Preparation method of flame-retardant leather for vehicles

Abstract

The invention discloses a preparation method of flame-retardant leather for vehicles, which comprises the following steps: S1, preparation of bridged organic silicon sol: stirring a bridged organic silicon precursor, water and inorganic acid in an organic solvent to carry out hydrolytic polymerization reaction so as to prepare the bridged organic silicon sol, and then carrying out post-treatment dehydration on the bridged organic silicon sol for later use; wherein the bridged organic silicon precursor is selected from a silsesquioxane precursor with a carbon-hydrogen bridged structure; s2, preparation of flame-retardant polyurethane coating paste: stirring and mixing the bridging organic silica sol, the brominated flame retardant and the antimony-containing flame retardant which are used for later use in the polyurethane coating paste, so as to prepare the flame-retardant polyurethane coating paste; s3, preparation of the flame-retardant leather for the vehicle: pretreatment of base cloth: soaking the base cloth in the impregnation liquid, taking out the base cloth, extruding the base cloth, and ironing the base cloth; the pretreated base cloth is coated with the flame-retardant polyurethane coating paste, standing is carried out, then solidification is carried out in solidification liquid, water washing, extrusion and drying are carried out, and the flame-retardant leather for the vehicle is prepared.

Description

Technical Field

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

[0002] Polyurethane (PU) is an organic polymer material, the main chain of which is composed of a hard segment consisting of isocyanate and a chain extender and a soft segment consisting of a polyol. Polyurethane can be prepared into coatings, foam plastics, elastomers, adhesives, rubber, synthetic leather, and waterproof materials due to its good weather resistance, wear resistance, and excellent mechanical properties. It is now widely used in a variety of fields such as construction, medical treatment, leather, functional materials, transportation, and military industry.

[0003] However, since the limiting oxygen index of polyurethane that has not been flame retardant treated is only about 8%, it is extremely flammable and releases a large amount of toxic gases (such as CO, HCN, etc.) during the combustion process. Therefore, relevant regulations stipulate that polyurethane must meet certain flame retardant standards before it can be put into practical applications (such as use in foams, coatings, etc.).

[0004] At present, one of the most common practices is to add flame retardants to polyurethane to impart and improve its flame retardant properties. However, while traditional flame retardants meet the flame retardant properties, they usually greatly damage the mechanical properties of polyurethane, which greatly limits the practical use of polyurethane. For traditional bromide-based flame-retardant polyurethane resin automotive leather, a large amount of flame retardant (DBDPE-Sb2O3) is added to its formula to improve the flame retardant effect, but this will cause the leather to fail to meet the requirements of comfort, high elasticity, high peeling and breathability. Summary of the invention

[0005] The invention provides a method for preparing flame-retardant leather for vehicles, aiming to solve the problems pointed out in the background technology.

[0006] The present invention is achieved through the following technical solutions:

[0007] The present invention provides a method for preparing flame-retardant leather for vehicles, the method comprising the following specific steps:

[0008] S1. Preparation of bridged organosilica sol:

[0009] Stirring a bridged organosilicon precursor, water and an inorganic acid in an organic solvent to perform a hydrolysis polymerization reaction, thereby preparing a bridged organosilicon sol, and then post-treating and dehydrating the bridged organosilicon sol for standby use;

[0010] Wherein, the bridged organosilicon precursor is a silsesquioxane precursor having a carbon-hydrogen bridged structure;

[0011] S2. Preparation of flame retardant polyurethane coating:

[0012] The above-mentioned bridged organic silicon sol, brominated flame retardant and antimony-containing flame retardant are stirred and mixed in the polyurethane coating to prepare a flame-retardant polyurethane coating;

[0013] S3. Preparation of flame-retardant leather for automobiles:

[0014] Pretreatment of base fabric: soak the base fabric in the impregnation liquid, take it out and squeeze it, and then iron it;

[0015] The flame-retardant polyurethane coating is coated on the pretreated base fabric, left to stand, and then coagulated in a coagulation liquid, washed, squeezed, and dried to obtain the flame-retardant leather for vehicles.

[0016] Specifically, the present invention is actually to prepare a kind of automotive leather which is synergistically flame-retardant by organic silicon-DBDPE-Sb2O3.

[0017] Furthermore, a method for preparing flame-retardant leather for automobiles: Step S1, first, add a bridged organosilicon precursor to an organic solvent, stir for 1 to 5 minutes, then add deionized water, continue stirring for 1 to 5 minutes, finally add an inorganic acid and immediately transfer to a water bath at 40 to 60°C and continue stirring for hydrolysis polymerization for 2 to 3 hours, thereby obtaining a bridged organosilicon sol.

[0018] Furthermore, a method for preparing flame-retardant leather for automobiles: in step S1, the molar ratio of the bridged organosilicon precursor, water and inorganic acid is 1:(100-120):(0.1-0.5); the inorganic acid is hydrochloric acid.

[0019] Furthermore, a method for preparing flame-retardant leather for automobiles: Step S1, placing the obtained bridged organic silicon sol in an oven at 40-60°C, drying it until the gram weight is reduced by more than 90% (the gram weight reduction is mainly reflected in the removal of water), and setting it aside.

[0020] Furthermore, a method for preparing flame-retardant leather for automobiles: the bridging organosilicon precursor in step S1 is selected from at least one of bis(triethoxysilyl)methane [Bis(triethoxysilyl)methane], 1,2-bis(triethoxysilyl)ethane [1,2-Bis(triethoxysilyl)ethane], and 1,3-bis(triethoxysilyl)propane [Bis(triethoxysilyl)propane].

[0021] Furthermore, a method for preparing flame-retardant leather for automobiles: the polyurethane coating described in step S2 includes the following components in parts by weight: 100 parts of polyurethane resin, 50 to 80 parts of N,N-dimethylformamide, 1 to 2 parts of accelerator SF-7, 1 to 2 parts of anti-curling agent SF-8i, 1 to 2 parts of leveling agent SF-311, 5 to 8 parts of paper powder and 5 to 8 parts of heavy calcium; the weight portion of the bridged organic silicon sol in the flame-retardant polyurethane coating is 0.1 to 1 part, the weight portion of the bromine-based flame retardant is 2 to 3 parts, and the weight portion of the antimony-containing flame retardant is 1 to 2 parts.

[0022] The above-mentioned accelerator SF-7, anti-curling agent SF-8i, leveling agent SF-311 and other auxiliary agents as well as brominated flame retardants and antimony-containing flame retardants were purchased from Shanghai Huide Technology Co., Ltd.

[0023] Furthermore, a method for preparing flame-retardant leather for automobiles: in step S2, the brominated flame retardant is decabromodiphenylethane (DBDPE), and the antimony-containing flame retardant is Sb2O3.

[0024] Furthermore, a method for preparing flame-retardant leather for a vehicle: the base fabric pretreatment in step S3 also includes a pre-solidification process, specifically: soaking the base fabric in an impregnation liquid, taking it out and squeezing it at a pressure of 6.0 to 8.0 kg, placing the base fabric in a pre-solidification liquid for pre-solidification after extrusion, taking it out and continuing to squeeze it at a pressure of 6.0 to 8.0 kg, and then ironing it at 120 to 150°C for 10 to 20 times to complete the pretreatment of the base fabric; wherein the impregnation liquid is an organic silicon sol formed by nano-scale silica particles dispersed in water, and the concentration of the organic silicon sol is 0.1 to 1.0 wt%; the pre-solidification liquid is an N,N-dimethylformamide aqueous solution with a concentration of 35.0 to 45.0 wt%.

[0025] Specifically, pre-solidification is mainly a pre-solidification treatment process for the base fabric. Impregnating the base fabric with a solution containing silicone can enhance the flame retardancy of the base fabric. The impregnated and pre-solidified base fabric can accelerate the solidification of the flame retardant polyurethane coating in a wet state and has a good solidification effect.

[0026] Furthermore, a method for preparing flame-retardant leather for automobiles is provided: step S3, coating the flame-retardant polyurethane coating on the pretreated base cloth with a coating thickness of 1.0 to 2.0 mm, standing for 1 to 2 minutes after coating, and then placing it in a coagulation liquid for coagulation, washing with clean water at 30 to 50°C, squeezing 40 to 80 times at a pressure of 6.0 to 8.0 kg, and finally drying at 120 to 150°C for 10 to 30 minutes to obtain flame-retardant leather for automobiles; wherein the coagulation liquid is an N,N-dimethylformamide aqueous solution with a concentration of 20.0 to 25.0 wt%.

[0027] Beneficial effects of the present invention:

[0028] (1) The flame-retardant leather for automobiles prepared by the present invention is synergistically flame-retardant by adding a self-made bridged organic silicon sol to a traditional brominated flame retardant. On the one hand, the amount of flame retardants (DBDPE, Sb2O3) can be reduced to avoid the destruction of the mechanical properties of polyurethane (PU) by the large-scale use of flame retardants, thereby ensuring the various properties of PU; on the other hand, the flame retardant effect of traditional flame retardants can be improved by the introduced organic silicon. Specifically, the bridged organic silicon sol introduced by the present invention includes polysiloxane and its derivatives. When heated, the silicon-oxygen bonds (-Si-O-) in the organic silicon molecules form silicon-carbon bonds (-Si-C-), absorbing a large amount of energy, thereby achieving the purpose of improving the flame retardant effect.

[0029] (2) The bridged organosilicon sol prepared by the sol-gel method in the method of the present invention forms an amorphous network structure after being coated on a base fabric and dried, and wraps the polyurethane material and the flame retardant (DBDPE-Sb2O3) inside. The surface of the organosilicon can withstand calcination at a temperature of 550 to 600°C under heating and ignition conditions. When the temperature exceeds this temperature, the silanol groups on the surface of the organosilicon will dehydrate and condense to produce water vapor, thereby diluting the concentration of the surface combustion-supporting gas, so that the internal bromine flame retardant and the external organosilicon flame retardant can cooperate in the combustion process to achieve a dual flame retardant effect, thereby improving the flame retardant effect.

[0030] (3) The automotive flame-retardant leather prepared by the present invention is actually an automotive leather that utilizes the synergistic flame retardancy of organic silicon-DBDPE-Sb2O3. The present invention significantly improves the flame retardancy of polyurethane materials through the synergistic use of flame retardants decabromodiphenylethane (DBDPE), antimony trioxide (Sb2O3) and self-made bridged organic silicon sol, and reduces the dosage of the two flame retardants DBDPE and Sb2O3. While ensuring the flame retardancy, it also avoids the decrease in the mechanical properties of the polyurethane material.

[0031] (4) The present invention prepares a bridged organosilicon sol by a sol-gel method, and uses it in combination with two flame retardants, DBDPE and Sb2O3, to achieve a synergistic flame retardant effect. By using it in combination with the bridged organosilicon sol, the amount of bromine-based flame retardant can be significantly reduced while ensuring the flame retardant effect of the material, thereby regulating the performance of the polyurethane resin. In addition, the special network structure of the bridged organosilicon sol prepared by the present invention is used to protect the diffusion combustion of the internal resin. It can also dehydrate and condense at high temperature to produce water vapor, thereby reducing the concentration of the surrounding combustion-supporting gas, which is beneficial to the improvement of the flame retardant effect.

[0032] (5) The present invention uses the bridging organosilicon sol and the brominated flame retardant together to achieve a dual flame retardant effect of internal and external combination. The external flame retardant is the organosilicon network structure, which allows the internal brominated flame retardant (DBDPE) and Sb2O3 to have better contact, producing more insoluble antimony trichloride, thereby improving the flame retardant properties of the polyurethane material from the inside. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Example 1

[0035] This embodiment 1 provides a method for preparing flame-retardant leather for automobiles, the method comprising the following specific steps:

[0036] S1. Preparation of bridged organosilica sol:

[0037] First, add a bridged organosilicon precursor to an organic solvent (ethanol), stir for 2 minutes, then add deionized water, continue stirring for 2 minutes, finally add a 3.7wt% inorganic acid (hydrochloric acid) and immediately transfer to a 50°C water bath and continue stirring for 2 hours to perform a hydrolysis polymerization reaction, thereby obtaining a bridged organosilicon sol, and then put the obtained bridged organosilicon sol into a 50°C oven to dry 90% of the water (the amount of water dried can be judged by the reduction in gram weight), and then set aside after drying;

[0038] The molar ratio of the bridged organosilicon precursor, water and inorganic acid is 1:120:0.3; the bridged organosilicon precursor is a silsesquioxane precursor having a carbon-hydrogen bridged structure, specifically 1,2-bis(triethoxysilyl)ethane;

[0039] S2. Preparation of flame retardant polyurethane coating:

[0040] To 80 parts of N,N-dimethylformamide, 1.0 parts of accelerator SF-7, 1.0 parts of anti-curling agent SF-8i, 1.0 parts of leveling agent SF-311, 8.0 parts of paper powder, 8.0 parts of heavy calcium were added respectively, and stirred evenly, and then 1.0 parts of the above-mentioned dried bridged organic silica sol, 2.0 parts of decabromodiphenylethane and 2.0 parts of Sb2O3 were added, and stirred evenly, and finally 100 parts of polyurethane resin were added, and then stirred at a speed of 1000 rpm for 10 minutes, so as to prepare a flame retardant polyurethane coating; wherein, the auxiliary agent components used in the flame retardant polyurethane coating were purchased from Shanghai Huide Technology Co., Ltd.;

[0041] S3. Preparation of flame-retardant leather for automobiles:

[0042] Pretreatment of base fabric: soak the base fabric in an impregnation liquid (organic silica sol formed by dispersing nano-scale silica particles in water with a concentration of 1.0 wt%), take it out and squeeze it at a pressure of 6.0 kg, and then place the base fabric in a pre-coagulation liquid (40.0 wt% N, N-dimethylformamide aqueous solution) for pre-coagulation, take it out and continue to squeeze it at a pressure of 6.0 kg, and then iron it at 130° C. for 10 times to complete the pretreatment of the base fabric;

[0043] The flame-retardant polyurethane coating obtained in the above step S2 is coated on the pretreated base fabric with a coating thickness of 2.0 mm. After coating, it is allowed to stand for 1 minute, and then placed in a coagulation liquid at a temperature of 20°C (a 20.0wt% N,N-dimethylformamide aqueous solution) for coagulation. After washing with clean water at 30°C, it is extruded at a pressure of 6.0 kg, and the extrusion is repeated 40 times. Finally, it is dried at 130°C for 15 minutes to obtain automotive flame-retardant leather.

[0044] Example 2

[0045] This embodiment 2 provides a method for preparing flame-retardant leather for automobiles, the method comprising the following specific steps:

[0046] S1. Preparation of bridged organosilica sol:

[0047] First, a bridged organosilicon precursor is added to an organic solvent (ethanol), stirred for 5 minutes, and then deionized water is added dropwise, and stirring is continued for 5 minutes, and finally a 3.7wt% inorganic acid (hydrochloric acid) is added dropwise and immediately transferred to a 40°C water bath and continuously stirred for hydrolysis polymerization for 3 hours, thereby obtaining a bridged organosilicon sol, and then the obtained bridged organosilicon sol is placed in a 55°C oven to dry 90% of the water (the amount of water dried can be judged by the reduction in gram weight), and then dried for standby use;

[0048] The molar ratio of the bridged organosilicon precursor, water and inorganic acid is 1:110:0.2; the bridged organosilicon precursor is a silsesquioxane precursor having a carbon-hydrogen bridged structure, specifically bis(triethoxysilyl)methane;

[0049] S2. Preparation of flame retardant polyurethane coating:

[0050] To 60 parts of N,N-dimethylformamide, 2.0 parts of accelerator SF-7, 1.5 parts of anti-curling agent SF-8i, 2.0 parts of leveling agent SF-311, 6.0 parts of paper powder, 6.0 parts of heavy calcium were added respectively, and stirred evenly, and then 1.0 parts of the above-mentioned dried bridged organic silica sol, 3.0 parts of decabromodiphenylethane and 1.0 parts of Sb2O3 were added, and stirred evenly, and finally 100 parts of polyurethane resin were added, and then stirred at a speed of 1000 rpm for 10 minutes, so as to prepare a flame retardant polyurethane coating; wherein the auxiliary agent components used in the flame retardant polyurethane coating were purchased from Shanghai Huide Technology Co., Ltd.;

[0051] S3. Preparation of flame-retardant leather for automobiles:

[0052] Pretreatment of base fabric: soak the base fabric in an impregnation liquid (organic silica sol formed by dispersing nano-scale silica particles in water with a concentration of 1.0wt%), take it out and squeeze it at a pressure of 8.0kg, and then place the base fabric in a pre-coagulation liquid (a 35.0wt% N,N-dimethylformamide aqueous solution) for pre-coagulation, take it out and continue to squeeze it at a pressure of 8.0kg, and then iron it at 120°C for 20 times to complete the pretreatment of the base fabric;

[0053] The flame-retardant polyurethane coating obtained in the above step S2 is coated on the pretreated base fabric with a coating thickness of 2.0 mm. After coating, it is allowed to stand for 2 minutes, and then placed in a coagulation liquid at a temperature of 22° C. (a 22.0 wt% N, N-dimethylformamide aqueous solution) for coagulation. After washing with clean water at 30° C., it is extruded at a pressure of 8.0 kg, and the extrusion is repeated 60 times. Finally, it is dried at 140° C. for 15 minutes to obtain automotive flame-retardant leather.

[0054] Example 3

[0055] This embodiment 3 provides a method for preparing flame-retardant leather for automobiles, the method comprising the following specific steps:

[0056] S1. Preparation of bridged organosilica sol:

[0057] First, add a bridged organosilicon precursor to an organic solvent (ethanol), stir for 3 minutes, then add deionized water, continue stirring for 3 minutes, finally add a 3.7wt% inorganic acid (hydrochloric acid) and immediately transfer to a 60°C water bath and continue stirring for 2 hours to perform a hydrolysis polymerization reaction, thereby obtaining a bridged organosilicon sol, and then put the obtained bridged organosilicon sol into a 50°C oven to dry 90% of the water (the amount of water dried can be judged by the reduction in gram weight), and then set aside after drying;

[0058] The molar ratio of the bridged organosilicon precursor, water and inorganic acid is 1:100:0.5; the bridged organosilicon precursor is a silsesquioxane precursor having a carbon-hydrogen bridged structure, specifically 1,2-bis(triethoxysilyl)ethane;

[0059] S2. Preparation of flame retardant polyurethane coating:

[0060] To 50 parts of N,N-dimethylformamide, 1.5 parts of accelerator SF-7, 2.0 parts of anti-curling agent SF-8i, 1.5 parts of leveling agent SF-311, 5.0 parts of paper powder, 5.0 parts of heavy calcium were added respectively, and stirred evenly, and then 0.1 parts of the above-mentioned dried bridged organic silica sol, 3.0 parts of decabromodiphenylethane and 2.0 parts of Sb2O3 were added, and stirred evenly, and finally 100 parts of polyurethane resin were added, and then stirred at a speed of 1000 rpm for 10 minutes, so as to prepare a flame retardant polyurethane coating; wherein, the auxiliary agent components used in the flame retardant polyurethane coating were purchased from Shanghai Huide Technology Co., Ltd.;

[0061] S3. Preparation of flame-retardant leather for automobiles:

[0062] Pretreatment of base fabric: soak the base fabric in an impregnation liquid (organic silica sol formed by dispersing nano-scale silica particles in water with a concentration of 0.5wt%), take it out and squeeze it at a pressure of 7.0kg, and then place the base fabric in a pre-coagulation liquid (45.0wt% N,N-dimethylformamide aqueous solution) for pre-coagulation, take it out and continue to squeeze it at a pressure of 7.0kg, and then iron it at 150°C for 10 times to complete the pretreatment of the base fabric;

[0063] The flame-retardant polyurethane coating obtained in the above step S2 is coated on the pretreated base fabric with a coating thickness of 2.0 mm. After coating, it is allowed to stand for 2 minutes, and then placed in a coagulation liquid (a 23.0 wt% N, N-dimethylformamide aqueous solution) at a temperature of 25°C for coagulation. After washing with clean water at 40°C, it is extruded at a pressure of 7.0 kg, and the extrusion is repeated 60 times. Finally, it is dried at 150°C for 10 minutes to obtain automotive flame-retardant leather.

[0064] Example 4

[0065] This embodiment 4 provides a method for preparing flame-retardant leather for automobiles, the method comprising the following specific steps:

[0066] S1. Preparation of bridged organosilica sol:

[0067] First, add a bridged organosilicon precursor to an organic solvent (ethanol), stir for 2 minutes, then add deionized water, continue stirring for 2 minutes, finally add a 3.7wt% inorganic acid (hydrochloric acid) and immediately transfer to a 50°C water bath and continue stirring for 2 hours to perform a hydrolysis polymerization reaction, thereby obtaining a bridged organosilicon sol, and then put the obtained bridged organosilicon sol into a 50°C oven to dry 90% of the water (the amount of water dried can be judged by the reduction in gram weight), and then set aside after drying;

[0068] The molar ratio of the bridged organosilicon precursor, water and inorganic acid is 1:120:0.3; the bridged organosilicon precursor is a silsesquioxane precursor having a carbon-hydrogen bridged structure, specifically 1,3-bis(triethoxysilyl)propane;

[0069] S2. Preparation of flame retardant polyurethane coating:

[0070] To 80 parts of N,N-dimethylformamide, 1.0 parts of accelerator SF-7, 1.0 parts of anti-curling agent SF-8i, 1.0 parts of leveling agent SF-311, 8.0 parts of paper powder, 8.0 parts of heavy calcium were added respectively, and stirred evenly, and then 1.0 parts of the above-mentioned dried bridged organic silica sol, 2.0 parts of decabromodiphenylethane and 2.0 parts of Sb2O3 were added, and stirred evenly, and finally 100 parts of polyurethane resin were added, and then stirred at a speed of 1000 rpm for 10 minutes, so as to prepare a flame retardant polyurethane coating; wherein, the auxiliary agent components used in the flame retardant polyurethane coating were purchased from Shanghai Huide Technology Co., Ltd.;

[0071] S3. Preparation of flame-retardant leather for automobiles:

[0072] Pretreatment of base fabric: soak the base fabric in an impregnation liquid (organic silica sol formed by dispersing nano-scale silica particles in water with a concentration of 1.0 wt%), take it out and squeeze it at a pressure of 6.0 kg, and then place the base fabric in a pre-coagulation liquid (40.0 wt% N, N-dimethylformamide aqueous solution) for pre-coagulation, take it out and continue to squeeze it at a pressure of 6.0 kg, and then iron it at 130° C. for 10 times to complete the pretreatment of the base fabric;

[0073] The flame-retardant polyurethane coating obtained in the above step S2 is coated on the pretreated base fabric with a coating thickness of 2.0 mm. After coating, it is allowed to stand for 1 minute, and then placed in a coagulation liquid at a temperature of 20°C (a 20.0wt% N,N-dimethylformamide aqueous solution) for coagulation. After washing with clean water at 30°C, it is extruded at a pressure of 6.0 kg, and the extrusion is repeated 40 times. Finally, it is dried at 130°C for 15 minutes to obtain automotive flame-retardant leather.

[0074] The difference between Example 4 and Example 1 is that the bridging organosilicon precursor selected in Example 4 is different from that in Example 1. Example 4 selects 1,3-bis(triethoxysilyl)propane, while Example 1 selects 1,2-bis(triethoxysilyl)ethane, and the rest are the same.

[0075] Comparative Example 1

[0076] The difference between Comparative Example 1 and Example 1 is that: in the process of preparing the flame-retardant polyurethane coating A in Comparative Example 1, the self-made bridging organosilicon sol in Example 1 is not added, and the rest is the same as Example 1; that is, the preparation process of the flame-retardant polyurethane coating A in Comparative Example 1 is:

[0077] To 80 parts of N,N-dimethylformamide, 1.0 part of accelerator SF-7, 1.0 part of anti-curling agent SF-8i, 1.0 part of leveling agent SF-311, 8.0 parts of paper powder, and 8.0 parts of heavy calcium were added respectively, and stirred evenly. Then, 2.0 parts of decabromodiphenylethane and 2.0 parts of Sb2O3 were added, and stirred evenly. Finally, 100 parts of polyurethane resin were added, and then stirred at 1000 rpm for 10 minutes to prepare flame retardant polyurethane coating A.

[0078] Comparative Example 2

[0079] The difference between Comparative Example 2 and Example 1 is that in the process of preparing the flame-retardant polyurethane coating B, only the self-made bridging organosilicon sol in Example 1 is added, and decabromodiphenylethane and Sb2O3 flame retardant are not added, and the rest is the same as Example 1; that is, the preparation process of the flame-retardant polyurethane coating B in Comparative Example 2 is:

[0080] To 80 parts of N,N-dimethylformamide, 1.0 part of accelerator SF-7, 1.0 part of anti-curling agent SF-8i, 1.0 part of leveling agent SF-311, 8.0 parts of paper powder, and 8.0 parts of heavy calcium were added respectively, and stirred evenly. Then, 1.0 part of the bridged organic silica sol prepared in Example 1 was added and stirred evenly. Finally, 100 parts of polyurethane resin was added, and then stirred at 1000 rpm for 10 minutes to prepare a flame retardant polyurethane coating B.

[0081] Comparative Example 3

[0082] The difference between Comparative Example 3 and Example 1 is that: in the process of preparing the polyurethane coating in Comparative Example 3, the self-made bridging organic silica sol, decabromodiphenylethane and Sb2O3 flame retardant in Example 1 are not added, and the rest is the same as Example 1; that is, the preparation process of the polyurethane coating in Comparative Example 3 is:

[0083] To 80 parts of N,N-dimethylformamide, 1.0 part of accelerator SF-7, 1.0 part of anti-curling agent SF-8i, 1.0 part of leveling agent SF-311, 8.0 parts of paper powder, and 8.0 parts of heavy calcium were added respectively, stirred evenly, and then 100 parts of polyurethane resin were added, and then stirred at 1000 rpm for 10 minutes to prepare a polyurethane coating.

[0084] test:

[0085] The flame retardant performance of the flame retardant leathers prepared in Examples 1 to 4 and Comparative Examples 1 to 3 was tested, and the test results are shown in Table 1 below:

[0086] Table 1 shows the flame retardant performance test results of flame retardant leather for automobiles of Examples 1 to 4 and Comparative Examples 1 to 3

[0087] Group Burning time Burning distance Burning speed GB8410 grade Example 1 12 seconds 0mm 0mm / min A-0 Example 2 18 seconds 0mm 0mm / min A-0 Example 3 23 seconds 0mm 0mm / min A-0 Example 4 19 seconds 0mm 0mm / min A-0 Comparative Example 1 55 seconds 12mm 13.3mm / min B Comparative Example 2 53 seconds 20mm 22.5mm / min B Comparative Example 3 90 seconds 254mm 169.3mm / min D

[0088] Combining the test results of Example 1 and Comparative Example 1, it can be seen that the burning time of Example 1 is shorter, and the burning distance of 0 indicates that the leather obtained in Example 1 did not burn. This also illustrates that the present invention can significantly improve the flame retardant properties of leather by adding the homemade bridged organosilicon sol, while the leather to which the bridged organosilicon sol of the present invention is not added (Comparative Example 1) has a longer burning time and a lower national standard flame retardant grade.

[0089] Combining the test results of Example 1, Example 3 and Comparative Example 1, it can be seen that in Example 3, due to the reduced amount of added bridging organosilicon sol, the burning time of the leather is increased, but compared with Comparative Example 1 in which no bridging organosilicon sol is added, the burning time of the leather in Example 3 is still significantly shorter, which shows that the homemade bridging organosilicon sol of the present invention still has a good flame retardant effect when used in small amounts.

[0090] Combining the test results of Example 1 and Example 4, it can be seen that there are slight differences in the burning time for using different types of organosilicon precursors, because the organosilicon network structure formed by 1,2-bis(triethoxysilyl)ethane used in Example 1 is denser than 1,3-bis(triethoxysilyl)propane used in Example 4, and the combustion blocking effect is better; but both have good flame retardant effects.

[0091] Combining the test results of Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that when Comparative Example 2 uses bridged organosilicon sol alone for flame retardancy, its synergistic flame retardant effect is significantly lower than that of Example 1 using bridged organosilicon-DBDPE-Sb2O3, but is close to the flame retardant effect of Comparative Example 1 using DBDPE and Sb2O3.

[0092] Combining the test results of Comparative Example 3 with that of Comparative Example 1, it can be seen that, compared with Comparative Example 3, in which only DBDPE and Sb2O3 flame retardants are used, the burning time of the leather obtained in Comparative Example 1 is shortened by about 35 seconds; Combining the test results of Comparative Example 3 with that of Comparative Example 2, it can be seen that, compared with Comparative Example 3, in which only Qiaolian organosilicon sol flame retardant is used, the burning time of the leather obtained in Comparative Example 2 is shortened by about 37 seconds; Combining the test results of Example 1 with that of Example 3, it can be seen that, by using the bridging organosilicon-DBDPE-Sb2O3 in a coordinated manner, Example 1 shortens the burning time of the obtained leather by about 78 seconds. It can be seen that the flame retardant properties of the leather obtained in Example 1 are greatly improved compared with those in Comparative Example 3, and 78>35+37. Therefore, it can be said that the present invention achieves the effect of 1+1>2 by using the bridging organosilicon sol, DBDPE and Sb2O3 flame retardants in a coordinated manner. The present invention uses bridged organic silica sol, DBDPE and Sb2O3 in a coordinated manner to form a double flame retardant effect, thereby significantly improving the flame retardant performance of leather.

[0093] The above are preferred embodiments of the present invention and are only used to explain the present invention, not to limit the present invention. Any obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing flame-retardant leather for automobiles, characterized in that: The method comprises the following steps: S1. Preparation of bridged organosilica sol: Stirring a bridged organosilicon precursor, water and an inorganic acid in an organic solvent to perform a hydrolysis polymerization reaction, thereby preparing a bridged organosilicon sol, and then post-treating and dehydrating the bridged organosilicon sol for standby use; Wherein, the bridged organosilicon precursor is a silsesquioxane precursor having a carbon-hydrogen bridged structure; S2. Preparation of flame retardant polyurethane coating: The above-mentioned bridged organic silicon sol, bromine flame retardant and antimony-containing flame retardant are stirred and mixed in the polyurethane coating to prepare a flame-retardant polyurethane coating; S3. Preparation of flame-retardant leather for automobiles: Pretreatment of base fabric: soak the base fabric in the impregnation liquid, take it out and squeeze it, and then iron it; The flame-retardant polyurethane coating is coated on the pretreated base fabric, left to stand, and then coagulated in a coagulation liquid, washed, squeezed, and dried to obtain the flame-retardant leather for vehicles.

2. The method for preparing a flame-retardant leather for automobile according to claim 1, characterized in that: Step S1, first, add a bridged organosilicon precursor to an organic solvent, stir for 1 to 5 minutes, then drop deionized water, continue stirring for 1 to 5 minutes, finally drop an inorganic acid and immediately transfer to a 40 to 60° C. water bath and continue stirring for 2 to 3 hours to perform a hydrolysis polymerization reaction, thereby obtaining a bridged organosilicon sol.

3. The method for preparing a flame-retardant leather for automobile according to claim 1 or 2, characterized in that: In step S1, the molar ratio of the bridging organosilicon precursor, water and inorganic acid is 1:(100-120):(0.1-0.5); the inorganic acid is hydrochloric acid.

4. The method for preparing a flame-retardant leather for automobile according to claim 1 or 2, characterized in that: Step S1, placing the obtained bridged organosilicon sol in an oven at 40-60° C. and drying it until the gram weight is reduced by more than 90%, and then setting it aside for use.

5. The method for preparing a flame-retardant leather for automobile according to claim 1 or 2, characterized in that: The bridging organosilicon precursor in step S1 is selected from at least one of bis(triethoxysilyl)methane, 1,2-bis(triethoxysilyl)ethane and 1,3-bis(triethoxysilyl)propane.

6. The method for preparing a flame-retardant leather for automobile according to claim 1, characterized in that: The polyurethane slurry described in step S2 includes the following components in parts by weight: 100 parts of polyurethane resin, 50-80 parts of N,N-dimethylformamide, 1-2 parts of accelerator SF-7, 1-2 parts of anti-curling agent SF-8i, 1-2 parts of leveling agent SF-311, 5-8 parts of paper powder and 5-8 parts of heavy calcium; The flame retardant polyurethane coating contains 0.1 to 1 parts by weight of the bridged organic silicon sol, 2 to 3 parts by weight of the bromine flame retardant, and 1 to 2 parts by weight of the antimony-containing flame retardant.

7. The method for preparing a flame-retardant leather for automobile according to claim 1 or 2, characterized in that: In step S2, the brominated flame retardant is decabromodiphenylethane, and the antimony-containing flame retardant is Sb2O3.

8. The method for preparing a flame-retardant leather for a vehicle according to claim 1, characterized in that: The base fabric pretreatment in step S3 also includes a pre-solidification process, specifically: The base fabric is immersed in the impregnation liquid, taken out and squeezed at a pressure of 6.0 to 8.0 kg, and then the base fabric is placed in a pre-solidification liquid for pre-solidification, and then taken out and squeezed at a pressure of 6.0 to 8.0 kg, and then ironed at 120 to 150° C. for 10 to 20 times to complete the pretreatment of the base fabric; The impregnation liquid is an organic silicon sol formed by dispersing nano-scale silicon dioxide particles in water, and the concentration of the organic silicon sol is 0.1-1.0wt%; the pre-solidification liquid is an N,N-dimethylformamide aqueous solution with a concentration of 35.0-45.0wt%.

9. The method for preparing a flame-retardant leather for automobile according to claim 1, characterized in that: Step S3, coating the flame retardant polyurethane coating on the pretreated base fabric with a coating thickness of 1.0 to 2.0 mm, standing for 1 to 2 minutes after coating, and then placing it in a coagulation liquid for coagulation, washing it with clean water at 30 to 50° C., squeezing it at a pressure of 6.0 to 8.0 kg for 40 to 80 times, and finally drying it at 120 to 150° C. for 10 to 30 minutes to obtain a flame retardant leather for automobiles; Wherein, the coagulation liquid is an N,N-dimethylformamide aqueous solution with a concentration of 20.0-25.0 wt%.