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CN-121991411-A - Difunctional ammonium polyphosphate flame retardant, preparation method thereof and flame-retardant thermoplastic polyurethane composite material

CN121991411ACN 121991411 ACN121991411 ACN 121991411ACN-121991411-A

Abstract

The invention relates to the technical field of flame retardants, and relates to a difunctional ammonium polyphosphate flame retardant, a preparation method thereof and a flame-retardant thermoplastic polyurethane composite material. The difunctional ammonium polyphosphate flame retardant with two functional groups is prepared by carrying out surface grafting modification on the crystal II ammonium polyphosphate by amine, ethanolamine and maleic anhydride containing terminal amino groups, and the flame retardant is applied to thermoplastic polyurethane TPU, so that the flame retardant can not only remarkably improve the flame retardant property of a composite material, but also maintain the mechanical strength of a matrix to the greatest extent.

Inventors

  • YU HONGLIANG
  • ZHANG YAN
  • CAO ZHENHU
  • FENG JIABING
  • MA CHANGCHANG

Assignees

  • 生阳新材料科技（宁波）有限公司

Dates

Publication Date
20260508
Application Date
20260409

Claims (10)

  1. 1. The difunctional ammonium polyphosphate flame retardant is characterized by having a structural formula shown in the following formula (1): Formula (1); wherein n >1000; r 1 includes at least one of -(CH 2 ) x -、-(CH 2 CH 2 NH) y -CH 2 CH 2 -、-(CH 2 CH 2 NH) z -; x is more than or equal to 2 and less than or equal to 6, and 1 is more than or equal to 1 y is less than or equal to 4, and z is more than or equal to 10.
  2. 2. The bifunctional ammonium polyphosphate flame retardant of claim 1, wherein the bifunctional ammonium polyphosphate flame retardant has two functional groups grafted to a crystalline type II ammonium polyphosphate backbone, the first functional group being a hydroxyethylamino group and the second functional group being an alkylene amino group or a polyalkyleneamino group having a maleimido group attached at the end.
  3. 3. The difunctional ammonium polyphosphate flame retardant of claim 1, wherein R 1 is derived from at least one of a C2-C6 alkyl diamine having 2 terminal amino groups, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine or polyethyleneimine.
  4. 4. A method of preparing the difunctional ammonium polyphosphate flame retardant of claim 1, comprising the steps of: Adding the crystal II ammonium polyphosphate into a mixed solution, heating to a reflux temperature of 75-95 ℃, dropwise adding amine and ethanolamine containing terminal amino groups, continuously stirring at the reflux temperature for 1-12 hours, after the reaction is finished, performing suction filtration, washing and drying to obtain a precursor, adding the precursor into an organic solvent, heating to a reaction temperature of 30-50 ℃, dropwise adding an organic solvent solution of maleic anhydride, then stirring at the reaction temperature for 1-12 hours, and after the reaction is finished, performing suction filtration, washing and drying to obtain the difunctional ammonium polyphosphate.
  5. 5. The method for preparing a bifunctional ammonium polyphosphate flame retardant of claim 4, wherein the mixed solution is a mixed solution of water and at least one of alcohol and dimethylformamide; The volume ratio of water in the mixed solution is 2-10vol%; And/or the alcohol comprises at least one of ethanol, methanol, ethylene glycol, or isopropanol.
  6. 6. The method for preparing a difunctional ammonium polyphosphate flame retardant according to claim 4, wherein the mass to volume ratio of the crystalline form II ammonium polyphosphate to the mixed solution is (10-50) g (100-500) mL; The mass ratio of the crystal II-type ammonium polyphosphate to the ethanolamine is (5-35) 1.
  7. 7. The method for producing a bifunctional ammonium polyphosphate flame retardant according to claim 4, wherein the molar ratio of maleic anhydride to amine containing terminal amino groups in the organic solvent solution of maleic anhydride is 1 (0.1 to 1.5); the concentration of the maleic anhydride in the organic solvent solution of the maleic anhydride is 1-5 mol/L.
  8. 8. The method of preparing a difunctional ammonium polyphosphate flame retardant of claim 4, wherein the organic solvent comprises at least one of dimethylformamide, ethanol, or isopropanol; the organic solvent solution of the maleic anhydride comprises at least one of dimethylformamide, ethanol or isopropanol.
  9. 9. A flame retardant thermoplastic polyurethane composite material characterized in that the raw material comprises the difunctional ammonium polyphosphate flame retardant according to any one of claims 1 to 3.
  10. 10. The flame retardant thermoplastic polyurethane composite material according to claim 9, wherein the addition amount of the difunctional ammonium polyphosphate flame retardant in the raw material of the flame retardant thermoplastic polyurethane composite material is 1-15 wt%.

Description

Difunctional ammonium polyphosphate flame retardant, preparation method thereof and flame-retardant thermoplastic polyurethane composite material Technical Field The invention belongs to the technical field of flame retardants, and relates to a difunctional ammonium polyphosphate flame retardant, a preparation method thereof and a flame-retardant thermoplastic polyurethane composite material. Background With the wide application of polyurethane elastomer (TPU) in the fields of electronic appliances, automobile parts, cable coating and the like, the fire hazard caused by the high flammability of the TPU is increasingly prominent, and the fire accident caused by the fire hazard has caused serious casualties and economic losses. Therefore, developing a high-efficiency flame-retardant system suitable for a high-molecular material has become a key subject for improving the safety of the material. Among the numerous additive flame retardants, ammonium polyphosphate (APP) has been attracting attention because of its excellent phosphorus-nitrogen synergistic flame retardant effect, low cost, low addition amount, and high thermal stability. Compared with the traditional halogen-containing flame retardant, APP has the characteristics of low smoke, low toxicity and no corrosive gas, is regarded as an environment-friendly flame retardant, and is recognized as a main stream substitute of the halogen-based flame retardant. Currently, commercially available ammonium polyphosphate is largely classified into crystalline form I and crystalline form II. Wherein, the crystal I is of a short chain structure, the average polymerization degree (n) is less than 100, the water solubility is high, the moisture absorption is easy, the thermal stability is poor, and the crystal I is mainly suitable for systems such as water-based paint, adhesive and the like. The crystal II is of a long-chain structure, the average degree of polymerization (n) is generally more than 1000, and the crystal II has extremely low water solubility, excellent hydrophobicity and thermal stability and wide processing adaptability, so that the crystal II is widely applied to the fields of thermoplastic plastics, thermosetting resins, textiles, wood and the like and is the main choice for halogen-free flame retardant modification of the polymer materials at present. However, despite the significant potential of crystalline form II ammonium polyphosphate in the flame retardant field, its use in nonpolar polymeric matrices such as TPU still faces a key bottleneck. Firstly, APP only serves as an acid source and a gas source to participate in flame-retardant reaction, lacks a char-forming component, and is difficult to form a compact expanded carbon layer alone in a combustion process, so that flame-retardant efficiency is limited. Secondly, more critical is that there is a severe polarity difference between APP and TPU matrix, resulting in poor interfacial compatibility between the two. Because APP has a strongly polar surface, while TPU is a nonpolar or weakly polar polymer, APP particles are difficult to achieve uniform dispersion in TPU, and are very prone to agglomeration and form significant phase interface defects. In practical application, the weak interface bonding not only causes stress concentration when the material is stressed, so that mechanical properties such as tensile strength, elongation at break and the like are obviously deteriorated, but also the agglomeration phenomenon damages microscopic distribution uniformity of the flame retardant, so that the synergistic flame retardant effect of phosphorus and nitrogen cannot be fully exerted, a continuous and compact expanded carbon layer is difficult to form, finally, the flame retardant efficiency is greatly reduced, and even the flame retardant grade requirement of practical application cannot be met. Therefore, how to improve the interfacial compatibility of APP and TPU matrix and give it a certain char forming ability while maintaining the excellent flame retardant property of APP has become a technical problem to be solved in the current flame retardant modification field. Disclosure of Invention The invention aims at solving the problems in the prior art and provides a difunctional ammonium polyphosphate flame retardant which is prepared by carrying out surface grafting modification on crystal type II ammonium polyphosphate by amine containing terminal amino groups, ethanolamine and maleic anhydride, wherein the flame retardant is applied to thermoplastic polyurethane TPU, so that the flame retardant not only can obviously improve the flame retardant property of a composite material, but also can maintain the mechanical strength of a matrix to the greatest extent. One object of the invention is achieved by the following technical scheme: A difunctional ammonium polyphosphate flame retardant has a structural formula shown in the following formula (1): Formula (1); wherein n >1000; r 1 includes at