unique molecular structure, can act as a "bridge" between different polymers, improving their compatibility.

[0003] There are three main ways in which compatibilizers improve compatibility: 1) Promoting compatibility: Copolymer compatibilizers interact with two or more polymers through different segments of their molecules, such as hydrogen bonds and van der Waals forces, thereby forming an interfacial layer between different polymers. This interfacial layer can reduce the interfacial tension between different polymers, making them easier to mix and disperse. 2) Promoting dispersion: During the blending process, copolymer compatibilizers can adsorb onto the surface of dispersed phase particles, forming a protective film to prevent particle aggregation and precipitation. 3) Enhancing interfacial bonding: Copolymer compatibilizers can form chemical bonds or physical adsorption between different polymers, thereby enhancing the interfacial bonding between them. This enhanced interfacial bonding can improve the mechanical properties and thermal stability of the blend.

[0004] Currently, commonly used compatibilizers are mainly divided into two categories: reactive and non-reactive. Reactive compatibilizers form covalent bonds at the phase interface through chemical reactions, resulting in strong interfacial bonding. The most common types are cyclic anhydride, epoxy, and carboxylic acid types. Non-reactive compatibilizers function through physical entanglement and the principle of "like dissolves like," allowing for more flexible application conditions, but with relatively lower interfacial bonding strength, such as various block copolymers. However, in the modification of existing composite materials, flame retardants and compatibilizers are generally added separately, with very few reports on flame-retardant compatibilizers. Summary of the Invention

[0005] To overcome the shortcomings of the existing technology, the present invention provides a core-shell structured flame-retardant POE compatibilizer and its application, which has the effects of flame retardancy and compatibilization.

[0006] The technical solution for achieving the objective of this invention is as follows: A core-shell structured flame-retardant POE compatibilizer, the preparation method of which includes the following steps: S1. Octadecyl-POSS is reacted with cysteine ​​via a mercapto-olefin click chemistry to obtain octa(cysteine)-substituted POSS; S2. The octa(cysteine)-substituted POSS undergoes a nucleophilic substitution reaction with 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene to give POSS-x(Cys-DOPO)-COOH, where x is a natural number between 4 and 8. S3. POSS-x(Cys-DOPO)-COOH is reacted with POE-g-GMA via a carboxyl-epoxy ring-opening esterification reaction to obtain a flame-retardant POE compatibilizer.

[0007] In one specific embodiment, the molar ratio of octavinyl-POSS to cysteine ​​is 1:(9.6~16).

[0008] In one specific embodiment, the reaction conditions for step S1 are photoinitiation or thermal initiation. Photoinitiation is UV irradiation at room temperature for 30 minutes to 2 hours; thermal initiation is reaction in azobisisobutyronitrile at a temperature of 60-70°C for 12-24 hours, and the reaction process requires maintaining an inert gas atmosphere.

[0009] In one specific embodiment, the molar ratio of the octa(cysteine)-substituted POSS to 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene is 1:(4~10), and the reaction conditions for step S2 are 20~60°C under acid-binding agent conditions, wherein the acid-binding agent is pyridine.

[0010] In one specific embodiment, the mass ratio of POSS-x(Cys-DOPO)-COOH to POE-g-GMA is (3.5~7.5):100.

[0011] In one specific embodiment, the mass ratio of POSS-x(Cys-DOPO)-COOH to POE-g-GMA is (4~6):100.

[0012] In one specific embodiment, the reaction conditions for step S3 are either a solution method or a melt method. The reaction temperature for the solution method is 90-110°C, and the reaction temperature of the melting section for the melt method is 140-150°C. The catalyst used is one or more of imidazole catalysts, quaternary ammonium salt catalysts, or tertiary phosphine catalysts.

[0013] The imidazole catalyst is selected from 2-ethyl-4-methylimidazolium, 1-methylimidazolium, or imidazolium; the quaternary ammonium salt catalyst is selected from tetrabutylammonium bromide, benzyltriethylammonium chloride, or tetrabutylammonium chloride; the tertiary phosphine catalyst is selected from triphenylphosphine or tributylphosphine; wherein the amount of catalyst used is 0.05-0.5 wt% of the mass of POE-g-GMA.

[0014] In one specific embodiment, the GMA grafting rate of the POE-g-GMA is 2~3wt%.

[0015] This invention also protects the application of the core-shell structured flame-retardant POE compatibilizer in halogen-free flame-retardant polyolefin cable materials, high-voltage cables for charging piles or new energy vehicles, surface treatment agents for inorganic nanofillers, and special coatings and adhesives.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a core-shell structured flame-retardant POE compatibilizer and its application. It uses a rigid flame retardant core, with an octavinyl POSS cage structure as the polyvinyl molecule, cysteine ​​as the linker, and densely loaded with four or more DOPO molecules, forming a molecularly dispersed flame-retardant region, avoiding the micron-level aggregation and interfacial defects of traditional flame retardants. The flexible compatibilizer shell uses POE-g-GMA with GMA side chains, linking POE segments to the flame-retardant core through chemical bonds, forming a micro-crosslinked core and a flexible polymer outer layer, thus maintaining thermoplastic melt processability while possessing an elastic core structure. Regarding flame retardant performance, POSS itself has a certain flame-retardant effect. At high temperatures, POSS can decompose to produce silica, forming a SiO2 glass layer on the surface of the burning material, blocking smoke escape, forming a physical barrier, isolating oxygen and heat, and playing a role in "char formation" and "isolation," reducing combustion dripping. DOPO is a classic phosphorus-containing flame retardant. During combustion, it functions through a dual flame-retardant mechanism involving both the gas and condensed phases. The gas phase captures free radicals, promoting complete combustion (reducing soot particles), while phosphorus catalyzes char formation, reducing volatile matter. Regarding compatibility, POE is a typical non-polar polymer, exhibiting poor compatibility with other polar materials (such as many flame retardants), easily leading to phase separation, decreased mechanical properties, and poor flame-retardant performance. Using POE-g-GMA as the reactive substrate, its epoxy groups possess a certain degree of polarity. Through carboxyl-epoxy ring-opening esterification, it reacts with the carboxyl groups of POSS-x(Cys-DOPO)-COOH, firmly grafting units containing POSS and DOPO onto the POE chain. This avoids the problems of easy precipitation and uneven dispersion common in traditional flame retardants, improving the uniformity of flame retardant dispersion within the polymer. Good compatibility can preserve the original excellent mechanical properties of POE to the greatest extent, while the uniform dispersion of flame retardants in polymers is the key to exerting their flame retardant properties. Improved compatibility helps to reduce interfacial resistance during processing and improve processing efficiency. Attached Figure Description

[0017] Figure 1 This is a flowchart of the synthesis of POSS-x(Cys-DOPO)-COOH.

[0018] Figure 2 The infrared spectra are those of POE-g-GMA and the flame-retardant compatibilizer of Example 1. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0021] The following describes the examples, comparative examples, and raw materials used: POE-g-GMA: GMA grafting rate 2-3wt%, SOG-03, Jia Yi Rong; Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this invention are all commercially available raw materials, and the raw materials used in each parallel experiment are the same.

[0022] Example 1

[0023] A hyperbranched flame-retardant POE compatibilizer and its preparation process are as follows: S1. A mercapto-olefin click chemistry reaction was carried out between octavinyl-POSS and cysteine: Under a nitrogen atmosphere, 0.1 mol of octavinyl-POSS was dissolved in anhydrous DMF to prepare a solution with a concentration of 50 mg / mL. 1 mol of cysteine ​​was dissolved in PBS buffer (pH 8.0) to prepare a solution with a concentration of 100 mg / mL. 0.2 mol of tris(2-carboxyethyl)phosphine was added to prevent cysteine ​​oxidation to cystine. The above solutions were mixed in a Schlenk tube, and 0.015 mol of Irgacure 2959 was added as a photoinitiator in the dark. The reaction was cycled three times with liquid nitrogen freezing-vacuuming-thawing, irradiated with 365 nm UV, and stirred at room temperature for 30 minutes to 2 hours. A nitrogen atmosphere was maintained during the reaction. The reaction was monitored by ¹H NMR. When the vinyl protons (δ 5.8-6.2) were detected... When the ppm signal disappears and a new -CH2-CH2-S- signal appears, the reaction is stopped. The reaction solution is slowly added dropwise to cold methanol with vigorous stirring. Cysteine ​​and the initiator remain in the supernatant, the product precipitates, and is collected by centrifugation (3000 rpm, 10 min). It is washed three times with methanol and dried under vacuum to obtain octa(cysteine) substituted POSS with a yield of 96%. S2. Nucleophilic substitution reaction of octa(cysteine)-substituted POSS with 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene (DOPO): 0.1 mol of octa(cysteine)-substituted POSS was dried under vacuum at 60 °C for 12 hours and dissolved in anhydrous pyridine to prepare a solution with a concentration of 30 mg / mL. 1 mol of 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene DOPO-Cl was dissolved in anhydrous pyridine to prepare a solution with a concentration of 1.0 mg / mL. In a dry three-necked flask, a solution of 8 mol / L substituted POSS (cysteine) was added. The mixture was bubbled with nitrogen for 30 minutes to remove oxygen. While maintaining a nitrogen atmosphere, DOPO-Cl solution was slowly added dropwise under an ice bath at 0–5 °C with stirring. After the addition was complete, the temperature was raised to 40 °C and the reaction was stirred for 4 hours. The reaction progress was monitored by TLC. After the reaction was complete, it was cooled to room temperature. Pyridine was recovered by vacuum distillation, and pyridine hydrochloride was removed by washing with deionized water. The solution was then dried under vacuum at 60 °C to obtain POSS-x(Cys-DOPO)-COOH, with a yield of 89.7%. S3. Carboxyl-epoxy ring-opening esterification reaction of POSS-x(Cys-DOPO)-COOH and POE-g-GMA: Place 5g of POSS-x(Cys-DOPO)-COOH in a dry Schlenk tube, add 10mL of anhydrous DMF, sonicate for 10 minutes, and gently heat (40℃) until the solution is clear and transparent. Add 100g of POE-g-GMA and 100mL of anhydrous toluene to a 250mL three-necked flask (equipped with a mechanical stirrer, nitrogen balloon, and reflux condenser). Heat in an oil bath to 110℃ and mechanically stir for 30 minutes until POE is completely dissolved into a homogeneous solution. Purge with nitrogen for 15 minutes to remove dissolved oxygen, cool to 90℃, and slowly add the POSS-x(Cys-DOPO)-COOH DMF solution dropwise (over 5 minutes) to the POE solution while stirring. Add 0.05g of... 2-Ethyl-4-methylimidazole was reacted under nitrogen protection at 90-100℃ for 8 hours with stirring. The reaction was stopped when the epoxy conversion rate reached 70-80% by infrared monitoring. The mixture was rapidly cooled to room temperature, and 0.1 mL of glacial acetic acid was added to quench the catalyst. The reaction solution was then slowly added dropwise to 800 mL of cold methanol (pre-cooled at -20℃) with stirring. The mixture was allowed to stand for 2 hours to remove unreacted POE-g-GMA. The mixture was centrifuged at 4℃ and 6000 rpm for 15 minutes. The white flocculent precipitate was collected and washed successively with 50 mL of cold methanol (0℃), 30 mL of deionized water, and 30 mL of cold diethyl ether. After each washing, the mixture was stirred and dispersed, then centrifuged. Finally, the mixture was vacuum dried at 40℃ for 48 hours to obtain a flame-retardant POE compatibilizer with a yield of 90.2%. The precipitate was a white to pale yellow elastic solid.

[0024] Among them, the infrared spectra of POE-g-GMA and flame-retardant POE compatibilizer are as follows: Figure 2As shown, potassium bromide (KBr) powder and sample powder were blended, ground, and compressed into tablets. The infrared spectrum of the sample was determined using a Nicolet 8700 FTIR spectra from the USA, with a scanning range of 4000-500 cm⁻¹. -1 Among them, the presence of hydroxyl groups, -NH, and Si-O-Si was detected in the infrared spectrum of the flame-retardant POE compatibilizer, and the signal of epoxy groups was weakened, proving that POSS-x(Cys-DOPO)-COOH was successfully grafted onto POE-g-GMA, and that some epoxy groups remained in POE-g-GMA.

[0025] Example 2

[0026] Compared with Example 1, the difference is that step S1 is modified as follows: S1. A thiol-olefin click chemistry reaction was carried out between octavinyl-POSS and cysteine: Under a nitrogen atmosphere, 0.1 mol of octavinyl-POSS was dissolved in anhydrous DMF to prepare a solution with a concentration of 50 mg / mL. 1 mol of cysteine ​​was dissolved in PBS buffer (pH 7.4), and 0.2 mol of tris(2-carboxyethyl)phosphine was added to prevent cysteine ​​oxidation to cystine, preparing a solution with a cysteine ​​concentration of 100 mg / mL. The above solutions were mixed in a Schlenk tube, and 0.08 mol of azobisisobutyronitrile was added as a thermal initiator. The reaction was cycled three times with liquid nitrogen freezing-vacuuming-thawing, and then stirred at 70°C for 24 hours. A nitrogen atmosphere was maintained during the reaction. ¹H NMR monitoring was performed when the vinyl protons (δ 5.8-6.2)... When the ppm signal disappears and a new -CH2-CH2-S- signal appears, the reaction is stopped. The reaction solution is slowly added dropwise to cold methanol with vigorous stirring. Cysteine ​​and the initiator remain in the supernatant. The product precipitates, is collected by centrifugation (3000 rpm, 10 min), washed three times with methanol, and dried under vacuum to obtain octa(cysteine) substituted POSS with a yield of 85%.

[0027] Example 3

[0028] Compared with Example 1, the difference lies in the following modification in step S3: S3. Select a co-rotating twin-screw extruder (L / D=40). Set the temperature from the feed port to the die head as follows: 110℃→130℃→140℃ (feed section)→145℃→145℃→140℃ (melt section)→130℃→135℃→140℃ (discharge section). Premix 10 parts by weight of POSS-x(Cys-DOPO)-COOH, 0.05 parts by weight of triphenylphosphine powder, and 90 parts by weight of POE in a mixer at 110℃ for 5 minutes (low shear) to prepare a 10% concentration masterbatch. Feed 100 parts by weight of POE-g-GMA into the main feed port of the co-rotating twin-screw extruder, and feed 50 parts by weight of POSS masterbatch into the side feed port. Set the speed to 150-200 rpm. At rpm and a residence time of 40-60 seconds, the melt is extruded through a die, water-cooled into strips (cold water temperature <20℃ to prevent post-crosslinking), and pelletized. The pellets are dried in a fluidized bed dryer at 80℃ for 30 minutes, immediately packaged, and sealed with nitrogen to obtain a flame-retardant POE compatibilizer with a yield of 96%.

[0029] Example 4

[0030] Compared with Example 1, the difference is that the amount of POSS-x(Cys-DOPO)-COOH added in step S3 is modified to 3.5g; Example 5

[0031] Compared with Example 1, the difference is that the amount of POSS-x(Cys-DOPO)-COOH added in step S3 is modified to 7.5g; Comparative Example 1 Compared with Example 1, the difference is that step S2 is omitted, and the octylcysteine-substituted POSS is directly reacted with POE-g-GMA. Comparative Example 2 Compared with Example 3, the difference is that steps S1 and S2 are not performed. Instead, 1.0g of octaphenyl-POSS, 2.6g of 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene, and 100g of POE-g-GMA are premixed and then extruded through a co-rotating twin-screw extruder to obtain a physically mixed flame retardant composite compatibilizer.

[0032] Comparative Example 3 Only for POE-g-GMA.

[0033] Application Examples 1-8 40 parts of mLLDPE (SP1520, Mitsui Chemicals), 10 parts of EVA (7350M, Formosa Plastics), 30 parts of aluminum hydroxide (average particle size 1-2 μm, Jinan Jinyingtai Chemical Co., Ltd.), and 5 parts of compatibilizer (for Application Examples 1-8, flame-retardant compatibilizers / flame-retardant composite compatibilizers / composite compatibilizers prepared in Examples 1-5 and Comparative Examples 1-3 were added respectively) were vacuum dried for 5 hours. The dried mLLDPE, EVA, aluminum hydroxide, and compatibilizer were added to a high-speed mixer, along with 2 parts of antioxidant (antioxidant 1790 and antioxidant 168, and antioxidant DLTDP were compounded in a mass ratio of 3:1:2) and 2 parts of lubricant (zinc stearate). The mixer was set to 800 r / min and mixed for 10 minutes, then set to 1600 r / min and mixed for 5 minutes. The obtained mixture was added to a twin-screw extruder, wherein the temperatures of each zone of the extruder barrel were 160, 170, 180, 180, 180, 180, 180, 180℃ (distillation head temperature), the main extruder speed was 300 r / min, the feed speed was 30 r / min, and the vacuum degree of the vacuum section was 0.04-0.08 MPa. The mixture was extruded to obtain halogen-free flame-retardant polyolefin cable material for performance testing.

[0034] The halogen-free flame-retardant polyolefin cable materials prepared in Examples 1-8 were used to prepare samples for the following performance tests: (1) Tensile strength: The tensile strength of halogen-free flame-retardant polyolefin cable material was tested according to standard GB / T 1040.2-2022. The sample type was 1A and the tensile speed was 50 mm / min.

[0035] (2) Vertical burning test: According to GB / T 2408-2021, the sample size is 130mm×13mm×3.2mm.

[0036] (3) Limiting oxygen index test: Refer to GB / T 2406.1-2008, the size of the test sample is 100mm×6.5mm×3mm.

[0037] (4) Smoke density test: Refer to GB / T 8627-2007, the size of the test sample is 75mm×75mm×3mm.

[0038] Table 1 Performance test results of application examples

[0039] As can be seen from the examples and comparative examples, the flame-retardant compatibilizer prepared by the present invention has both flame-retardant and compatibility effects. While achieving high-efficiency flame retardancy, it does not affect the mechanical properties of halogen-free flame-retardant polyolefin cable materials, thus meeting the requirements for low smoke, anti-dripping, and environmentally friendly flame retardancy in halogen-free flame-retardant polyolefin cable materials. Comparative Example 1 shows that without the addition of 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene, the flame retardant rating cannot reach V-0. However, because POSS can form a SiO2 glass layer on the surface of the burning material, the anti-dripping effect is good. Comparative Example 2 shows that the flame-retardant compatibilizer prepared by physical mixing is prone to problems such as agglomeration and migration precipitation, resulting in less than ideal flame-retardant and anti-dripping effects. Comparative Example 3 only adds inorganic flame retardants, resulting in insufficient flame-retardant performance.

[0040] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A core-shell structured flame-retardant POE compatibilizer, characterized in that, The preparation method of the flame-retardant POE compatibilizer includes the following steps: S1. Octadecyl-POSS is reacted with cysteine ​​via a mercapto-olefin click chemistry to obtain octa(cysteine)-substituted POSS; S2. The octa(cysteine)-substituted POSS undergoes a nucleophilic substitution reaction with 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene to give POSS-x(Cys-DOPO)-COOH, where x is a natural number between 4 and 8. S3. POSS-x(Cys-DOPO)-COOH is reacted with POE-g-GMA via a carboxyl-epoxy ring-opening esterification reaction to obtain a flame-retardant POE compatibilizer.

2. The core-shell structured flame-retardant POE compatibilizer as described in claim 1, characterized in that, The molar ratio of octavinyl-POSS to cysteine ​​is 1:(9.6~16).

3. The core-shell structured flame-retardant POE compatibilizer as described in claim 1, characterized in that, The reaction conditions for step S1 are photo-initiated or thermal-initiated. Photo-initiation is UV irradiation at room temperature for 30 minutes to 2 hours; thermal initiation is reaction in azobisisobutyronitrile at a temperature of 60-70°C for 12-24 hours, and an inert gas atmosphere must be maintained during the reaction process.

4. The core-shell structured flame-retardant POE compatibilizer as described in claim 1, characterized in that, The molar ratio of the octa(cysteine)-substituted POSS to 10-chloro-9,10-dihydro-9-oxa-10-phosphaphenanthrene is 1:(4~10). The reaction conditions for step S2 are 20~60℃ under acid-binding agent conditions, wherein the acid-binding agent is pyridine.

5. The core-shell structured flame-retardant POE compatibilizer as described in claim 1, characterized in that, The mass ratio of POSS-x(Cys-DOPO)-COOH to POE-g-GMA is (3.5~7.5):

100.

6. The core-shell structured flame-retardant POE compatibilizer as described in claim 5, characterized in that, The mass ratio of POSS-x(Cys-DOPO)-COOH to POE-g-GMA is (4~6):

100.

7. The core-shell structured flame-retardant POE compatibilizer as described in claim 1, characterized in that, The reaction conditions for step S3 are either solution method or melt method. The reaction temperature for solution method is 90-110℃, and the reaction temperature of the melting section for melt method is 140-150℃. The catalyst used is one or more of imidazole catalyst, quaternary ammonium salt catalyst or tertiary phosphine catalyst.

8. The core-shell structured flame-retardant POE compatibilizer as described in claim 1, characterized in that, The GMA grafting rate of the POE-g-GMA is 2~3wt%.

9. The application of the core-shell structured flame-retardant POE compatibilizer as described in any one of claims 1-8 in halogen-free flame-retardant polyolefin cable materials, high-voltage cables for charging piles or new energy vehicles, surface treatment agents for inorganic nanofillers, and special coatings and adhesives.

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