Preparation method of aminophosphorylated nano calcium / phosphorus-nitrogen agent synergistic flame-retardant polypropylene material

Abstract

The invention discloses a preparation method of an aminophosphorylated nano calcium / phosphorus-nitrogen agent synergistic flame-retardant polypropylene material, which comprises the following steps: adding 10-20g of nano calcium carbonate into 200mL of absolute ethyl alcohol or deionized water, and treating for 30 minutes by using an ultrasonic dispersion instrument; the preparation method comprises the following steps: dissolving 5-15g of a phosphorus source compound in deionized water; slowly adding a phosphorus source compound and a nitrogen source compound into the nano calcium carbonate dispersion liquid; putting the mixed solution on a magnetic stirrer, and reacting for several hours; regulating the pH value of the reaction system to be neutral by using NaOH or HCl; after the reaction is finished, washing the nano calcium carbonate with deionized water for multiple times, carrying out vacuum drying at 80 DEG C after centrifugal washing, and crushing to obtain phosphorus-nitrogen flame-retardant nano calcium carbonate; the preparation method comprises the following steps: mixing phosphorus-nitrogen flame-retardant nano calcium carbonate with dried polypropylene, a phosphorus-nitrogen flame retardant and an antioxidant at a high speed, carrying out melt blending granulation by virtue of a double-screw extruder, and finally carrying out injection molding by virtue of an injection molding machine, so as to obtain the phosphoramidated nano calcium / phosphorus-nitrogen agent synergistic flame-retardant polypropylene material / phosphorus-nitrogen flame retardant compounded flame-retardant polypropylene composite material.

Description

TECHNICAL FIELD

[0001] The application relates to the field of high polymer material flame-retardant technology, in particular to a preparation method of amino-phosphated nano calcium / phosphorus-nitrogen agent synergistic flame-retardant polypropylene material. BACKGROUND

[0002] Polypropylene (PP) is widely used in the fields of automobiles and electronics due to its light weight and chemical resistance, but its limiting oxygen index (LOI) is only 17%-18%, belonging to flammable materials. Traditional flame-retardant schemes have obvious defects: halogen-based flame retardants (such as decabromodiphenyl ether) release toxic gases during combustion; aluminum / magnesium hydroxide needs to be added by more than 50 wt% to be effective, which seriously damages the mechanical properties; phosphorus-nitrogen flame retardants have low efficiency when used alone, and the LOI is limited and easy to migrate and precipitate. Nano calcium carbonate (CaCO3) as a cheap filler can improve the rigidity of PP, but the hydrophilic surface leads to agglomeration, and has no contribution to flame retardant. In the prior art, although the modification of CaCO3 by silane coupling agent improves the dispersibility, the silane coupling agent is easy to decompose at high temperature; the CaCO3 coated with stearic acid has poor compatibility with the flame retardant. Therefore, it is urgent to develop a synergistic system with efficient flame retardation, mechanical enhancement and environmental friendliness. SUMMARY

[0003] In view of the above problems, the application provides a preparation method of amino-phosphated nano calcium / phosphorus-nitrogen agent synergistic flame-retardant polypropylene material, which can effectively solve the problems of poor stability, low flame-retardant efficiency, poor compatibility with resin and low mechanical properties of flame-retardant PP of existing flame retardants.

[0004] According to one object of the application, the application provides a preparation method of amino-phosphated nano calcium / phosphorus-nitrogen agent synergistic flame-retardant polypropylene material, which comprises the following steps: Step 1), 10-20 g of nano calcium carbonate is taken and added into 200 mL of anhydrous ethanol or deionized water, and treated by an ultrasonic wave dispersing instrument for 30 minutes; Step 2), an appropriate amount of a phosphorus source compound is dissolved in an appropriate amount of deionized water; at the same time, the phosphorus source compound and an appropriate amount of a nitrogen source compound are slowly added into the nano calcium carbonate dispersion liquid; Step 3), the mixed liquid in step 2) is placed on a magnetic stirrer and reacted for several hours; NaOH or HCl is used to adjust the pH of the reaction system to neutral; Step 4), after the reaction is completed, the nano calcium carbonate is washed with deionized water for multiple times, centrifugally washed, vacuum dried at 80 DEG C, and crushed to obtain phosphorus-nitrogen flame-retardant nano calcium carbonate (P-N-CaCO3); Step 5), the phosphorus-nitrogen flame retardant nano calcium carbonate in step 4) is mixed with dried polypropylene, a phosphorus-nitrogen flame retardant and an antioxidant at high speed, then is melt blended and granulated through a double-screw extruder, and finally is injection molded through an injection molding machine to obtain an amino-phosphated nano calcium carbonate / phosphorus-nitrogen agent synergistic flame-retardant polypropylene material / phosphorus-nitrogen flame-retardant polypropylene composite material.

[0005] Further, in step 2), the content of the phosphorus source compound is 5-15 g; the phosphorus source compound is sodium hexametaphosphate; and the content of the nitrogen source compound is 10-20% of the mass of the nano calcium carbonate; the nitrogen source compound is urea or amino-methylene phosphonic acid.

[0006] Further, in step 3), the reaction temperature is 50-70°C; and the reaction time is 3-6 h.

[0007] Further, in step 5), the phosphorus-nitrogen flame retardant is ammonium polyphosphate (APP, the degree of polymerization is greater than or equal to 1000); and the antioxidant is 1010.

[0008] Further, in step 5), according to weight parts, the polypropylene is 60-70 parts, the phosphorus-nitrogen flame retardant is 20-30 parts, the phosphorus-nitrogen synergistically modified nano calcium carbonate is 5-10 parts, and the antioxidant is 0.5 part.

[0009] Further, in step 5), the temperature range of the extruder is 190-210°C; the rotation speed of the feeder is 7 rpm, and the rotation speed of the main machine is 8 rpm; the temperature range of the injection molding machine is 200-210°C, the injection pressure is 70 MPa, and the cooling time is 15-20 s.

[0010] The present application has the following beneficial effects: The amino / phosphated synergistically modified CaCO3 acts as a flame-retardant synergistic agent and a reinforcing filler, on the one hand, and on the other hand, the alkyl chains on the surface of the amino / phosphated synergistically modified CaCO3 are entangled with the molecular chains of PP to improve the interfacial bonding force. 2+ The P and N elements on the surface of the amino / phosphated synergistically modified CaCO3 have a synergistic effect in the combustion process, can replace part of the high-priced APP, and significantly reduce the overall cost. The amino / phosphated synergistically modified CaCO3 is coated with a large number of amino and phosphonic groups, and it is difficult to directly contact with APP, thereby overcoming the side effects between traditional nano calcium carbonate and APP and reducing the flame-retardant efficiency of APP. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 The present application has the following beneficial effects: Figure 2Flame Retardant PP Bending Modulus and Impact Performance Chart Figure 3 Flame Retardant PP Thermogravimetric Curve Chart. DETAILED DESCRIPTION

[0012] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0013] Embodiment 1 A preparation method of an aminophosphorylated nano calcium / phosphorus-nitrogen agent synergistic flame-retardant polypropylene material, comprising the following steps: Step 1), 10-20 g of nano calcium carbonate is taken and added to 200 mL of anhydrous ethanol or deionized water, and treated by an ultrasonic wave dispersing instrument for 30 minutes; Step 2), 5-15 g of sodium hexametaphosphate is taken and dissolved in an appropriate amount of deionized water; at the same time, 10-20% of a nitrogen source compound (urea or aminomethylene phosphonic acid) is slowly added to the nano calcium carbonate dispersion liquid; Step 3), the mixed solution of step 2) is placed on a magnetic stirrer and reacted at 50-70°C for 3-6 hours; during the reaction, NaOH or HCl is used to adjust the pH of the reaction system to neutral; Step 4), after the reaction is completed, the nano calcium carbonate is washed with deionized water for multiple times, centrifuged and washed, and then vacuum dried at 80°C to obtain phosphorus-nitrogen flame-retardant nano calcium carbonate.

[0014] Step 5), the phosphorus-nitrogen flame-retardant nano calcium carbonate of step 4) is mixed at high speed with dried polypropylene, APP, and antioxidant 1010 (according to the weight parts, polypropylene 69.5 parts, phosphorus-nitrogen flame retardant 25 parts, phosphorus-nitrogen synergistically modified nano calcium carbonate 5 parts, and antioxidant 0.5 part), and then melt blended and granulated by a double-screw extruder (the temperature interval of the extruder is 190-210°C; the rotation speed of the feeder is 7 rpm, and the rotation speed of the main machine is 8 rpm), and finally, injection molding is performed by an injection molding machine (the temperature interval of the injection molding machine is 200-210°C, the injection pressure is 70 MPa, and the cooling time is 15-20 s), to obtain an aminophosphorylated synergistically modified nano calcium carbonate, an aminophosphorylated nano calcium / phosphorus-nitrogen agent synergistic flame-retardant polypropylene material, and a phosphorus-nitrogen flame-retardant polypropylene composite material.

[0015] Figure 1 and Figure 2The mechanical properties of the aminophosphorylation synergistic modified nano-calcium carbonate, aminophosphorylated nano-calcium / phosphorus nitrogen agent synergistic flame retardant polypropylene material / phosphorus nitrogen flame retardant compound flame retardant polypropylene composite material of the present invention are shown in the figure.

[0016] like Figure 1 As shown, the flexural strength of pure PP is 31.0 MPa. After adding 30% APP, the flexural strength of the PP+30% APP composite increases to 34.0 MPa. When 25% APP+5% PN-CaCO3 is added, the flexural strength of flame-retardant PP increases to 36.8 MPa, which is 18.7% higher than that of pure PP. This indicates that the synergistic use of APP and PN-CaCO3 can improve the flexural strength of flame-retardant PP.

[0017] like Figure 2 As shown, the flexural modulus and impact strength of pure PP are 780.6 MPa and 7.24 kJ / m, respectively. 2 After adding 25% APP + 5% PN-CaCO3, the flexural modulus and impact strength of flame-retardant PP increased to 1491.2 MPa and 10.75 kJ / m², respectively. 2 .

[0018] Figure 3 Here is the TG diagram of this flame-retardant PP, as shown. Figure 3 As shown, pure PP decomposes completely at high temperatures, leaving no residue. After adding 30% APP, the PP composite material begins to degrade at lower temperatures, with a residue weight of 4.4% at 700℃. When 25% APP + 5% PN-CaCO3 are added, the residue weight of flame-retardant PP at 700℃ is 21.0%, indicating that the synergistic addition of APP and PN-CaCO3 can promote the char formation of flame-retardant PP.

[0019] Table 1. Comparison of flame-retardant PP combustion performance.

[0020] As shown in Table 1, the LOI value of pure PP is 17.2, with no flammability rating, and it exhibits severe dripping during combustion. After adding 30% APP, the LOI of the PP composite material reaches 26.5%, with a flame retardancy rating of V-1, and slight dripping occurs during combustion. When 25% APP + 5% PN-CaCO3 are added, the LOI value of the flame-retardant PP increases to 32.3%, the flame retardant rating reaches V-0, and there is no dripping during combustion. This indicates that the synergistic use of APP and PN-CaCO3 can significantly improve the flame retardancy of flame-retardant PP.

[0021] The synergistic flame-retardant mechanism of the amino / phosphorylated modified nano calcium carbonate is that the amino and phosphoric acid groups are firmly grafted on the surface of CaCO3 through Ca-O-P covalent bond; the exposed -NH2 groups form a P-N-H hydrogen bond network with the phosphorus-nitrogen flame retardant (APP), thereby inhibiting the migration of the flame retardant; and the amino / phosphorylated synergistically modified CaCO3 promotes the densification of the carbon layer during combustion.

[0022] The present application has a dual function of a complex system, uses inorganic flame retardant in combination with a phosphorus-nitrogen complex scheme, can fully combine the advantages of each other, complement each other's deficiencies, and improve the flame-retardant efficiency; the rigid core of the amino / phosphorylated synergistically modified CaCO3 improves the mechanical properties of PP, and the surface alkyl chain (-R) improves the interfacial compatibility.

[0023] Compared with the traditional flame-retardant PP preparation technology, the present application uses a "one-dose dual-effect" modification design, and the amino / phosphorylated synergistically modified CaCO3 simultaneously acts as a flame-retardant synergist and a reinforcing filler, on the one hand, the Ca 2+ catalyzes the crosslinking of the carbon layer, and on the other hand, the surface alkyl chain is entangled with the PP molecular chain, thereby improving the interfacial bonding force. This technology has environmental protection and cost advantages, the halogen-free formula in the preparation process meets the RoHS directive, at the same time, the water-based modification process used does not discharge organic solvents, and will not pollute the environment. The P and N elements on the surface of the amino / phosphorylated synergistically modified CaCO3 have a synergistic effect in the combustion process, can replace part of the high-priced APP, and the comprehensive cost is significantly reduced. The surface of the amino / phosphorylated synergistically modified CaCO3 is covered by a large number of amino and phosphoric acid groups, which is difficult to directly contact with APP, thereby overcoming the side effects of the reaction between the traditional nano calcium carbonate and APP, and reducing the problem of the flame-retardant efficiency of APP. The amino on the surface of the amino / phosphorylated synergistically modified CaCO3 forms an ionic bond with the phosphoric acid group of APP, thereby inhibiting the migration of the flame retardant to the surface of PP, and making it have higher long-term stability. When P-N-CaCO3 is used in combination with APP, more inert gases such as CO2 and NH3 are generated, thereby diluting oxygen and inhibiting combustion; at the same time, the calcium oxide, P and N elements generated after the decomposition of P-N-CaCO3 form a "phosphorus-nitrogen-calcium" crosslinked carbon layer through a chemical reaction, thereby further delaying combustion.

[0024] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing aminophosphated nano-calcium / phosphonitrile agent synergistic flame-retardant polypropylene material, characterized in that, The method comprises the following steps: Step 1), 10-20 g of nano calcium carbonate is taken and added into 200 mL of anhydrous ethanol or deionized water, and treated by an ultrasonic disperser for 30 minutes; Step 2), 5-15 g of a phosphorus source compound is dissolved in deionized water; meanwhile, the phosphorus source compound and a nitrogen source compound are slowly added into the nano calcium carbonate dispersion liquid; Step 3), the mixture in step 2) is placed on a magnetic stirrer and reacted for several hours; NaOH or HCl is used to adjust the pH of the reaction system to neutral; Step 4), after the reaction is completed, the nano calcium carbonate is washed with deionized water for multiple times, dried at 80°C under vacuum after centrifugal washing, and crushed to obtain a phosphorus-nitrogen flame-retardant nano calcium carbonate; Step 5), the phosphorus-nitrogen flame-retardant nano calcium carbonate in step 4) is mixed with dried polypropylene, a phosphorus-nitrogen flame-retardant agent and an antioxidant at high speed, then melt-blended, granulated by a double-screw extruder, and finally injection molded by an injection molding machine to obtain a phosphorus-nitrogen flame-retardant nano calcium carbonate / ammonium phosphonate / phosphorus-nitrogen agent synergistic flame-retardant polypropylene material / phosphorus-nitrogen flame-retardant agent compounded flame-retardant polypropylene composite material.

2. The method of preparing aminophosphated nanocalcium / phosphonitrilic agent synergistic flame-retardant polypropylene material according to claim 1, characterized in that, In step 2), the phosphorus source compound is sodium hexametaphosphate; the nitrogen source compound is urea or aminomethylene phosphonic acid, and the content of the nitrogen source compound is 10-20% of the mass of the nano calcium carbonate.

3. The method of preparing the aminophosphorylated nano-calcium / phosphonitrilic agent synergistic flame-retardant polypropylene material according to claim 1, characterized in that, In step 3), the reaction temperature is 50-70°C, and the reaction time is 3-6 h.

4. The method of preparing the aminophosphorylated nano-calcium / phosphonitrilic agent synergistic flame-retardant polypropylene material according to claim 1, characterized in that, In step 5), the phosphorus-nitrogen flame-retardant agent is ammonium polyphosphate APP with a polymerization degree of ≥1000; and the antioxidant is 1010.

5. The method of preparing aminophosphated nanocalcium / phosphonitrilic agent synergistic flame retardant polypropylene material according to claim 1, characterized in that, In step 5), according to weight parts, the polypropylene is 60-70 parts, the phosphorus-nitrogen flame-retardant agent is 20-30 parts, the phosphorus-nitrogen synergistically modified nano calcium carbonate is 5-10 parts, and the antioxidant is 0.5 part.

6. The process for preparing the aminophosphorylated nano-calcium / phosphonitrilic agent synergistic flame-retardant polypropylene material according to claim 1, characterized in that, In step 5), the temperature range of the extruder is 190-210°C; the rotation speed of the feeder is 7 rpm, and the rotation speed of the main machine is 8 rpm; the temperature range of the injection molding machine is 200-210°C, the injection pressure is 70 MPa, and the cooling time is 15-20 s.

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