A hydrazide-based phosphorus-nitrogen synergistic reaction type flame retardant, a preparation method and application thereof

Abstract

This invention belongs to the field of flame retardant technology, and discloses an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant, its preparation method, and its application. In the structural formula of the acylhydrazine-based phosphorus-nitrogen synergistic flame retardant, R1 and R2 are each independently selected from methyl, ethyl, or phenyl; R3 is a p-phenyl group, a meta-phenyl group, or (CH2). y R4 represents a p-phenyl group, a meta-phenyl group, or (CH2). m The preparation method involves amidation of dihydrazide and an organophosphorus compound, followed by polycondensation, to obtain a hydrazide-based phosphorus-nitrogen synergistic flame retardant. Its application involves mixing the hydrazide-based phosphorus-nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol, and catalyst II, followed by sequential esterification and polycondensation reactions to obtain a hydrophilic flame-retardant polyester. This invention features a simple and safe preparation process, free of toxic organic reagents, and the prepared hydrazide-based phosphorus-nitrogen synergistic flame retardant exhibits high flame retardant efficiency, good durability, and excellent mechanical and hydrophilic properties.

Description

Technical Field

[0001] This invention belongs to the field of flame retardant technology, and relates to an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant, its preparation method, and its application. Background Technology

[0002] Polyethylene terephthalate (PET), a typical polyester material formed by the polycondensation of terephthalic acid (PTA) and ethylene glycol (EG), is widely used in fibers, films, packaging bottles, and electronic appliances due to its non-toxicity, good weather resistance, and excellent stability. However, PET material has a limiting oxygen index (LOI) of only 21%~22%, classifying it as a flammable material. Combustion in air poses serious safety hazards, making research on its flame-retardant modification urgent and important.

[0003] Currently, flame retardant modification of PET mainly relies on physical blending with additive flame retardants or copolymerization modification with reactive flame retardants. Additive flame retardants (such as phosphorus-based, nitrogen-based, and phosphorus-nitrogen synergistic types) are introduced through melt blending. For example, patent applications CN120289799A and CN119462765A use phosphorus-nitrogen flame retardants blended with polyester. While this improves flame retardancy, it also presents problems such as uneven dispersion and easy migration and precipitation of the flame retardant. To achieve the ideal flame retardant rating, the amount added needs to be significantly increased, which often leads to a significant decrease in the mechanical properties of the PET matrix (such as strength and toughness), limiting its application in high-precision structural components.

[0004] Compared to physical blending, copolymerization modification, by chemically bonding reactive flame retardants into the PET molecular chain, can impart more durable flame retardancy to the material. However, existing copolymerization modification technologies still face multiple bottlenecks.

[0005] Patent applications CN105541917B and CN120904428A describe the preparation of phosphorus-nitrogen synergistic reactive polyester flame retardants, which are introduced into polyesters via copolymerization modification. However, while achieving flame retardancy and durability, this method degrades the mechanical properties of the polyester. Furthermore, the preparation process utilizes large amounts of toxic organic solvents, which is detrimental to industrial production, increases production costs, poses safety hazards, and creates significant environmental pressure.

[0006] Furthermore, copolymer-modified flame retardants are reactive flame retardants, mostly with hydrophobic structures, which reduce the hydrophilicity of PET, limiting their application in textiles, medical devices, and other fields requiring hydrophilic comfort. Although existing technologies have attempted to balance flame retardancy and hydrophilicity (e.g., CN103483573B introduces hydrophilic groups to copolymerize with flame-retardant structures), the chemical properties of the flame-retardant groups (containing PO bonds) and hydrophilic groups (such as polyethylene glycol and sulfonates) differ significantly, easily leading to phase separation or functional interference, resulting in decreased overall performance. Moreover, the negative impact of flame retardants on the mechanical properties of polyester has not been effectively addressed. In addition, phosphorus in existing reactive flame retardants mostly exists in the form of PO bonds; their single phosphorus-containing components have low flame-retardant efficiency, and the high-temperature instability of PO bonds limits their application in high-temperature processing scenarios.

[0007] Therefore, it is of great significance to study an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant, its preparation method, and its application in order to solve the above problems. Summary of the Invention

[0008] The purpose of this invention is to address the problems existing in the prior art and to provide an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant, its preparation method, and its application.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] An acylhydrazine-based phosphorus-nitrogen synergistic flame retardant, the structural formula of which is: ;

[0011] Where x = 5~10; n = 0~5; R1 and R2 are each independently selected from methyl, ethyl, or phenyl; R3 is a p-phenyl group, a meta-phenyl group, or (CH2). y y = 1~4; R4 is a p-phenyl group, a meta-phenyl group, or (CH2). m m = 0~3.

[0012] The present invention also provides a method for preparing an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant as described above, wherein a diacylhydrazine is subjected to an amidation reaction with an organophosphorus compound, followed by polycondensation, thereby obtaining an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant.

[0013] As a preferred technical solution:

[0014] The preparation method of the hydrazide-based phosphorus-nitrogen synergistic flame retardant described above includes the following specific preparation steps:

[0015] (1) After mixing the aqueous solution of the dihydrazide compound, catalyst I, and the organophosphorus compound, the mixture is heated to 160-180℃ at a heating rate of 1-5℃ / min under normal pressure and nitrogen atmosphere for a pre-reaction of 1-1.5h. At 160-180℃, the organophosphorus compound and the dihydrazide compound begin to react in the aqueous solution of the dihydrazide compound, gradually turning the solid raw material into a liquid environment, thereby creating a heterogeneous reaction system. This prevents the solid raw material from undergoing solid-solid reactions, thus avoiding thermal decomposition of the raw material due to uneven heating. The normal pressure and nitrogen atmosphere can remove moisture from the reaction system in time, avoiding its influence on the amidation reaction in step (2).

[0016] (2) The reaction system of step (1) is heated to 180-200℃ at a heating rate of 1-5℃ / min to carry out the amidation reaction until the amount of water produced reaches 90% of the theoretical value. Then, the polycondensation reaction is carried out for 1-2 hours at a vacuum of 50-100Pa and a temperature of 190-210℃ to obtain the acylhydrazine phosphorus nitrogen synergistic flame retardant.

[0017] The preparation method of the hydrazide-based phosphorus-nitrogen synergistic flame retardant described above, wherein the organophosphorus compound is one or more of phenylphosphonic acid, methylphosphonic acid, ethylphosphonic acid, dimethyl methylphosphonate, dimethyl ethylphosphonate, and dimethyl phenylphosphonate.

[0018] In the method described above, the dihydrazide compound is one or more of terephthalic acid dihydrazide, isophthalic acid dihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, and adipate dihydrazide.

[0019] The preparation method of the hydrazide-based phosphorus-nitrogen synergistic flame retardant described above, wherein the mass ratio of water to hydrazide in the aqueous solution of the hydrazide compound is 5~10:1; and the molar ratio of hydrazide to organophosphorus compound is 1.05~1.35:1.

[0020] In the preparation method of the hydrazide-based phosphorus-nitrogen synergistic flame retardant described above, catalyst I is one or more of dibutyltin dilaurate, tetrabutyl titanate, antimony trioxide, antimony acetate, antimony glycolate, and 1,8-diazabicycloundec-7-ene (DBU); in the hydrazide-based phosphorus-nitrogen synergistic flame retardant, the content of catalyst I is 300~1000 ppm.

[0021] The present invention also provides a method for preparing hydrophilic flame-retardant polyester, wherein the above-mentioned acylhydrazine phosphorus nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol and catalyst II are mixed and then subjected to esterification reaction and polycondensation reaction in sequence to obtain hydrophilic flame-retardant polyester.

[0022] As a preferred technical solution:

[0023] The preparation method of the hydrophilic flame-retardant polyester described above is as follows: An acylhydrazine phosphorus-nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol, and catalyst II are mixed and then subjected to an esterification reaction at 225-235°C for 1-2 hours under nitrogen protection. Following this, a polycondensation reaction is carried out at 265-275°C for 2.5-4.5 hours under a vacuum of 50-100 Pa, thereby obtaining the hydrophilic flame-retardant polyester.

[0024] In the preparation method of the hydrophilic flame-retardant polyester described above, the molar ratio of terephthalic acid, ethylene glycol and hydrazide-based phosphorus-nitrogen synergistic flame retardant is 50:52.5~67.5:1~5; and the content of catalyst II in the hydrophilic flame-retardant polyester is 300~1000ppm.

[0025] In the preparation method of the hydrophilic flame-retardant polyester described above, catalyst II is one or more of tetrabutyl titanate, antimony trioxide, antimony acetate, dibutyltin dilaurate, and antimony glycolate.

[0026] The preparation method of the hydrophilic flame retardant polyester described above has a limiting oxygen index of 30-36%, a vertical flammability rating of UL-94 of V-0, a tensile strength of 35-42 MPa, an elongation at break of 20-40%, and a water contact angle of 35-60°.

[0027] Invention principle:

[0028] This invention prepares a hydrazide-based phosphorus-nitrogen synergistic flame retardant by amidation and polycondensation of dihydrazide compounds and organophosphorus compounds, and then introduces it into the PET molecular chain segment through copolymerization modification, effectively inhibiting flame retardant migration and precipitation. Compared with single phosphorus and nitrogen-based flame retardants, the hydrazide-based phosphorus-nitrogen synergistic flame retardant exerts a synergistic flame retardant effect in both the gas phase and condensed phase during polyester combustion, improving flame retardant efficiency.

[0029] The lone pair electrons in the tertiary amine group of the hydrazide-based phosphorus-nitrogen synergistic flame retardant enhance the polarity and hydrogen bonding ability of the polyester, thereby improving the hydrophilicity of the material.

[0030] The tertiary amine group of the hydrazide-based phosphorus-nitrogen synergistic flame retardant can react and consume the acid groups such as phosphoric acid and carboxyl groups generated during high-temperature synthesis, effectively eliminating the autocatalytic sites of polyester thermal degradation and hydrolysis, inhibiting molecular chain breakage during synthesis and processing, thereby maintaining the polymer molecular weight and good mechanical properties.

[0031] Furthermore, common phosphate ester flame retardants are prepared by reacting phosphoric acid with hydroxyl groups. The resulting PO bonds are prone to high-temperature hydrolysis (PO bonds readily hydrolyze at high temperatures to form acidic compounds such as phosphoric acid, which can cause acid degradation during the synthesis of flame retardants and polymers). In contrast, this invention involves the reaction of the amino group in the diacylhydrazine group with phosphoric acid to form a phosphoramide bond (PN bond, which is less prone to breakage and more stable than the PO bond). This eliminates the formation of PO bonds, reducing the high-temperature hydrolysis or pyrolysis problem during the synthesis of acylhydrazine-based phosphorus-nitrogen co-reactive flame retardants (where the amidation reaction generates water).

[0032] Beneficial effects:

[0033] (1) The weakly basic tertiary amine group in the hydrazide-based phosphorus-nitrogen synergistic flame retardant of the present invention can significantly reduce the influence of the terminal carboxyl group during the heat treatment of flame-retardant PET polyester and maintain good mechanical properties. Moreover, the lone pair electrons contained in the tertiary amine enhance the interaction between polyester and water molecules and enhance the hydrophilicity of flame-retardant PET polyester.

[0034] (2) When the hydrazide-based phosphorus-nitrogen synergistic reactive flame retardant of the present invention is applied to polyester materials, it has excellent flame retardant efficiency and plays the role of phosphorus-nitrogen synergistic gas-phase and condensed-phase flame retardant. The vertical burning rating reaches V-0 level. At the same time, the flame retardant forms a stable chemical bond with the polyester material and is not easy to migrate or precipitate. In addition, the hydrazide-based phosphorus-nitrogen synergistic reactive flame retardant for polyester prepared by the present invention has high flame retardant efficiency, good durability and excellent mechanical and hydrophilic properties. It can not only meet the flame retardant and hydrophilic requirements of PET materials, but is also suitable for the modification of materials such as PBT, PTT, PBAT, PBS and PBST.

[0035] (3) The preparation method of the acylhydrazine phosphorus nitrogen synergistic reaction flame retardant of the present invention is simple, no toxic reagents are used in the reaction process, and the reaction conditions are mild, which can be carried out for industrial production. Attached Figure Description

[0036] Figure 1 The infrared spectrum of the hydrophilic flame-retardant polyester of Example 1 of the present invention;

[0037] Figure 2 This is a water contact angle test diagram of the hydrophilic flame-retardant polyester in Embodiment 3 of the present invention; in the diagram, the blue line is the interface baseline of the water droplet on the hydrophilic flame-retardant polyester film in the water contact angle test, the red line of the ellipse is the water contact angle water droplet fitting curve, and the cyan line on the ellipse is the tangent line at the intersection of the interface baseline and the fitting line. The left angle formed by the tangent line and the interface baseline is L: 39.226°, and the right angle is R: 39.806°. Therefore, the contact angle is CA: 39.516°.

[0038] Figure 3A scanning electron microscope image of the char layer after conical calorimetry combustion of the hydrophilic flame-retardant polyester of Example 1 of the present invention.

[0039] Figure 4 The infrared spectrum of the acylhydrazine-based phosphorus-nitrogen synergistic flame retardant prepared in Example 1 of this invention. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0041] The manufacturers and brands mentioned in the following embodiments are merely examples. The core of this invention lies in the technical solution itself, and it is not intended to limit specific manufacturers or brands. Products from other manufacturers and brands that meet the technical requirements and performance indicators specified in this invention can also meet the application requirements of this invention and are all feasible choices.

[0042] The test methods for the relevant performance indicators in the following embodiments and comparative examples are as follows:

[0043] Limiting oxygen index: The limiting oxygen index of the specimens was tested in accordance with ASTM D2863-0951, "Test method for measuring the minimum oxygen concentration (oxygen index) that supports the combustion of plastic-like candles".

[0044] Vertical flammability rating: The vertical flammability rating of the specimens was tested in accordance with ASTM D1230-94, "Standard Test Method for Flammability of Clothing and Textiles".

[0045] Tensile strength and elongation at break: The tensile strength and elongation at break of the specimens were tested in accordance with ISO 527-1:2012 "Determination of tensile properties of plastics - Part 1: General" at a test speed of 50 mm / min.

[0046] Water contact angle: The hydrophilic flame-retardant polyester samples prepared in each embodiment were placed on a polyimide film and heated to 270°C on a flat vulcanizing apparatus to hot press them into a film. The film was then naturally cooled to room temperature to obtain a hydrophilic flame-retardant polyester film, which was used as a sample. The water contact angle of the sample was then tested according to GB / T 30693-2014 "Measurement of Water Contact Angle of Plastic Film". Five parallel tests were performed on the same sample, and the average value was taken.

[0047] Example 1

[0048] A method for preparing a hydrophilic flame-retardant polyester, comprising the following steps:

[0049] (1) Raw material preparation;

[0050] Dihydrazide compounds: dihydrazide terephthalate;

[0051] Catalyst I: Dibutyltin dilaurate;

[0052] Organophosphorus compounds: phenylphosphonic acid;

[0053] Catalyst II: Tetrabutyl titanate;

[0054] (2) Preparation of acylhydrazine-based phosphorus-nitrogen synergistic flame retardant;

[0055] (2.1) After mixing the aqueous solution of dihydrazide compound (composed of water and dihydrazide compound in a mass ratio of 5:1), catalyst I and organophosphorus compound, the mixture was heated to 160℃ for 1.5h under normal pressure and nitrogen atmosphere at a heating rate of 1℃ / min; wherein the molar ratio of dihydrazide compound to organophosphorus compound was 1.05:1;

[0056] (2.2) The reaction system of step (2.1) was heated to 180℃ at a heating rate of 1℃ / min for amidation reaction until the amount of water produced reached 90% of the theoretical value. Then, a polycondensation reaction was carried out for 2 hours under a vacuum of 50Pa and a temperature of 190℃ to obtain an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant (its infrared spectrum is shown in Figure 1). Figure 4 As shown in the figure, at 3379 cm -1 A stretching vibration peak of NH appeared nearby, at 1713 cm⁻¹. -1 A C=O stretching vibration peak appeared nearby, at 1406 cm⁻¹. -1 An infrared absorption peak for CN appeared nearby, at 1270 cm⁻¹. -1 A stretching vibration peak of P=O appeared nearby, and at 965 cm⁻¹ -1 The presence of a PN peak nearby indicates that the hydrazide-based phosphorus-nitrogen synergistic flame retardant has been successfully synthesized. Specifically, the content of catalyst I in the hydrazide-based phosphorus-nitrogen synergistic flame retardant is 300 ppm.

[0057] The final structural formula of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is as follows:

[0058] .

[0059] In the formula, x = 6; the number average molecular weight of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is 2000 g / mol;

[0060] (3) After mixing the hydrazide-based phosphorus-nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol and catalyst II, the mixture was subjected to esterification at 225°C for 2 hours under nitrogen protection, followed by polycondensation at 265°C for 4.5 hours under a vacuum of 50 Pa, thereby obtaining a hydrophilic flame-retardant polyester (its infrared spectrum is shown in Figure 1). Figure 1 As shown in the figure, at 1713 cm -1 The presence of a stretching vibration peak at C=O in the ester group nearby indicates the formation of the polyester backbone; at 3318 cm⁻¹ -1 The stretching vibration peak of NH appeared nearby, at 1523 cm⁻¹. -1 An infrared absorption peak for CN appeared nearby, at 1261 cm⁻¹. -1 A stretching vibration peak of P=O appeared nearby, and at 953 cm⁻¹ -1 The presence of a PN peak nearby indicates that the hydrophilic flame-retardant polyester has been successfully synthesized. The molar ratio of terephthalic acid, ethylene glycol, and hydrazide-based phosphorus-nitrogen synergistic flame retardant is 50:52.5:5, and the content of catalyst II in the hydrophilic flame-retardant polyester is 1000 ppm.

[0061] The final hydrophilic flame-retardant polyester has a limiting oxygen index of 36%, a vertical flammability rating of UL-94 (V-0), a tensile strength of 35 MPa, an elongation at break of 40%, and a water contact angle of 35°.

[0062] According to ISO 5660-1:2015 standard, the combustion performance of hydrophilic flame-retardant polyester was tested using a cone calorimeter. The scanning electron microscope image of the char layer after combustion is shown below. Figure 3 As shown in the figure, the flame retardant mechanism of hydrophilic flame retardant polyester is the flame retardant effect of both the gas phase and the condensed phase.

[0063] Example 2

[0064] A method for preparing a hydrophilic flame-retardant polyester, comprising the following steps:

[0065] (1) Raw material preparation;

[0066] Diacylhydrazide compounds: dimethyl isophthalate dihydrazide;

[0067] Catalyst I: Antimony trioxide;

[0068] Organophosphorus compounds: composed of methylphosphonic acid and phenylphosphonic acid in a mass ratio of 1:1;

[0069] Catalyst II: Antimony trioxide;

[0070] (2) Preparation of acylhydrazine-based phosphorus-nitrogen synergistic flame retardant;

[0071] (2.1) After mixing the aqueous solution of dihydrazide compound (composed of water and dihydrazide compound in a mass ratio of 8:1), catalyst I and organophosphorus compound, the mixture was heated to 170℃ for 1.3h under normal pressure and nitrogen atmosphere at a heating rate of 3℃ / min; wherein the molar ratio of dihydrazide compound to organophosphorus compound was 1.25:1;

[0072] (2.2) The reaction system of step (2.1) is heated to 190℃ at a heating rate of 3℃ / min for amidation reaction until the amount of water produced reaches 90% of the theoretical value. Then, a polycondensation reaction is carried out for 1.5h under a vacuum of 80Pa and a temperature of 200℃ to obtain an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant. The catalyst I content in the acylhydrazine-based phosphorus-nitrogen synergistic flame retardant is 600ppm.

[0073] The final structural formula of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is as follows:

[0074] .

[0075] In the formula, x+n=10; the number average molecular weight of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is 4500 g / mol;

[0076] (3) After mixing the hydrazide-based phosphorus-nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol and catalyst II, the mixture was subjected to esterification at 230°C for 1.5 h under nitrogen protection, and then subjected to polycondensation at 270°C for 3.5 h under vacuum of 70 Pa, thereby obtaining a hydrophilic flame retardant polyester; wherein the molar ratio of terephthalic acid, ethylene glycol and hydrazide-based phosphorus-nitrogen synergistic flame retardant was 50:67.5:1, and the content of catalyst II in the hydrophilic flame retardant polyester was 300 ppm.

[0077] The final hydrophilic flame-retardant polyester has a limiting oxygen index of 30%, a vertical flammability rating of UL-94 (V-0), a tensile strength of 42 MPa, an elongation at break of 20%, and a water contact angle of 60°.

[0078] Example 3

[0079] A method for preparing a hydrophilic flame-retardant polyester, comprising the following steps:

[0080] (1) Raw material preparation;

[0081] Dihydrazide compounds: malonyl hydrazide;

[0082] Catalyst I: 1,8-diazabicycloundec-7-ene;

[0083] Organophosphorus compounds: ethylphosphonic acid;

[0084] Catalyst II: Antimony acetate;

[0085] (2) Preparation of acylhydrazine-based phosphorus-nitrogen synergistic flame retardant;

[0086] (2.1) After mixing the aqueous solution of dihydrazide compound (composed of water and dihydrazide compound in a mass ratio of 10:1), catalyst I and organophosphorus compound, the mixture was heated to 180℃ for 1h under normal pressure and nitrogen atmosphere at a heating rate of 5℃ / min; wherein the molar ratio of dihydrazide compound to organophosphorus compound was 1.35:1;

[0087] (2.2) The reaction system of step (2.1) is heated to 200℃ at a heating rate of 5℃ / min to carry out an amidation reaction until the amount of water produced reaches 90% of the theoretical value. Then, a polycondensation reaction is carried out for 1 hour under a vacuum of 100Pa and a temperature of 210℃ to obtain an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant. In the acylhydrazine-based phosphorus-nitrogen synergistic flame retardant, the content of catalyst I is 1000ppm.

[0088] The final structural formula of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is as follows:

[0089] ,

[0090] In the formula, x = 5; the number average molecular weight of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is 1500 g / mol;

[0091] (3) After mixing the hydrazide-based phosphorus-nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol and catalyst II, the mixture was subjected to esterification at 235°C for 1 hour under nitrogen protection, and then polycondensed at 275°C for 2.5 hours under a vacuum of 100 Pa to obtain a hydrophilic flame retardant polyester. The molar ratio of terephthalic acid, ethylene glycol and hydrazide-based phosphorus-nitrogen synergistic flame retardant was 50:55.5:4, and the content of catalyst II in the hydrophilic flame retardant polyester was 900 ppm.

[0092] The final hydrophilic flame-retardant polyester has a limiting oxygen index of 35%, a vertical flammability rating of UL-94 V-0, a tensile strength of 36 MPa, an elongation at break of 36%, and a water contact angle (the water contact angle test result of one sample during the test is shown in the figure). Figure 2 (As shown) at 40°.

[0093] Example 4

[0094] A method for preparing a hydrophilic flame-retardant polyester, comprising the following steps:

[0095] (1) Raw material preparation;

[0096] Dihydrazide compounds: glutaric acid dihydrazide;

[0097] Catalyst I: Tetrabutyl titanate;

[0098] Organophosphorus compound: dimethyl methylphosphonate;

[0099] Catalyst II: Dibutyltin dilaurate;

[0100] (2) Preparation of acylhydrazine-based phosphorus-nitrogen synergistic flame retardant;

[0101] (2.1) After mixing the aqueous solution of dihydrazide compound (composed of water and dihydrazide compound in a mass ratio of 7:1), catalyst I and organophosphorus compound, the mixture was heated to 180℃ for 1.4h under normal pressure and nitrogen atmosphere at a heating rate of 4℃ / min; wherein the molar ratio of dihydrazide compound to organophosphorus compound was 1.1:1;

[0102] (2.2) The reaction system of step (2.1) is heated to 195℃ at a heating rate of 2℃ / min for amidation reaction until the amount of water produced reaches 90% of the theoretical value. Then, a polycondensation reaction is carried out for 1.5h under a vacuum of 70Pa and a temperature of 205℃ to obtain an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant. The catalyst I content in the acylhydrazine-based phosphorus-nitrogen synergistic flame retardant is 700ppm.

[0103] The final structural formula of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is as follows:

[0104] ,

[0105] In the formula, x = 7; the number average molecular weight of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is 2000 g / mol;

[0106] (3) After mixing the hydrazide-based phosphorus-nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol and catalyst II, the mixture was subjected to esterification at 230°C for 1.5 h under nitrogen protection, and then subjected to polycondensation at 270°C for 3.5 h under vacuum of 80 Pa, thereby obtaining a hydrophilic flame retardant polyester; wherein the molar ratio of terephthalic acid, ethylene glycol and hydrazide-based phosphorus-nitrogen synergistic flame retardant was 50:58.5:3, and the content of catalyst II in the hydrophilic flame retardant polyester was 500 ppm.

[0107] The final hydrophilic flame-retardant polyester has a limiting oxygen index of 34%, a vertical flammability rating of UL-94 (V-0), a tensile strength of 37 MPa, an elongation at break of 32%, and a water contact angle of 45°.

[0108] Example 5

[0109] A method for preparing a hydrophilic flame-retardant polyester, comprising the following steps:

[0110] (1) Raw material preparation;

[0111] Diacylhydrazide compounds: succinic diacylhydrazide;

[0112] Catalyst I: Composed of antimony acetate and tetrabutyl titanate in a mass ratio of 1:1;

[0113] Organophosphorus compound: dimethyl phenylphosphonate;

[0114] Catalyst II: Antimony Glycol;

[0115] (2) Preparation of acylhydrazine-based phosphorus-nitrogen synergistic flame retardant;

[0116] (2.1) After mixing the aqueous solution of dihydrazide compound (composed of water and dihydrazide compound in a mass ratio of 6:1), catalyst I and organophosphorus compound, the mixture was heated to 180℃ for 1.2h under normal pressure and nitrogen atmosphere at a heating rate of 3℃ / min; wherein the molar ratio of dihydrazide compound to organophosphorus compound was 1.2:1;

[0117] (2.2) The reaction system of step (2.1) is heated to 200℃ at a heating rate of 4℃ / min to carry out an amidation reaction until the amount of water produced reaches 90% of the theoretical value. Then, a polycondensation reaction is carried out for 1 hour under a vacuum of 90Pa and a temperature of 210℃ to obtain an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant. The catalyst I content in the acylhydrazine-based phosphorus-nitrogen synergistic flame retardant is 900ppm.

[0118] The final structural formula of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is as follows:

[0119] ,

[0120] In the formula, x = 10; the number average molecular weight of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is 3500 g / mol;

[0121] (3) After mixing the hydrazide-based phosphorus-nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol and catalyst II, the mixture was subjected to esterification at 225°C for 2 hours under nitrogen protection, and then polycondensed at 265°C for 4 hours under vacuum of 90 Pa to obtain a hydrophilic flame retardant polyester. The molar ratio of terephthalic acid, ethylene glycol and hydrazide-based phosphorus-nitrogen synergistic flame retardant was 50:61.5:2, and the content of catalyst II in the hydrophilic flame retardant polyester was 600 ppm.

[0122] The final hydrophilic flame-retardant polyester has a limiting oxygen index of 33%, a vertical flammability rating of UL-94 (V-0), a tensile strength of 39 MPa, an elongation at break of 28%, and a water contact angle of 50°.

[0123] Example 6

[0124] A method for preparing a hydrophilic flame-retardant polyester, comprising the following steps:

[0125] (1) Raw material preparation;

[0126] Diacylhydrazide compounds: composed of oxalic acid dihydrazide and adipic acid dihydrazide in a mass ratio of 1:1;

[0127] Catalyst I: Antimony Glycol;

[0128] Organophosphorus compound: Dimethyl ethylphosphonate;

[0129] Catalyst II: Composed of antimony acetate and antimony glycol in a mass ratio of 1:1;

[0130] (2) Preparation of acylhydrazine-based phosphorus-nitrogen synergistic flame retardant;

[0131] (2.1) An aqueous solution of a dihydrazide compound (composed of water and a dihydrazide compound in a mass ratio of 9:1), catalyst I and an organophosphorus compound were mixed and then heated to 170°C for 1.1 h at a heating rate of 2°C / min in a nitrogen atmosphere at atmospheric pressure; wherein the molar ratio of the dihydrazide compound to the organophosphorus compound was 1.3:1;

[0132] (2.2) The reaction system of step (2.1) is heated to 185℃ at a heating rate of 5℃ / min to carry out an amidation reaction until the amount of water produced reaches 90% of the theoretical value. Then, a polycondensation reaction is carried out for 1.5h under a vacuum of 60Pa and a temperature of 195℃ to obtain an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant. The catalyst I content in the acylhydrazine-based phosphorus-nitrogen synergistic flame retardant is 800ppm.

[0133] The final structural formula of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is as follows:

[0134] ,

[0135] In the formula, x+n=9; the number average molecular weight of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is 4000g / mol;

[0136] (3) After mixing the hydrazide-based phosphorus-nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol and catalyst II, the mixture was subjected to esterification at 235°C for 1 hour under nitrogen protection, and then polycondensed at 275°C for 3 hours under vacuum of 60 Pa to obtain a hydrophilic flame retardant polyester. The molar ratio of terephthalic acid, ethylene glycol and hydrazide-based phosphorus-nitrogen synergistic flame retardant was 50:64.5:2, and the content of catalyst II in the hydrophilic flame retardant polyester was 800 ppm.

[0137] The final hydrophilic flame-retardant polyester has a limiting oxygen index of 32.5%, a vertical flammability rating of UL-94 (V-0), a tensile strength of 40 MPa, an elongation at break of 27%, and a water contact angle of 52°.

Claims

1. A method for preparing a hydrophilic flame-retardant polyester, characterized in that, A hydrophilic flame-retardant polyester was prepared by mixing an acylhydrazine-based phosphorus-nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol and catalyst II and then subjecting them to esterification and polycondensation reactions in sequence. The structural formula of the hydrazide-based phosphorus-nitrogen synergistic flame retardant is: ； Where x = 5~10; n = 0~5; R1 and R2 are each independently selected from methyl, ethyl, or phenyl; R3 is a p-phenyl group, a meta-phenyl group, or (CH2). y y = 1~4; R4 is a p-phenyl group, a meta-phenyl group, or (CH2). m m = 0~3.

2. The method for preparing a hydrophilic flame-retardant polyester according to claim 1, characterized in that, The preparation method of hydrazide-based phosphorus-nitrogen synergistic flame retardant is as follows: dihydrazide is subjected to an amidation reaction with an organophosphorus compound, followed by polycondensation, thereby obtaining the hydrazide-based phosphorus-nitrogen synergistic flame retardant.

3. The method for preparing a hydrophilic flame-retardant polyester according to claim 2, characterized in that, The specific preparation steps for hydrazide-based phosphorus-nitrogen synergistic flame retardants are as follows: (1) After mixing the aqueous solution of dihydrazide compound, catalyst I and organophosphorus compound, the mixture is heated to 160-180℃ at a heating rate of 1-5℃ / min in a normal pressure nitrogen environment for a pre-reaction of 1-1.5h; (2) The reaction system of step (1) is heated to 180-200℃ at a heating rate of 1-5℃ / min to carry out the amidation reaction until the amount of water produced reaches 90% of the theoretical value. Then, the polycondensation reaction is carried out for 1-2 hours at a vacuum of 50-100Pa and a temperature of 190-210℃ to obtain the acylhydrazine phosphorus nitrogen synergistic flame retardant.

4. The method for preparing a hydrophilic flame-retardant polyester according to claim 3, characterized in that, The organophosphorus compound is one or more of phenylphosphonic acid, methylphosphonic acid, ethylphosphonic acid, dimethyl methylphosphonate, dimethyl ethylphosphonate, and dimethyl phenylphosphonate; the dihydrazide compound is one or more of terephthalic acid dihydrazide, isophthalic acid dihydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, and adipic acid dihydrazide; the catalyst I is one or more of dibutyltin dilaurate, tetrabutyl titanate, antimony trioxide, antimony acetate, antimony glycolate, and 1,8-diazabicycloundec-7-ene.

5. The method for preparing a hydrophilic flame-retardant polyester according to claim 3, characterized in that, In the aqueous solution of dihydrazide compounds, the mass ratio of water to dihydrazide compounds is 5~10:1; the molar ratio of dihydrazide compounds to organophosphorus compounds is 1.05~1.35:1; and the content of catalyst I is 300~1000 ppm.

6. The method for preparing a hydrophilic flame-retardant polyester according to claim 1, characterized in that, The specific preparation method of hydrophilic flame-retardant polyester is as follows: after mixing hydrazide-based phosphorus-nitrogen synergistic flame retardant, terephthalic acid, ethylene glycol and catalyst II, esterification reaction is carried out at 225~235℃ for 1~2h under nitrogen protection, and then polycondensation reaction is carried out at 265~275℃ for 2.5~4.5h under vacuum of 50~100Pa, thereby obtaining hydrophilic flame-retardant polyester.

7. The method for preparing a hydrophilic flame-retardant polyester according to claim 6, characterized in that, The molar ratio of terephthalic acid, ethylene glycol and hydrazide-based phosphorus-nitrogen synergistic flame retardant is 50:52.5~67.5:1~5; the content of catalyst II in hydrophilic flame retardant polyester is 300~1000ppm.

8. The method for preparing a hydrophilic flame-retardant polyester according to claim 7, characterized in that, Catalyst II is one or more of tetrabutyl titanate, antimony trioxide, antimony acetate, dibutyltin dilaurate, and antimony glycolate.

9. A method for preparing a hydrophilic flame-retardant polyester according to any one of claims 1 to 8, characterized in that, The limiting oxygen index of hydrophilic flame-retardant polyester is 30~36%, the vertical flammability rating is V-0 in UL-94, the tensile strength is 35~42MPa, the elongation at break is 20~40%, and the water contact angle is 35~60°.

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