Macromolecular phosphorus-nitrogen flame-retardant composite material as well as preparation method and application thereof

Abstract

The invention provides a macromolecular phosphorus-nitrogen flame-retardant composite material as well as a preparation method and application thereof, and belongs to the technical field of flame retardants. The novel weather-resistant intumescent flame retardant is synthesized by introducing a metal catalyst, a polyfunctional group cross-linking agent and a synergist into a piperazine pyrophosphate and melamine phosphate system. A new method and a new formula are provided for an intumescent flame retardant system, the flame retardant effect of the phosphorus-nitrogen intumescent flame retardant in a polypropylene material is improved, the dispersity and the water resistance of the flame retardant in a base material are improved, the addition amount of the flame retardant is reduced, and the flame retardant efficiency is improved. And the migration resistance of the white powdery phosphorus-nitrogen intumescent flame retardant in a dark polypropylene material is also improved. The invention has important application prospects in the field of flame-retardant materials, and can promote the development and innovation of the industry.

Description

Technical Field

[0001] The invention relates to the technical field of flame retardants, and in particular to a macromolecular phosphorus-nitrogen flame retardant composite material and a preparation method and application thereof. Background Art

[0002] Polypropylene is a polymer formed by the addition polymerization of propylene. It is a white waxy material with a translucent appearance. It has the advantages of low density, low cost, and good comprehensive performance. It is widely used in household appliances, plastic pipes, construction, automobiles and other technical fields. However, due to the melting point of polypropylene at 189 °C and the heat deformation temperature at 105 °C, the rigidity is relatively poor and the dimensional shrinkage rate is large. In addition, the limiting oxygen index of polypropylene is low (17.4 ~ 18.5), the burning speed is fast, the heat is high, and it is accompanied by the phenomenon of molten droplets, which can easily cause fire. In order to improve its safety and practicality, in addition to meeting its relevant mechanical properties, it also needs to be flame-retardant modified.

[0003] In the field of flame retardant of polypropylene materials, intumescent flame retardant is the most important one. Halogen-free intumescent flame retardant (IFR) has excellent properties such as low smoke, non-toxic, halogen-free, and the formation of carbon layer can effectively prevent polymer droplets, which meets the current industry requirements of smoke suppression, low toxicity and high efficiency in the field of flame retardancy. Piperazine pyrophosphate is an intumescent flame retardant that integrates acid source, carbon source and gas source. It has the characteristics of high carbonization efficiency, good thermal stability and low hygroscopicity. However, due to the characteristics of low pH, high water solubility and easy moisture absorption of piperazine pyrophosphate, it has the problems of corroding the screw, easy precipitation, and easy agglomeration during storage. The low melt index of piperazine pyrophosphate and polypropylene materials in the process of extrusion sheet processing will cause poor dispersion during the extrusion sheet process, and the sheet will have quality defects such as pitting, white spots, and unstable flame retardant properties. At present, a large number of experiments have been conducted to improve the application of piperazine pyrophosphate in PP materials through compounding and modification. However, after compounding with melamine phosphate, although the amount of flame retardant added is reduced and the flame retardant performance is improved, due to the simple physical mixing, the problem of high water solubility and easy migration of the product always exists, resulting in the use of piperazine pyrophosphate and melamine phosphate compound products in PP materials being restricted, especially the problem of easy migration is particularly prominent in dark substrates. Summary of the invention

[0004] The purpose of the present invention is to provide a macromolecular phosphorus-nitrogen flame-retardant composite material, a preparation method and application thereof, by introducing a multifunctional cross-linking agent, a metal catalyst and a synergist into the compound system of piperazine pyrophosphate and melamine phosphate, the flame retardant performance and weather resistance of the compound flame retardant are effectively improved, and then a high flame retardant and high weather resistance PP material is synthesized.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions: The present invention provides a polymer, wherein the polymer comprises a structure as shown in the following formula 1: Formula 1 The value of n is an integer between 1 and 3.

[0006] The present invention also provides the use of the polymer as a flame retardant or in the preparation of a flame retardant.

[0007] The present invention also provides a method for preparing a macromolecular phosphorus-nitrogen flame retardant composite material, comprising the following steps: S1, mixing piperazine pyrophosphate, melamine phosphate and a metal catalyst, and obtaining a polymer 1 through a polymerization reaction; S2, mixing polymer 1, a synergist and a multifunctional cross-linking agent, and reacting to obtain a macromolecular phosphorus-nitrogen flame-retardant composite material.

[0008] Preferably, the mass ratio of the piperazine pyrophosphate to melamine phosphate is 1-3:1.

[0009] Preferably, in S1, the polymerization reaction time is 1.5 to 2.5 hours; The polymerization reaction temperature is 220-260°C; In S2, the mass ratio of the synergist to the cross-linking agent is 3:1.5-2.5; The total addition amount of the synergist and the cross-linking agent is 3-8 wt %.

[0010] Preferably, the metal catalyst is selected from one or more of ferric chloride, cupric chloride, cobalt chloride, nickel chloride, zinc chloride, magnesium oxide or aluminum oxide.

[0011] Preferably, the synergist is selected from one or more of PER, ALP, ODOPB, BDP, melam or melamine.

[0012] Preferably, the multifunctional crosslinking agent is selected from one or more of dioctylphosphoacyloxy titanate, 4-amino-1-butanol, 1,3,5-tris(trimethoxysilylpropyl)isocyanurate, N,N-methylenebisacrylamide, bis(2-hydroxyethyl)amino(trihydroxymethyl)methane or N-(β-aminoethyl)-γ-aminopropyltriethoxysilane.

[0013] The present invention also provides a macromolecular phosphorus-nitrogen flame retardant composite material prepared by the synthesis method.

[0014] The present invention also provides a flame retardant material, comprising a plastic substrate and a flame retardant; the flame retardant contains the above polymer or the above macromolecular phosphorus-nitrogen flame retardant composite material.

[0015] Beneficial effects of the present invention: The present invention introduces a metal catalyst, a multifunctional crosslinking agent and a synergist into a system of piperazine pyrophosphate and melamine phosphate. The metal catalyst plays a certain catalytic promotion role, the crosslinking agent plays a bridge role in the compounding system, and the crosslinking agent contains a large number of multifunctional functional groups, which increases the molecular weight while also increasing the dispersibility of the macromolecule, so that the macromolecular flame retardant itself has a certain self-lubricating effect. The synergist mainly improves the anti-dripping property, smoke suppression property and carbonization property. A new type of weather-resistant intumescent flame retardant is synthesized by the joint action of the metal catalyst, the multifunctional crosslinking agent and the synergist, and then a composite material with high weather resistance and high flame retardancy is synthesized with a polypropylene material. The present invention provides a new method and a new formula for an intumescent flame retardant system, which improves the flame retardant effect of the phosphorus-nitrogen intumescent flame retardant in the polypropylene material while maintaining a small change in the mechanical properties of the substrate itself, improves the dispersibility and water resistance of the flame retardant in the substrate, reduces the amount of the flame retardant added, and improves the migration resistance of the white powdery phosphorus-nitrogen intumescent flame retardant in the dark polypropylene material. The present invention has important application prospects in the field of flame retardant materials and may promote the development and innovation of the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A synthetic route for modified piperazine pyrophosphate / melamine phosphate polymers; Figure 2 is the infrared spectrum of the modified piperazine pyrophosphate / melamine phosphate complex; Figure 3 is the thermogravimetric analysis diagram of the modified piperazine pyrophosphate / melamine phosphate complex; Figure 4 This is the weather resistance result diagram of piperazine pyrophosphate / melamine phosphate composite before modification; Figure 5 This is the weather resistance result of the modified piperazine pyrophosphate / melamine phosphate complex. DETAILED DESCRIPTION

[0017] The technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0018] Example 1. Synthesis of modified piperazine pyrophosphate / melamine phosphate polymer The composite nitrogen-phosphorus intumescent flame retardant is prepared by adding a metal catalyst, a cross-linking agent and a synergist. The synthesis route is as follows: Figure 1 As shown, n = 1 ~ 3, PPAP: MP = (1 ~ 3): 1, the unmodified polymer is referred to as MPA, and the modified polymer is referred to as MPA-HWR.

[0019] The specific steps are as follows: In a 10 L kneader, piperazine pyrophosphate and melamine phosphate were added at room temperature, wherein the mass ratio of piperazine pyrophosphate to melamine phosphate was 2: 1, and the metal catalyst was 5 wt%. The system temperature was raised to 240°C under a nitrogen atmosphere, and the reaction was stirred for 2 hours to terminate the reaction, and then cooled to room temperature to obtain a polymer MPA. The obtained polymer MPA was added to a stirring kettle at room temperature, and a synergist and a multifunctional cross-linking agent were added in turn and stirred at room temperature for 2 hours to obtain a white solid powder product MPA-HWR with a yield of 95% to 98%. The mass ratio of the synergist to the cross-linking agent was 3: 2, and the total addition amount was 5 wt%.

[0020] The metal catalyst is selected from ferric chloride; The synergist is selected from PER; The multifunctional crosslinking agent is selected from dioctylphosphoacyloxytitanate.

[0021] 2. Infrared spectroscopy (FT-IR) analysis Through infrared spectroscopy analysis, the product structure was characterized, such as Figure 2 shown. Figure 2 The double peak of the antisymmetric stretching vibration of NH in -NH2 appears at 3464 cm -1 and 3391cm -1 NH3 + The stretching vibration peak and bending vibration peak appear at 3121cm -1 and 1518 cm -1 The absorption peak of CC appears at 1266 cm -1 ; The stretching vibration peak of P=O appears at 1138 cm -1 The stretching vibration peak of PO appears at 1167 cm -1 and 1067 cm -1 The stretching vibration peak of P-OH appears at 974 cm -1 The stretching vibration peak of POP appears at 882 cm -1 The characteristic peak of triazine ring is 1673 cm -1 The stretching vibration peak of C=N at 1455 cm -1 The stretching vibration peak of CN at 779 cm -1 The triazine ring bending vibration front at.

[0022] 3. Thermogravimetric analysis In order to meet the processing requirements of plastics, flame retardants must have good thermal stability. The thermal stability of the modified composites was evaluated by thermogravimetric analysis. Figure 3 .Depend on Figure 3It can be seen that the decomposition temperature is 270 ℃, and the temperatures at which the modified composite loses 1.0%, 2.0% and 5.0% of its weight are 274 ℃, 278 ℃ and 289 ℃ respectively. When the composite loses 10% of its weight, the temperature exceeds 300 ℃. This shows that the composite flame retardant has good thermal stability.

[0023] 4. Comparison of migration resistance of modified composite flame retardant in black polypropylene material, see Figures 4 and 5 : The composite flame retardants before and after modification were added to black polypropylene materials respectively, and the weather resistance of the two boards was compared in a double 85 environment. White spots appeared on the surface of sample a, while no white spots precipitated on sample b, indicating that the unmodified flame retardant compound precipitated in the polypropylene material, and the modified composite flame retardant was relatively stable in the polypropylene material.

[0024] 5. Preparation of modified piperazine pyrophosphate / melamine phosphate polymer / polypropylene The dried PP (100 ℃, 12 h), modified composite flame retardant, lubricant, and antioxidant are mixed in a certain proportion. The lubricant antioxidant is 0.5 wt% -1.5 wt%, and the flame retardant is 10 wt% -25 wt%. Under certain process parameters, it is extruded by a twin-screw extruder, cut and granulated by a pelletizer, and finally injection molded by an injection molding machine to obtain standard specimens for mechanical and combustion performance tests. The tensile strength and flexural strength of PP composite materials are tested according to GB / T 1040-2018 standard, the tensile speed is 10 mm / min, and the specimen size is 160×10×4 mm 3 , bending speed 10 mm / min, specimen size 80×10×4 mm 3 The impact test is in accordance with GB / T 1843-1996, and the sample size is 80×10×4 mm 3 (V-notch). Limiting oxygen index test is based on GB / T 2406.2-2009 standard, sample size is 10×10×4mm 3 ; Vertical burning test: According to UL-94 standard, the sample size is 125×13×5 mm 3 .

[0025] Table 1 Flame retardant test data of PP and its composites Performance test samples UL-94 LOI / % PP combustion 17.50 PP / 10%MPA-HWR combustion 23.22 PP / 15%MPA-HWR V-1 26.07 PP / 20%MPA-HWR V-0 31.21 PP / 25%MPA-HWR V-0 31.40 As can be seen from Table 1, when no flame retardant is added, the LOI value of PP material is 17.50, which is a flammable material. When the addition amount of MPA-HWR flame retardant is 10 wt%, the LOI value increases to 23.22. As the flame retardant MPA-HWR increases, the LOI value also increases. When the addition amount of flame retardant MPA-HWR is 20 wt%, UL-94 reaches V-0 level, and the LOI value is 31.21, which has reached the flame retardant level. When the flame retardant is added by 25 wt%, the combustion level remains unchanged, and the LOI value increases slightly. The above data show that the flame retardant MPA-HWR has high flame retardant properties.

[0026] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A polymer, characterized in that The polymer comprises a structure as shown in Formula 1 below: Formula 1 The value of n is an integer between 1 and 3.

2. Use of the polymer according to claim 1 as a flame retardant or in the preparation of a flame retardant.

3. A method for preparing a macromolecular phosphorus-nitrogen flame retardant composite material, characterized in that: The following steps are involved: S1, mixing piperazine pyrophosphate, melamine phosphate and a metal catalyst to obtain a polymer 1 through a polymerization reaction; S2, mixing polymer 1, a synergist and a multifunctional cross-linking agent, and reacting to obtain a macromolecular phosphorus-nitrogen flame-retardant composite material.

4. The preparation method according to claim 3, characterized in that: The mass ratio of the piperazine pyrophosphate to melamine phosphate is 1-3:

1.

5. The preparation method according to claim 3, characterized in that: In S1, the polymerization reaction time is 1.5 to 2.5 hours; The polymerization reaction temperature is 220-260°C; In S2, the mass ratio of the synergist to the cross-linking agent is 3:1.5-2.5; The total addition amount of the synergist and the cross-linking agent is 3-8 wt %.

6. The preparation method according to claim 3, characterized in that: The metal catalyst is selected from one or more of ferric chloride, cupric chloride, cobalt chloride, nickel chloride, zinc chloride, magnesium oxide or aluminum oxide.

7. The preparation method according to claim 3, characterized in that: The synergist is selected from one or more of PER, ALP, ODOPB, BDP, melam or melamine.

8. The preparation method according to claim 3, characterized in that: The multifunctional crosslinking agent is selected from one or more of dioctylphosphoacyloxy titanate, 4-amino-1-butanol, 1,3,5-tris(trimethoxysilylpropyl)isocyanurate, N,N-methylenebisacrylamide, bis(2-hydroxyethyl)amino(trihydroxymethyl)methane or N-(β-aminoethyl)-γ-aminopropyltriethoxysilane.

9. A macromolecular phosphorus-nitrogen flame retardant composite material prepared by the preparation method according to any one of claims 3 to 8.

10. A flame retardant material, characterized in that: Includes plastic substrates and flame retardants; The flame retardant contains the polymer described in claim 1 or the macromolecular phosphorus-nitrogen flame retardant composite material described in claim 9.

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