Phosphorus-containing micromolecular chain extender flame-retardant modified polyurethane elastomer and preparation method thereof

Abstract

The invention relates to the technical field of polyurethane flame retardance, and discloses a phosphorus-containing micromolecular chain extender flame-retardant modified polyurethane elastomer, which is prepared by taking a phenyl phosphate diol compound as a micromolecular diol chain extender and participating in a polyurethane polymerization reaction process, so as to obtain the phosphorus-containing micromolecular chain extender flame-retardant modified polyurethane elastomer. The phenyl phosphate diol compound is used as a reactive flame retardant and is added into a molecular chain of the polyurethane elastomer, the mechanical strength and tensile property of the polyurethane elastomer are hardly influenced, and in the high-temperature combustion process, the phenyl phosphate diol compound is heated and decomposed to generate a phosphoric acid derivative which can be used as a dehydrating agent, so that the mechanical strength and tensile property of the polyurethane elastomer are greatly improved. The effect of promoting char formation is achieved, a compact carbon layer is generated on the surface of the elastomer, and the effects of blocking oxygen and inhibiting emission of toxic smoke are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of polyurethane flame retardancy, in particular to a phosphorus-containing small molecule chain extender flame retardant modified polyurethane elastomer and a preparation method thereof. Background Art

[0002] Polyurethane has the advantages of good thermal stability, chemical resistance, excellent mechanical properties, good electrical properties, and easy processing. It can be made into polyurethane plastics, polyurethane foams, polyurethane coatings, polyurethane elastomers and other materials, and is used in adhesives, coatings, synthetic leather and other materials. Among them, polyurethane elastomers have the characteristics of high elasticity of rubber and rigidity of plastic, and have the advantages of wear resistance, aging resistance, high hardness and good elasticity. They have important applications in shoemaking, leather making, clothing, medical equipment and national defense supplies. However, traditional polyurethane elastomers have poor flame retardant properties, are easy to burn, and produce a large amount of toxic smoke, which limits the practical application of polyurethane elastomers. Therefore, improving the flame retardant properties of polyurethane elastomers has become a research hotspot.

[0003] At present, the flame retardant properties of high molecular materials such as polyurethane are improved mainly by adding flame retardants to the material matrix. Flame retardants can be divided into nitrogen-phosphorus flame retardants, organic phosphorus flame retardants, bromine flame retardants, etc. according to their types. Among them, organic phosphorus flame retardants have good carbonization and flame retardant inhibition effects and are a commonly used flame retardant. Flame retardants can be divided into additive flame retardants and reactive flame retardants according to the way they are added. Compared with additive flame retardants, reactive flame retardants act as polymerization monomers and participate in the polymerization process of polymers, so that the polymer material itself has flame retardant properties and the flame retardancy is more durable. In addition, reactive flame retardants have little effect on the mechanical properties and performance of polymer materials. Therefore, it is an effective strategy to develop and manufacture new flame-retardant polymerization monomers, participate in polyurethane polymerization reactions, and obtain highly flame-retardant polyurethane elastomers. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a flame retardant modified polyurethane elastomer containing a phosphorus small molecule chain extender and a preparation method thereof, which solves the problem that the traditional polyurethane elastomer has poor flame retardancy.

[0005] To achieve the above object, the present invention provides the following technical solution: a flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender, and a preparation method of the flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender comprises the following steps: (1) Add tetrahydrofuran solvent, small molecule diol and activator to a reaction bottle, add phenylphosphonyl dichloride dropwise in an ice-water bath atmosphere, stir evenly and then carry out substitution reaction, remove the solvent by vacuum distillation, wash with ether and purify by recrystallization to obtain phenyl phosphate diol compounds.

[0006] (2) Nitrogen is introduced into the reaction flask, and a macromolecular polyol is added. After vacuum dehydration, diphenylmethane diisocyanate is added, and the reaction is heated to 75-85 °C for 30-60 min. A catalyst dibutyltin dilaurate is added, and the reaction is performed for 1-3 h. A phenyl phosphate diol compound is then added to carry out a chain extension reaction to obtain a polyurethane prepolymer.

[0007] (3) The polyurethane prepolymer is poured into a mold, thermally cured to form a gel, and then placed in a flat vulcanizer for hot pressing to obtain a phosphorus-containing small molecule chain extender flame retardant modified polyurethane elastomer.

[0008] Preferably, the small molecule diol in step (1) is any one of ethylene glycol, 1,3-propylene glycol or 1,4-butanediol.

[0009] Preferably, the activating agent in step (1) is any one of triethylamine or diisopropylethylamine.

[0010] Preferably, the mass ratio of the activator, the small molecule diol and phenylphosphonic acid dichloride in step (1) is 110-130:65-95:100.

[0011] Preferably, the temperature of the substitution reaction in step (1) is 15-50°C, and the reaction time is 6-24 h.

[0012] Preferably, the structural formula of the phenyl phosphate diol compound in step (1) is , or One of them.

[0013] Preferably, the macromolecular polyol in step (2) is one of polytetrahydrofuran diol and polycaprolactone polyol.

[0014] Preferably, the mass ratio of the macromolecular polyol, diphenylmethane diisocyanate, dibutyltin dilaurate and phenyl phosphate diol compound in step (2) is 100:50-80:0.1-0.3:2-8.

[0015] Preferably, the temperature of the chain extension reaction in step (2) is 60-70° C., and the reaction time is 2-4 h.

[0016] Preferably, the temperature of the hot pressing treatment in step (2) is 90-120° C., the pressure is 4-6 MPa, and the hot pressing time is 20-40 min.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: The flame-retardant modified polyurethane elastomer with phosphorus-containing small molecule chain extender is characterized in that a hydroxyl group of a small molecule diol undergoes a substitution reaction with a chlorine atom of phenylphosphonyl dichloride to obtain a phenyl phosphate diol compound. A phosphate diol compound is obtained by a simple and efficient synthesis method. The phosphate diol compound is used as a small molecule diol to replace traditional 1,4-butanediol or 1,6-hexanediol as a chain extender and participates in a polyurethane polymerization reaction. The flame-retardant modified polyurethane elastomer with phosphorus-containing small molecule chain extender is obtained by further hot pressing. The phenyl phosphate diol compound is used as a reactive flame retardant and is added to the molecular chain of the polyurethane elastomer, which has almost no effect on the mechanical strength and tensile properties of the polyurethane elastomer. In the process of high-temperature combustion, the phenyl phosphate diol compound is thermally decomposed to produce phosphoric acid derivatives, which can be used as a dehydrating agent and have the effect of promoting carbonization, so that a dense carbon layer is produced on the surface of the elastomer, which plays a role in blocking oxygen and inhibiting the emission of toxic smoke. In addition, a free radical inhibitor can be produced to inhibit the chain reaction of combustion, thereby having an excellent natural effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the reaction formula of phenylphosphonyl dichloride and ethylene glycol; Figure 2 It is the reaction formula of phenylphosphonyl dichloride and 1,3-propylene glycol; Figure 3 It is the reaction formula of phenylphosphonyl dichloride and 1,4-butanediol. DETAILED DESCRIPTION

[0019] To achieve the above object, the present invention provides the following specific implementation methods and examples: A method for preparing a flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender comprises the following steps: (1) Add tetrahydrofuran solvent to a reaction bottle, add an activator, a small molecule diol and phenylphosphonic dichloride in a mass ratio of 110-130:65-95:100 in an ice water bath atmosphere, wherein the activator is any one of triethylamine or diisopropylethylamine, and the small molecule diol is any one of ethylene glycol, 1,3-propylene glycol or 1,4-butanediol, stir evenly and then carry out a substitution reaction, the reaction temperature is 15-50 ° C, the reaction time is 6-24 h, and the solvent is removed by vacuum distillation, washed with ether and purified by recrystallization to obtain a phenyl phosphate diol compound with the structural formula , or One of them.

[0020] (2) nitrogen is introduced into the reaction flask, and a macromolecular polyol is added, wherein the macromolecular polyol is one of polytetrahydrofuran diol or polycaprolactone polyol. After vacuum dehydration, diphenylmethane diisocyanate is added, and the mixture is heated to 75-85°C for 30-60 min. Then, a catalyst dibutyltin dilaurate is added, and the mixture is reacted for 1-3 h. Then, a phenyl phosphate diol compound is added, wherein the mass ratio of the macromolecular polyol, diphenylmethane diisocyanate, dibutyltin dilaurate and phenyl phosphate diol compound is 100:50-80:0.1-0.3:2-8, and a chain extension reaction is carried out. The reaction temperature is 60-70°C and the reaction time is 2-4 h to obtain a polyurethane prepolymer.

[0021] (3) The polyurethane prepolymer is poured into a mold, thermally cured to form a gel, and then placed in a flat vulcanizer for hot pressing at a temperature of 90-120 °C, a pressure of 4-6 MPa, and a hot pressing time of 20-40 min to obtain a phosphorus-containing small molecule chain extender flame retardant modified polyurethane elastomer. Example 1

[0022] (1) Add tetrahydrofuran solvent to the reaction bottle, add activator triethylamine, ethylene glycol and phenylphosphonic acid dichloride in a mass ratio of 110:65:100 in an ice water bath atmosphere, stir evenly and carry out substitution reaction. The reaction temperature is 15 °C and the reaction time is 24 h. Remove the solvent by vacuum distillation, wash with ether and purify by recrystallization to obtain bis(2-hydroxyethyl)phenylphosphonate with the structural formula: .

[0023] (2) Nitrogen was introduced into the reaction flask, and a macromolecular polyol polytetrahydrofuran diol was added. After vacuum dehydration, diphenylmethane diisocyanate was added, and the mixture was heated to 85°C for 40 min. A catalyst dibutyltin dilaurate was added and the mixture was reacted for 1 h. Then bis(2-hydroxypropyl)phenylphosphonate was added, wherein the mass ratio of polytetrahydrofuran diol, diphenylmethane diisocyanate, dibutyltin dilaurate and bis(2-hydroxyethyl)phenylphosphonate was 100:50:0.1:2. A chain extension reaction was carried out at a reaction temperature of 60°C for 3 h to obtain a polyurethane prepolymer.

[0024] (3) The polyurethane prepolymer is poured into a mold, thermally cured to form a gel, and then placed in a flat vulcanizer for hot pressing at a temperature of 120 °C, a pressure of 6 MPa, and a hot pressing time of 30 min to obtain a flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender. Example 2

[0025] (1) Add tetrahydrofuran solvent to the reaction bottle, add activator diisopropylethylamine, 1,3-propylene glycol and phenylphosphonic acid dichloride in a mass ratio of 150:80:100 in an ice water bath atmosphere, stir evenly and carry out substitution reaction. The reaction temperature is 50 °C and the reaction time is 12 h. Remove the solvent by vacuum distillation, wash with ether and purify by recrystallization to obtain bis(2-hydroxypropyl)phenylphosphonate with the structural formula: .

[0026] (2) Nitrogen was introduced into the reaction flask, and a macromolecular polyol polycaprolactone polyol was added. After vacuum dehydration, diphenylmethane diisocyanate was added, and the mixture was heated to 80°C for 60 min. A catalyst dibutyltin dilaurate was added and the mixture was reacted for 3 h. Then bis(2-hydroxypropyl)phenylphosphonate was added, wherein the mass ratio of polycaprolactone polyol, diphenylmethane diisocyanate, dibutyltin dilaurate and bis(2-hydroxypropyl)phenylphosphonate was 100:60:0.15:4. A chain extension reaction was carried out at a reaction temperature of 70°C for 4 h to obtain a polyurethane prepolymer.

[0027] (3) The polyurethane prepolymer is poured into a mold, thermally cured to form a gel, and then placed in a flat vulcanizer for hot pressing at a temperature of 100 °C, a pressure of 4 MPa, and a hot pressing time of 30 min to obtain a flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender. Example 3

[0028] (1) Add tetrahydrofuran solvent to the reaction bottle, add activator triethylamine, 1,3-propylene glycol and phenylphosphonic acid dichloride in a mass ratio of 125:80:100 in an ice water bath atmosphere, stir evenly and carry out substitution reaction. The reaction temperature is 15 °C and the reaction time is 12 h. Remove the solvent by vacuum distillation, wash with ether and purify by recrystallization to obtain bis(2-hydroxypropyl)phenylphosphonate with the structural formula: .

[0029] (2) Nitrogen was introduced into the reaction flask, and a macromolecular polyol polycaprolactone polyol was added. After vacuum dehydration, diphenylmethane diisocyanate was added, and the mixture was heated to 80°C for 30 min. Then, a catalyst dibutyltin dilaurate was added and the mixture was reacted for 3 h. Then, bis(2-hydroxypropyl)phenylphosphonate was added, wherein the mass ratio of polycaprolactone polyol, diphenylmethane diisocyanate, dibutyltin dilaurate and bis(2-hydroxypropyl)phenylphosphonate was 100:70:0.25:6. A chain extension reaction was carried out at a reaction temperature of 70°C for 4 h to obtain a polyurethane prepolymer.

[0030] (3) The polyurethane prepolymer is poured into a mold, thermally cured to form a gel, and then placed in a flat vulcanizer for hot pressing at a temperature of 90 °C, a pressure of 6 MPa, and a hot pressing time of 30 min to obtain a flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender. Example 4

[0031] (1) Add tetrahydrofuran solvent to the reaction bottle, add activator diisopropylethylamine, 1,4-butanediol and phenylphosphonic acid dichloride in a mass ratio of 130:95:100 in an ice-water bath atmosphere, stir evenly and carry out substitution reaction. The reaction temperature is 50 °C and the reaction time is 24 h. Remove the solvent by vacuum distillation, wash with ether and purify by recrystallization to obtain bis(2-hydroxybutyl)phenylphosphonate with the structural formula: .

[0032] (2) Nitrogen was introduced into the reaction flask, and a macromolecular polyol polytetrahydrofuran diol was added. After vacuum dehydration, diphenylmethane diisocyanate was added, and the mixture was heated to 85°C for 60 min. A catalyst dibutyltin dilaurate was added and the mixture was reacted for 3 h. Then bis(2-hydroxybutyl)phenylphosphonate was added, wherein the mass ratio of polytetrahydrofuran diol, diphenylmethane diisocyanate, dibutyltin dilaurate and bis(2-hydroxybutyl)phenylphosphonate was 100:80:0.3:8. A chain extension reaction was carried out at a reaction temperature of 70°C for 4 h to obtain a polyurethane prepolymer.

[0033] (3) The polyurethane prepolymer is poured into a mold, thermally cured to form a gel, and then placed in a flat vulcanizer for hot pressing at a temperature of 120 °C, a pressure of 6 MPa, and a hot pressing time of 40 min to obtain a flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender.

[0034] Comparative Example 1 (1) Add tetrahydrofuran solvent to the reaction bottle, add activator triethylamine, ethylene glycol and phenylphosphonic acid dichloride in a mass ratio of 110:65:100 in an ice water bath atmosphere, stir evenly and carry out substitution reaction. The reaction temperature is 40 °C and the reaction time is 12 h. Remove the solvent by vacuum distillation, wash with ether and purify by recrystallization to obtain bis(2-hydroxyethyl)phenylphosphonate with the structural formula: .

[0035] (2) Nitrogen was introduced into the reaction flask, and a macromolecular polyol polycaprolactone polyol was added. After vacuum dehydration, diphenylmethane diisocyanate was added, and the mixture was heated to 85°C for 30 min. Then, a catalyst dibutyltin dilaurate was added and the mixture was reacted for 2 h. Then, bis(2-hydroxyethyl)phenylphosphonate was added, wherein the mass ratio of polycaprolactone polyol, diphenylmethane diisocyanate, dibutyltin dilaurate and bis(2-hydroxyethyl)phenylphosphonate was 100:40:0.1:0.8. A chain extension reaction was carried out at a reaction temperature of 70°C for 2 h to obtain a polyurethane prepolymer.

[0036] (3) The polyurethane prepolymer is poured into a mold, thermally cured to form a gel, and then placed in a flat vulcanizer for hot pressing at a temperature of 120 °C, a pressure of 5 MPa, and a hot pressing time of 20 min to obtain a flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender.

[0037] Comparative Example 2 (1) Add tetrahydrofuran solvent to the reaction bottle, add activator diisopropylethylamine, 1,4-butanediol and phenylphosphonic acid dichloride in a mass ratio of 130:95:100 in an ice-water bath atmosphere, stir evenly and carry out substitution reaction. The reaction temperature is 50 °C and the reaction time is 12 h. Remove the solvent by vacuum distillation, wash with ether and purify by recrystallization to obtain bis(2-hydroxybutyl)phenylphosphonate with the structural formula: .

[0038] (2) Nitrogen was introduced into the reaction flask, and a macromolecular polyol polycaprolactone polyol was added. After vacuum dehydration, diphenylmethane diisocyanate was added, and the reaction was heated to 85°C for 40 min. Then, a catalyst dibutyltin dilaurate was added and the reaction was carried out for 2 h. Then, bis(2-hydroxybutyl)phenylphosphonate was added, wherein the mass ratio of polycaprolactone polyol, diphenylmethane diisocyanate, dibutyltin dilaurate and bis(2-hydroxybutyl)phenylphosphonate was 100:95:0.3:10. A chain extension reaction was carried out at a reaction temperature of 65°C and a reaction time of 4 h to obtain a polyurethane prepolymer.

[0039] (3) The polyurethane prepolymer is poured into a mold, thermally cured to form a gel, and then placed in a flat vulcanizer for hot pressing at a temperature of 120 °C, a pressure of 5 MPa, and a hot pressing time of 30 min to obtain a phosphorus-containing small molecule chain extender flame retardant modified polyurethane elastomer.

[0040] The limiting oxygen index and flame retardant properties of polyurethane elastomers modified by phosphorus-containing small molecule chain extenders were tested using an HC-2 digital oxygen index tester.

[0041]

[0042] The tensile properties and tear strength of polyurethane elastomers modified by flame retardant phosphorus-containing small molecule chain extenders were tested using the XT-5200 universal testing machine.

[0043]

Claims

1. A flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender, characterized in that: The preparation method of the flame retardant modified polyurethane elastomer containing phosphorus small molecule chain extender comprises the following steps: (1) Add tetrahydrofuran solvent, small molecule diol and activator to a reaction bottle, add phenylphosphonyl dichloride dropwise in an ice-water bath atmosphere, stir evenly and then carry out substitution reaction, remove the solvent by vacuum distillation, wash with ether and purify by recrystallization to obtain phenyl phosphate diol compound; (2) nitrogen is introduced into the reaction flask, a macromolecular polyol is added, and after vacuum dehydration, diphenylmethane diisocyanate is added, heated to 75-85°C, reacted for 30-60 min, and then a catalyst dibutyltin dilaurate is added, reacted for 1-3 h, and then a phenyl phosphate diol compound is added to carry out a chain extension reaction to obtain a polyurethane prepolymer; (3) The polyurethane prepolymer is poured into a mold, thermally cured to form a gel, and then placed in a flat vulcanizer for hot pressing to obtain a phosphorus-containing small molecule chain extender flame retardant modified polyurethane elastomer.

2. The flame retardant modified polyurethane elastomer of claim 1, characterized in that: The small molecule diol in step (1) is any one of ethylene glycol, 1,3-propylene glycol or 1,4-butanediol.

3. The flame retardant modified polyurethane elastomer containing phosphorus small molecule chain extender according to claim 1, characterized in that: The activating agent in step (1) is any one of triethylamine and diisopropylethylamine.

4. The flame retardant modified polyurethane elastomer containing phosphorus small molecule chain extender according to claim 1, characterized in that: The mass ratio of the activator, the small molecule diol and phenylphosphonic acid dichloride in the step (1) is 110-130:65-95:

100.

5. The flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender according to claim 1, characterized in that: The temperature of the substitution reaction in step (1) is 15-50°C, and the reaction time is 6-24 h.

6. The flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender according to claim 1, characterized in that: The structural formula of the phenyl phosphate diol compound in step (1) is , or One of them.

7. The flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender according to claim 1, characterized in that: The macromolecular polyol in step (2) is one of polytetrahydrofuran diol and polycaprolactone polyol.

8. The flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender according to claim 1, characterized in that: The mass ratio of the macromolecular polyol, diphenylmethane diisocyanate, dibutyltin dilaurate and phenyl phosphate diol compound in the step (2) is 100:50-80:0.1-0.3:2-8.

9. The flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender according to claim 1, characterized in that: The temperature of the chain extension reaction in step (2) is 60-70°C, and the reaction time is 2-4 hours.

10. The flame retardant modified polyurethane elastomer containing a phosphorus-containing small molecule chain extender according to claim 1, characterized in that: The temperature of the hot pressing treatment in step (2) is 90-120°C, the pressure is 4-6 MPa, and the hot pressing time is 20-40 min.

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