A Si-PNC quaternary hybrid flame retardant system composition and its preparation method

Abstract

A Si-P-N-C quaternary hybrid flame-retardant system composition and its preparation method are disclosed. The method involves adding a nitrogen-phosphorus flame retardant, a thermoplastic resin, and a silane coupling agent to a graphene oxide suspension, followed by a functionalization reaction to obtain a graphene oxide-grafted nitrogen-phosphorus flame retardant and a graphene oxide-grafted thermoplastic resin. The graphene oxide-grafted nitrogen-phosphorus flame retardant and the graphene oxide-grafted thermoplastic resin are then mixed with modified wollastonite and a silane coupling agent to obtain the Si-P-N-C quaternary hybrid flame-retardant system composition. This invention, based on modified wollastonite, introduces a nitrogen-phosphorus flame retardant, a thermoplastic resin, and graphene oxide, which not only gives the system composition excellent compatibility with the polymer matrix, resulting in better mechanical and processing properties, but also demonstrates excellent flame-retardant performance due to the synergistic flame-retardant effect of Si, P, N, and C.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a Si-PNC quaternary hybrid flame retardant system composition and its preparation method. Background Technology

[0002] Wollastonite is a unique needle-like fiber with excellent insulation, wear resistance, and a high refractive index, making it a good filler material for plastics and rubber products. Adding wollastonite powder to rubber and plastic products can not only improve the impact strength and flowability of the materials, but also enhance their tensile strength, impact strength, linear tensile strength, and molding shrinkage. However, as an inorganic filler, if wollastonite is directly added to polymers, the difference in interfacial properties leads to poor compatibility and uneven dispersion, resulting in a decrease in the mechanical properties of the matrix material. Studies have shown that mixing two or more flame retardants can achieve a synergistic flame-retardant effect. For example, mixing phosphorus-based and nitrogen-based flame retardants has a synergistic flame-retardant effect, which can greatly improve the flame retardancy of the material; however, the poor compatibility between the materials affects the mechanical strength. Therefore, there is an urgent need to study a system composition that combines multiple flame retardants to achieve a synergistic flame-retardant effect without affecting the mechanical strength of the material. Summary of the Invention

[0003] The purpose of this invention is to address the aforementioned problems in the prior art by providing a Si-PNC quaternary hybrid flame-retardant system composition and its preparation method that can balance synergistic flame-retardant effect and material mechanical strength.

[0004] To achieve the above objectives, the technical solution of the present invention is as follows:

[0005] In a first aspect, the present invention provides a method for preparing a Si-PNC quaternary hybrid flame retardant system composition, the preparation method comprising:

[0006] S1. Add nitrogen-phosphorus flame retardant, thermoplastic resin and silane coupling agent to graphene oxide suspension, and obtain graphene oxide-grafted nitrogen-phosphorus flame retardant and graphene oxide-grafted thermoplastic resin through functionalization reaction.

[0007] S2. Mix the graphene oxide-grafted nitrogen-phosphorus flame retardant, the graphene oxide-grafted thermoplastic resin, the modified wollastonite, and the silane coupling agent to obtain the Si-PNC quaternary hybrid flame retardant system composition.

[0008] The nitrogen-phosphorus flame retardant is any one of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, melamine polyphosphate, and piperazine pyrophosphate.

[0009] The thermoplastic resin is either polyetheretherketone or MQ resin.

[0010] The silane coupling agent is any one of KH-550, KH-560, KH-570, and KH-590.

[0011] The modified wollastonite is prepared by placing wollastonite fibers and a silane coupling agent in a high-speed mixer and stirring at high speed to obtain modified wollastonite.

[0012] The mass ratio of the nitrogen-phosphorus flame retardant, thermoplastic resin, and silane coupling agent in S1 is 5-8:2-4:1-1.2; the mass ratio of the graphene-grafted nitrogen-phosphorus flame retardant, graphene-grafted thermoplastic resin, modified wollastonite, and silane coupling agent in S2 is 5-8:88-95:1-1.2.

[0013] The addition ratio of the nitrogen-phosphorus flame retardant to the graphene oxide suspension is 5-8g:0.5L; the concentration of the graphene oxide suspension is 5-8g / L.

[0014] The functionalization reaction conditions are: heating to 73-80℃ and refluxing under nitrogen for 10-12 hours.

[0015] In step S1, the reaction product obtained from the functionalization reaction is dried under vacuum at 105-110°C to obtain a nitrogen-phosphorus flame retardant grafted with graphene oxide and a thermoplastic resin grafted with graphene oxide.

[0016] Secondly, the present invention provides a Si-PNC quaternary hybrid flame retardant system composition, wherein the Si-PNC quaternary hybrid flame retardant system composition is prepared by the aforementioned preparation method.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The preparation method of the Si-PNC quaternary hybrid flame retardant system composition of the present invention involves first grafting graphene oxide onto a nitrogen-phosphorus flame retardant and a thermoplastic resin, and then mixing and modifying the grafted nitrogen-phosphorus flame retardant, thermoplastic resin, and modified wollastonite to obtain the Si-PNC quaternary hybrid flame retardant system composition. This design, based on modified wollastonite, utilizes a silane coupling agent to introduce a nitrogen-phosphorus flame retardant, thermoplastic resin, and graphene oxide. On the one hand, because the silane coupling agent possesses multiple active functional groups such as amino, epoxy, and vinyl groups, the resulting system composition exhibits excellent compatibility with the polymer matrix, thus possessing better mechanical and processing properties. On the other hand, the synergistic flame retardancy of Si, P, N, and C results in superior flame retardant performance. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the structure of the nitrogen-phosphorus flame retardant grafted with graphene oxide described in this invention.

[0020] Figure 2 This is a schematic diagram of the structure of the thermoplastic resin grafted with graphene oxide described in this invention.

[0021] Figure 3 This is a schematic diagram of the structure of the Si-PNC quaternary hybrid flame retardant system composition described in this invention. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings.

[0023] See Figure 1 A method for preparing a Si-PNC quaternary hybrid flame retardant system composition, the preparation method comprising:

[0024] S1. Add nitrogen-phosphorus flame retardant, thermoplastic resin and silane coupling agent to graphene oxide suspension, and obtain graphene oxide-grafted nitrogen-phosphorus flame retardant and graphene oxide-grafted thermoplastic resin through functionalization reaction.

[0025] S2. Mix the graphene oxide-grafted nitrogen-phosphorus flame retardant, the graphene oxide-grafted thermoplastic resin, the modified wollastonite, and the silane coupling agent to obtain the Si-PNC quaternary hybrid flame retardant system composition.

[0026] The nitrogen-phosphorus flame retardant is any one of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, melamine polyphosphate, and piperazine pyrophosphate.

[0027] The thermoplastic resin is either polyetheretherketone or MQ resin.

[0028] The silane coupling agent is any one of KH-550, KH-560, KH-570, and KH-590.

[0029] The modified wollastonite is prepared by placing wollastonite fibers and a silane coupling agent in a high-speed mixer and stirring at high speed to obtain modified wollastonite.

[0030] The mass ratio of the nitrogen-phosphorus flame retardant, thermoplastic resin, and silane coupling agent in S1 is 5-8:2-4:1-1.2; the mass ratio of the graphene-grafted nitrogen-phosphorus flame retardant, graphene-grafted thermoplastic resin, modified wollastonite, and silane coupling agent in S2 is 5-8:88-95:1-1.2.

[0031] The addition ratio of the nitrogen-phosphorus flame retardant to the graphene oxide suspension is 5-8g:0.5L; the concentration of the graphene oxide suspension is 5-8g / L.

[0032] The functionalization reaction conditions are: heating to 73-80℃ and refluxing under nitrogen for 10-12 hours.

[0033] In step S1, the reaction product obtained from the functionalization reaction is dried under vacuum at 105-110°C to obtain a nitrogen-phosphorus flame retardant grafted with graphene oxide and a thermoplastic resin grafted with graphene oxide.

[0034] A Si-PNC quaternary hybrid flame retardant system composition, wherein the Si-PNC quaternary hybrid flame retardant system composition is prepared by the aforementioned preparation method.

[0035] Example 1:

[0036] A method for preparing a Si-PNC quaternary hybrid flame retardant system composition comprises the following steps:

[0037] S1. 2.5 g of graphene oxide was suspended in 500 mL of tetrahydrofuran solvent and treated in an ultrasonic bath for 30 min to obtain a graphene oxide suspension. 50 g of nitrogen-phosphorus flame retardant, 30 g of thermoplastic resin, and 10 g of silane coupling agent were added to the obtained graphene oxide suspension while stirring. The mixture was then heated to 75 °C and refluxed under nitrogen for 12 h to carry out a functionalization reaction to obtain the reaction product. The reaction product was dried overnight under vacuum at 80 °C to remove the solvent, yielding a structure as shown below. Figure 1 The nitrogen-phosphorus flame retardant grafted with graphene oxide shown has the following structure: Figure 2 The thermoplastic resin grafted with graphene oxide shown is wherein the nitrogen-phosphorus flame retardant is 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO); the thermoplastic resin is polyetheretherketone; and the silane coupling agent is KH-550.

[0038] S2. Place 1000g of wollastonite fiber and 10g of silane coupling agent in a high-speed mixer and stir at high speed to obtain modified wollastonite; mix 5g of graphene oxide-grafted nitrogen-phosphorus flame retardant, 3g of graphene oxide-grafted thermoplastic resin and 90g of modified wollastonite, and then add 1g of silane coupling agent dropwise to obtain the structure as shown. Figure 3 The Si-PNC quaternary hybrid flame retardant system composition shown is described.

[0039] Example 2:

[0040] A method for preparing a Si-PNC quaternary hybrid flame retardant system composition comprises the following steps:

[0041] S1. 3g of graphene oxide was suspended in 500mL of tetrahydrofuran solvent and treated in an ultrasonic bath for 30min to obtain a graphene oxide suspension. 80g of a nitrogen-phosphorus flame retardant, 40g of thermoplastic resin, and 1.2g of silane coupling agent were added to the graphene oxide suspension while stirring. The mixture was heated to 75℃ and refluxed under nitrogen for 12h to carry out a functionalization reaction to obtain the reaction product. The reaction product was dried overnight under vacuum at 80℃ to remove the solvent, yielding a graphene oxide-grafted nitrogen-phosphorus flame retardant and a graphene oxide-grafted thermoplastic resin. The nitrogen-phosphorus flame retardant was piperazine pyrophosphate; the thermoplastic resin was MQ resin; and the silane coupling agent was KH-560.

[0042] S2. Place 1000g of wollastonite fiber and 10g of silane coupling agent in a high-speed mixer and stir at high speed to obtain modified wollastonite; mix 6.5g of graphene oxide-grafted nitrogen-phosphorus flame retardant, 4g of graphene oxide-grafted thermoplastic resin and 95g of modified wollastonite, and then add 1.2g of silane coupling agent dropwise to obtain the Si-PNC quaternary hybrid flame retardant system composition.

[0043] Example 3:

[0044] A method for preparing a Si-PNC quaternary hybrid flame retardant system composition comprises the following steps:

[0045] S1. 4g of graphene oxide was suspended in 500mL of tetrahydrofuran solvent and treated in an ultrasonic bath for 30min to obtain a graphene oxide suspension. 6g of a nitrogen-phosphorus flame retardant, 2g of thermoplastic resin, and 1.1g of silane coupling agent were added to the graphene oxide suspension while stirring. The mixture was heated to 75℃ and refluxed under nitrogen for 12h to carry out a functionalization reaction to obtain the reaction product. The reaction product was dried overnight under vacuum at 80℃ to remove the solvent, yielding a graphene oxide-grafted nitrogen-phosphorus flame retardant and a graphene oxide-grafted thermoplastic resin. The nitrogen-phosphorus flame retardant was melamine polyphosphate; the thermoplastic resin was MQ resin; and the silane coupling agent was KH-570.

[0046] S2. Place 1000g of wollastonite fiber and 10g of silane coupling agent in a high-speed mixer and stir at high speed to obtain modified wollastonite; mix 8g of graphene oxide-grafted nitrogen-phosphorus flame retardant, 5g of graphene oxide-grafted thermoplastic resin and 88g of modified wollastonite, and then add 1.1g of silane coupling agent dropwise to obtain the Si-PNC quaternary hybrid flame retardant system composition.

[0047] Example 4:

[0048] A method for preparing a Si-PNC quaternary hybrid flame retardant system composition comprises the following steps:

[0049] S1. 2.5g of graphene oxide was suspended in 500mL of tetrahydrofuran solvent and treated in an ultrasonic bath for 30min to obtain a graphene oxide suspension. 6g of a nitrogen-phosphorus flame retardant, 4g of thermoplastic resin, and 1g of silane coupling agent were added to the graphene oxide suspension while stirring. The mixture was heated to 75℃ and refluxed under nitrogen for 12h to carry out a functionalization reaction to obtain the reaction product. The reaction product was dried overnight under vacuum at 80℃ to remove the solvent, yielding a graphene oxide-grafted nitrogen-phosphorus flame retardant and a graphene oxide-grafted thermoplastic resin. The nitrogen-phosphorus flame retardant was melamine polyphosphate; the thermoplastic resin was MQ resin; and the silane coupling agent was KH-590.

[0050] S2. Place 1000g of wollastonite fiber and 10g of silane coupling agent in a high-speed mixer and stir at high speed to obtain modified wollastonite; mix 7g of graphene oxide-grafted nitrogen-phosphorus flame retardant, 5g of graphene oxide-grafted thermoplastic resin and 90g of modified wollastonite, and then add 1g of silane coupling agent dropwise to obtain the Si-PNC quaternary hybrid flame retardant system composition.

[0051] Comparative Example 1:

[0052] At room temperature, 90g of modified wollastonite, 5g of DOPO, 3g of polyether ether ketone, and 0.5g of graphene oxide were added to a high-speed mixer, and 1g of silane coupling agent KH550 was added dropwise. After high-speed stirring, a Si-PNC quaternary mixture was obtained.

[0053] Comparative Example 2:

[0054] 1000g of wollastonite fiber and 10g of silane coupling agent were placed in a high-speed mixer and stirred at high speed to obtain modified wollastonite.

[0055] Performance verification:

[0056] To verify that the system composition described in this invention possesses better mechanical properties and excellent flame retardant properties, flame-retardant synthetic resin compositions were obtained by adding 100 parts by weight of polypropylene (based on JIS K7210, with a load of 2.16 kg and a melt flow rate of 8 g / 10 min at 230°C) to a polypropylene resin composition, along with 0.1 parts by weight of calcium stearate (organic nucleating agent), 0.1 parts by weight of tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate methyl]methane (phenolic antioxidant), 0.1 parts by weight of tris(2,4-di-tert-butylphenyl) phosphite (phosphorus antioxidant), and 0.3 parts by weight of glyceryl monostearate (lubricant). Examples 1-4 and Comparative Examples 1-2 were then added to each of the obtained flame-retardant synthetic resin compositions. In the obtained flame-retardant synthetic resin compositions, the mass percentage of the products of Examples 1-4 and Comparative Examples 1-2 was 35%. The obtained flame-retardant synthetic resin composition was pressed at 220℃ and 5-15MPa for 15 min to obtain test pieces. Surface testing, flame retardancy testing, and oxygen index testing were performed on the test pieces.

[0057] Surface testing: The compatibility of nitrogen-phosphorus flame retardants, modified wollastonite, graphene oxide and polypropylene resin matrix is ​​determined by whether the surface of the test piece is smooth and whether there are white spots.

[0058] Flame retardancy test: A test piece was prepared as a strip with a length of 127 mm, a width of 12.7 mm, and a thickness of 1.6 mm. The strip was placed vertically and brought into contact with the flame of the burner at the lower end for 10 seconds. After removing the flame, the time it took for the flame to extinguish on the strip was measured. Then, after the first flame extinguishing, a second flame contact was conducted for 10 seconds, and the time it took for the flame to extinguish on the strip was measured again. Additionally, it was evaluated whether the cotton below the strip ignited due to a falling spark. Based on the burning times of the first and second tests and whether the cotton ignited, the flammability rating was determined according to the UL-94V standard. For the flammability rating, V-0 is the highest, with flame retardancy decreasing in the order of V-1 and V-2.

[0059] Oxygen Index Test: Prepare a test piece into a strip with a length of 150 mm, a width of 10 mm, and a thickness of 4 mm. Draw a line at 50 mm from one end and insert the other end into the sample holder of the combustion tube. Adjust the concentration of nitrogen and oxygen, and then ignite the top of the sample with an igniter for no more than 30 seconds. Remove the igniter and start timing immediately. The minimum oxygen concentration required for the sample to burn for exactly 3 minutes or 50 mm before naturally extinguishing is the oxygen index.

[0060] The test results are shown in Table 1:

[0061] Table 1. Results of surface testing, flame retardancy test, and oxygen index test.

[0062]

[0063]

[0064] As shown in Table 1, when the Si-PNC quaternary hybrid flame-retardant system compositions prepared in Examples 1-4 were added to the polypropylene resin composition at a dosage of 35 parts by mass, all the resulting test pieces passed the UL-94 flame retardancy test, with oxygen indices greater than 34. Furthermore, the test pieces had smooth surfaces without white spots, indicating good flame retardant and processing properties. In contrast, the test pieces obtained by adding Comparative Examples 1-2 as flame retardants to the polypropylene resin composition at a dosage of 35 parts by mass failed the UL-94 flame retardancy test, with oxygen indices of only 27 and 28, and rough surfaces with white spots, indicating that their flame retardant and processing properties were worse than those of Examples 1-4. These results demonstrate that the Si-PNC quaternary hybrid flame-retardant system compositions prepared in this invention possess superior flame retardant properties, as well as superior mechanical and processing properties.

[0065] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. A method for preparing a Si-PNC quaternary hybrid flame retardant system composition, characterized in that: The preparation method includes: S1. Add nitrogen-phosphorus flame retardant, thermoplastic resin and silane coupling agent to graphene oxide suspension, and obtain graphene oxide-grafted nitrogen-phosphorus flame retardant and graphene oxide-grafted thermoplastic resin through functionalization reaction. S2. Mix the nitrogen-phosphorus flame retardant grafted with graphene oxide, the thermoplastic resin grafted with graphene oxide, the modified wollastonite, and the silane coupling agent to obtain the Si-PNC quaternary hybrid flame retardant system composition. The mass ratio of the nitrogen-phosphorus flame retardant, thermoplastic resin, and silane coupling agent in S1 is 5-8:2-4:1-1.2; the mass ratio of the graphene-grafted nitrogen-phosphorus flame retardant, graphene-grafted thermoplastic resin, modified wollastonite, and silane coupling agent in S2 is 5-8:3-5:88-95:1-1.

2. The addition ratio of the nitrogen-phosphorus flame retardant to the graphene oxide suspension is 5-8g:0.5L; the concentration of the graphene oxide suspension is 5-8g / L. The nitrogen-phosphorus flame retardant is any one of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, melamine polyphosphate, and piperazine pyrophosphate. The thermoplastic resin is either polyetheretherketone or MQ resin.

2. The method for preparing a Si-PNC quaternary hybrid flame retardant system composition according to claim 1, characterized in that: The silane coupling agent is any one of KH-550, KH-560, KH-570, and KH-590.

3. The method for preparing a Si-PNC quaternary hybrid flame retardant system composition according to claim 1, characterized in that: The modified wollastonite is prepared by placing wollastonite fibers and a silane coupling agent in a high-speed mixer and stirring at high speed to obtain modified wollastonite.

4. The method for preparing a Si-PNC quaternary hybrid flame retardant system composition according to claim 1, characterized in that: The functionalization reaction conditions are: heating to 73-80℃ and refluxing under nitrogen for 10-12 hours.

5. The method for preparing a Si-PNC quaternary hybrid flame retardant system composition according to claim 1, characterized in that: In step S1, the reaction product obtained from the functionalization reaction is dried under vacuum at 105-110°C to obtain a nitrogen-phosphorus flame retardant grafted with graphene oxide and a thermoplastic resin grafted with graphene oxide.

6. A Si-PNC quaternary hybrid flame retardant system composition, characterized in that: The Si-PNC quaternary hybrid flame retardant system composition is prepared by the preparation method according to any one of claims 1-5.

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