Flame-retardant polyurethane hot melt adhesive and preparation method thereof

Abstract

The invention discloses a flame-retardant polyurethane hot melt adhesive and a preparation method thereof, and belongs to the technical field of hot melt adhesives. Comprising the following raw materials in parts by weight: 30-50 parts of polybutylene adipate glycol, 35-55 parts of polypropylene oxide glycol, 25-50 parts of MDI, 6-18 parts of modified dihydric alcohol, 0.1-0.3 part of a catalyst, 3-5 parts of a lubricant and 3-7 parts of an antioxidant. The polyurethane hot melt adhesive is prepared by a two-step method, no solvent is added, and the method is environment-friendly; mDI is selected as isocyanate, so that the hot melt adhesive is endowed with excellent stability and mechanical properties; wherein various groups in modified dihydric alcohol molecules can achieve a synergistic effect, so that the flame retardance, the heat resistance and a certain degree of mechanical properties of the hot melt adhesive are remarkably enhanced, and the hot melt adhesive is stable in performance and not easy to fall off; therefore, the prepared hot melt adhesive is excellent in mechanical property, has stable and efficient flame retardance and heat resistance, is environmentally friendly, and has important application value in the technical field of hot melt adhesives.

Description

Technical Field

[0001] The invention belongs to the technical field of hot melt adhesives, and in particular relates to a flame retardant polyurethane hot melt adhesive and a preparation method thereof. Background Art

[0002] With the continuous improvement of people's environmental awareness this year, hot melt adhesive, as a plastic adhesive, changes its physical state with temperature within a certain temperature range, while its chemical properties remain unchanged. It is non-toxic and odorless. Because the product itself is solid, it is easy to package, transport, store, solvent-free, pollution-free, and non-toxic. It also has the advantages of simple production process, high added value, high bonding strength, and fast speed. It has been rapidly developed in the automotive, electronic and electrical, wood processing, book binding, and food packaging industries.

[0003] The types of hot melt adhesives are mainly divided into EVA hot melt adhesives, polyurethane hot melt adhesives, polyamide hot melt adhesives, polyester hot melt adhesives, etc. Among them, polyurethane hot melt adhesives have excellent bonding strength, good high and low temperature resistance, water resistance, and chemical corrosion resistance. Usually, polyurethane hot melt adhesives are divided into two categories: thermoplastic polyurethane hot melt adhesives and reactive polyurethane hot melt adhesives. Among them, reactive polyurethane hot melt adhesives have the characteristics of high initial viscosity and fast positioning speed of hot melt adhesives. However, after the reactive polyurethane hot melt adhesive is cured, due to the presence of a large number of carbamate, urea, biuret and other groups in the system, the heat resistance of the cured system is poor. Not only that, with the improvement of people's safety awareness, the problem of poor flame retardant performance of polyurethane hot melt adhesives has also been exposed, limiting its scope of use. The commonly used additive flame retardants on the market are prone to migration and exudation in the polyurethane matrix, resulting in the loss of flame retardant properties. Therefore, it is urgent to solve the above problems to meet the higher requirements in the field of hot melt adhesive technology. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a flame retardant polyurethane hot melt adhesive and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a flame retardant polyurethane hot melt adhesive comprises the following steps:

[0007] A1. Add polybutylene adipate diol and polyoxypropylene diol into a reaction kettle, start heating, and after the mixture is melted, start stirring. When the temperature reaches 100°C, turn on the vacuum pump, and perform vacuum dehydration for 3-5 hours under the condition of vacuum degree ≥ 0.098MPa to obtain dehydrated polyol;

[0008] A2. Preheat diphenylmethane diisocyanate (MDI) to 55-65° C., then put it into the reactor of step A1, introduce nitrogen into the reactor as a protective gas, add modified diol, control the reaction temperature to 70-80° C., stir the reaction for 1-3 hours, and then add a catalyst, a lubricant and an antioxidant, stir the reaction at 70-80° C. for 1-2 hours, and then heat it to 100° C., evacuate the air bubbles and remove volatile impurities to obtain a flame-retardant polyurethane hot melt adhesive.

[0009] Furthermore, the raw materials are calculated in parts by weight as follows: 30-50 parts of polybutylene adipate diol, 35-55 parts of polyoxypropylene diol, 25-50 parts of MDI, 6-18 parts of modified diol, 0.1-0.3 parts of catalyst, 3-5 parts of lubricant, and 3-7 parts of antioxidant.

[0010] Furthermore, in step A2, the catalyst is one of stannous octoate and dibutyltin dilaurate.

[0011] Furthermore, in step A2, the lubricant is one of stearic acid and paraffin.

[0012] Furthermore, the antioxidant in step A2 is a hindered phenol antioxidant.

[0013] The reactive polyurethane hot melt adhesive is prepared through a two-step method. No solvent is added during the reaction process, which saves costs and is environmentally friendly. In addition, MDI is selected as the isocyanate because it has a rigid benzene ring structure, which gives the hot melt adhesive excellent stability and mechanical properties. Finally, an organic tin catalyst is used with good catalytic effect.

[0014] Further, the modified diol is prepared by the following steps:

[0015] S1. Add diethylenetriamine, stearic acid, dicyclohexylcarbodiimide (DCC, dehydrating agent) and diethyl ether to a three-necked flask equipped with a stirring reflux device, stir and mix well, place in a water bath at 55°C, reflux for 4 hours, filter after the reaction, remove the solvent by vacuum distillation, wash with anhydrous ethanol 2-3 times, and vacuum dry to obtain intermediate 1; the ratio of diethylenetriamine, stearic acid, dicyclohexylcarbodiimide and diethyl ether is 12.2g:28.4g:20.6g:150mL;

[0016] Under the action of the dehydrating agent, the amino group in the diethylenetriamine molecule and the carboxyl group in the stearic acid molecule undergo an amidation reaction. By controlling the molar ratio of the two to be close to 1:1 and the diethylenetriamine to be slightly excessive, only one amino group on the diethylenetriamine participates in the reaction to obtain the intermediate 1. The specific reaction process is as follows:

[0017]

[0018] S2. Add 4,4'-sulfonyl dibenzoic acid and toluene to a three-necked flask equipped with a stirring device, mix, heat to 30°C and stir continuously, introduce nitrogen, add intermediate 1 and dicyclohexylcarbodiimide, mix and stir evenly, heat to 60°C, and keep warm for 8 hours. After the reaction is completed, most of the solvent is evaporated, and then purified by column chromatography (the eluent is a mixed solvent of petroleum ether / ethyl acetate, and the volume ratio of the two is 5:1), and the eluent is evaporated to obtain intermediate 2; the ratio of the amount of 4,4'-sulfonyl dibenzoic acid, toluene, intermediate 1, and dicyclohexylcarbodiimide is 30.6g:300mL:74.9g:41.2g;

[0019] The carboxyl group on 4,4'-sulfonyldibenzoic acid and the amino group of intermediate 1 undergo an amidation reaction, and intermediate 2 is obtained by controlling the molar ratio of the two to be close to 1:2 and a slight excess of intermediate 1. The specific reaction process is as follows:

[0020]

[0021] S3. At room temperature, in a three-necked flask equipped with a stirring device, mix intermediate 2, p-chlorobenzaldehyde, toluene and triethylamine uniformly under nitrogen protection, gradually heat to 75°C, keep warm for 8 hours, filter, remove part of the solvent by vacuum distillation, and purify by column chromatography (the eluent is a mixed solvent of petroleum ether / ethyl acetate, the volume ratio of the two is 5:1), remove the eluent by rotary evaporation, and vacuum dry to obtain intermediate 3; the ratio of the amount of intermediate 2, p-chlorobenzaldehyde, toluene and triethylamine is 100.8g:29.2g:300mL:30mL;

[0022] Intermediate 1 undergoes a nucleophilic substitution reaction with p-chlorobenzaldehyde. By controlling the molar ratio of the two to be close to 1:2 and a slight excess of p-chlorobenzaldehyde, triethylamine is used as an acid-binding agent to remove hydrogen chloride generated by the reaction and accelerate the reaction to obtain intermediate 3. The structure of intermediate 3 is shown below:

[0023]

[0024] S4. Add intermediate 3, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and toluene to a three-necked flask with a reflux condenser and mechanical stirring, mix, and continue to introduce N2 protection, heat to 90°C, stir for 30 minutes, then heat to 140°C, keep warm for 6 hours, and after the reaction is completed, filter under reduced pressure, wash the filter residue with a mixed solvent of ethyl acetate and petroleum ether (the volume ratio of the two is 1:1) for 3-4 times, and vacuum dry to obtain a modified diol; the ratio of intermediate 3, DOPO and toluene used is 121.6g:45.1g:300mL;

[0025] The active PH bond in the DOPO structure can react with the C=O bond of the aldehyde group in the intermediate 3 molecule. By controlling the molar ratio of the two to be close to 2:1, two aldehyde groups on the intermediate 3 participate in the reaction to obtain a modified diol; the structure of the modified diol is shown below:

[0026]

[0027] Since the prepared modified diol contains two hydroxyl groups in the molecule, it can participate in the isocyanate polymerization reaction under the action of the catalyst and connect to the polyurethane macromolecular chain, making it difficult for the modified diol to precipitate and fall off, thereby improving the stability of the modified diol and enabling it to perform its performance stably for a long time; in addition, the modified diol molecule also contains diphenyl sulfone, DOPO and a long carbon chain structure, among which diphenyl sulfone has good high temperature resistance and thermal oxidation resistance, and is desulfurized by heat to generate SO2, sulfurous acid and water, which can promote the Fries rearrangement reaction of the matrix and accelerate the carbonization of the matrix, which can Effectively enhance the flame retardant and smoke suppression properties of the matrix; not only that, DOPO is an environmentally friendly flame retardant with the advantages of high efficiency and low toxicity, good thermal stability, strong flame retardant durability, and can also promote the dehydration of the material surface into a carbon elastomer to achieve condensed phase flame retardancy, and can synergize with diphenyl sulfone to greatly enhance the flame retardant properties of the matrix; not only that, DOPO can further enhance the thermal stability of the matrix; finally, the introduced long carbon chain is a methylene chain segment, which can improve the mechanical properties of the matrix, and can also be interspersed in the polymer chain of the matrix, more tightly connected to the matrix, and further improve the stability of the modified diol.

[0028] Beneficial effects of the present invention:

[0029] 1. The present invention prepares the polyurethane hot melt adhesive by a two-step method, and no solvent is added during the reaction process, which is environmentally friendly;

[0030] 2. The selection of MDI as isocyanate gives the hot melt adhesive excellent stability and mechanical properties;

[0031] 3. The various groups in the obtained modified diol molecules can play a synergistic role, significantly enhancing the flame retardancy, heat resistance and a certain degree of mechanical properties of the hot melt adhesive, and the performance is long-lasting and stable and not easy to fall off;

[0032] Therefore, the hot melt adhesive prepared by the present invention has excellent mechanical properties, stable and efficient flame retardancy and heat resistance, and is environmentally friendly, and has important application value in the field of hot melt adhesive technology. DETAILED DESCRIPTION

[0033] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Embodiment 1

[0035] Preparation of modified diols:

[0036] S1. Add 12.2 g of diethylenetriamine, 28.4 g of stearic acid, 20.6 g of dicyclohexylcarbodiimide and 150 mL of ether into a three-necked flask equipped with a stirring reflux device, stir and mix evenly, place in a 55° C. water bath, reflux for 4 h, filter, remove the solvent by vacuum distillation, wash 3 times with anhydrous ethanol, and dry in vacuo to obtain intermediate 1;

[0037] S2, in a three-necked flask equipped with a stirring device, add 30.6g 4,4'-sulfonyldibenzoic acid and 300mL toluene, mix, heat to 30°C and stir continuously, introduce nitrogen, add 74.9g intermediate 1 and 41.2g dicyclohexylcarbodiimide, mix and stir evenly, heat to 60°C, keep warm and react for 8h, after the reaction is completed, evaporate most of the solvent, and then purify by column chromatography (the eluent is a mixed solvent of petroleum ether / ethyl acetate, the volume ratio of the two is 5:1), and evaporate the eluent to obtain intermediate 2;

[0038] S3. At room temperature, under nitrogen protection, in a three-necked flask equipped with a stirring device, 100.8 g of intermediate 2, 29.2 g of p-chlorobenzaldehyde, 300 mL of toluene and 30 mL of triethylamine were mixed evenly, and the temperature was gradually raised to 75°C. The reaction was kept warm for 8 hours. After the reaction was completed, the mixture was filtered, and some solvents were removed by distillation under reduced pressure. The mixture was purified by column chromatography (the eluent was a mixed solvent of petroleum ether / ethyl acetate in a volume ratio of 5:1), the eluent was removed by rotary evaporation, and the mixture was dried in vacuo to obtain intermediate 3.

[0039] S4. In a three-necked flask equipped with a reflux condenser and mechanical stirring, add 121.6 g of intermediate 3, 45.1 g of DOPO and 300 mL of toluene, mix, and continue to introduce N2 for protection. Heat to 90 ° C. After stirring for 30 min, heat to 140 ° C. and keep the temperature for 6 h. After the reaction is completed, filter under reduced pressure, wash the residue three times with a mixed solvent of ethyl acetate and petroleum ether (the volume ratio of the two is 1:1), and dry in vacuo to obtain a modified diol.

[0040] Embodiment 2

[0041] Preparation of modified diols:

[0042] S1. Add 24.4 g of diethylenetriamine, 56.8 g of stearic acid, 41.2 g of dicyclohexylcarbodiimide and 300 mL of ether into a three-necked flask equipped with a stirring reflux device, stir and mix evenly, place in a 55° C. water bath, reflux for 4 h, filter after the reaction, remove the solvent by vacuum distillation, wash with anhydrous ethanol 3 times, and vacuum dry to obtain intermediate 1;

[0043] S2, in a three-necked flask equipped with a stirring device, add 61.2g 4,4'-sulfonyldibenzoic acid and 600mL toluene, mix, heat to 30°C and stir continuously, introduce nitrogen, add 149.8g intermediate 1 and 82.4g dicyclohexylcarbodiimide, mix and stir evenly, heat to 60°C, keep warm and react for 8h, after the reaction is completed, evaporate most of the solvent, and then purify by column chromatography (the eluent is a mixed solvent of petroleum ether / ethyl acetate, the volume ratio of the two is 5:1), and evaporate the eluent to obtain intermediate 2;

[0044] S3. At room temperature, under nitrogen protection, in a three-necked flask equipped with a stirring device, 201.6 g of intermediate 2, 58.4 g of p-chlorobenzaldehyde, 600 mL of toluene and 60 mL of triethylamine were mixed evenly, and the temperature was gradually raised to 75°C. The reaction was kept warm for 8 hours. After the reaction was completed, the mixture was filtered, and some solvents were removed by distillation under reduced pressure. The mixture was purified by column chromatography (the eluent was a mixed solvent of petroleum ether / ethyl acetate in a volume ratio of 5:1), the eluent was removed by rotary evaporation, and the mixture was dried in vacuo to obtain intermediate 3.

[0045] S4. Add 243.2 g of intermediate 3, 90.2 g of DOPO and 600 mL of toluene into a three-necked flask with a reflux condenser and mechanical stirring, mix, and continue to introduce N2 for protection. Raise the temperature to 90°C, stir for 30 min, then raise the temperature to 140°C, and keep the temperature for 6 h. After the reaction is completed, filter under reduced pressure, wash the residue four times with a mixed solvent of ethyl acetate and petroleum ether (the volume ratio of the two is 1:1), and dry in vacuo to obtain a modified diol.

[0046] Embodiment 3

[0047] A1. Add 30 g of polybutylene adipate diol and 35 g of polyoxypropylene diol into a reactor, start heating, and after the mixture melts, start stirring. When the temperature reaches 100° C., turn on the vacuum pump, and perform vacuum dehydration for 3 h under the condition of vacuum degree ≥ 0.098 MPa to obtain dehydrated polyol;

[0048] A2, 25g of diphenylmethane diisocyanate was preheated to 55°C, and then put into the reactor of step A1, nitrogen was introduced into the reactor as a protective gas, and 6g of the modified diol prepared in Example 1 was added, the reaction temperature was controlled to 70°C, the reaction was stirred for 1h, and the reaction was completed, and then 0.1g of stannous octoate, 3g of stearic acid and 3g of antioxidant 1010 were added, and the reaction was stirred at 70°C for 1h. The reaction was completed, and then the temperature was raised to 100°C, and evacuated to remove bubbles and volatile impurities to obtain a flame retardant polyurethane hot melt adhesive.

[0049] Embodiment 4

[0050] A1. Add 40 g of polybutylene adipate diol and 45 g of polyoxypropylene diol into a reactor, start heating, and after the mixture melts, start stirring. When the temperature reaches 100° C., turn on the vacuum pump, and perform vacuum dehydration for 4 h under the condition of vacuum degree ≥ 0.098 MPa to obtain dehydrated polyol;

[0051] A2. Preheat 35 g of diphenylmethane diisocyanate to 60 ° C, then put it into the reactor of step A1, introduce nitrogen into the reactor as a protective gas, add 12 g of the modified diol prepared in Example 2, control the reaction temperature to 75 ° C, stir the reaction for 1-3 h, and then add 0.2 g of dibutyltin dilaurate, 4 g of paraffin and 5 g of antioxidant 1010. Stir the reaction at 75 ° C for 1.5 h. After the reaction is completed, heat it to 100 ° C, evacuate to remove bubbles and volatile impurities, and obtain a flame retardant polyurethane hot melt adhesive.

[0052] Embodiment 5

[0053] A1. Add 50 g of polybutylene adipate diol and 55 g of polyoxypropylene diol into a reactor, start heating, and after the mixture melts, start stirring. When the temperature reaches 100° C., turn on the vacuum pump, and perform vacuum dehydration for 5 h under the condition of vacuum degree ≥ 0.098 MPa to obtain dehydrated polyol;

[0054] A2. Preheat 50 g of diphenylmethane diisocyanate to 65 ° C, then put it into the reactor of step A1, introduce nitrogen into the reactor as a protective gas, add 18 g of the modified diol prepared in Example 2, control the reaction temperature to 80 ° C, stir the reaction for 3 h, and then add 0.3 g of dibutyltin dilaurate, 5 g of paraffin and 7 g of antioxidant 1010. Stir the reaction at 80 ° C for 2 h. After the reaction is completed, heat it to 100 ° C, evacuate the air bubbles and remove volatile impurities to obtain a flame retardant polyurethane hot melt adhesive.

[0055] Comparative Example 1

[0056] A commercially available phosphorus-based flame retardant of equal quality was used to replace the modified diol in Example 5, and the remaining steps were the same as in Example 5 to prepare a polyurethane hot melt adhesive.

[0057] Comparative Example 2

[0058] Use commercially available polyurethane hot melt adhesive.

[0059] Embodiments 3, 4, 5 and comparative examples 1 and 2 were made into corresponding shapes according to different standards and the following performance tests were performed:

[0060] The shear strength after 72 hours was measured according to the national standard GB / T 7124-2008 "Determination of tensile shear strength of adhesives"; the shear strength after 72 hours of hot air oxidation was measured at 150°C, and the shear strength retention rate was calculated; shear strength retention rate = shear strength after test / shear strength before test × 100%;

[0061] The smoke density is measured using the national standard GB / T 8323.2-2008 "Plastic smoke generation Part 2: Single chamber method for determination of smoke density test method";

[0062] The limiting oxygen index of the sample was determined according to the national standard GB / T 2406-2008 "Test Method for Combustion Performance of Plastics". After leaving Examples 3, 4, 5 and Comparative Example 1 at room temperature for 180 days, the limiting oxygen index was determined again.

[0063] The measured results are shown in the following table:

[0064]

[0065] It can be seen from the above table that the hot melt adhesive prepared in the embodiment of the present invention has higher mechanical properties, flame retardancy and heat resistance than the comparative example, and has stable performance, and has important application value in the field of hot melt adhesive technology.

[0066] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0067] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A method for preparing a flame retardant polyurethane hot melt adhesive, characterized in that: The following steps are involved: A1. Add polybutylene adipate diol and polyoxypropylene diol into a reaction kettle, start heating, and after the mixture is melted, start stirring. When the temperature reaches 100° C., turn on the vacuum pump for vacuum dehydration to obtain dehydrated polyol; A2. Preheat diphenylmethane diisocyanate to 55-65°C, then put it into the reactor of step A1, introduce nitrogen into the reactor, add modified diol, control the reaction temperature to 70-80°C, stir the reaction for 1-3h, and then add a catalyst, a lubricant and an antioxidant, stir the reaction at 70-80°C for 1-2h, and then heat to 100°C, evacuate to remove bubbles, and obtain a flame-retardant polyurethane hot melt adhesive.

2. The method for preparing a flame retardant polyurethane hot melt adhesive according to claim 1, characterized in that: The modified diol is prepared by the following steps: S1, diethylenetriamine, stearic acid, dicyclohexylcarbodiimide and diethyl ether were stirred and mixed uniformly, and then placed in a water bath at 55°C for reflux reaction for 4 hours. After the reaction was completed, the mixture was filtered, distilled under reduced pressure, washed and dried under vacuum to obtain intermediate 1; S2, 4,4'-sulfonyldibenzoic acid and toluene were mixed, heated to 30°C and stirred continuously, nitrogen was introduced, intermediate 1 and dicyclohexylcarbodiimide were added, mixed and stirred evenly, the temperature was raised to 60°C, and the reaction was kept warm for 8 hours. After the reaction was completed, rotary evaporation was performed, column chromatography was performed for purification, and rotary evaporation was performed to obtain intermediate 2; S3, at room temperature, under nitrogen protection, the intermediate 2, p-chlorobenzaldehyde, toluene and triethylamine were mixed evenly, and the temperature was gradually raised to 75°C, and the reaction was kept at this temperature for 8 hours. After the reaction was completed, the intermediate 3 was obtained by filtration, vacuum distillation, column chromatography purification, rotary evaporation, and vacuum drying. S4. Mix the intermediate 3, DOPO and toluene, and continue to introduce N2 for protection. Heat to 90°C, stir for 30 min, then heat to 140°C and keep the temperature for 6 h. After the reaction is completed, filter under reduced pressure, wash the filter residue, and dry in vacuo to obtain a modified diol.

3. The method for preparing a flame retardant polyurethane hot melt adhesive according to claim 2, characterized in that: In step S1, the ratio of diethylenetriamine, stearic acid, dicyclohexylcarbodiimide and ether is 12.2 g: 28.4 g: 20.6 g: 150 mL.

4. The method for preparing a flame retardant polyurethane hot melt adhesive according to claim 2, characterized in that: In step S2, the ratio of the amount of 4,4'-sulfonyldibenzoic acid, toluene, intermediate 1, and dicyclohexylcarbodiimide is 30.6 g: 300 mL: 74.9 g: 41.2 g.

5. The method for preparing a flame retardant polyurethane hot melt adhesive according to claim 2, characterized in that: In step S3, the ratio of the amount of intermediate 2, p-chlorobenzaldehyde, toluene and triethylamine is 100.8 g:29.2 g:300 mL:30 mL.

6. The method for preparing a flame retardant polyurethane hot melt adhesive according to claim 2, characterized in that: In step S4, the ratio of the amount of intermediate 3, DOPO, and toluene is 121.6 g:45.1 g:300 mL.

7. The method for preparing a flame retardant polyurethane hot melt adhesive according to claim 1, characterized in that: The raw materials are calculated in parts by weight as follows: 30-50 parts of polybutylene adipate diol, 35-55 parts of polyoxypropylene diol, 25-50 parts of MDI, 6-18 parts of modified diol, 0.1-0.3 parts of catalyst, 3-5 parts of lubricant, and 3-7 parts of antioxidant.

8. A flame retardant polyurethane hot melt adhesive, characterized in that: Prepared according to the method according to any one of claims 1 to 7.

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