A zinc ion grafted modified melamine pyrophosphate and a polypropylene flame retardant material

Abstract

The application provides a zinc ion grafted melamine pyrophosphate and a polypropylene flame retardant material, and belongs to the technical field of flame retardant raw material development. The zinc ion grafted melamine pyrophosphate is obtained through a specific preparation method, and the catalytic charring process and the target of stabilizing the carbon layer are realized. The design brings a synergistic effect to the intumescent flame retardant system, further improves the flame retardant effect, thereby reducing the demand amount of the flame retardant, and the mechanical properties of the material can be maintained. The innovation helps to reduce the preparation cost of the flame retardant material and improve the production efficiency. The application has important application prospect in the field of flame retardant materials, and promotes the development and innovation of the industry.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of flame retardant raw material development, and in particular to zinc ion grafted and modified melamine pyrophosphate and a polypropylene flame retardant material. BACKGROUND

[0002] Polypropylene (PP) is one of the five basic resins widely used in the current industry, and is widely used in many industries such as electronics, chemical industry and packaging due to its light weight, convenient processing and excellent chemical resistance. However, the flammable problem and low oxygen index of PP material limit its ignition when encountering fire. In severe combustion, PP not only releases a large amount of heat energy, but also produces a large amount of molten droplets attached to the flame, greatly increasing the risk of fire spread and posing a serious threat to people's life and property safety. Therefore, it is particularly important to improve the fire performance of PP material, which has a profound influence on its wider application and future development.

[0003] In the process of fireproof modification of PP material, there are many kinds of common flame retardant additives, including halogen-containing compounds, inorganic compounds, phosphorus-containing compounds, nitrogen-containing compounds and intumescent flame retardants. Among them, halogen-containing flame retardants are widely used due to their small addition amount and good flame retardant effect, but their high smoke emission and high toxicity limit their application field; inorganic flame retardants have low flame retardant efficiency and need to be filled in large amounts to meet the fireproof standard, and their poor compatibility with PP not only increases the processing difficulty but also reduces the mechanical strength of the polymer; although phosphorus-based flame retardants such as red phosphorus have excellent fireproof performance, they may release toxic gases such as PH3 during processing, and have poor compatibility with materials, which limits their application range; nitrogen-based flame retardants such as melamine cyanurate (MCA) and melamine (MA) have poor compatibility with materials, and when the filling amount is large, the dispersibility is poor, so the flame retardant efficiency is not high when they are used alone to flame retard polymer materials.

[0004] For the fireproof modification of PP system, intumescent flame retardant is a common choice. Among them, phosphorus-nitrogen intumescent system is considered to be more suitable for these systems, but due to its large addition amount, it will cause certain damage to the mechanical properties of the material and increase the processing difficulty.

[0005] Chinese patent CN103910907A discloses a preparation method of graphene oxide grafted modified melamine pyrophosphate flame retardant, comprising the following specific steps: melamine and anhydrous sodium pyrophosphate are added into distilled water, and the system is uniformly dispersed by fully stirring; the above system is added with graphene oxide colloidal solution uniformly dispersed by ultrasonic dispersion, and a dilute solution of a protonic acid serving as a catalyst and a stabilizer is added dropwise to adjust the pH value of the reaction system; the system is heated and stirred to react; after the reaction is completed, the reaction product is subjected to suction filtration, washing and drying to obtain the graphene oxide modified melamine pyrophosphate halogen-free flame retardant. The preparation method provided by the application is efficient, easy to operate and friendly to the environment, and the prepared halogen-free intumescent flame retardant has small particle size and high thermal stability, and can be used not only in a halogen-free system of polyolefin, but also in polyamide, polyester, rubber and intumescent fireproof coating.

[0006] However, other intumescent flame retardants with better performance still need to be developed in the prior art. SUMMARY

[0007] The application aims to provide a zinc ion grafted modified melamine pyrophosphate and a polypropylene flame retardant material, which have excellent flame retardant effect and can maintain the mechanical properties of the material while reducing the amount of flame retardant required.

[0008] In order to achieve the above application purposes, the application provides the following technical solutions.

[0009] The application provides a preparation method of zinc ion grafted modified melamine pyrophosphate, comprising the following steps.

[0010] Zinc pyrophosphate, melamine and water are mixed, and the temperature is increased to 70-90 DEG C to react, so as to obtain the zinc ion grafted modified melamine pyrophosphate.

[0011] Preferably, the molar ratio of the melamine to the zinc pyrophosphate is 1-2:1.

[0012] Preferably, the amount of water is 1-3 times the total weight of the melamine and the zinc pyrophosphate.

[0013] Preferably, the temperature increase is performed within 30 min.

[0014] After the temperature increase is completed, the pH value is adjusted.

[0015] The pH value is adjusted to 0.1-1.0.

[0016] The reagent used for adjusting the pH value is hydrochloric acid.

[0017] Preferably, the reaction time is 1-6 h.

[0018] The progress of the reaction includes first reacting for 1-2 hours, and then again heating to 70-90 DEG C in the middle, and reacting for 1-3 hours.

[0019] Preferably, the zinc ion grafted modified melamine pyrophosphate further includes filtering, washing and drying treatment;

[0020] The temperature of the drying treatment is 100-120 DEG C.

[0021] The application also provides the zinc ion grafted modified melamine pyrophosphate prepared by the above preparation method.

[0022] The application also provides the application of the above zinc ion grafted modified melamine pyrophosphate in preparing intumescent flame retardant.

[0023] The application also provides a polypropylene flame retardant material, and the raw materials of the polypropylene flame retardant material include polypropylene, silane coupling agent and the above zinc ion grafted modified melamine pyrophosphate.

[0024] Preferably, the addition amount of the silane coupling agent is 1-5 wt% based on the amount of polypropylene;

[0025] The addition amount of the flame retardant is 15-30 wt%.

[0026] The application has the following beneficial effects:

[0027] The application realizes the catalytic charring process and the goal of stabilizing the carbon layer by obtaining a zinc ion grafted modified melamine pyrophosphate through a specific preparation method. This design brings a synergistic effect to the intumescent flame retardant system, further improves the flame retardant effect, thereby reducing the demand amount of the flame retardant, and can maintain the mechanical properties of the material. This innovation helps to reduce the preparation cost of the flame retardant material and improve the production efficiency. The application has important application prospects in the field of flame retardant materials and promotes the development and innovation of the industry. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is the reaction principle diagram for the preparation method of the application;

[0029] Figure 2 It is the infrared spectrum of DMPY and Zn-DMPY. DETAILED DESCRIPTION

[0030] The application provides a preparation method of zinc ion grafted modified melamine pyrophosphate, including the following steps: mixing zinc pyrophosphate, melamine and water, heating to 70-90 DEG C to react, and obtaining zinc ion grafted modified melamine pyrophosphate.

[0031] In the present application, the molar ratio of the melamine and zinc pyrophosphate is preferably 1-2:1, the amount of water is preferably 1-3 times the total weight of melamine and zinc pyrophosphate, the temperature increase is preferably performed within 30 min; after the temperature increase is completed, it is also preferably followed by adjusting the pH; the pH adjustment is preferably adjusted to 0.1-1.0; the reagent used for the pH adjustment is preferably hydrochloric acid, the reaction time is preferably 1-6 h; the reaction process preferably includes first reacting for 1-2 h, then increasing the temperature to 70-90°C again, and reacting for 1-3 h; the zinc ion grafted modified melamine pyrophosphate also preferably includes filtration, washing and drying treatment; the drying temperature is preferably 100-120°C.

[0032] The preparation method of the present application is as shown in Figure 1

[0033] The present application also provides a zinc ion grafted modified melamine pyrophosphate prepared by the above preparation method.

[0034] The present application also provides the use of the above zinc ion grafted modified melamine pyrophosphate in the preparation of intumescent flame retardants.

[0035] The present application also provides a polypropylene flame retardant material, the raw materials of which include polypropylene, a silane coupling agent and the above zinc ion grafted modified melamine pyrophosphate; preferably, based on the amount of polypropylene, the addition amount of the silane coupling agent is 1-5 wt%, and the addition amount of the flame retardant is 15-30 wt%.

[0036] The technical solutions provided by the present application will be described in detail below in conjunction with the examples, but they should not be understood as limiting the scope of protection of the present application. Example

[0037] In a 500 mL four-necked flask equipped with a thermometer, a mechanical stirrer, an equal-pressure dropping funnel and a reflux condenser, zinc pyrophosphate, melamine and deionized water were added at room temperature, the molar ratio of melamine to zinc pyrophosphate was 2:1, and the amount of deionized water was 2 times the total amount of the raw materials. The reaction mixture was gradually heated to 80°C within 20 min, hydrochloric acid was added to adjust the pH of the reaction system to 0.1, and the reaction was continued for 1 h. Then the temperature was continuously increased to 80°C, and the reaction was continued for 1 h. After the reaction was completed, the reaction mixture was cooled to room temperature and filtered, the obtained white solid was washed several times with distilled water, and dried in an oven at 110°C to constant weight. Finally, a white solid powder product was obtained with a yield of 94%. Example

[0038] ​In a 500 mL four-necked flask, equipped with a thermometer, a mechanical stirrer, an equal-pressure dropping funnel and a reflux condenser, zinc pyrophosphate, melamine and deionized water were added at room temperature, the molar ratio of melamine to zinc pyrophosphate was 1:1, and the amount of deionized water was 2 times the total amount of raw materials. The reaction mixture was gradually heated to 80°C within 20 min, hydrochloric acid was added to adjust the pH of the reaction system to 0.2, and the reaction was continued for 1.5 h. Then continue to heat to constant temperature 80°C, continue to react for 1.5 h. After the reaction was completed, the reaction mixture was cooled to room temperature and filtered, and the white solid obtained was washed several times with distilled water and dried in an oven at 110°C to constant weight. The final white solid powder product was obtained with a yield of 93%. Example

[0039] In a 500 mL four-necked flask, equipped with a thermometer, a mechanical stirrer, an equal-pressure dropping funnel and a reflux condenser, zinc pyrophosphate, melamine and deionized water were added at room temperature, the molar ratio of melamine to zinc pyrophosphate was 2:1, and the amount of deionized water was 3 times the total amount of raw materials. The reaction mixture was gradually heated to 80°C within 20 min, hydrochloric acid was added to adjust the pH of the reaction system to 0.1, and the reaction was continued for 2 h. Then continue to heat to constant temperature 85°C, continue to react for 3 h. After the reaction was completed, the reaction mixture was cooled to room temperature and filtered, and the white solid obtained was washed several times with distilled water and dried in an oven at 110°C to constant weight. The final white solid powder product was obtained with a yield of 96%. Example

[0040] In a 500 mL four-necked flask, equipped with a thermometer, a mechanical stirrer, an equal-pressure dropping funnel and a reflux condenser, zinc pyrophosphate, melamine and deionized water were added at room temperature, the molar ratio of melamine to zinc pyrophosphate was 2:1, and the amount of deionized water was 2 times the total amount of raw materials. The reaction mixture was gradually heated to 80°C within 20 min, hydrochloric acid was added to adjust the pH of the reaction system to 0.5, and the reaction was continued for 1.5 h. Then continue to heat to constant temperature 70°C, continue to react for 1.5 h. After the reaction was completed, the reaction mixture was cooled to room temperature and filtered, and the white solid obtained was washed several times with distilled water and dried in an oven at 110°C to constant weight. The final white solid powder product was obtained with a yield of 93%. Example

[0041] In a 500 mL four-necked flask, equipped with a thermometer, a mechanical stirrer, an equal-pressure dropping funnel and a reflux condenser, zinc pyrophosphate, melamine and deionized water were added at room temperature, the molar ratio of melamine to zinc pyrophosphate was 1.5:1, and the amount of deionized water was 3 times the total amount of raw materials. The reaction mixture was gradually heated to 80°C within 20 min, hydrochloric acid was added to adjust the pH of the reaction system to 0.1-1.0, and the reaction was continued for 1-2 h. Then continue to heat to constant temperature 90°C, continue to react for 2 h. After the reaction was completed, the reaction mixture was cooled to room temperature and filtered, and the white solid obtained was washed with distilled water several times and dried in an oven at 110°C to constant weight. Finally, white solid powder product was obtained with a yield of 94%

[0042] The material prepared in Example 1 (denoted as Zn-DMPY) was subjected to infrared spectrum (FT-IR) analysis

[0043] The anti-symmetric stretching vibration doublet of N-H in -NH2 appeared at 3464 cm -1 and 3391 cm -1 ; the stretching vibration peak and the bending vibration peak of NH3 + appeared at 3121 cm -1 and 1518 cm -1 , respectively; the stretching vibration peak of P=O appeared at 1331 cm -1 , the stretching vibration peak of P-O appeared at 1167 cm -1 and 1067 cm -1 , the stretching vibration peak of P-OH appeared at 961 cm -1 , the stretching vibration peak of P-O-P appeared at 891 cm -1 , the characteristic peak of triazine ring was the stretching vibration peak of C=N at 1679 cm -1 , the stretching vibration peak of C-N at 1407 cm -1 , and the bending vibration peak of triazine ring at 779 cm -1 .

[0044] Comparing the infrared spectrum curves of Zn-DMPY and DMPY, the peak intensity at 961 cm -1 of the Zn-DMPY curve was weakened, and the peak intensity at 1167 cm -1 was increased, indicating that when the metal ion coordinates with the hydroxyl group on DMPY, it inhibits the appearance of the P-OH stretching vibration characteristic peak to some extent, and enhances the P-O stretching vibration characteristic peak intensity.

[0045] Preparation of melamine polyphosphate modified by metal ions (Zn-DMPY) / polypropylene (PP)

[0046] The dried PP (100 o C, 12h), Zn-DMPY and silane coupling agent were mixed in proportion, wherein the silane coupling agent was 3wt%, and the flame retardant was 18wt~25wt%. Extrusion was performed through a double screw extruder, cutting and granulation were performed through a cutter, and finally injection molding was performed through an injection molding machine to obtain standard samples for mechanical and combustion performance tests. According to the GB / T 1040-2018 standard, the tensile strength and bending strength of the PP composite were tested, the tensile speed was 10mm / min, and the sample size was 160×10×4mm 3 , the bending speed was 10mm / min, and the sample size was 80×10×4mm 3 . The impact test was performed according to the standard GB / T 1843-1996, and the sample size was 80×10×4mm 3 (V-shaped notch). The limiting oxygen index test was performed according to the standard GB / T 2406.2-2009, and the sample size was 10×10×4mm 3 ; the vertical burning test was performed according to the UL94 standard, and the sample size was 125×13×5mm 3 .

[0047] The results are shown in Tables 1~4 below.

[0048] Table 1. Flame retardant performance test data of PP and its composite

[0049] Performance test samples UL-94 LOI / % PP Burn 17.50 PP / 18% DMPY Burn 20.65 PP / 25% DMPY V-2 26.07 PP / 30% DMPY V-1 29.05 PP / 35% DMPY V-0 31.15 PP / 18% Zn-DMPY Burn 23.28 PP / 20% Zn-DMPY V-2 25.91 PP / 22% Zn-DMPY V-1 28.74 PP / 25% Zn-DMPY V-0 31.68

[0050] From the data in Table 1, we can see that in each system, the LOI increases with the increase of the amount of flame retardant, and the Zn-DMPY system has better flame retardant effect. When unmodified DMPY is added, the amount reaches 35% to reach UL-94 V-0 level. When the flame retardant system with Zn-DMPY is added, the amount is 25%, the LOI is 31.68 at this time, and it meets the UL-94 V-0 level, reaching a higher flame retardant requirement. The above all shows that zinc ions indeed play a synergistic effect in the flame retardant system.

[0051] Table 2. Mechanical performance test data of PP and its composite

[0052] From the data in Table 2, we can see that the mechanical properties of the flame retardant PP system relative to the pure system have a large decrease in general, which shows that the flame retardant plays a role in destroying the mechanical properties of the composite system to some extent. The difference of the flame retardant and the amount of addition affect the mechanical properties of the composite system. Under the same addition ratio, the mechanical properties of the Zn-DMPY flame retardant system after modification are better than those of the unmodified DMPY flame retardant system.

[0053] Table 3. Flame retardant performance test data of PP / Mg-DMPY, PP / Al-DMPY composite materials

[0054] Table 4. Mechanical performance test data of PP / Mg-DMPY, PP / Al-DMPY composite materials

[0055] From Table 3 and Table 4, it can be seen that, under the same addition ratio, the flame retardant performance and mechanical performance of the modified Zn-DMPY flame retardant system are superior to those of the Mg-DMPY flame retardant system and the Al-DMPY flame retardant system.

[0056] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, several improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A polypropylene flame retardant material, characterized in that, The raw material of the polypropylene flame-retardant material comprises polypropylene, silane coupling agent and zinc ion grafted modified melamine pyrophosphate; The preparation method of the zinc ion grafted modified melamine pyrophosphate comprises the following steps: Mixing zinc pyrophosphate, melamine and water, and heating to 70-90 DEG C to react, to obtain zinc ion grafted modified melamine pyrophosphate; The molar ratio of the melamine and zinc pyrophosphate is 1-2:1; The water is used in an amount of 1-3 times of the total weight of the melamine and zinc pyrophosphate; The heating is performed within 30 min; After the heating, pH is adjusted; The pH is adjusted to 0.1-1.0; The reagent for adjusting the pH is hydrochloric acid; The total reaction time is 1-6 h; The reaction process comprises first reacting for 1-2 h, and then heating to 70-90 DEG C again, and reacting for 1-3 h; The zinc ion grafted modified melamine pyrophosphate further comprises filtration, washing and drying treatment; The drying temperature is 100-120 DEG C.

2. The polypropylene flame retardant material of claim 1, wherein, The addition amount of the silane coupling agent is 1-5 wt% based on the amount of the polypropylene; The addition amount of the flame retardant is 15-30 wt%.

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