Nano SiO2 synergistic P-N flame-retardant waterborne polyurethane and preparation method thereof

Abstract

The invention provides nano SiO2 synergistic P-N flame-retardant waterborne polyurethane and a preparation method of the nano SiO2 synergistic P-N flame-retardant waterborne polyurethane. The nano SiO2 synergistic P-N flame-retardant waterborne polyurethane is prepared from the following raw materials in parts by weight: 40 to 50 parts of an alcoholic hydroxyl group-containing monomer, 80 to 100 parts of diisocyanate, 0.05 to 0.15 part of a catalyst, 30 to 40 parts of a solvent, 5 to 15 parts of cationic hydrophilic dihydric alcohol, 2 to 10 parts of micromolecular dihydric alcohol, 5 to 7 parts of nitrogen and phosphorus-containing dihydric alcohol, 5 to 15 parts of a neutralizing agent, 7 to 10 parts of alkoxy silane, 110 to 130 parts of water and 7 to 10 parts of methyltrimethoxysilane. The limit oxygen index of the nano SiO2 synergistic P-N flame-retardant waterborne polyurethane can reach 29%, the combustion grade is grade A, the application prospect is wide, and the market value is high; the preparation method is simple to operate and low in cost, and has relatively good practicability and economical efficiency.

Description

Technical Field

[0001] The present application relates to the technical field of polymer composite materials, and in particular to a nano-SiO2 synergistic PN flame-retardant waterborne polyurethane and a preparation method thereof. Background Art

[0002] Waterborne polyurethane (WPU) is a material with water as the dispersion medium. It has the advantages of no pollution, high chemical stability, good mechanical properties and good compatibility. Therefore, it is widely used in coatings, adhesives, leather finishing agents, fiber surface treatment agents and other fields; however, due to the low limiting oxygen index of waterborne polyurethane and the problem of easy generation of toxic gases during combustion, its application range is greatly limited. In order to improve the flame retardant properties of waterborne polyurethane, a reactive flame retardant method is usually used. Flame retardant monomers are introduced into the polyurethane chain by means of chemical reactions such as copolymerization or grafting. With strong intermolecular forces, the flame retardant elements are not easy to fall off or migrate, thereby giving the product self-flame retardant properties. At present, the main research on reactive flame retardant waterborne polyurethane is still based on PN flame retardant elements, but the content of flame retardant elements introduced by this method is low, and the flame retardant mechanism involved is single, which makes it difficult to reach the standard of high flame retardant grade. Therefore, it is usually used to work together with one or several flame retardants, synergize each other's advantages, and complement each other's strengths and weaknesses, which can greatly improve the flame retardant properties of polymer materials.

[0003] Since the 1980s, silicon has been used as a flame retardant element with the advantages of no pollution, less smoke, non-toxicity, high efficiency and anti-dripping. Its flame retardant principle mainly follows the condensation phase mechanism, that is, during the combustion of the polymer, silicon decomposes to produce amorphous SiO2, or Si-O-Si chain links cross-link with the material matrix to block the carbon layer. The cross-linked condensation phase on the polymer surface can effectively reduce the internal and external heat exchange, thereby effectively preventing further thermal decomposition of the protected matrix. Among the many different forms of silicon-based flame retardants, nano-SiO2 is one of the most common flame retardant materials. Because nano-SiO2 has a three-dimensional network structure and a large number of active hydroxyl groups on the surface, it is easy to bond with the groups on the surface of waterborne polyurethane, thereby improving the thermal stability and chemical stability of the polymer. Therefore, nano-SiO2 has gradually become the main development direction of synergistic flame retardants.

[0004] Nano-SiO2 has high surface activity and large specific surface area, which is very different from the solubility parameters of polyurethane. If a simple physical blending modification method is used, the nano-SiO2 content is low and it is easy to aggregate and it is difficult to evenly disperse in the polyurethane material, thus affecting the flame retardant properties of the material. How to control the reaction conditions, optimize the reaction process, increase the doping amount of nano-SiO2 and its compatibility with polyurethane is the key to obtaining nano-SiO2 synergistic PN flame retardant waterborne polyurethane composite materials with good performance. Summary of the invention

[0005] Based on the problems existing in the background technology, the present application provides a nano-SiO2 synergistic PN flame-retardant waterborne polyurethane and its preparation method on the basis of improving the content and uniform dispersion of nano-SiO2. The preparation method of the present application uses nitrogen-phosphorus diols and alkoxysilanes as chain extenders, introduces them into waterborne polyurethane segments by reacting with diisocyanates, and synthesizes polyurethane prepolymers; then, methyltrimethoxysilane is added in the prepolymer emulsification stage for hydrolysis and condensation to obtain nano-SiO2 / PN flame-retardant waterborne polyurethane hybrid materials. The co-hydrolysis and condensation of embedded silane alkoxysilane and methyltrimethoxysilane not only increases the doping amount of nano-SiO2, but also introduces chemical bonds between the inorganic phase and the organic phase. There is a strong interaction force between the two phases, which can better overcome the agglomeration of nano-SiO2 particles, improve the compatibility and dispersibility between the two phases, and the obtained composite material has high strength, excellent flame retardant performance, good heat resistance, and realizes the synergistic effect of SiO2 and PN flame retardant, which can meet the use requirements of various fields.

[0006] Specifically, according to the first aspect of the present application, a nano-SiO2 synergistic PN flame-retardant water-based polyurethane is provided, comprising the following raw materials: 40 to 50 parts of alcohol-hydroxyl monomers, 80 to 100 parts of diisocyanates, 0.05 to 0.15 parts of catalysts, 30 to 40 parts of solvents, 5 to 15 parts of cationic hydrophilic diols, 2 to 10 parts of small molecule diols, 5 to 7 parts of nitrogen-phosphorus diols, 5 to 15 parts of neutralizers, 7 to 10 parts of alkoxysilanes, 110 to 130 parts of water, and 7 to 10 parts of methyltrimethoxysilane.

[0007] Furthermore, the alcohol hydroxyl-containing monomer is one of polycarbonate diol, polybutylene adipate, polyethylene glycol, polypropylene glycol, or a combination of any of them.

[0008] Preferably, the molecular weight of the alcoholic hydroxyl group-containing monomer is 800-4000.

[0009] Furthermore, the diisocyanate is hexamethylene diisocyanate and / or isophorone diisocyanate.

[0010] Furthermore, the catalyst is one of dibutyltin dilaurate, bis(dimethylaminoethyl)ether, dimethylaminoethoxyethanol, dimethylethanolamine, N,N-(bis(dimethylaminopropyl)isopropanolamine) and triethylenediamine, or a combination of any of them.

[0011] Furthermore, the solvent is N-methylpyrrolidone.

[0012] Furthermore, the cationic hydrophilic diol is N-methyldiethanolamine and / or diethanolamine.

[0013] Furthermore, the small molecule diol is one of 1,4-butanediol, 1,6-hexanediol, pentanediol, diethylene glycol, or any combination thereof.

[0014] Furthermore, the nitrogen-phosphorus-containing diol is N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester.

[0015] Furthermore, the neutralizing agent is acetic acid.

[0016] Furthermore, the alkoxysilane is one of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-aminoethyl-3-aminopropyltriethoxysilane, and N-2-aminoethyl-3-aminopropyltrimethoxysilane, or a combination of any two of them.

[0017] According to a second aspect of the present application, a method for preparing the aforementioned nano-SiO2 synergistic PN flame-retardant waterborne polyurethane is provided, comprising the following steps:

[0018] (1) Adding alcoholic hydroxyl monomers by weight into a flask equipped with a stirring blade, a thermometer and a condensing device, raising the temperature to 115 to 120° C., and vacuum dehydrating for 2 to 2.5 hours at a pressure of -0.05 to -0.1 KPa;

[0019] (2) After the vacuum dehydration is completed, the system is filled with nitrogen, the temperature is lowered to 80-90° C., and the catalyst, solvent, and diisocyanate are added in sequence (using a constant pressure funnel to add dropwise at a specified dropwise speed), and the temperature is maintained for reaction for 2-2.5 hours;

[0020] (3) lowering the temperature to 50-60° C., adding cationic hydrophilic diol and small molecule diol in sequence, and reacting for 2-2.5 hours; adding nitrogen-phosphorus diol for chain extension, and reacting for 1-3 hours; finally, adding a neutralizing agent, and reacting for 30-50 minutes;

[0021] (4) lowering the reaction temperature to room temperature, adding alkoxysilane, and reacting for 1 to 1.5 hours to obtain a waterborne polyurethane prepolymer;

[0022] (5) Emulsification: 100 to 110 parts by weight of water are slowly added to the waterborne polyurethane prepolymer obtained in step (4) under high-speed stirring until the phase is inverted to form an emulsion, and methyltrimethoxysilane is added dropwise. The reaction is carried out for 2 to 3 hours, and the remaining water is continued to be added to adjust the solid content of the emulsion to 30 wt% to 40 wt%. The emulsion is then poured out from the reaction container, and impurities are filtered to obtain a nano-SiO2 synergistic PN flame-retardant waterborne polyurethane emulsion.

[0023] Furthermore, in step (1), the flask is a three-necked flask or a four-necked flask.

[0024] Furthermore, in step (2), the dripping speed is set to 20 to 40 drops / minute, preferably 30 drops / minute.

[0025] Furthermore, in step (4), the room temperature is 20 to 30°C.

[0026] Furthermore, in step (5), the high-speed stirring speed is controlled to be 3000-3400 r / min.

[0027] Compared with the prior art, this application has the following beneficial effects:

[0028] 1. This application selects different types of flame retardant monomers and improves the flame retardant properties of waterborne polyurethane by means of chain extension and gel-sol composite modification.

[0029] 2. The present application adopts nitrogen-phosphorus diol to modify waterborne polyurethane. The nitrogen-phosphorus diol enters the matrix unit of polyurethane in the form of chain extension, and the PN in the side chain gives the material good flame retardant properties. In addition, the present application uses two different organosilicon as raw materials, and through the sol-gel effect, the alkoxysilane embedded in the chain segment and the methyltrimethoxysilane added externally are condensed and hydrolyzed to form a three-dimensional network structure of Si-O-Si, thereby increasing the doping amount of nano-SiO2. As the cross-linking density of nano-SiO2 gradually increases, the compatibility of the organic phase and the inorganic phase is enhanced, overcoming the technical problem that the modified material caused by the large specific surface area, high surface activity and easy aggregation of nano-SiO2 in the process of modifying polyurethane cannot be dispersed uniformly. At the same time, the modification of nano-SiO2 enhances the interaction between the polyurethane molecular chains, making the molecular chains less likely to deform and hydrolyze, thereby making the waterborne polyurethane improve the flame retardant properties while the mechanical strength, hydrolysis resistance, stability and adhesion of the material are also significantly improved, which is suitable for more complex application environments.

[0030] 3. The nitrogen-phosphorus-containing diols, alkoxysilanes, and methyltrimethoxysilane in this application are all reactive flame retardant monomers. In the waterborne polyurethane matrix prepared by this scheme, the nano-SiO2 has a Si-O-Si cross-linked network as the skeleton (the concrete structure is as follows Figure 1 As shown in the figure, the polymer forms a dense thermosetting structure when burning, preventing heat exchange between the inside and outside of the substrate, while the PN group in the side chain plays a flame retardant role in the gas phase and condensed phase, showing a violent blow-out phenomenon. The dual modification of nano-SiO2 organic-inorganic hybrid network and PN elements can synergistically enhance the flame retardant properties of waterborne polyurethane.

[0031] 4. The waterborne polyurethane prepared in this application has good stability, flame retardant elements do not migrate, smoke suppression performance is good, and the flame retardant effect is safe, environmentally friendly, and long-lasting, which can meet the application requirements in the fields of fabric coating and leather dipping. At the same time, this application has low cost, simple preparation method, good processability suitable for ordinary equipment, and is very easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] According to the following description of the drawings, the purpose, features and advantages of the specific implementation cases of the present application are described in detail, which will help those skilled in the art to better understand the practical significance of the present application.

[0033] Figure 1 It is a schematic structural diagram of a nano-SiO2 synergistic PN flame-retardant waterborne polyurethane composite material of the present application.

[0034] Figure 2 This is an infrared spectrum of a nano-SiO2 synergistic PN flame-retardant waterborne polyurethane of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme of the present application will be clearly and completely described below in conjunction with the specific embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other in the absence of conflict. The present application will be described in detail below in conjunction with the embodiments.

[0036] Exploring the subject matter described in this application by referring to specific implementation cases will help those skilled in the art to have a deeper understanding of the significance of this application. These implementation cases are not limited to the scope of protection, examples or applicability described in the claims. Without exceeding the scope of this specification, the addition ratio and arrangement of the elements under discussion can be adjusted. Each example can add various processes, or replace, omit, or supplement each component according to actual needs. In addition, the features described specifically can be combined in different examples.

[0037] The following shows a synthesis route of a nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to a specific embodiment of the present application.

[0038]

[0039] It should be pointed out that this implementation is only used to introduce in detail the technical solution of the nano-SiO2 synergistic PN flame-retardant water-based polyurethane and preparation method of the present application, and does not constitute a limitation on the scope of the present application.

[0040] Below, through specific examples, the technical solution for synthesizing the nano-SiO2 synergistic PN flame-retardant waterborne polyurethane of the present application is further described in detail.

[0041] Embodiment 1:

[0042] The following raw materials are prepared by weight: 45 parts of alcohol-hydroxyl monomers (all polybutylene adipate (2000)), 90 parts of diisocyanates (all hexamethylene diisocyanate), 0.1 parts of catalysts (all dibutyltin dilaurate), 35 parts of N-methylpyrrolidone, 10 parts of cationic hydrophilic diols (all N-methyldiethanolamine), 8 parts of small molecule diols (all diethylene glycol), 10 parts of acetic acid, 6 parts of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, 7 parts of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane, 110 parts of water, and 7 parts of methyltrimethoxysilane.

[0043] (1) Polybutylene adipate (2000) monomer is placed in a four-necked flask equipped with a stirring blade, a thermometer and a condensing device, the temperature is raised to 115-120° C., and vacuum dehydration is performed at a pressure of -0.1 KPa for 2-2.5 hours.

[0044] (2) After the vacuum dehydration is completed, the system is filled with nitrogen, the temperature is lowered to 80-90° C., dibutyltin dilaurate and hexamethylene diisocyanate are added to the four-necked flask in sequence (using a constant pressure funnel to add at a dropping rate of 30 drops / min), and then N-methylpyrrolidone is added to reduce the viscosity of the system, and the mixture is stirred at this temperature for 2-2.5 hours.

[0045] (3) The temperature is lowered to 50-60° C., and N-methyldiethanolamine and diethylene glycol are added to the reaction system in sequence, and the mixture is stirred for reaction for 2-2.5 hours; then N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester is added to carry out chain extension reaction for 1-3 hours; finally, acetic acid is added for neutralization, and the reaction is carried out for 40 minutes.

[0046] (4) The reaction temperature is lowered to room temperature, N-2-aminoethyl-3-aminopropylmethyldiethoxysilane is added, and the reaction is stirred for 1 to 1.5 hours to obtain a polyurethane prepolymer.

[0047] (5) Slowly add 100 parts of water to the obtained polyurethane prepolymer at a speed of 3000 r / min until the phase is inverted to form an emulsion, then add methyltrimethoxysilane dropwise, react for 2 to 3 hours, continue to add 10 parts of water to adjust the solid content of the emulsion to 30wt% to 40wt%, filter out impurities, and obtain nano-SiO2 synergistic PN flame-retardant water-based polyurethane.

[0048] Embodiment 2:

[0049] The following raw materials are prepared by weight: 45 parts of alcohol-hydroxyl monomers (all polybutylene adipate (2000)), 90 parts of diisocyanates (all hexamethylene diisocyanate), 0.1 parts of catalysts (all dibutyltin dilaurate), 35 parts of N-methylpyrrolidone, 10 parts of cationic hydrophilic diols (all N-methyldiethanolamine), 8 parts of small molecule diols (all diethylene glycol), 10 parts of acetic acid, 6 parts of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, 8 parts of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane, 110 parts of water, and 8 parts of methyltrimethoxysilane.

[0050] Steps (1) to (5) are the same as the process flow in Example 1.

[0051] Embodiment 3:

[0052] (1) The following raw materials are prepared by weight: 45 parts of alcohol-hydroxyl monomer (all polybutylene adipate (2000)), 90 parts of diisocyanate (all hexamethylene diisocyanate), 0.1 parts of catalyst (all dibutyltin dilaurate), 35 parts of N-methylpyrrolidone, 10 parts of cationic hydrophilic diol (all N-methyldiethanolamine), 8 parts of small molecule diol (all diethylene glycol), 10 parts of acetic acid, 6 parts of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, 9 parts of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane, 110 parts of water, and 9 parts of methyltrimethoxysilane.

[0053] Steps (1) to (5) are the same as the process flow in Example 1.

[0054] Embodiment 4:

[0055] (1) The following raw materials are prepared by weight: 45 parts of alcohol-hydroxyl monomer (all polybutylene adipate (2000)), 90 parts of diisocyanate (all hexamethylene diisocyanate), 0.1 parts of catalyst (all dibutyltin dilaurate), 35 parts of N-methylpyrrolidone, 10 parts of cationic hydrophilic diol (all N-methyldiethanolamine), 8 parts of small molecule diol (all diethylene glycol), 10 parts of acetic acid, 6 parts of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, 10 parts of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane, 110 parts of water, and 10 parts of methyltrimethoxysilane.

[0056] Steps (1) to (5) are the same as the process flow in Example 1.

[0057] Embodiment 5:

[0058] (1) The following raw materials are prepared by weight: 40 parts of alcohol-hydroxyl monomer (all of which are polycarbonate diol (3000)), 80 parts of diisocyanate (all of which are isophorone diisocyanate), 0.08 parts of catalyst (all of which are dimethylaminoethoxyethanol), 30 parts of N-methylpyrrolidone, 6 parts of cationic hydrophilic diol (all of which are diethanolamine), 5 parts of small molecule diol (all of which are pentanediol), 5 parts of acetic acid, 5 parts of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, 7 parts of N-2-aminoethyl-3-aminopropyltriethoxysilane, 120 parts of water, and 8 parts of methyltrimethoxysilane.

[0059] Except that the pressure in step (1) is replaced by -0.05 KPa, the neutralization reaction time in step (3) is replaced by 50 minutes, and the rotation speed in step (5) is replaced by 3400 r / min, steps (1) to (5) are the same as the process flow in Example 1.

[0060] Embodiment 6:

[0061] (1) The following raw materials are prepared by weight: 50 parts of alcohol-hydroxyl monomers (all polyethylene glycol (1000)), 100 parts of diisocyanates (all isophorone diisocyanate), 0.15 parts of catalysts (0.05 parts of dimethylethanolamine and 0.1 parts of N,N-(bis(dimethylaminopropyl)isopropanolamine), 40 parts of N-methylpyrrolidone, 15 parts of cationic hydrophilic diols (8 parts of N-methyldiethanolamine and 7 parts of diethanolamine), 10 parts of small molecule diols (5 parts of 1,4-butanediol and 5 parts of 1,6-hexanediol), 15 parts of acetic acid, 7 parts of diethyl N,N-bis(2-hydroxyethyl)aminomethylenephosphonate, 10 parts of N-2-aminoethyl-3-aminopropyltrimethoxysilane, 130 parts of water, and 8 parts of methyltrimethoxysilane.

[0062] Steps (1) to (5) are the same as the process flow in Example 1, except that the dropping speed in step (2) is replaced by 40 drops / minute, the neutralization reaction time in step (3) is replaced by 30 minutes, and the rotation speed in step (5) is replaced by 3200 r / min.

[0063] Embodiment 7:

[0064] (1) The following raw materials are prepared by weight: 46 parts of alcohol-hydroxyl monomer (all polybutylene adipate (2000)), 92 parts of diisocyanate (all hexamethylene diisocyanate), 0.12 parts of catalyst (all triethylenediamine), 37 parts of N-methylpyrrolidone, 12 parts of cationic hydrophilic diol (all diethanolamine), 5 parts of small molecule diol (all 1,6-hexanediol), 7 parts of acetic acid, 6 parts of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, 8 parts of N-2-aminoethyl-3-aminopropyltriethoxysilane, 120 parts of water, and 9 parts of methyltrimethoxysilane.

[0065] Steps (1) to (5) are the same as the process flow in Example 1.

[0066] Comparative Example 1:

[0067] The following raw materials are prepared by weight: 45 parts of alcohol-hydroxyl monomers (all polybutylene adipate (2000)), 90 parts of diisocyanates (all hexamethylene diisocyanate), 0.1 parts of catalysts (all dibutyltin dilaurate), 35 parts of N-methylpyrrolidone, 10 parts of cationic hydrophilic diols (all N-methyldiethanolamine), 8 parts of small molecule diols (all diethylene glycol), 10 parts of acetic acid, and 110 parts of water.

[0068] (1) Polybutylene adipate (2000) monomer is placed in a four-necked flask equipped with a stirring blade, a thermometer and a condensing device, the temperature is raised to 115-120° C., and vacuum dehydration is performed at a pressure of -0.1 KPa for 2-2.5 hours.

[0069] (2) After the vacuum dehydration is completed, the system is filled with nitrogen, the temperature is lowered to 80-90° C., dibutyltin dilaurate and hexamethylene diisocyanate are added to the four-necked flask in sequence (adding at a prescribed dropping speed using a constant pressure funnel), and then N-methylpyrrolidone is added to reduce the viscosity of the system, and the mixture is stirred at this temperature for 2-2.5 hours.

[0070] (3) The temperature is lowered to 50-60° C., and N-methyldiethanolamine and diethylene glycol are added to the reaction system in sequence, and the mixture is stirred and reacted for 2-2.5 hours; acetic acid is then added for neutralization, and the mixture is reacted for 40 minutes to obtain a polyurethane prepolymer.

[0071] (4) The reaction temperature is lowered to room temperature, and 100 parts of water are slowly added to the obtained polyurethane prepolymer at a rotation speed of 3000 r / min until the phase is inverted to form an emulsion, and then 10 parts of water are added to adjust the solid content of the emulsion to 30wt% to 40wt%, and impurities are filtered to obtain an unmodified waterborne polyurethane.

[0072] Comparative Example 2:

[0073] The following raw materials are prepared by weight: 45 parts of alcohol-hydroxyl monomers (all polybutylene adipate (2000)), 90 parts of diisocyanates (all hexamethylene diisocyanate), 0.1 parts of catalysts (all dibutyltin dilaurate), 35 parts of N-methylpyrrolidone, 10 parts of cationic hydrophilic diols (all N-methyldiethanolamine), 8 parts of small molecule diols (all diethylene glycol), 6 parts of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, 10 parts of acetic acid, and 110 parts of water.

[0074] (1) The process is the same as that of Comparative Example 1.

[0075] (2) The process is the same as that of Comparative Example 1.

[0076] (3) The temperature is lowered to 50-60° C., and N-methyldiethanolamine and diethylene glycol are added to the reaction system in sequence, and the mixture is stirred for reaction for 2-2.5 hours; then, N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester is added to carry out chain extension reaction for 1-3 hours; finally, acetic acid is added for neutralization, and the reaction is carried out for 40 minutes to obtain a polyurethane prepolymer.

[0077] (4) A PN flame-retardant waterborne polyurethane was prepared in the same process as in Comparative Example 1.

[0078] Comparative Example 3:

[0079] The following raw materials are prepared by weight: 45 parts of alcohol-hydroxyl monomers (all polybutylene adipate (2000)), 90 parts of diisocyanates (all hexamethylene diisocyanate), 0.1 parts of catalysts (all dibutyltin dilaurate), 35 parts of N-methylpyrrolidone, 10 parts of cationic hydrophilic diols (all N-methyldiethanolamine), 8 parts of small molecule diols (all diethylene glycol), 6 parts of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester, 10 parts of acetic acid, 7 parts of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane, and 110 parts of water.

[0080] (1) The process is the same as that of Comparative Example 1.

[0081] (2) The process is the same as that of Comparative Example 1.

[0082] (3) Lower the temperature to 50-60° C., add N-methyldiethanolamine and diethylene glycol to the reaction system in sequence, and stir to react for 2-2.5 hours; then add N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester to carry out chain extension reaction for 1-3 hours; add acetic acid to neutralize, and react for 40 minutes.

[0083] (4) The reaction temperature is lowered to room temperature, N-2-aminoethyl-3-aminopropylmethyldiethoxysilane is added, and the reaction is stirred for 1 to 1.5 hours to obtain a polyurethane prepolymer.

[0084] (5) Slowly add 100 parts of water to the obtained polyurethane prepolymer at a rotation speed of 3000 r / min until the phase is inverted to form an emulsion, and then continue to add 10 parts of water to adjust the solid content of the emulsion to 30wt%-40wt%, and filter out impurities to obtain a silicone synergistic PN flame-retardant water-based polyurethane.

[0085] Comparative Example 4:

[0086] The following raw materials are prepared by weight: 45 parts of alcohol-hydroxyl monomers (all polybutylene adipate (2000)), 90 parts of diisocyanates (all hexamethylene diisocyanate), 0.1 parts of catalysts (all dibutyltin dilaurate), 35 parts of N-methylpyrrolidone, 10 parts of cationic hydrophilic diols (all N-methyldiethanolamine), 8 parts of small molecule diols (all diethylene glycol), 10 parts of acetic acid, 7 parts of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane, 110 parts of water, and 7 parts of methyltrimethoxysilane.

[0087] (1) The process is the same as that of Comparative Example 1.

[0088] (2) The process is the same as that of Comparative Example 1.

[0089] (3) The temperature was lowered to 50-60° C., and N-methyldiethanolamine and diethylene glycol were added to the reaction system in sequence, and the mixture was stirred for reaction for 2-2.5 hours; acetic acid was then added for neutralization, and the mixture was reacted for 40 minutes.

[0090] (4) The reaction temperature is lowered to room temperature, N-2-aminoethyl-3-aminopropylmethyldiethoxysilane is added, and the reaction is stirred for 1 to 1.5 hours to obtain a polyurethane prepolymer.

[0091] (5) 100 parts of water are slowly added to the obtained polyurethane prepolymer at a rotation speed of 3000 r / min until the phase is inverted to form an emulsion, and methyltrimethoxysilane is added dropwise to react for 2 to 3 hours. 10 parts of water are continuously added to adjust the solid content of the emulsion to 30 wt% to 40 wt%, and impurities are filtered to obtain a nano-SiO2 flame-retardant water-based polyurethane.

[0092] The infrared spectrum of the nano-SiO2 synergistic PN flame-retardant waterborne polyurethane synthesized by the method of Example 1 of the present application is as follows Figure 2 As shown. Figure 2 It can be observed that 3391cm -1 There is an absorption peak of NH at 1726cm -1 There is a more obvious stretching vibration peak of the C=O bond in the carbamate bond nearby, indicating the formation of the carbamate bond. -1 There is no obvious absorption peak nearby, indicating that the isocyanate group has reacted completely. -1 The characteristic absorption peak of P=O is 1096cm -1 The peak at is the stretching vibration peak of Si-O-Si. From the above spectrum, we can know that nano-SiO2 and PN type flame retardant successfully modified polyurethane.

[0093] Performance Testing:

[0094] Each sample in the above comparative example and the example was made into a polyurethane film. The test standard for the limiting oxygen index was ASTM D2863, the test standard for the emulsion particle size was GB / T2794-1995, the test standard for the elongation at break was GB / T1040.1-2018, and the test standard for the emulsion stability was GB / T6753.3-1986.

[0095] The performance tests of the comparative example and the example are shown in Table 1.

[0096] Table 1 Comparative Example and Example Performance Test

[0097]

[0098] Comparative Example 1 is a waterborne polyurethane without flame retardant modification, Comparative Example 2 is a waterborne polyurethane modified by introducing PN flame retardant, Comparative Example 3 is a waterborne polyurethane modified by introducing PN flame retardant and block organosilane, and Comparative Example 4 is a waterborne polyurethane modified by introducing block organosilane and adding organosilane (co-hydrolyzed and condensed to generate nano-SiO2); by comparison with Examples 1-7, it is found that the introduction of nano-SiO2 and PN flame retardant in waterborne polyurethane in this application has a synergistic enhancement effect on the flame retardant properties of waterborne polyurethane; and in Examples 1-4, as the content of organosilicon increases, the limiting oxygen index and elongation at break gradually increase, and the particle size does not increase significantly, indicating that as the content of nano-SiO2 increases, the three-dimensional network of Si-O-Si forms a denser thermosetting structure, strengthens the interaction between polyurethane molecular chains, and enhances the compatibility of organic phase and inorganic phase.

[0099] In summary, the flame retardant properties of the nano-SiO2 synergistic PN flame-retardant waterborne polyurethane prepared in this application are greatly improved, and the mechanical strength, hydrolysis resistance, stability and adhesion of the material are also significantly improved, which is suitable for more complex application environments; and the emulsion has good stability, the flame retardant elements do not migrate, the smoke suppression performance is good, the flame retardant effect is safe, environmentally friendly and durable; the cost is low, the preparation method is simple, it has good processability to adapt to ordinary equipment, and it is very easy to realize industrial production. The above is only a preferred embodiment of the present application, and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the above embodiments, a person skilled in the art should understand that the technical solutions described in the above embodiments can still be modified, or some of the technical features can be replaced by equivalents; and these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A nano-SiO2 synergistic PN flame-retardant waterborne polyurethane, characterized in that: Contains the following raw materials, each raw material by weight: 40-50 parts of alcoholic hydroxyl monomers; 80-100 parts of diisocyanates; 0.05-0.15 parts of catalysts; 30-40 parts of solvents; 5-15 parts of cationic hydrophilic diols; 2-10 parts of small molecule diols; 5-7 parts of nitrogen and phosphorus-containing diols; 5-15 parts of neutralizers; 7-10 parts of alkoxysilanes; 110-130 parts of water and 7-10 parts of methyltrimethoxysilane.

2. The nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to claim 1, characterized in that: The alcohol hydroxyl-containing monomer is one of polycarbonate diol, polybutylene adipate, polyethylene glycol, polypropylene glycol, or any combination thereof.

3. The nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to claim 1, characterized in that: The molecular weight of the alcoholic hydroxyl group-containing monomer is 800-4000.

4. The nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to claim 1, characterized in that: The diisocyanate is hexamethylene diisocyanate and / or isophorone diisocyanate.

5. The nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to claim 1, characterized in that: The catalyst is one of dibutyltin dilaurate, bis(dimethylaminoethyl)ether, dimethylaminoethoxyethanol, dimethylethanolamine, N,N-(bis(dimethylaminopropyl)isopropanolamine) and triethylenediamine, or a combination of any of the above.

6. The nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to claim 1, characterized in that: The solvent is N-methylpyrrolidone; and the neutralizing agent is acetic acid.

7. The nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to claim 1, characterized in that: The cationic hydrophilic diol is N-methyldiethanolamine and / or diethanolamine.

8. The nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to claim 1, characterized in that: The small molecule diol is one of 1,4-butanediol, 1,6-hexanediol, pentanediol, and diethylene glycol, or a combination of any of them.

9. The nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to claim 1, characterized in that: The nitrogen-phosphorus-containing diol is N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester.

10. The nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to claim 1, characterized in that: The alkoxysilane is one of N-2-aminoethyl-3-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-aminoethyl-3-aminopropyltriethoxysilane, and N-2-aminoethyl-3-aminopropyltrimethoxysilane, or a combination of any of them.

11. A method for preparing the nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to any one of claims 1 to 10, characterized in that: The following steps are involved: (1) Adding alcoholic hydroxyl monomers by weight into a flask equipped with a stirring blade, a thermometer and a condensing device, raising the temperature to 115 to 120° C., and vacuum dehydrating for 2 to 2.5 hours at a pressure of -0.05 to -0.1 KPa; (2) After the vacuum dehydration is completed, the system is filled with nitrogen, the temperature is lowered to 80-90° C., the catalyst, solvent, and diisocyanate are added in sequence, and the temperature is maintained for reaction for 2-2.5 hours; (3) lowering the temperature to 50-60° C., adding cationic hydrophilic diol and small molecule diol in sequence, and reacting for 2-2.5 hours; adding nitrogen-phosphorus diol for chain extension, and reacting for 1-3 hours; finally, adding a neutralizing agent, and reacting for 30-50 minutes; (4) lowering the reaction temperature to room temperature, adding alkoxysilane, and reacting for 1 to 1.5 hours to obtain a waterborne polyurethane prepolymer; (5) Emulsification: 100 to 110 parts by weight of water are slowly added to the waterborne polyurethane prepolymer obtained in step (4) under high-speed stirring until the phase is inverted to form an emulsion, and methyltrimethoxysilane is added dropwise. The reaction is carried out for 2 to 3 hours, and the remaining water is continued to be added to adjust the solid content of the emulsion to 30 wt% to 40 wt%. The emulsion is then poured out from the reaction container, and impurities are filtered to obtain the nano-SiO2 synergistic PN flame-retardant waterborne polyurethane.

12. The method for preparing the nano-SiO2 synergistic PN flame-retardant waterborne polyurethane according to claim 11, characterized in that: In the step (5), the high-speed stirring speed is controlled to be 3000-3400 r / min.

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