A method for preparing flame-retardant polyurethane sponge material

Abstract

The invention discloses a method for preparing a flame-retardant polyurethane sponge material, and belongs to the technical field of sponge materials. The invention comprises the following raw materials in parts by weight: 20-40 parts of diphenylmethane diisocyanate, 40-60 parts of polyether polyols, 3-6 parts of foaming agents, 4-6 parts of pore-opening agents, 4-8 parts of deionized water, 1-3 parts of tetramethylethylenediamine, 2-4 parts of antioxidants, and 5-15 parts of modified polyols. The prepared polyurethane sponge material is compared with conventional polyurethane sponge materials, and modified polyols are added as one of the raw materials. Various functional groups are contained in the modified polyols to play a synergistic role, which significantly improves the flame retardancy, antibacterial property, water resistance and mechanical strength of the material to a certain extent, and the performance of the modified polyols is long-term stable. Therefore, the polyurethane sponge material prepared by the present invention has stable and efficient flame retardancy, antibacterial property and water resistance, and excellent mechanical properties, and has important application value in the technical field of sponge materials.

Description

[0001] The invention belongs to the technical field of sponge materials, and in particular relates to a method for preparing a flame retardant polyurethane sponge material. Background Art

[0002] Sponge is a very common porous material with good water absorption. Some of it has good elasticity, deformation recovery and other properties. It can be used to clean items or to produce some comfortable and soft cushions.

[0003] The commonly used sponges are made of wood cellulose fibers or foamed plastic polymers. There are also natural sponges made from sponge animals, most of which are used for body cleaning or painting. The common sponge material is polyurethane sponge. Polyurethane is a common polymer material that is widely used to make various "sponge" products. Polyurethane sponge has excellent cushioning, heat insulation and sound insulation properties. It is used in many industries, such as the automotive industry, battery industry, cosmetics industry, bra underwear manufacturing industry and high-end furniture manufacturing industry. However, polyurethane sponge is highly flammable and lacks self-extinguishing properties. When exposed to flames or high temperatures, it is easy to burn and release harmful gases and smoke, which endangers people's health. Studies have shown that halogen flame retardants can solve the problem of low flame retardant properties of polyurethane sponges through melt blending, chemical modification and surface coating. Halogen flame retardants are cheap, used in small amounts and have good flame retardant effects, but they release toxic and harmful gases when burning, which is limited in application. Secondly, the porous structure of polyurethane sponge is easy to breed bacteria. Furniture such as pillows and sofas made from it as raw materials will have adverse effects on health when in contact with the human body. Therefore, based on the above problems, it is urgent to invent a polyurethane sponge material with excellent flame retardancy and antibacterial properties to meet the higher demands in the field of sponge material technology. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a method for preparing a flame retardant polyurethane sponge material.

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

[0006] A method for preparing a flame retardant polyurethane sponge material comprises the following steps:

[0007] Diphenylmethane diisocyanate (MDI), polyether polyol, foaming agent, cell opening agent, deionized water, tetramethylethylenediamine (catalyst), antioxidant and modified polyol are stirred at high speed, added into a high-pressure foaming machine for foaming, and then placed in a constant temperature box for aging after foaming to obtain a flame-retardant polyurethane sponge material.

[0008] Furthermore, the raw materials are calculated in parts by weight as follows: 20-40 parts of diphenylmethane diisocyanate, 40-60 parts of polyether polyol, 3-6 parts of foaming agent, 4-6 parts of pore opening agent, 4-8 parts of deionized water, 1-3 parts of tetramethylethylenediamine, 2-4 parts of antioxidant, and 5-15 parts of modified polyol.

[0009] Furthermore, the antioxidant is one of triphenyl phosphite and diphenyl isooctyl phosphite.

[0010] Further, the modified polyol is prepared by the following steps:

[0011] S1. In a three-necked flask equipped with a stirring device, triphenylphosphine (PPh3), 3-bromopropionic acid and toluene were mixed, and the temperature was raised to 55°C. The mixture was stirred for 4 hours. After the reaction was completed, the solvent was removed by distillation under reduced pressure to obtain intermediate 1. The ratio of triphenylphosphine, 3-bromopropionic acid and toluene was 26.2 g:15.1 g:100 mL.

[0012] Triphenylphosphine reacts with the bromine group of 3-bromopropionic acid to obtain the quaternary phosphonium product intermediate 1; the specific reaction process is as follows:

[0013] ;

[0014] S2. In a three-necked flask equipped with a stirring device, triethanolamine, intermediate 1 and N,N-dimethylformamide (DMF) were mixed and stirred evenly, and then dibutyltin oxide (catalyst) and dicyclohexylcarbodiimide (DCC) were added, and the temperature was raised to 85°C for reaction for 4 hours. Stirring was continued during the reaction. After the reaction was completed, the mixture was filtered, and some solvents were removed by rotary evaporation. The mixture was then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate in a volume ratio of 3:2), and the eluent was removed by rotary evaporation to obtain intermediate 2. The ratio of triethanolamine, intermediate 1, N,N-dimethylformamide, dibutyltin oxide and dicyclohexylcarbodiimide was 15.4 g:33.5 g:120 mL:0.2 g:20.6 g.

[0015] Under the catalysis of dibutyltin oxide and DCC, the hydroxyl group on triethanolamine and the carboxyl group on intermediate 1 undergo esterification reaction. By controlling the molar ratio of the two to be close to 1:1 and the triethanolamine to be slightly excessive, only one hydroxyl group on triethanolamine participates in the reaction to obtain intermediate 2. The specific reaction process is shown below:

[0016] ;

[0017] S3. In a three-necked flask equipped with a stirring device, thioglycolic acid, intermediate 2 and N,N-dimethylformamide were mixed and stirred evenly, and then dibutyltin oxide (catalyst) and dicyclohexylcarbodiimide (dehydrating agent) were added, and the temperature was raised to 90°C for reaction for 6 hours. Stirring was continued during the reaction. After the reaction was completed, the mixture was filtered, and some solvents were removed by vacuum distillation. The mixture was purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate in a volume ratio of 3:4), and the eluent was removed by rotary evaporation to obtain intermediate 3. The ratio of thioglycolic acid, intermediate 2, N,N-dimethylformamide, dibutyltin oxide and DCC was 10.6 g:48.7 g:150 mL:0.3 g:20.6 g.

[0018] Under the catalysis of dibutyltin oxide and dicyclohexylcarbodiimide, the carboxyl group on the thioglycolic acid and the hydroxyl group on the intermediate 2 undergo an esterification reaction. By controlling the molar ratio of the two to be close to 1:1 and the intermediate 2 to be slightly excessive, only one hydroxyl group on the intermediate 2 participates in the reaction to obtain the intermediate 3. The specific reaction process is as follows:

[0019] ;

[0020] S4. Add intermediate 3, AIBN (azobisisobutyronitrile) and N,N-dimethylformamide to a three-necked flask equipped with a stirring device, stir and mix well, then drop tetramethyltetravinylcyclotetrasiloxane, maintain the temperature of the system at 80°C, and react for 6 hours. After the reaction is completed, first remove part of the solvent by rotary evaporation, and then purify by column chromatography (the eluent is a mixed solvent of ethyl acetate / petroleum ether, and the volume ratio of the two is 2:5), and remove the eluent by rotary evaporation to obtain a modified polyol; the ratio of the amount of intermediate 3, AIBN, N,N-dimethylformamide, and tetramethyltetravinylcyclotetrasiloxane is 221.6g:5.8g:500mL:34.4g;

[0021] Under the action of AIBN, the unsaturated carbon-carbon double bond on the tetramethyltetravinylcyclotetrasiloxane molecule undergoes a thiol-ene click reaction with the -SH on the intermediate 3. By controlling the molar ratio of the two to be close to 1:4, a modified polyol is obtained. The specific reaction process is as follows:

[0022] ;

[0023] The obtained modified polyol has a cyclic siloxane core and -OH molecular chains with a dendrite structure distributed around it, so that the modified polyol can form a cross-linked polyurethane network structure during the polymerization with isocyanate, which can improve the mechanical properties of the polyurethane matrix to a certain extent, and also make the modified polyol less likely to precipitate and fall off, thereby improving the long-term stability of the performance of the modified polyol; in addition, the modified polyol molecule also contains Si-O bonds, N, S heteroatoms and quaternary phosphonium salt structures, among which the cyclic siloxane contains multiple Si-O bonds with higher bond energy and certain hydrophobicity, and the ester group and benzene ring are also hydrophobic groups. The quaternary phosphonium salt functional groups introduced by the siloxane can improve the waterproof performance of the matrix together. In addition, the layered silica formed by the degradation of siloxane during combustion migrates to the surface of the carbon layer, making the carbon layer denser and inhibiting the oxidation of the carbon layer. It can synergize with the N and S heteroatoms to significantly enhance the flame retardant and smoke suppression properties of the matrix. Finally, the introduced quaternary phosphonium salt functional groups, in which the positively charged phosphonium ions are adsorbed on the surface of the bacteria, can interact with the negatively charged cell membrane of the bacteria, penetrate the cell wall, combine with the cell membrane, destroy the surface structure of the cell, cause the intracellular substances to flow out, and stop the respiratory function of the bacteria, leading to cell death. Compared with quaternary ammonium salts, it has better antibacterial activity and greatly enhances the antibacterial properties of the matrix.

[0024] Beneficial effects of the present invention:

[0025] Compared with conventional polyurethane sponge materials, the polyurethane sponge material prepared by the present invention adds modified polyol as one of the raw materials. The modified polyol contains various functional groups and plays a synergistic role, which significantly improves the flame retardancy, antibacterial property, water resistance and a certain degree of mechanical strength of the polyurethane sponge material. In addition, the modified polyol can participate in the polymerization process of polyurethane, which ensures the long-term stability of the performance of the modified polyol. Therefore, the polyurethane sponge material prepared by the present invention has stable and efficient flame retardancy, antibacterial property and water resistance, and excellent mechanical properties, and has important application value in the field of sponge material technology. DETAILED DESCRIPTION

[0026] 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.

[0027] Example 1

[0028] Preparation of modified polyols:

[0029] S1. In a three-necked flask equipped with a stirring device, 26.2 g of triphenylphosphine, 15.1 g of 3-bromopropionic acid and 100 mL of toluene were mixed, and the temperature was raised to 55° C. The mixture was stirred for 4 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure to obtain intermediate 1.

[0030] S2. In a three-necked flask equipped with a stirring device, 15.4 g of triethanolamine, 33.5 g of intermediate 1 and 120 mL of N,N-dimethylformamide were mixed and stirred evenly, and then 0.2 g of dibutyltin oxide and 20.6 g of dicyclohexylcarbodiimide were added, and the temperature was raised to 85° C. for reaction for 4 h. Stirring was continued during the reaction. After the reaction was completed, the mixture was filtered, and part of the solvent was removed by rotary evaporation. The mixture was then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two was 3:2), and the eluent was removed by rotary evaporation to obtain intermediate 2;

[0031] S3, in a three-necked flask equipped with a stirring device, 10.6 g of thioglycolic acid, 48.7 g of intermediate 2 and 150 mL of N, N-dimethylformamide were mixed and stirred evenly, and then 0.3 g of dibutyltin oxide and 20.6 g of dicyclohexylcarbodiimide were added, and the temperature was raised to 90°C for reaction for 6 h. Stirring was continued during the reaction. After the reaction was completed, the mixture was filtered, and part of the solvent was removed by distillation under reduced pressure. Then, the mixture was purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two was 3:4), and the eluent was removed by rotary evaporation to obtain intermediate 3;

[0032] S4. Add 221.6 g of intermediate 3, 5.8 g of AIBN and 500 mL of N,N-dimethylformamide into a three-necked flask equipped with a stirring device, stir and mix well, then drop 34.4 g of tetramethyltetravinylcyclotetrasiloxane, maintain the temperature of the system at 80°C, and react for 6 hours. After the reaction is completed, first remove part of the solvent by rotary evaporation, and then purify by column chromatography (the eluent is a mixed solvent of ethyl acetate / petroleum ether, and the volume ratio of the two is 2:5), and remove the eluent by rotary evaporation to obtain a modified polyol.

[0033] Example 2

[0034] Preparation of modified polyols:

[0035] S1. In a three-necked flask equipped with a stirring device, 52.4 g of triphenylphosphine, 30.2 g of 3-bromopropionic acid and 200 mL of toluene were mixed, and the temperature was raised to 55° C. The mixture was stirred for 4 h. After the reaction was completed, the solvent was removed by distillation under reduced pressure to obtain intermediate 1.

[0036] S2. In a three-necked flask equipped with a stirring device, 30.8 g of triethanolamine, 67.0 g of intermediate 1 and 240 mL of N,N-dimethylformamide were mixed and stirred evenly, and then 0.4 g of dibutyltin oxide and 41.2 g of dicyclohexylcarbodiimide were added, and the temperature was raised to 85° C. for reaction for 4 h. Stirring was continued during the reaction. After the reaction was completed, the mixture was filtered, and part of the solvent was removed by rotary evaporation. The mixture was then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two was 3:2), and the eluent was removed by rotary evaporation to obtain intermediate 2;

[0037] S3, in a three-necked flask equipped with a stirring device, 21.2g of thioglycolic acid, 97.4g of intermediate 2 and 300mL of N,N-dimethylformamide were mixed and stirred evenly, and then 0.6g of dibutyltin oxide and 41.2g of dicyclohexylcarbodiimide were added, and the temperature was raised to 90°C for reaction for 6h, and stirring was continued during the reaction. After the reaction was completed, the mixture was filtered, and part of the solvent was removed by distillation under reduced pressure, and then purified by column chromatography (the eluent was a mixed solvent of benzene / ethyl acetate, and the volume ratio of the two was 3:4), and the eluent was removed by rotary evaporation to obtain intermediate 3;

[0038] S4. Add 443.2 g of intermediate 3, 11.6 g of AIBN and 1000 mL of N,N-dimethylformamide into a three-necked flask equipped with a stirring device, stir and mix evenly, then drop 34.4 g of tetramethyltetravinylcyclotetrasiloxane, maintain the temperature of the system at 80°C, and react for 6 hours. After the reaction is completed, first remove part of the solvent by rotary evaporation, and then purify by column chromatography (the eluent is a mixed solvent of ethyl acetate / petroleum ether, and the volume ratio of the two is 2:5), and remove the eluent by rotary evaporation to obtain a modified polyol.

[0039] Example 3

[0040] 20g of diphenylmethane diisocyanate, 40g of polyether polyol 330N, 3g of sodium dodecyl sulfate, 4g of pore opener BDM-3, 4g of deionized water, 1g of tetramethylethylenediamine, 2g of triphenyl phosphite and 5g of the modified polyol prepared in Example 1 were stirred at high speed for 30s, then added into a high-pressure foaming machine for foaming, and after foaming, placed in a constant temperature box at 50°C for aging for 72h to obtain a flame-retardant polyurethane sponge material.

[0041] Example 4

[0042] 30g of diphenylmethane diisocyanate, 50g of polyether polyol 330N, 4g of sodium dodecyl sulfate, 5g of pore opener BDM-3, 6g of deionized water, 2g of tetramethylethylenediamine, 3g of diphenyl isooctyl phosphite and 10g of the modified polyol prepared in Example 2 were stirred at high speed for 30s, then added into a high-pressure foaming machine for foaming, and after foaming, placed in a constant temperature box at 50°C for aging for 72h to obtain a flame-retardant polyurethane sponge material.

[0043] Example 5

[0044] 40g of diphenylmethane diisocyanate, 60g of polyether polyol 330N, 6g of sodium dodecyl sulfate, 6g of pore opener BDM-3, 8g of deionized water, 3g of tetramethylethylenediamine, 4g of diphenyl isooctyl phosphite and 15g of the modified polyol prepared in Example 2 were stirred at high speed for 30s, then added into a high-pressure foaming machine for foaming, and after foaming, placed in a constant temperature box at 50°C for aging for 72h to obtain a flame-retardant polyurethane sponge material.

[0045] Comparative Example 1

[0046] The modified polyol in Example 5 was replaced by polypropylene glycol of the same mass, and the remaining steps were the same as those in Example 5 to obtain a sponge material.

[0047] Comparative Example 2

[0048] The modified polyol in Example 5 was replaced by a commercially available halogen flame retardant of equal mass, and the remaining steps were the same as those in Example 5 to obtain a sponge material.

[0049] Examples 3-5 and comparative examples 1-2 were made into corresponding shapes according to different test standards and subjected to the following performance tests:

[0050] The tensile strength was determined using the national standard GB / T 6344-2008 "Determination of tensile strength and elongation at break of polymer porous elastic materials";

[0051] The national standard GB / T 2406.1-2008 "Determination of Combustion Behavior of Plastics by Oxygen Index Method" is used to measure the oxygen index of the sample before and after being placed at room temperature for 180 days;

[0052] The smoke density is measured using the national standard GB / T 8627-2007 "Test method for smoke density of burning or decomposition of building materials";

[0053] The antibacterial rate of Staphylococcus aureus and Escherichia coli was determined using the standard WS / T 650-2019 “Antibacterial and antibacterial effect evaluation method”;

[0054] Place the sample on the water surface for 5 minutes, and when it is saturated with adsorption, remove it to the grid in time, let it stand for 1 minute, weigh it and calculate the water absorption rate of the modified sponge; water absorption rate = (mass after water absorption g-mass before water absorption g) / mass before water absorption g;

[0055] The measured results are shown in the following table:

[0056] ;

[0057] It can be seen from the above table that the polyurethane sponge material prepared in the embodiment of the present invention has stable and efficient flame retardancy, antibacterial and waterproof properties, and excellent mechanical properties, and has important application value in the field of sponge material technology.

[0058] 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.

[0059] 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 similar ways. As long as they do not deviate from the invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing a flame retardant polyurethane sponge material, characterized in that: The following steps are involved: Diphenylmethane diisocyanate, polyether polyol, foaming agent, cell opening agent, deionized water, tetramethylethylenediamine, antioxidant and modified polyol are stirred at high speed and foamed, and then aged to obtain a flame retardant polyurethane sponge material; The raw materials are calculated by weight as follows: 20-40 parts of diphenylmethane diisocyanate, 40-60 parts of polyether polyol, 3-6 parts of foaming agent, 4-6 parts of pore opening agent, 4-8 parts of deionized water, 1-3 parts of tetramethylethylenediamine, 2-4 parts of antioxidant, and 5-15 parts of modified polyol; Wherein, the modified polyol is prepared by the following steps: S1. Triphenylphosphine, 3-bromopropionic acid and toluene were mixed and reacted at 55°C for 4 hours. After the reaction was completed, the mixture was distilled under reduced pressure to obtain intermediate 1. The ratio of triphenylphosphine, 3-bromopropionic acid and toluene was 26.2 g:15.1 g:100 mL. S2. Triethanolamine, intermediate 1 and N,N-dimethylformamide are mixed and stirred evenly, and then dibutyltin oxide and dicyclohexylcarbodiimide are added, and the mixture is reacted at 85° C. for 4 hours with continuous stirring during the reaction. After the reaction is completed, the mixture is filtered, rotary evaporated, purified by column chromatography, and rotary evaporated to obtain intermediate 2; the ratio of triethanolamine, intermediate 1, N,N-dimethylformamide, dibutyltin oxide and dicyclohexylcarbodiimide is 15.4 g:33.5 g:120 mL:0.2 g:20.6 g; S3, thioglycolic acid, intermediate 2 and N, N-dimethylformamide are mixed and stirred evenly, and then dibutyltin oxide and dicyclohexylcarbodiimide are added, and the mixture is reacted at 90° C. for 6 hours, and the mixture is stirred continuously during the reaction. After the reaction is completed, the mixture is filtered, distilled under reduced pressure, purified by column chromatography, and rotary evaporated to obtain intermediate 3; the ratio of thioglycolic acid, intermediate 2, N, N-dimethylformamide, dibutyltin oxide, and DCC is 10.6 g:48.7 g:150 mL:0.3 g:20.6 g; S4. Stir and mix the intermediate 3, AIBN and N,N-dimethylformamide evenly, then drop tetramethyltetravinylcyclotetrasiloxane, and react at 80°C for 6 hours. After the reaction is completed, perform rotary evaporation, purify by column chromatography, and obtain modified polyol by rotary evaporation. The usage ratio of intermediate 3, AIBN, N,N-dimethylformamide and tetramethyltetravinylcyclotetrasiloxane is 221.6 g:5.8 g:500 mL:34.4 g.

2. The method for preparing a flame retardant polyurethane sponge material according to claim 1, characterized in that: The antioxidant is one of triphenyl phosphite and diphenyl isooctyl phosphite.