阅读说明：本技术 一种阻燃性pu合成革及其制备方法 (Flame-retardant PU synthetic leather and preparation method thereof ) 是由 胡超群 于 2021-08-12 设计创作，主要内容包括：本发明提供一种阻燃性PU合成革,包括合成革胚料和表面处理层,该表面处理层组分为聚氨酯、架桥剂、增粘剂和平滑剂；该合成革胚料包括基布层、接着层和表面层,组分选自聚氨酯、架桥剂、增粘剂、溶解介质、硬化剂、触媒、溶剂、阻燃剂和颜料制作而成；通过对各层的改善和专门的制备方法,使PU合成革在火源中的可燃性降低,蔓延速度减缓,不容易形成大面积燃烧,且离开火源后能很快熄灭,不再燃烧。(The invention provides flame-retardant PU synthetic leather, which comprises a synthetic leather blank and a surface treatment layer, wherein the surface treatment layer comprises polyurethane, a bridging agent, a tackifier and a smoothing agent; the synthetic leather blank comprises a base cloth layer, an adhesion layer and a surface layer, and is prepared from polyurethane, a bridging agent, a tackifier, a dissolving medium, a hardening agent, a catalyst, a solvent, a flame retardant and pigment; by improving each layer and a special preparation method, the flammability of the PU synthetic leather in a fire source is reduced, the spreading speed is slowed down, large-area combustion is not easy to form, and the PU synthetic leather can be extinguished quickly after leaving the fire source and can not be combusted.)

1. A flame retardant PU synthetic leather is characterized in that: the synthetic leather comprises a synthetic leather blank and a surface treatment layer, wherein the surface treatment layer comprises the following components in percentage by mass: 89.0-91.0 percent of polyurethane, 1.5-3.5 percent of bridging agent, 0.5-1.5 percent of tackifier and 6.0-8.0 percent of smoothing agent.

2. The flame retardant PU synthetic leather of claim 1, wherein: the synthetic leather blank comprises a base cloth layer, an adhesion layer and a surface layer, wherein the surface layer comprises the following components in percentage by mass: 60.8 to 69.8 percent of polyurethane, 1.7 to 3.7 percent of bridging agent, 2.0 to 8.0 percent of tackifier, 10.5 to 16.5 percent of pigment and 12.0 to 15.0 percent of dissolving medium.

3. The flame retardant PU synthetic leather of claim 2, wherein: the following layers comprise the following components in percentage by mass: 25.3 to 27.7 percent of polyurethane, 35.6 to 39.3 percent of hardener, 0.06 to 1.04 percent of accelerant, 3.4 to 5.4 percent of solvent, 25.0 to 35.0 percent of flame retardant and 0.6 to 1.6 percent of pigment.

4. The flame retardant PU synthetic leather of claim 2, wherein: the base cloth layer is woven fabric, the thickness of the base cloth layer is 800-1000 mu m, and the mass of the base cloth layer is 220g/m²～390g/m²。

5. The method for preparing the flame-retardant PU synthetic leather according to any one of claims 1 to 4, comprising the following steps:

s1 surface layer preparation, wherein the surface layer preparation comprises surface layer solution preparation, surface layer solution defoaming treatment, surface layer solution coating processing and surface layer drying and forming to obtain a surface layer;

s2 manufacturing an adhesion layer, wherein the manufacturing of the adhesion layer comprises the steps of preparing an adhesion layer solution, coating the adhesion layer solution, drying and forming the adhesion layer to obtain the adhesion layer;

s3, bonding and adhering the surface layer obtained in the step S1, the bonding layer obtained in the step S2 and the base cloth layer together to form a synthetic leather blank;

s4, peeling, namely peeling the synthetic leather blank obtained in the step S3 from the release paper mold to obtain a synthetic leather blank;

s5, curing, namely curing the synthetic leather blank obtained in the step S4 in an oven, and cooling to obtain a cured synthetic leather blank;

s6 surface layer treatment, namely performing surface layer treatment on the cured synthetic leather blank obtained in the step S6 to obtain a surface treatment layer; the surface layer treatment comprises the steps of preparing surface treatment layer liquid, coating, processing and baking the surface treatment layer liquid to obtain the finished synthetic leather.

6. The method for preparing flame-retardant PU synthetic leather according to claim 5, wherein: the stirring speed of the prepared surface layer solution in the step S1 is 600 rpm-800 rpm, the stirring time is 60 min-65 min, and the viscosity of the surface layer solution is 3000 cps-5000 cps; the treatment time of the surface layer solution defoaming treatment in the step S1 is 60 min-65 min.

7. The method for preparing flame-retardant PU synthetic leather according to claim 6, wherein: the speed of the surface layer solution coating processing of the step S1 is 9m/min to 11m/min, and the using amount is 75g/m²～125g/m²(ii) a And S1, drying and forming the surface layer at 100-125 deg.c for 2-3 min.

8. The method for preparing flame-retardant PU synthetic leather according to claim 5, wherein: the stirring speed of the prepared solution of the bonding layer in the step S2 is 700 rpm-1000 rpm; the coating speed of the solution of the adhesive layer in the step S2 is 9-11 m/minThe dosage is 153g/m²～187g/m²(ii) a And S2, drying and forming the adhesive layer at 125-135 ℃ for 2.5-3.5 min, wherein the drying degree of the adhesive layer is 70-80%.

9. The method for preparing flame-retardant PU synthetic leather according to claim 5, wherein: the speed of bonding in the step S3 is 8-10 m/min, and the bonding pressure is 0.2-0.3 MPa.

10. The method for preparing flame-retardant PU synthetic leather according to claim 5, wherein: step S6, the stirring speed of the prepared surface treatment layer liquid is 400 rpm-600 rpm, the stirring time is 60 min-65 min, and the viscosity of the surface treatment layer liquid is 1200 cps-1800 cps; the coating speed of the surface treatment layer liquid in the step S6 is 13-15 m/min, and the using amount is 50g/m²～60g/m²(ii) a And S6, baking and forming the surface treatment layer at 95-130 ℃ for 2-3 min.

Technical Field

The invention relates to the technical field of preparation of waterborne polyurethane composite materials, in particular to flame-retardant PU synthetic leather and a preparation method of the flame-retardant PU synthetic leather.

Background

The improvement of the flame retardant property of the water-based environment-friendly PU synthetic leather provides a new technical idea for creating healthy, safe and environment-friendly automotive interior products, the flame retardant property is deeply researched, the horizontal combustion speed of the water-based environment-friendly PU synthetic leather is improved to be less than or equal to 80mm/min, and the requirements of the horizontal combustion property, the vertical combustion property, the molten drop test, the smoke density, the oxygen index classification and other indexes of the combustion safety property of the interior materials of the seats in the new national standard of the combustion characteristic of the automotive interior materials are basically met, the expected target is achieved, the requirements of customers are met, but safety is free of trivial matters, the environment-friendly, non-toxic and safe road and future of the automotive interior are far, and a space for further improvement is provided.

The host factory has higher and higher requirements on indexes such as odor, formaldehyde content and VOC emission of automotive interior PU and fabric, and also provides more requirements on flame retardant processing technology, and the combustion characteristics of interior materials in the national standard GB8410-2006 Combustion characteristics of automotive interior materials must meet the following technical requirements: the burning speed is not more than 100 mm/min; however, although various conventional large aqueous PU environment-friendly synthetic leathers have certain improvements in odor, formaldehyde content and VOC emission, the flame retardant property is difficult to be continuously stabilized at a lower level. Therefore, the invention provides novel flame-retardant PU synthetic leather and a preparation method of the flame-retardant PU synthetic leather.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the flame-retardant PU synthetic leather which comprises a base cloth layer, an adhesion layer, a surface layer and a surface treatment layer, wherein the flame retardant property of each layer is improved by improving the components of each layer, so that the aims of prolonging the service life of the product and improving the yield of the product are fulfilled.

In order to achieve the purpose, the invention provides flame-retardant PU synthetic leather which comprises a synthetic leather blank and a surface treatment layer, wherein the surface treatment layer comprises the following components in percentage by mass: 89.0 to 91.0 percent of polyurethane, 1.5 to 3.5 percent of bridging agent, 0.5 to 1.5 percent of tackifier and 6.0 to 8.0 percent of smoothing agent;

the synthetic leather blank comprises a base cloth layer, an adhesion layer and a surface layer, wherein the surface layer comprises the following components in percentage by mass: 60.8-69.8% of polyurethane, 1.7-3.7% of bridging agent, 2.0-8.0% of tackifier, 10.5-16.5% of pigment and 12.0-15.0% of dissolving medium, wherein the dissolving medium is water;

the following layers comprise the following components in percentage by mass: 25.3 to 27.7 percent of polyurethane, 35.6 to 39.3 percent of hardener, 0.06 to 1.04 percent of accelerant, 3.4 to 5.4 percent of solvent, 25.0 to 35.0 percent of flame retardant and 0.6 to 1.6 percent of pigment;

the base cloth layer is woven fabric such as fiber, cotton, woven fabric and non-woven fabric, the thickness of the base cloth layer is 800-1000 μm, and the mass is 220g/m²～390g/m²。

The bridging agent is a multifunctional carbodiimide polymer, and the tackifier is an alkaline tackifier, such as an acrylic polymer; the smoothing agent is silicon and silicon polymer thereof; the hardening agent is a yellowing-resistant hardening agent, the catalyst is a special catalyst formed by amine organic acid salt, the solvent is butanone and polycondensate thereof, and the flame retardant is a phosphorus flame retardant.

In order to achieve the above object, the present invention also provides a preparation method of the flame retardant PU synthetic leather, comprising the steps of:

s1 surface layer preparation, wherein the surface layer preparation comprises surface layer solution preparation, surface layer solution defoaming treatment, surface layer solution coating processing and surface layer drying and forming to obtain a surface layer;

s2 manufacturing an adhesion layer, wherein the manufacturing of the adhesion layer comprises the steps of preparing an adhesion layer solution, coating the adhesion layer solution, drying and forming the adhesion layer to obtain the adhesion layer;

s3, bonding and adhering the surface layer obtained in the step S1, the bonding layer obtained in the step S2 and the base cloth layer together to form a synthetic leather blank;

s4, peeling, namely peeling the synthetic leather blank obtained in the step S3 from the release paper mold to obtain a synthetic leather blank;

s5, curing, namely curing the synthetic leather blank obtained in the step S4 in an oven, and cooling to obtain a cured synthetic leather blank;

s6 surface layer treatment, namely performing surface layer treatment on the cured synthetic leather blank obtained in the step S6 to obtain a surface treatment layer; the surface layer treatment comprises the steps of preparing surface treatment layer liquid, coating, processing and baking the surface treatment layer liquid to obtain the finished synthetic leather.

Preferably, the production environment temperature of the step S1 to the step S6 is 0 ℃ to 40 ℃, and the production environment humidity is 20% to 80%; step S1 and step S2 may be performed simultaneously, or the surface layer of step S1 may be first formed and the subsequent layer of step S2 may be formed.

Further, the stirring speed of the prepared surface layer solution in the step S1 is 600 rpm-800 rpm, the stirring time is 60 min-65 min, and the viscosity of the surface layer solution is 3000 cps-5000 cps; the treatment time of the surface layer solution defoaming treatment in the step S1 is 60 min-65 min. The prepared surface layer solution is defoamed by a circulating defoaming machine, so that the defoaming effect is fully ensured, and the surface layer solution is prevented from air entering in the conveying process during circulating use so as to improve the surface layer coating quality.

Preferably, the speed of the surface layer solution coating process in the step S1 is 9 m/min-11 m/min, and the using amount is 75g/m²～125g/m²(ii) a And S1, drying and forming the surface layer at 100-125 deg.c for 2-3 min.

Further, the stirring speed of the prepared adhesive layer solution in the step S2 is 700rpm to 1000 rpm; the coating speed of the solution of the adhesive layer in the step S2 is 9-11 m/min, and the using amount is 153g/m²～187g/m²(ii) a And S2, drying and forming the adhesive layer at 125-135 ℃ for 2.5-3.5 min, wherein the drying degree of the adhesive layer is 70-80%.

Furthermore, the bonding speed of the step S3 is 8-10 m/min, and the bonding pressure is 0.2-0.3 MPa.

Further, the curing treatment temperature in the step S5 is 125-135 ℃, and the time is 2-10 min.

Step S6, the stirring speed of the prepared surface treatment layer liquid is 400 rpm-600 rpm, the stirring time is 60 min-65 min, and the viscosity of the surface treatment layer liquid is 1200 cps-1800 cps; the coating speed of the surface treatment layer liquid in the step S6 is 13-15 m/min, and the using amount is 50g/m²～60g/m²(ii) a And S6, baking and forming the surface treatment layer at 95-130 ℃ for 2-3 min.

Compared with the prior art, the invention has the following beneficial effects:

1. the flame-retardant PU synthetic leather comprises a base cloth layer, a bonding layer, a surface layer and a surface treatment layer, and through improving the components of each layer, the flammability of the material in a fire source is reduced, the spreading speed is slowed down, large-area combustion is not formed, and the material can be quickly self-extinguished after leaving the fire source and does not burn any more. The process is applied to improve the flame retardance of the waterborne environment-friendly PU synthetic leather product, the original burning speed is not more than 100mm/min, the burning speed is not more than 80mm/min, and multiple indexes such as oxygen index and smoke density are increased.

2. By a special preparation method, the flame retardance of the raw materials is fully exerted, and the problem that the flame retardance of the existing product is unstable is solved; particularly, in the step S2, the adhesive layer is manufactured by adjusting the addition amount of the flame retardant (from 28.5 g/square meter to 31.6 g/square meter) and adjusting the viscosity of the adhesive layer preparation fluid (from 10000cps ± 1000 to 7000cps ± 1000), so as to improve the problem of uneven dispersion of the flame retardant due to large viscosity, improve the coating quality of the flame retardant, further realize qualified flame retardant performance of the product, avoid the problem of poor physical properties, improve the yield, and meet the requirements of customers.

3. The flame-retardant PU synthetic leather provided by the invention has the advantages that the strength of the synthetic leather is improved through the waterborne polyurethane raw material and the synthetic leather structure with specific components, the component properties of the product and the preparation process, so that the purpose of prolonging the service life of the product is achieved, and the product competitiveness is improved.

Drawings

FIG. 1 is a process flow chart of a preparation method of flame-retardant PU synthetic leather according to the invention;

FIG. 2 is a schematic cross-sectional view of a flame-retardant PU synthetic leather according to the present invention;

the labels in the figure are: 1-base cloth layer, 2-adhesion layer, 3-surface layer, 4-surface treatment layer and 5-synthetic leather blank.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples, so that those skilled in the art can fully understand the technical contents of the present invention. It should be understood that the following examples are intended to further illustrate the present invention and should not be construed as limiting the scope of the present invention, and that certain insubstantial modifications and adaptations of the invention by those skilled in the art based on the foregoing description are intended to be covered by the present invention. The specific process parameters and the like of the following examples are also only one example of suitable ranges, i.e., those skilled in the art can select the appropriate ranges through the description herein, and are not limited to the specific values exemplified below.

The invention provides flame-retardant PU synthetic leather, which comprises a synthetic leather blank 5 and a surface treatment layer 4, wherein the synthetic leather blank 5 comprises a base cloth layer 1, an adhesion layer 2 and a surface layer 3, the adhesion layer 2 is arranged between the base cloth layer 1 and the surface layer 3, and the surface treatment layer 4 is coated on the surface layer 3. The surface treatment layer 4 comprises polyurethane, a bridging agent, a tackifier and a smoothing agent; the surface treatment layer 4 comprises the following components in percentage by mass: 89.0 to 91.0 percent of polyurethane, 1.5 to 3.5 percent of bridging agent, 0.5 to 1.5 percent of tackifier and 6.0 to 8.0 percent of smoothing agent; the bridging agent is multifunctional carbodiimide polymer, and the tackifier is alkaline tackifier, such as acrylic polymer; the smoothing agent is silicon series and silicon polymer thereof.

The surface layer 3 comprises polyurethane, a bridging agent, a tackifier, pigment and a dissolving medium; the surface layer 3 comprises the following components in percentage by mass: 60.8 to 69.8 percent of polyurethane, 1.7 to 3.7 percent of bridging agent, 2.0 to 8.0 percent of tackifier, 10.5 to 16.5 percent of pigment, 12.0 to 15.0 percent of dissolving medium and water.

The adhesion layer 2 comprises polyurethane, a hardener, a catalyst, a solvent, a flame retardant and a pigment; the following layer 2 comprises the following components in percentage by mass: 25.3 to 27.7 percent of polyurethane, 35.6 to 39.3 percent of hardener, 0.06 to 1.04 percent of accelerant, 3.4 to 5.4 percent of solvent, 25.0 to 35.0 percent of flame retardant and 0.6 to 1.6 percent of pigment; the hardening agent is yellowing resistant, the catalyst is special catalyst formed by amine organic acid salt, the solvent is butanone and polycondensate thereof, and the flame retardant is phosphorus flame retardant.

The base fabric layer is a woven fabric such as fiber, cotton, woven fabric and nonwoven fabric, preferably, the base fabric layer has a thickness of 800 μm to 1000 μm and a mass of 220g/m²～390g/m²。

The invention also provides a preparation method for preparing the flame-retardant PU synthetic leather, which comprises the following steps:

s1 surface layer preparation, wherein the surface layer 3 preparation comprises surface layer solution preparation, surface layer solution defoaming treatment, surface layer solution coating processing and surface layer drying and forming to obtain a surface layer 3; the stirring speed of the prepared surface layer solution is 600 rpm-800 rpm, the stirring time is 60 min-65 min, and the viscosity of the surface layer solution is 3000 cps-5000 cps.

The treatment time of the surface layer solution defoaming treatment in the step S1 is 60 min-65 min. The prepared surface layer solution is defoamed by a circulating defoaming machine, so that the defoaming effect is fully ensured, and the surface layer solution is prevented from air entering in the conveying process during circulating use so as to improve the surface layer coating quality. The speed of the surface layer solution coating processing is 9 m/min-11 m/min, and the using amount is 75g/m²～125g/m². The surface layer is dried and formed at the temperature of 100-125 ℃ for 2-3 min.

S2 manufacturing an adhesion layer, wherein the manufacturing of the adhesion layer 2 comprises preparing an adhesion layer solution, coating the adhesion layer solution, and drying and forming the adhesion layer to obtain the adhesion layer 2; the stirring speed of the prepared solution of the adhesive layer is 700rpm to 1000 rpm. The speed of the coating processing of the solution of the adhesive layer is 9m/min to 11m/min, and the using amount is 153g/m²～187g/m². The drying and forming temperature of the subsequent layer is 125-135 ℃, the time is 2.5-3.5 min, and the drying degree of the subsequent layer is 70-80%.

S3, bonding and adhering the surface layer 3 obtained in the step S1, the bonding layer 2 obtained in the step S2 and the base cloth layer 1 together to form a synthetic leather blank 5; the bonding speed is 8m/min to 10m/min, and the bonding pressure is 0.2MPa to 0.3 MPa.

S4, peeling, namely peeling the synthetic leather blank 5 obtained in the step S3 from the release paper mold to obtain the synthetic leather blank 5;

s5, curing, namely curing the synthetic leather blank 5 obtained in the step S4 in an oven and cooling to obtain a cured synthetic leather blank; the curing treatment temperature is 125-135 ℃, and the curing treatment time is 2-10 min.

S6 surface layer treatment, namely performing surface layer treatment on the cured synthetic leather blank obtained in the step S6 to obtain a surface treatment layer 4; the surface layer treatment comprises the steps of preparing surface treatment layer liquid, coating, processing and baking the surface treatment layer liquid to obtain the finished synthetic leather. The stirring speed of the prepared surface treatment layer liquid is 400-600 rpm, the stirring time is 60-65 min, and the viscosity of the surface treatment layer liquid is 1200-1800 cps; coating with surface treatment layer liquidThe processing speed is 13m/min to 15m/min, and the using amount is 50g/m²～60g/m²The baking forming temperature of the surface treatment layer is 95-130 ℃, and the time is 2-3 min.

Example 1:

according to the flame-retardant PU synthetic leather and the preparation method thereof provided by the embodiment, a release paper mold and a base fabric layer are prepared firstly; the production environment temperature is 0-40 ℃, and the production environment humidity is 20-80%.

S1 surface layer preparation, namely according to the material components of the surface layer 3, selecting 60.8% of polyurethane, 2.8% of bridging agent carbodiimide, 5.0% of alkaline tackifier, 13.9% of inorganic pigment iron oxide and carbon black, and the balance of dissolving medium water to prepare a surface layer solution; the stirring speed of the prepared surface layer solution is 600 rpm-800 rpm, the stirring time is 60 min-65 min, and the viscosity of the obtained surface layer solution is 3800 cps; fully defoaming the surface layer solution for 60-65 min; the coating speed of the surface layer solution is 9m/min, and the use amount is 75g/m²～125g/m²(ii) a Drying and forming the surface layer at 100-125 deg.c for 3.3 min.

S2 subsequent layer preparation: according to the material components of the adhesion layer 2, 25.7% of polyurethane, 35.6% of yellowing-resistant hardener polyol polyurethane, 0.06% of medium amine organic acid salt, 3.4% of solvent butanone, 25.0% of phosphorus flame retardant, 0.6% of inorganic pigment iron oxide and carbon black are selected in percentage by mass to prepare an adhesion layer solution; the stirring speed of the solution of the adhesion layer is 700 rpm-1000 rpm; the coating speed of the solution for the adhesive layer was 11m/min, and the amount used was 153g/m²～187g/m²(ii) a The drying and forming temperature of the subsequent layer is 125-135 ℃, the time is 2.7min, and the drying degree of the subsequent layer is 80%.

S3, bonding and adhering the surface layer 3 obtained in the step S1, the bonding layer 2 obtained in the step S2 and the base cloth layer 1 together to form a synthetic leather blank 5; the bonding speed is 8m/min to 10m/min, and the bonding pressure is 0.2MPa to 0.3 MPa.

S4, peeling, namely peeling the synthetic leather blank 5 obtained in the step S3 from the release paper mold to obtain the synthetic leather blank 5;

s5, curing, namely curing the synthetic leather blank 5 obtained in the step S4 in an oven and cooling to obtain a cured synthetic leather blank; the curing treatment temperature is 125-135 ℃, and the curing treatment time is 2-10 min.

S6 surface layer treatment: according to the material components of the surface treatment layer liquid of the surface treatment layer 4, 89.0% of polyurethane, 1.5% of bridging agent carbodiimide, 0.5% of alkaline tackifier and 7.0% of smoothing agent silicon are selected in percentage by mass to prepare the surface treatment layer liquid; the stirring speed of the surface treatment layer liquid is 400 rpm-600 rpm, the stirring time is 60 min-65 min, and the viscosity of the surface treatment layer liquid is 1500 cps; the coating speed of the surface treatment layer liquid is 13m/min, and the using amount is 50g/m²～60g/m²The baking forming temperature of the surface treatment layer is 95-130 ℃, and the time is 3 min.

The flame-retardant PU synthetic leather prepared by the method is subjected to performance test, and the results are shown in Table 1. As can be seen from the comparative examples in Table 1, the flame-retardant PU synthetic leather provided by the invention has the advantages that various performances are greatly improved, the flame retardancy of the raw materials is fully exerted under the condition of the same deformation, the problem that the flame retardancy of the existing product is unstable is solved, the flame-retardant performance of the product is qualified, no other problems of poor physical properties exist, the yield is improved, and the requirements of the standard and customers are met.

Example 2:

the difference between the other flame-retardant PU synthetic leather and the preparation method thereof provided in this example and example 1 is that:

s1 surface layer preparation, according to the material components of the surface layer 3, selecting 64.8% of polyurethane, 1.7% of bridging agent carbodiimide, 8.0% of alkaline tackifier, 16.5% of inorganic pigment iron oxide and carbon black, and the balance of dissolving medium water to prepare a surface layer solution; the stirring speed of the prepared surface layer solution is 600 rpm-800 rpm, the stirring time is 60 min-65 min, and the viscosity of the obtained surface layer solution is 4500 cps; fully defoaming the surface layer solution for 60-65 min; the speed of the surface layer solution coating process is 11m/min, and the usage amount is 75g/m²～125g/m²(ii) a Surface ofDrying and forming the layers at the temperature of 100-125 ℃ for 2.7 min.

S2 subsequent layer preparation: according to the material components of the adhesive layer 2, an adhesive layer solution is prepared by selecting 26.7% of polyurethane, 37.5% of yellowing-resistant hardener polyol polyurethane, 1.04% of intermediate amine organic acid salt, 4.4% of solvent butanone, 30.0% of phosphorus flame retardant, 1.0% of inorganic pigment iron oxide and carbon black in percentage by mass; the stirring speed of the solution of the adhesion layer is 700 rpm-1000 rpm; the coating speed of the solution for the adhesive layer was 10m/min, and the amount used was 153g/m²～187g/m²(ii) a The drying and forming temperature of the subsequent layer is 125-135 ℃, the time is 3min, and the drying degree of the subsequent layer is 75%.

S6 surface layer treatment: according to the material components of the surface treatment layer liquid of the surface treatment layer 4, 91.0 percent of polyurethane, 3.5 percent of bridging agent carbodiimide, 1.5 percent of alkaline tackifier and 8.0 percent of smoothing agent silicon are selected in percentage by mass to prepare the surface treatment layer liquid; the stirring speed of the surface treatment layer liquid is 400 rpm-600 rpm, the stirring time is 60 min-65 min, and the viscosity of the surface treatment layer liquid is 1800 cps; the coating speed of the surface treatment layer liquid is 12m/min, and the using amount is 50g/m²～60g/m²The baking forming temperature of the surface treatment layer is 95-130 ℃, and the time is 2 min.

The flame-retardant PU synthetic leather prepared by the method is subjected to performance test, and the results are shown in Table 1.

Example 3:

the difference between the flame retardant PU synthetic leather provided in this example and the preparation method thereof and the example 1 is that:

s1 surface layer preparation, according to the material components of the surface layer 3, selecting 69.8% of polyurethane, 3.7% of bridging agent carbodiimide, 2.0% of alkaline tackifier, 10.5% of inorganic pigment iron oxide and carbon black, and the balance of dissolving medium water to prepare a surface layer solution; the stirring speed of the prepared surface layer solution is 600 rpm-800 rpm, the stirring time is 60 min-65 min, and the viscosity of the obtained surface layer solution is 4500 cps; fully defoaming the surface layer solution for 60-65 min; speed of solution coating process of surface layerThe degree is 10m/min, and the usage amount is 75g/m²～125g/m²(ii) a Drying and forming the surface layer at 100-125 deg.c for 3 min.

S2 subsequent layer preparation: according to the material components of the adhesion layer 2, 27.7% of polyurethane, 39.3% of yellowing-resistant hardener polyol polyurethane, 1.04% of intermediate amine organic acid salt, 5.4% of solvent butanone, 35.0% of phosphorus flame retardant, 1.6% of inorganic pigment iron oxide and carbon black are selected in percentage by mass to prepare an adhesion layer solution; the stirring speed of the solution of the adhesion layer is 700 rpm-1000 rpm; the coating speed of the solution for the adhesive layer was 9m/min, and the amount used was 153g/m²～187g/m²(ii) a The drying and forming temperature of the subsequent layer is 125-135 ℃, the time is 3.3min, and the drying degree of the subsequent layer is 70%.

S6 surface layer treatment: according to the material components of the surface treatment layer liquid of the surface treatment layer 4, selecting 90.0% of polyurethane, 2.5% of bridging agent carbodiimide, 0.75% of alkaline tackifier and 6.0% of smoothing agent silicon in percentage by mass to prepare the surface treatment layer liquid; the stirring speed of the surface treatment layer liquid is 400 rpm-600 rpm, the stirring time is 60 min-65 min, and the viscosity of the surface treatment layer liquid is 1800 cps; the coating speed of the surface treatment layer liquid is 15m/min, and the using amount is 50g/m²～60g/m²The baking forming temperature of the surface treatment layer is 95-130 ℃, and the time is 2.5 min.

The flame-retardant PU synthetic leather prepared by the method is subjected to performance test, and the results are shown in Table 1.

Through the embodiment, the performance of the flame-retardant PU synthetic leather disclosed by the invention is greatly improved, wherein the flame retardance of the raw materials is fully exerted under the condition of the same deformation, the problem that the flame retardance of the existing product is unstable is solved, the qualified flame-retardant performance of the product is realized, the problem of poor physical property is avoided, the yield is improved, and the requirements of customers are met. Has wide application prospect.

It should be noted that the above-mentioned preferred embodiments are merely illustrative of the technical concepts and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.