Flame-retardant polyurethane sponge for automobile and preparation method thereof

Abstract

The invention discloses flame-retardant polyurethane sponge for an automobile and a preparation method of the flame-retardant polyurethane sponge, and relates to the technical field of polyurethane sponge production. Comprising the following raw materials in parts by mass: 80 to 100 parts of polyether polyol, 45 to 55 parts of diphenylmethane diisocyanate, 2.5 to 3.5 parts of deionized water, 0.2 to 0.5 part of dibutyltin dilaurate, 1.0 to 2.5 parts of silicone oil and 15 to 25 parts of a flame-retardant intermediate. The flame retardant property of the polyurethane sponge is effectively enhanced by adding the micromolecular flame retardant component and applying the direct-current electric field, the flame retardant capacity of the material is directly improved by adding the micromolecular flame retardant component, and the direct-current electric field drives polar molecules in a flame retardant intermediate to directionally migrate and accumulate towards a bottom electrode, so that the flame retardant property of the polyurethane sponge is improved. The flame-retardant effective components are preliminarily enriched at the bottom, effective flame retardance can be carried out on bottom battery flames when a new energy automobile is on fire, and the escape probability of people is increased.

Description

Technical Field

[0001] This invention relates to the field of polyurethane foam production technology, and more specifically, to a flame-retardant polyurethane foam for automobiles and its preparation method. Background Art

[0002] With the rapid development of new energy vehicles, their safety performance, especially fire prevention and flame retardancy, has received increasing attention. In real life, fires in new energy vehicles are generally caused by the burning of the battery at the bottom of the car, which then spreads from the bottom to the interior of the car. Bottom battery fires are a common and dangerous situation. Once a fire starts, if the seats and other parts inside the car cannot be effectively flame-retarded, the fire will spread rapidly, seriously threatening the lives of the people inside the car and making it extremely difficult for them to escape.

[0003] Traditional automotive polyurethane foam has significant shortcomings in flame retardant performance, making it difficult to meet the stringent fire safety requirements of new energy vehicles. When exposed to flames, ordinary polyurethane foam, due to the relatively uniform distribution of flame retardants, cannot effectively retard the key ignition source—the bottom battery flame—when a new energy vehicle catches fire. Moreover, some flame retardants migrate and are lost over time, leading to a gradual decline in flame retardant performance and an inability to maintain a stable protective effect in the long term, resulting in problems of low practicality and functionality.

[0004] No effective solutions have yet been proposed to address the problems in the relevant technologies. Summary of the Invention

[0005] In view of the problems in related technologies, this invention proposes a flame-retardant polyurethane foam for automobiles and its preparation method, so as to overcome the above-mentioned technical problems existing in the existing related technologies.

[0006] Therefore, the specific technical solution adopted by the present invention is as follows:

[0007] A flame-retardant polyurethane foam for automobiles comprises the following raw materials in parts by weight: wherein the raw materials consist of 80-100 parts of polyether polyol, 45-55 parts of diphenylmethane diisocyanate, 2.5-3.5 parts of deionized water, 0.2-0.5 parts of dibutyltin dilaurate, 1.0-2.5 parts of silicone oil, and 15-25 parts of flame-retardant intermediate;

[0008] The flame-retardant intermediate is prepared by the following steps:

[0009] Step 1: Add tricresyl phosphate and epoxidized soybean oil to the reaction vessel, turn on the stirrer and stir at room temperature for 15-20 minutes to mix them thoroughly. While stirring, slowly add triisopropylphenyl phosphate to the reaction vessel and continue stirring for 10-15 minutes to fully disperse the small molecule flame retardant components in the mixture.

[0010] Step 2: Slowly add benzoyl peroxide to the reactor while turning on the heating mantle to raise the temperature inside the reactor to 70-80°C. Stir to decompose the initiator and initiate the reaction. Slowly add butyl acrylate through a dropping funnel, keeping the temperature inside the reactor at 70-80°C and stirring continuously during the addition. After the addition is complete, continue the reaction for 1-2 hours to allow the monomer to fully polymerize and obtain the flame-retardant intermediate.

[0011] In a preferred embodiment, the mass ratio of tricresyl phosphate, epoxidized soybean oil, triisopropylphenyl phosphate, benzoyl peroxide, and butyl acrylate used in steps 1 and 2 is 5:3:2:1:2, and the stirring speed in step 1 is 200-300 r / min.

[0012] In a preferred embodiment, the stirring speed is maintained at 250 r / min in step 2, the reaction time for the initiator decomposition to initiate the reaction is 2-3 hours, and the butyl acrylate is slowly added dropwise through the dropping funnel over a period of 1.5 hours.

[0013] A method for preparing flame-retardant polyurethane foam for automobiles includes the following preparation steps:

[0014] S1. Weigh the following raw materials by mass: the raw materials consist of 80-100 parts polyether polyol, 45-55 parts diphenylmethane diisocyanate, 2.5-3.5 parts deionized water, 0.2-0.5 parts dibutyltin dilaurate, 1.0-2.5 parts silicone oil, and 15-25 parts flame retardant intermediate;

[0015] S2. Add the polyether polyol to a high-speed stirring tank, then add deionized water, dibutyltin dilaurate, silicone oil and flame retardant intermediate in sequence. Turn on the stirring tank and stir until all components are fully mixed and homogeneous to obtain the premix.

[0016] S3. Transfer the premix to the reactor, slowly add diphenylmethane diisocyanate, stir at high speed for 30 seconds to obtain the mixture, and quickly pour the mixture into the preheated foaming mold to allow the mixture to foam in the mold until the foam fully expands and solidifies.

[0017] S4. Remove the foamed sponge from the mold and place it in an oven to cure it, so as to obtain cured polyurethane sponge. Place the cured polyurethane sponge car mat in a polytetrafluoroethylene insulating tank, attach metal electrode plates to the upper and lower surfaces and connect them to a DC power supply. Apply a DC electric field to drive the tricresyl phosphate and triisopropylphenyl phosphate molecules in the flame retardant intermediate to migrate and accumulate towards the bottom electrode, so as to obtain flame retardant polyurethane sponge for automobiles.

[0018] In a preferred embodiment, the stirring speed of the stirring vessel in S2 is 300-500 r / min, the stirring time is 10-15 minutes, and the temperature inside the stirring vessel is set to 25°C.

[0019] In a preferred embodiment, the stirring speed of the high-speed stirrer in S3 is 750 r / min, the preheating temperature of the foaming mold is 45-55℃, and the reaction time of the foaming reaction is 15-20 minutes.

[0020] In a preferred embodiment, the temperature in the oven in step S4 is set to 65-85°C, and the curing time is 3-5 hours.

[0021] In a preferred embodiment, the DC power supply in S4 is stepped up to an electric field strength of 200-600V / m at a rate of 50V / min, and then subjected to constant pressure treatment at 55-65℃ for 8-12 hours, with the hydroxyl value of the polyether polyol being 56mgKOH / g.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. This invention effectively enhances the flame retardant properties of polyurethane foam by adding small-molecule flame retardant components and applying a DC electric field. The addition of small-molecule flame retardant components directly improves the flame retardant ability of the material itself, while the DC electric field drives the polar molecules in the flame retardant intermediate to migrate and accumulate towards the bottom electrode, so that the effective flame retardant components are initially enriched at the bottom, which can effectively retard the bottom battery flame when a new energy vehicle catches fire, increasing the chance of personnel escape.

[0024] 2. By adding small-molecule flame-retardant components, the flame-retardant performance can be further improved with the increase of usage time. In the actual use of new energy vehicles, due to the temperature difference between the top and bottom of the car mat, the small-molecule components in the flame-retardant intermediate migrate to the bottom of the car mat where the temperature is lower by utilizing the diffusion motion characteristics of molecules under the temperature gradient. As the years of use increase, the flame-retardant components at the bottom are further enriched, which can better delay the fire in the car and leave more time for people to escape.

[0025] 3. This invention applies a DC electric field to the cured polyurethane foam, utilizing the characteristic that polar molecules are driven by Coulomb force to migrate directionally towards the positive electrode. This causes the effective flame-retardant components in the flame-retardant intermediate to migrate and accumulate directionally at the bottom of the foam, forming bottom enrichment. This bottom enrichment phenomenon allows the foam to more effectively exert its flame-retardant effect and delay the spread of flames when the bottom battery of a new energy vehicle catches fire. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart of a method for preparing flame-retardant polyurethane foam for automobiles according to an embodiment of the present invention. Detailed Implementation

[0028] To further illustrate the various embodiments, the present invention provides accompanying drawings, which are part of the disclosure of the present invention. These drawings are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these drawings, those skilled in the art should be able to understand other possible implementation methods and the advantages of the present invention. The components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0029] According to an embodiment of the present invention, a flame-retardant polyurethane foam for automobiles and a method for preparing the same are provided.

[0030] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments:

[0031] Example 1:

[0032] According to an embodiment of the present invention, a flame-retardant polyurethane foam for automobiles comprises the following raw materials in parts by weight: wherein the raw materials consist of 80-100 parts of polyether polyol, 45-55 parts of diphenylmethane diisocyanate, 2.5-3.5 parts of deionized water, 0.2-0.5 parts of dibutyltin dilaurate, 1.0-2.5 parts of silicone oil, and 15-25 parts of flame-retardant intermediate;

[0033] The flame-retardant intermediate is prepared by the following steps:

[0034] Step 1: Add tricresyl phosphate and epoxidized soybean oil to the reaction vessel, turn on the stirrer and stir at room temperature for 15-20 minutes to mix them thoroughly. While stirring, slowly add triisopropylphenyl phosphate to the reaction vessel and continue stirring for 10-15 minutes to fully disperse the small molecule flame retardant components in the mixture.

[0035] Step 2: Slowly add benzoyl peroxide to the reactor while turning on the heating mantle to raise the temperature inside the reactor to 70-80°C. Stir to decompose the initiator and initiate the reaction. Slowly add butyl acrylate through a dropping funnel, keeping the temperature inside the reactor at 70-80°C and stirring continuously during the addition. After the addition is complete, continue the reaction for 1-2 hours to allow the monomer to fully polymerize and obtain the flame-retardant intermediate.

[0036] The mass ratio of tricresyl phosphate, epoxidized soybean oil, triisopropylphenyl phosphate, benzoyl peroxide, and butyl acrylate used in steps 1 and 2 is 5:3:2:1:2, and the stirring speed in step 1 is 200-300 r / min.

[0037] It should be noted that by uniformly dispersing tricresyl phosphate in the epoxidized soybean oil carrier, a good foundation can be provided for subsequent reactions. At the same time, the introduction of small molecule flame retardants with high molecular thermal activity allows the current flame-retardant polyurethane foam for automobiles to be used continuously with the seat cushions. Under the temperature difference between the top and bottom of the car seat cushions, the effective components of the flame-retardant intermediates can be further accumulated at the bottom, thereby slowing down the penetration of the bottom battery flames into the vehicle interior when a new energy vehicle catches fire, creating conditions for people to escape.

[0038] In step 2, the stirring speed is maintained at 250 r / min, the reaction time for the initiator to decompose and initiate the reaction is 2-3 hours, and the butyl acrylate is slowly added dropwise through the dropping funnel over a period of 1.5 hours.

[0039] It should be noted that the polymerization reaction of butyl acrylate with other components is initiated, which encapsulates the flame-retardant active ingredient in the polymer network and ensures the stability of the small molecule flame retardant in the system.

[0040] A method for preparing flame-retardant polyurethane foam for automobiles includes the following preparation steps:

[0041] S1. Weigh the following raw materials by mass: the raw materials consist of 80-100 parts polyether polyol, 45-55 parts diphenylmethane diisocyanate, 2.5-3.5 parts deionized water, 0.2-0.5 parts dibutyltin dilaurate, 1.0-2.5 parts silicone oil, and 15-25 parts flame retardant intermediate;

[0042] S2. Add the polyether polyol to a high-speed stirring tank, then add deionized water, dibutyltin dilaurate, silicone oil and flame retardant intermediate in sequence. Turn on the stirring tank and stir until all components are fully mixed and homogeneous to obtain the premix.

[0043] S3. Transfer the premix to the reactor, slowly add diphenylmethane diisocyanate, stir at high speed for 30 seconds to obtain the mixture, and quickly pour the mixture into the preheated foaming mold to allow the mixture to foam in the mold until the foam fully expands and solidifies.

[0044] S4. Remove the foamed sponge from the mold and place it in an oven to cure it to obtain cured polyurethane sponge. Place the cured polyurethane sponge car mat in a polytetrafluoroethylene insulating tank, attach metal electrode plates to the upper and lower surfaces and connect them to a DC power supply. Apply a DC electric field to drive the tricresyl phosphate and triisopropylphenyl phosphate molecules in the flame retardant intermediate to migrate and accumulate towards the bottom electrode to obtain flame retardant polyurethane sponge for automobiles.

[0045] The stirring speed of the stirring vessel in S2 is 300-500 r / min, the stirring time is 10-15 minutes, and the temperature inside the stirring vessel is set to 25℃.

[0046] The stirring speed of the high-speed stirrer in S3 is 750 r / min, the preheating temperature of the foaming mold is 45-55℃, and the reaction time of the foaming reaction is 15-20 minutes.

[0047] The temperature in the oven in S4 is set to 65-85℃, and the curing time is 3-5 hours;

[0048] In S4, the DC power supply is stepped up to an electric field strength of 200-600V / m at a rate of 50V / min, and then subjected to constant pressure treatment at 55-65℃ for 8-12 hours. The hydroxyl value of the polyether polyol is 56mgKOH / g.

[0049] Example 2:

[0050] The specific process and preparation flow of a flame-retardant polyurethane foam for automotive applications are as follows:

[0051] The first step is to weigh the following raw materials according to the mass percentages: the raw materials consist of 80 parts polyether polyol, 45 parts diphenylmethane diisocyanate, 2.5 parts deionized water, 0.2 parts dibutyltin dilaurate, 1.0 part silicone oil, and 15 parts flame retardant intermediate.

[0052] Step 2: Add 80 parts of polyether polyol to a high-speed mixing tank, then add 2.5 parts of deionized water, 0.2 parts of dibutyltin dilaurate, 1.0 part of silicone oil and 15 parts of flame retardant intermediate in sequence. Turn on the mixing tank and stir at 000 r / min for 10 minutes until all components are fully mixed and uniform. During the stirring process, control the temperature inside the high-speed mixing tank at 25℃ to obtain the premix.

[0053] Step 3: Transfer the premix to the reactor, slowly add 45 parts of diphenylmethane diisocyanate, stir at 750 r / min for 30 seconds to obtain the mixture, quickly pour the mixture into the foaming mold preheated to 45-55℃, so that the mixture can foam in the mold, and react for 15 minutes until the foam is fully expanded and cured.

[0054] Step 4: Remove the foamed sponge from the mold and place it in an oven at 65-85℃ for 3 hours to obtain cured polyurethane sponge. Place the cured polyurethane sponge car mat in a polytetrafluoroethylene insulating tank, attach metal electrode plates to the upper and lower surfaces and connect them to a DC power supply. Apply a DC electric field of 450V / m for 10 hours to drive the tricresyl phosphate and triisopropylphenyl phosphate molecules in the flame retardant intermediate to migrate and accumulate towards the bottom electrode to obtain flame retardant polyurethane sponge for automobiles. The DC power supply is stepped up to the target electric field strength at 50V / min and treated under constant pressure at 55-65℃. The polar molecules are driven by Coulomb force to migrate directionally towards the positive electrode and accumulate at the bottom of the sponge.

[0055] The flame-retardant intermediate is prepared by the following steps:

[0056] Step 1: Add tricresyl phosphate and epoxidized soybean oil to the reaction vessel, turn on the stirrer and stir at 200-300 r / min for 15-20 minutes at room temperature to ensure that the two are fully mixed. While stirring, slowly add triisopropylphenyl phosphate to the reaction vessel and continue stirring at 200-300 r / min for 10-15 minutes to ensure that the small molecule flame retardant components are fully dispersed in the mixture.

[0057] Step 2: Slowly add benzoyl peroxide to the reactor while turning on the heating mantle to raise the temperature inside the reactor to 70-80℃. Stir at 250r / min to decompose the initiator and initiate the reaction. The reaction time is 2-3 hours. Slowly add butyl acrylate through a dropping funnel, keeping the temperature inside the reactor at 70-80℃ and stirring continuously during the addition. After the addition is complete, continue the reaction for 1-2 hours to allow the monomer to fully polymerize and obtain the flame-retardant intermediate. The addition time of butyl acrylate through the dropping funnel is 1.5 hours.

[0058] The polyether polyol used has a hydroxyl value of 56 mg KOH / g, and the mass ratio of tricresyl phosphate, epoxidized soybean oil, triisopropylphenyl phosphate, benzoyl peroxide, and butyl acrylate is 5:3:2:1:2.

[0059] Example 3:

[0060] The specific process and preparation flow of a flame-retardant polyurethane foam for automotive applications are as follows:

[0061] The first step is to weigh the following raw materials according to the mass percentages: the raw materials consist of 100 parts polyether polyol, 55 parts diphenylmethane diisocyanate, 3.5 parts deionized water, 0.5 parts dibutyltin dilaurate, 2.5 parts silicone oil, and 25 parts flame retardant intermediate.

[0062] Step 2: Add 100 parts of polyether polyol to a high-speed mixing tank, then add 3.5 parts of deionized water, 0.5 parts of dibutyltin dilaurate, 2.5 parts of silicone oil and 25 parts of flame retardant intermediate in sequence. Turn on the mixing tank and stir at a speed of 400 r / min for 15 minutes until all components are fully mixed and uniform. During the stirring process, control the temperature inside the high-speed mixing tank at 25℃ to obtain the premix.

[0063] Step 3: Transfer the premix to the reactor, slowly add 55 parts of diphenylmethane diisocyanate, stir at 750 r / min for 30 seconds to obtain the mixture, quickly pour the mixture into the foaming mold preheated to 45-55℃, so that the mixture can foam in the mold, and react for 25 minutes until the foam is fully expanded and cured.

[0064] Step 4: Remove the foamed sponge from the mold and place it in an oven at 65-85℃ for 5 hours to obtain cured polyurethane sponge. Place the cured polyurethane sponge car mat in a polytetrafluoroethylene insulating tank, attach metal electrode plates to the upper and lower surfaces and connect them to a DC power supply. Apply a DC electric field of 450V / m for 10 hours to drive the tricresyl phosphate and triisopropylphenyl phosphate molecules in the flame retardant intermediate to migrate and accumulate towards the bottom electrode to obtain flame retardant polyurethane sponge for automobiles. The DC power supply is stepped up to the target electric field strength at 50V / min and treated under constant pressure at 55-65℃. The polar molecules are driven by Coulomb force to migrate directionally towards the positive electrode and accumulate at the bottom of the sponge.

[0065] The flame-retardant intermediate is prepared by the following steps:

[0066] Step 1: Add tricresyl phosphate and epoxidized soybean oil to the reaction vessel, turn on the stirrer and stir at 200-300 r / min for 15-20 minutes at room temperature to ensure that the two are fully mixed. While stirring, slowly add triisopropylphenyl phosphate to the reaction vessel and continue stirring at 200-300 r / min for 10-15 minutes to ensure that the small molecule flame retardant components are fully dispersed in the mixture.

[0067] Step 2: Slowly add benzoyl peroxide to the reactor while turning on the heating mantle to raise the temperature inside the reactor to 70-80℃. Stir at 250r / min to decompose the initiator and initiate the reaction. The reaction time is 2-3 hours. Slowly add butyl acrylate through a dropping funnel, keeping the temperature inside the reactor at 70-80℃ and stirring continuously during the addition. After the addition is complete, continue the reaction for 1-2 hours to allow the monomer to fully polymerize and obtain the flame-retardant intermediate. The addition time of butyl acrylate through the dropping funnel is 1.5 hours.

[0068] The polyether polyol used has a hydroxyl value of 56 mg KOH / g, and the mass ratio of tricresyl phosphate, epoxidized soybean oil, triisopropylphenyl phosphate, benzoyl peroxide, and butyl acrylate is 5:3:2:1:2.

[0069] Comparative Example 1:

[0070] The section in step 4 of Example 2, which describes "placing the cured polyurethane sponge car mat in a polytetrafluoroethylene insulating tank, attaching metal electrode plates to the upper and lower surfaces and connecting them to a DC power supply, applying a DC electric field of 450V / m for 10 hours to drive the tricresyl phosphate and triisopropylphenyl phosphate molecules in the flame-retardant intermediate to migrate and accumulate towards the bottom electrode, thereby obtaining a flame-retardant polyurethane sponge for automobiles, wherein the DC power supply is stepped up to the target electric field strength at 50V / min, and constant pressure treatment is performed at 55-65℃, causing polar molecules to migrate directionally towards the positive electrode under the drive of Coulomb force and accumulate at the bottom of the sponge," is removed. Simultaneously, the section in step 2 of the flame-retardant intermediate preparation, which describes "slowly adding triisopropylphenyl phosphate to the reaction vessel under stirring, continuing stirring at 200-300r / min for 10-15 minutes to fully disperse the small molecule flame-retardant components in the mixture," is also removed. All other raw materials remain unchanged, and a flame-retardant polyurethane sponge for automobiles is prepared.

[0071] Comparative Example 2:

[0072] The fourth step in Example 3, which involves placing the cured polyurethane foam car mat in a polytetrafluoroethylene insulating tank, attaching metal electrode plates to the upper and lower surfaces and connecting them to a DC power supply, applying a DC electric field of 450V / m for 10 hours to drive the tricresyl phosphate and triisopropylphenyl phosphate molecules in the flame-retardant intermediate to migrate and accumulate towards the bottom electrode to obtain a flame-retardant polyurethane foam for automobiles, wherein the DC power supply is stepped up to the target electric field strength at 50V / min, and constant pressure treatment is performed at 55-65℃, and polar molecules are driven by Coulomb force to migrate directionally towards the positive electrode and accumulate at the bottom of the sponge, is removed. At the same time, the second step in the preparation of the flame-retardant intermediate, which involves slowly adding triisopropylphenyl phosphate to the reaction vessel under stirring and continuing to stir at 200-300r / min for 10-15 minutes to fully disperse the small molecule flame-retardant components in the mixture, is removed. The remaining raw materials remain unchanged, and a flame-retardant polyurethane foam for automobiles is prepared.

[0073] Experimental Example 1:

[0074] The flame-retardant polyurethane foams for automobiles obtained in Examples 2 and 3 and Comparative Examples 1 and 2 were subjected to performance tests, including physical and mechanical property tests, flame-retardant property tests, flame retardant distribution uniformity tests, and new energy vehicle combustion simulation tests. The test results are shown in Tables 1, 2, and 3.

[0075] Table 1: Test Table of Flame Retardant Performance of Flame Retardant Polyurethane Foam for Automotive Use

[0076] Test metrics Example 2 Example 3 Comparative Example 1 Comparative Example 2 Limiting Oxygen Index (LOI%) 32.2 34.6 25.3 28.2 Top layer (wt%) 2.1 1.8 6.5 6.8 Intermediate layer (wt%) 4.5 4.8 6.2 6.4 Bottom layer (wt%) 8.9 9.3 6.0 5.9 Bottom enrichment ratio (wt%) 4.24:1 5.17:1 0.92:1 0.87:1

[0077] The limiting oxygen index (LOI) refers to the minimum oxygen concentration required for a material to maintain stable combustion in an oxygen-nitrogen mixed gas flow under specified conditions. It is expressed as the volume percentage of oxygen. The higher the OX, the better the flame retardant performance of the material. Five samples with dimensions of 150 mm × 5 mm × 10 mm were cut from the sponge samples prepared in Examples 2 and 3 and Comparative Examples 1 and 2, respectively. The samples were vertically mounted on the sample clamp of the oxygen index tester. The gas flow rate of the instrument was adjusted so that the oxygen-nitrogen mixed gas passed through the combustion tube at a certain flow rate. The top of the sample was ignited, and the combustion of the sample was observed. The minimum oxygen concentration at which the sample could maintain combustion was recorded. Each sample was tested five times, and the average value was taken.

[0078] Each sample was cut into small pieces and fixed on the sample stage with conductive adhesive. Gold sputtering was applied to improve the conductivity of the samples. The microstructure of the samples was observed using a scanning electron microscope. Energy dispersive spectroscopy analysis was performed on different parts such as the top, middle and bottom to measure the content of characteristic elements in the flame retardant. Each sample was tested three times at different parts, and the average value was taken. The difference in flame retardant content in different parts was calculated to evaluate the uniformity of flame retardant distribution.

[0079] It can be seen that adding small molecule flame retardant components can enhance the flame retardant properties of polyurethane foam. A DC electric field can cause the effective flame retardant components in the polyurethane foam to be initially enriched at the bottom, which is convenient for flame retardant treatment of the bottom battery flame when a new energy vehicle catches fire, thereby increasing the chances of people escaping.

[0080] Table 2: Test Table of Physical and Mechanical Properties of Flame-Retardant Polyurethane Foam for Automotive Use

[0081] Test metrics Example 2 Example 3 Comparative Example 1 Comparative Example 2 <![CDATA[Density (kg / m 3 )]]> 42.5 43.1 41.8 43.0 Tensile strength (kPa) 95.3 98.7 101.2 104.5 Tear strength (N / cm) 3.8 3.9 4.2 4.3 Compression set (%) 6.2 5.9 4.1 3.8

[0082] The physical and mechanical properties of the sponge samples prepared in Examples 2 and 3 and Comparative Examples 1 and 2 were tested according to GB / T 6669, GB / T 10808, GB / T 6344 and GB / T 6343, respectively. It can be seen that the electric field treatment has a limited effect on the mechanical properties.

[0083] Table 3: Simulation Test Table for Combustion of Flame-Retardant Polyurethane Foam for Automotive New Energy Vehicles

[0084]

[0085]

[0086] Samples from Examples 2 and 3, and Comparative Examples 1 and 2 were cut into 150×150×50mm pieces and placed in a temperature-controlled device for gradient aging treatment according to the table to accelerate the simulation of actual service life (see Table 4). A propane spray gun was used to simulate the combustion of batteries in new energy electric vehicles. An adjustable sample holder was installed above the propane spray gun to hold the samples after temperature difference treatment. The propane spray gun was ignited, and the flame size was adjusted to ensure that the flame stably and evenly contacts the bottom of the sample. The flame penetration time and maximum spread height of different samples were recorded. Each sample was tested 3 times, and the average value was taken.

[0087] Table 4: Gradient Table

[0088] Simulated service life Top temperature Bottom temperature Processing time Simulated service life Initial state - - - Initial state 1 year 45℃ 25℃ 72 hours 1 year 3 years 50℃ 25℃ 216 hours 3 years

[0089] It can be seen that polyurethane foam treated with DC electric field and with the addition of small molecule flame retardant components can further enrich the effective flame retardant components at the bottom of the foam as the usage time increases, so as to delay the fire inside the vehicle when the new energy vehicle catches fire and leave more escape space.

[0090] It should be noted that during the actual use of new energy vehicles, due to factors such as human contact with the seat cushion and direct sunlight, a temperature difference will occur between the top and bottom of the new energy vehicle seat cushion. As the years of use increase, the small molecule components in the flame retardant intermediate will migrate to the bottom of the seat cushion, where the temperature is lower, by utilizing the diffusion characteristics of molecules under the temperature gradient.

[0091] In summary, this invention effectively enhances the flame retardant properties of polyurethane foam by adding small-molecule flame retardant components and applying a DC electric field. The addition of small-molecule flame retardant components directly improves the flame retardant ability of the material itself, while the DC electric field drives the polar molecules in the flame retardant intermediate to migrate and accumulate towards the bottom electrode, so that the effective flame retardant components are initially enriched at the bottom. This can effectively retard the bottom battery flame when a new energy vehicle catches fire, increasing the chances of personnel escaping.

[0092] By applying a DC electric field to the cured polyurethane foam, the effective flame-retardant components in the flame-retardant intermediate are directed to migrate and accumulate at the bottom of the foam, forming bottom enrichment. This bottom enrichment phenomenon allows the foam to play a more targeted flame-retardant role and delay the spread of flames when the bottom battery of a new energy vehicle catches fire.

[0093] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flame-retardant polyurethane foam for automobiles, characterized in that, The raw materials include the following parts by weight: 80-100 parts polyether polyol, 45-55 parts diphenylmethane diisocyanate, 2.5-3.5 parts deionized water, 0.2-0.5 parts dibutyltin dilaurate, 1.0-2.5 parts silicone oil, and 15-25 parts flame retardant intermediate. The flame-retardant intermediate is prepared by the following steps: Step 1: Add tricresyl phosphate and epoxidized soybean oil to the reaction vessel, turn on the stirrer and stir at room temperature for 15-20 minutes to mix them thoroughly. While stirring, slowly add triisopropylphenyl phosphate to the reaction vessel and continue stirring for 10-15 minutes to fully disperse the small molecule flame retardant components in the mixture. Step 2: Slowly add benzoyl peroxide to the reactor while turning on the heating mantle to raise the temperature inside the reactor to 70-80°C. Stir to decompose the initiator and initiate the reaction. Slowly add butyl acrylate through a dropping funnel, keeping the temperature inside the reactor at 70-80°C and stirring continuously during the addition. After the addition is complete, continue the reaction for 1-2 hours to allow the monomer to fully polymerize and obtain the flame-retardant intermediate.

2. The flame-retardant polyurethane foam for automobiles according to claim 1, characterized in that, The mass ratio of tricresyl phosphate, epoxidized soybean oil, triisopropylphenyl phosphate, benzoyl peroxide, and butyl acrylate used in steps 1 and 2 is 5:3:2:1:2, and the stirring speed in step 1 is 200-300 r / min.

3. The flame-retardant polyurethane foam for automobiles according to claim 1, characterized in that, In step 2, the stirring speed is maintained at 250 r / min, the reaction time for the initiator to decompose and initiate the reaction is 2-3 hours, and the butyl acrylate is slowly added dropwise through the dropping funnel over a period of 1.5 hours.

4. A method for preparing flame-retardant polyurethane foam for automobiles as described in any one of claims 1-3, characterized in that, The preparation steps include the following: S1. Weigh the following raw materials by mass: the raw materials consist of 80-100 parts polyether polyol, 45-55 parts diphenylmethane diisocyanate, 2.5-3.5 parts deionized water, 0.2-0.5 parts dibutyltin dilaurate, 1.0-2.5 parts silicone oil, and 15-25 parts flame retardant intermediate; S2. Add the polyether polyol to a high-speed stirring tank, then add deionized water, dibutyltin dilaurate, silicone oil and flame retardant intermediate in sequence. Turn on the stirring tank and stir until all components are fully mixed and homogeneous to obtain the premix. S3. Transfer the premix to the reactor, slowly add diphenylmethane diisocyanate, stir at high speed for 30 seconds to obtain the mixture, and quickly pour the mixture into the preheated foaming mold to allow the mixture to foam in the mold until the foam fully expands and solidifies. S4. Remove the foamed sponge from the mold and place it in an oven to cure it, so as to obtain cured polyurethane sponge. Place the cured polyurethane sponge car mat in a polytetrafluoroethylene insulating tank, attach metal electrode plates to the upper and lower surfaces and connect them to a DC power supply. Apply a DC electric field to drive the tricresyl phosphate and triisopropylphenyl phosphate molecules in the flame retardant intermediate to migrate and accumulate towards the bottom electrode, so as to obtain flame retardant polyurethane sponge for automobiles.

5. The method for preparing a flame-retardant polyurethane foam for automobiles according to claim 4, characterized in that, The stirring speed of the stirring vessel in S2 is 300-500 r / min, the stirring time is 10-15 minutes, and the temperature inside the stirring vessel is set to 25℃.

6. The flame-retardant polyurethane foam for automobiles and its preparation method according to claim 4, characterized in that, The stirring speed of the high-speed stirrer in S3 is 750 r / min, the preheating temperature of the foaming mold is 45-55℃, and the reaction time of the foaming reaction is 15-20 minutes.

7. The method for preparing a flame-retardant polyurethane foam for automobiles according to claim 4, characterized in that, The temperature in the oven in S4 is set to 65-85℃, and the curing time is 3-5 hours.

8. The method for preparing a flame-retardant polyurethane foam for automobiles according to claim 4, characterized in that, In S4, the DC power supply is stepped up to an electric field strength of 200-600V / m at a rate of 50V / min, and then subjected to constant pressure treatment at 55-65℃ for 8-12 hours. The hydroxyl value of the polyether polyol is 56mgKOH / g.

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