Environment-friendly high-flame-retardant multi-layer composite polyurethane synthetic leather and preparation method thereof

Abstract

The invention provides environment-friendly high-flame-retardant multi-layer composite polyurethane synthetic leather and a preparation method thereof, belongs to the technical field of synthetic leather, and solves the problems that more middle layers exist in the production process of the existing synthetic leather, and the production period of the middle layers is long, the production cost is low and the like no matter the middle layers are gradually coated or are respectively produced on different production lines and then are sequentially bonded. And a production line of the latter is large in occupied area and required equipment, high in cost, low in production efficiency and the like. The synthetic leather is prepared from composite fiber base cloth, a flame-retardant middle layer and a wear-resistant surface layer which are sequentially laminated, wherein the flame-retardant middle layer comprises a phosphorus-nitrogen flame-retardant layer, an inorganic flame-retardant layer and a nano flame-retardant layer which are sequentially laminated from bottom to top. The method has the advantage that each layer of the synthetic leather is simultaneously produced on a single production line by adopting single equipment.

Description

Technical Field

[0001] The present invention belongs to the technical field of synthetic leather, and relates to a multi-layer composite polyurethane synthetic leather, in particular to an environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather and a preparation method thereof. Background Art

[0002] In recent years, domestic and foreign researchers have been committed to developing environmentally friendly polyurethane synthetic leather, mainly focusing on the research and application of waterborne polyurethane resins. However, waterborne polyurethane still has deficiencies in film-forming properties, mechanical properties, etc., which limit its wide application. At the same time, in order to improve the flame retardant performance of synthetic leather, the method of adding flame retardants is usually adopted, but traditional flame retardants have problems such as easy migration and poor durability, which affect the service life and safety of materials. Therefore, developing a multi-layer composite polyurethane synthetic leather with both environmental friendliness, high flame retardancy and excellent mechanical properties has become a research hotspot in this field.

[0003] After retrieval, for example, a Chinese patent document discloses an environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather and a preparation method thereof [Application No.: CN202110390398.4; Publication No.: CN113106765B]. This synthetic leather adopts a multi-layer composite design, and by adding different flame retardants and additives in different layer structures, it realizes that the polyurethane synthetic leather can not only meet basic use, but also greatly improve the flame retardant performance of the polyurethane synthetic leather.

[0004] Although the synthetic leather disclosed in this patent uses different combustion aids and additives to improve the flame retardant performance, there are many intermediate layers in the production process of this synthetic leather. Whether the intermediate layers are gradually coated or produced separately on different production lines and then bonded in sequence, the former has a long production cycle, and the latter has a large floor area for the production line, requires a lot of equipment and high costs, and the production efficiency is relatively low. Summary of the Invention

[0005] The purpose of the present invention is to address the above problems existing in the prior art and propose an environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather and a preparation method thereof. The technical problem to be solved by this invention is: how to realize the simultaneous production of each layer of the synthetic leather on a single production line using a single device.

[0006] The purpose of the present invention can be achieved by the following technical solutions: An environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather, characterized in that it includes a composite fiber base fabric, a flame retardant intermediate layer and a wear-resistant surface layer that are sequentially laminated from bottom to top, and the flame retardant intermediate layer includes a phosphorus-nitrogen-based flame retardant layer, an inorganic flame retardant layer and a nano flame retardant layer that are sequentially laminated from bottom to top; The phosphorus-nitrogen-based flame retardant layer is composed of the following raw materials in parts by mass: 100-120 parts of waterborne polyurethane resin, 5-10 parts of short glass fiber filaments, 3-5 parts of nano-silica, 1-2 parts of silane coupling agent, 2-5 parts of foaming agent, 1-2 parts of stabilizer, 0.5-1 part of thickening agent, 5-10 parts of bio-based plasticizer, 10-15 parts of ammonium polyphosphate, and 5-10 parts of melamine cyanurate; The inorganic flame retardant layer is composed of the following raw materials in parts by mass: 100-120 parts of waterborne polyurethane resin, 5-10 parts of short glass fiber filaments, 3-5 parts of nano-silica, 1-2 parts of silane coupling agent, 2-5 parts of foaming agent, 1-2 parts of stabilizer, 0.5-1 part of thickening agent, 5-10 parts of bio-based plasticizer, 20-30 parts of aluminum hydroxide, and 10-15 parts of magnesium hydroxide; The nano flame retardant layer is composed of the following raw materials in parts by mass: 100-120 parts of waterborne polyurethane resin, 5-10 parts of short glass fiber filaments, 3-5 parts of nano-silica, 1-2 parts of silane coupling agent, 2-5 parts of foaming agent, 1-2 parts of stabilizer, 0.5-1 part of thickening agent, 5-10 parts of bio-based plasticizer, and 3-5 parts of nano-layered double hydroxide.

[0007] Preferably, an environmentally friendly adhesive layer is bonded between the composite fiber base fabric, the phosphorus-nitrogen-based flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer, and the wear-resistant surface layer. The environmentally friendly adhesive layer is composed of the following raw materials in parts by mass: 80-100 parts of waterborne polyurethane resin, 3-5 parts of crosslinking agent, 0.5-1 part of wetting agent, and 10-20 parts of deionized water.

[0008] Preferably, the wear-resistant surface layer is composed of the following raw materials in parts by mass: 100-120 parts of waterborne polyurethane resin, 5-10 parts of short glass fiber filaments, 3-5 parts of nano-silica, 1-2 parts of silane coupling agent, 2-5 parts of foaming agent, 1-2 parts of stabilizer, 0.5-1 part of thickening agent, 5-10 parts of bio-based plasticizer, 3-5 parts of organosilicon wear-resistant agent, 2-4 parts of polytetrafluoroethylene particles, 0.5-1 part of carbon nanotubes, 1-3 parts of matting agent, 1-2 parts of hand feel agent, 0.5-1 part of leveling agent, 1-2 parts of ultraviolet absorber, 1-2 parts of antistatic agent, 1-2 parts of antibacterial agent, 2-4 parts of nano-aluminum oxide, and 1-3 parts of nano-silica.

[0009] Another object of the present invention is to provide a preparation method of an environmentally friendly high flame retardant multi-layer composite polyurethane synthetic leather, including the following steps: S1. Weigh waterborne polyurethane resin, crosslinking agent, wetting agent, and deionized water in proportion, mix them evenly to obtain an environmentally friendly polyurethane adhesive. The composite fiber base fabric is sequentially washed, dried, coiled, and installed on the production line, and the environmentally friendly polyurethane adhesive is applied to obtain a base fabric with adhesive; S2. Weigh waterborne polyurethane resin, short glass fiber filaments, nano-silica, silane coupling agent, foaming agent, stabilizer, thickener, and bio-based plasticizer proportionally, obtain the base slurry after foaming, and transport it to each production unit on each layer of the production line; S3. Simultaneously produce the flame-retardant intermediate layer and the wear-resistant surface layer: Add ammonium polyphosphate and melamine cyanurate proportionally to 1 / 7 of the base slurry, heat and stir evenly to obtain the phosphorus-nitrogen-based flame-retardant slurry, roll-coat it on the adhesive base fabric to obtain the basis of the phosphorus-nitrogen-based flame-retardant layer, and recycle the excess phosphorus-nitrogen-based flame-retardant slurry at the same time; S4. Add aluminum hydroxide and magnesium hydroxide proportionally to 2 / 3 of the base slurry, heat and stir evenly to obtain the inorganic flame-retardant slurry, roll-coat it on the release paper to obtain the basis of the inorganic flame-retardant layer, and recycle the excess inorganic flame-retardant slurry at the same time; S5. Add nano-layered double hydroxides proportionally to 1 / 7 of the base slurry, heat and stir evenly to obtain the nano flame-retardant slurry, roll-coat it on the release paper to obtain the basis of the nano flame-retardant layer, and recycle the excess nano flame-retardant slurry at the same time; S6. Add organosilicon wear-resistant agent, polytetrafluoroethylene particles, carbon nanotubes, matting agent, hand feel agent, leveling agent, ultraviolet absorber, antistatic agent, antibacterial agent, nano-aluminum oxide and nano-silica proportionally to 1 / 7 of the base slurry, heat and stir evenly to obtain the surface layer slurry, roll-coat it on the release paper to obtain the basis of the surface layer, and recycle the excess surface layer slurry at the same time; S7. Simultaneously dry the basis of the phosphorus-nitrogen-based flame-retardant layer, the inorganic flame-retardant layer, the nano flame-retardant layer and the surface layer. During the transmission process, the release paper is recycled by the rubber roller to obtain the phosphorus-nitrogen-based flame-retardant layer, the inorganic flame-retardant layer, the nano flame-retardant layer and the wear-resistant surface layer. Apply environmentally friendly polyurethane glue on the surfaces of the phosphorus-nitrogen-based flame-retardant layer, the inorganic flame-retardant layer, and the nano flame-retardant layer, dry after pressing to obtain the environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather.

[0010] Preferably, the thickness of the phosphorus-carbon-based flame-retardant layer is 0.1 - 0.3 mm, the inorganic flame-retardant layer is 0.5 - 2.0 mm, the nano flame-retardant layer is 0.1 - 0.3 mm, and the basis of the surface layer is 0.1 - 0.3 mm; Preferably, the roll-coating speed is 5 - 20 m / min, the roll-coating pressure is 0.2 - 0.5 MPa, the drying temperature is 80 - 120 °C, and the drying time is 3 - 10 min.

[0011] Preferably, the equipment used in the steps S1 - S7 is a synthetic leather production device. The synthetic leather production device includes a driving conveyor belt. The number of driving conveyor belts is four, which are distributed vertically. A base fabric is provided on the driving conveyor belt at the lowermost position, and release papers are provided on the remaining three driving conveyor belts. Coating rollers are provided on both the release papers and the base fabric. An inorganic flame retardant layer, a nano flame retardant layer, and a wear-resistant surface layer are successively laid on the three release papers from bottom to top. A phosphazene flame retardant layer is pasted on the base fabric. A rubber roller rolls at the left end below the release paper. Glue applicators are provided on the phosphazene flame retardant layer, the inorganic flame retardant layer, and the nano flame retardant layer. The glue applicators are located on the left side of the rubber roller. A laminating machine is provided on the phosphazene flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer, and the wear-resistant surface layer. Moreover, the phosphazene flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer, and the wear-resistant surface layer all pass through the input end of the laminating machine. A dryer is provided between the right side of the laminating machine, the rubber roller, and the coating roller.

[0012] With the above structure, the rubber roller is a roller body made of silicone material with adhesive on its surface. It can stick and wind back one end of the release paper with the phosphazene flame retardant layer, inorganic flame retardant layer, nano flame retardant layer, and wear-resistant surface layer prepared on its surface during rotation, realizing the production of the phosphazene flame retardant layer, inorganic flame retardant layer, nano flame retardant layer, and wear-resistant surface layer without coating on the surface of the base fabric, and transmitting it to the laminating machine.

[0013] A foaming machine is placed in front of the base fabric. The discharge port flange of the foaming machine is connected to a screw pump. The output end flange of the screw pump is connected to a shunt pipe. The number of discharge ports of the shunt pipe is four, and mixing tanks are fixed at all four discharge ports. A metering valve is flange-connected between the shunt pipe and the mixing tanks. The four mixing tanks are distributed vertically and are on the same vertical horizontal line. A motor is fixed on the uppermost mixing tank. The output end of the motor is fixed to a main rotating shaft through a coupling. The main rotating shaft vertically penetrates through the left position in the four mixing tanks. A number of transverse paddle blades are fixed on the main rotating shaft, and all the transverse paddle blades are located inside the mixing tanks. The main rotating shaft is rotationally connected to four longitudinal paddle blades through a transmission part, and all the four longitudinal paddle blades are located inside the mixing tanks. A heating plate is fixed at the bottom of the inner wall of the mixing tank, and a feeding cylinder is integrally formed at the front end of the mixing tank. A discharge port is provided at the lower position at the rear end of the mixing tank. The discharge port flange is connected to a metering pump. The output end flange of the metering pump is connected to a discharge long cylinder. The coating roller rotates at the position below the discharge long cylinder.

[0014] With the above structure, the same materials required for each layer are poured into the foaming machine for unified foaming to form the basic slurry. The screw pump transports the basic slurry into the shunt pipe. The metering valve takes the extrusion slurry required for each layer in the shunt pipe and enters it into the mixing tank. Then, the different raw materials of the phosphorus-nitrogen flame-retardant layer, inorganic flame-retardant layer, nano flame-retardant layer, and wear-resistant surface layer are respectively put into the corresponding mixing tanks from the feed cylinder. After the feeding is completed, the motor is run to drive the main rotating shaft to rotate. The transverse blades rotate with the main rotating shaft, and the longitudinal blades further stir the basic slurry and additives in the mixing tank. The heating plate maintains the temperature in the mixing tank during the stirring process to keep the slurry in a foaming state, realizing the preparation of the slurries for each layer. The metering pump extracts the slurry in the mixing tank and outputs it from the discharge long tube and drips it onto the roller body of the coating roller. The coating roller rotates to evenly roll-coat the slurry on the base cloth or release paper. Each layer uses a single foaming machine and motor to realize the foaming and mixing of four slurries, and at the same time prepares and coats the three intermediate layers with different flame-retardant effects. After the coating is completed, each layer is conveyed to the bottom of the dryer with the base cloth and release paper to be dried. After drying, the rubber roller recovers the release paper, and the formed inorganic flame-retardant layer, nano flame-retardant layer, and wear-resistant surface layer are conveyed towards the laminating machine. Before reaching the laminating machine, the coating machine applies environmentally friendly polyurethane glue on the surfaces of the nitrogen-based flame-retardant layer, inorganic flame-retardant layer, and nano flame-retardant layer. After the coating is completed, each layer enters the laminating machine to combine the four layers at the same time. After laminating, the glue is dried by the dryer to complete the production of the composite synthetic leather. Subsequent subjective non-essential requirements such as embossing and cutting are realized by external equipment. The production lines of each layer are combined to achieve a longitudinal distribution and combination of the production lines. The composite synthetic leather layers are produced simultaneously on the same longitudinal production line, and the mixing material equipment overlaps, fundamentally saving production costs and production floor space, saving production energy consumption and being environmentally friendly, and significantly improving production efficiency.

[0015] An installation plate is fixed on the left side of the discharge long tube. A scraper is fixed at the position near the left side of the bottom of the installation plate. Two rotating rods distributed left and right are penetrated through the installation plate. Synchronous wheels are key-connected to the bottoms of the rotating rods. A synchronous belt is engaged on the two synchronous wheels. A third gear is key-connected to the top end of the rotating rod on the left side. Four fourth gears are key-connected to the main rotating shaft. The four fourth gears are respectively located at the tops of the four mixing tanks. The fourth gear is engaged with the third gear. A number of spring shafts are evenly fixed on the synchronous belt. A scraping box is fixed at the end of the spring shaft away from the synchronous belt. The scraping box contacts the scraper. A replenishing port is opened on the scraping box. A recovery box is fixed at the rear end of the mixing tank through a return pipe. A rubber rod is vertically fixed in the recovery box. The rubber rod contacts the scraping box. There are two recovery boxes and they are located on the front and rear sides of the base cloth. A collecting pipe is communicated between the two recovery boxes, and the collecting pipe slopes downward and forward. Flow guiding grooves are communicated on both the left and right sides of the recovery box, and the bottoms of the inner walls of the flow guiding grooves slope towards the position of the recovery box. The slurry in the front recovery box is pumped into the mixing tank through the return pipe by a liquid pump (the output end of the liquid pump is fixed to the mixing tank, and the input end of the liquid pump is fixed to the return pipe).

[0016] With the above structure, during the transmission process, the phosphorus-nitrogen flame-retardant layer, inorganic flame-retardant layer, nano flame-retardant layer, and wear-resistant surface layer after coating pass through a squeegee, achieving the limitation of the coating thickness. Moreover, the rotation of the motors used for mixing the materials of each layer drives the parts used in the slurry recovery process. And the parts used for slurry recovery in each layer and the parts used for mixing the mixed materials in each layer are all driven by one motor, greatly realizing the synchronous production of each layer of synthetic leather and the sharing of equipment, saving production costs. Also, the recovery of excess and overflowed slurry avoids the situation where the slurry falls and mixes during the longitudinal synchronous production of each layer, not only recovering the slurry to save costs but also achieving isolation to prevent the upper-layer slurry from falling to the lower layer. The slurry does not flow to the ground, which can maintain the workshop environment, is environmentally friendly, and ensures the uniform thickness of the synthetic leather, improving the quality of the synthetic leather.

[0017] The transmission part includes a first gear key-connected to the main rotating shaft. A rotating shaft is rotatably connected in the mixing tank. A second gear and a first bevel gear are key-connected to the rotating shaft. The second gear meshes with the first gear. A connecting rod is fixed in the mixing tank. A rotating cylinder is fixed at the bottom of the connecting rod. A mounting rod is rotatably connected in the rotating cylinder. A second bevel gear is key-connected to the left end of the mounting rod. The longitudinal paddle is fixed to the right end of the mounting rod.

[0018] With the above structure, through the transmission part, a single motor simultaneously drives the horizontal and vertical rotations in four mixing tanks, improving the stirring uniformity by complicating the mixing direction. The eight rotational operations in the four mixing tanks are all achieved by one motor, which not only saves costs but also improves the efficiency by simultaneous production.

[0019] Compared with the prior art, the environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather and its preparation method have the following advantages: 1. By setting common raw materials in the three-layer flame-retardant intermediate layer and the wear-resistant surface layer and extracting them as the base slurry, the same foaming of the base slurry is realized, and the unity of raw materials between layers enhances the interfacial bonding force, thereby improving the radial tensile load and elongation at break, reducing the physical and chemical property differences between layers, reducing the index differences, and optimizing the flame-retardant ability.

[0020] 2. Through unified foaming, separately mixing different raw materials, and simultaneously preparing and coating the three intermediate layers with different flame-retardant effects. After coating, each layer is conveyed with the base cloth and the release paper to the bottom of the dryer for drying. After drying, the release paper is recovered by a rubber roller, and the formed inorganic flame-retardant layer, nano flame-retardant layer, and wear-resistant surface layer are conveyed towards the laminating machine. Before reaching the laminating machine, an environmentally friendly polyurethane adhesive is applied to the surfaces of the nitrogen-based flame-retardant layer, inorganic flame-retardant layer, and nano flame-retardant layer by a coating machine. After coating, each layer enters the laminating machine to combine the four layers simultaneously. After lamination, the glue is dried by a dryer. The preparation process realizes the unification of the production line, produces simultaneously, and directly laminates each layer uniformly, greatly improving the production efficiency and simplifying the process.

[0021] 3. By merging the production lines and sharing the production equipment at each layer, a single foaming machine is used to foam the base slurry, and a single motor drives the paddles in the mixing tanks at each layer. The production lines are distributed and combined longitudinally, and the various layers of composite synthetic leather are produced simultaneously on the same longitudinal production line with the mixing equipment overlapping. This fundamentally saves production costs and production floor space, saves production energy consumption, is environmentally friendly, and significantly improves production efficiency.

[0022] 4. By merging the production lines and sharing the production equipment on each layer, and utilizing the rotation of the motors used for mixing the materials on each layer to drive the parts used in the slurry recovery process, the synchronous production and equipment sharing of each layer of synthetic leather can be achieved to a great extent, saving production costs. The excess and overflowing slurry can be recovered to avoid the slurry falling and mixing during the longitudinal synchronous production of each layer. The scraper has a limited height, and the scraper box recovers the slurry on the scraper while also replenishing the slurry at a higher place to a lower place. This not only recovers the slurry and saves costs, but also achieves isolation to prevent the upper layer of slurry from falling to the lower layer. The slurry does not flow to the ground, which can maintain the workshop environment, be environmentally friendly, ensure the uniform thickness of the synthetic leather, and improve the quality of the synthetic leather.

[0023] 5. Through the transmission part, a single motor can simultaneously drive the horizontal and vertical rotation of the four mixing tanks, so as to improve the mixing uniformity by complicating the mixing direction. A total of eight rotations in the four mixing tanks are realized by one motor, which saves costs and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the preparation process steps of the present invention.

[0025] Figure 2 It is a structural schematic diagram of the present invention.

[0026] Figure 3 It is a structural schematic diagram of four mixing tanks in the present invention.

[0027] Figure 4 It is a schematic diagram of the structure in which one motor drives all the blades in the present invention.

[0028] Figure 5 yes Figure 4 A magnified view of the structure at point A in the middle.

[0029] Figure 6 It is a structural schematic diagram of the motor transmission to the synchronous wheel in the present invention.

[0030] Figure 7 It is a structural schematic diagram of the motor indirectly driving the scraper box in the present invention.

[0031] Figure 8 It is a structural schematic diagram of the slurry recovery flow to the recovery box in the present invention.

[0032] Figure 9 is Figure 8 An enlarged view of the structure at position B in the figure.

[0033] Figure 10 It is a schematic structural diagram of the recycling of the slurry in the recycling box to the mixing tank in the present invention.

[0034] Figure 11 It is an experimental result table of Examples 1 to 4.

[0035] In the figure: 1, driving conveyor belt; 2, base fabric; 3, release paper; 4, laminating machine; 501, foaming machine; 502, screw pump; 503, shunt pipe; 601, mixing tank; 602, motor; 603, main rotating shaft; 604, transverse paddle; 605, longitudinal paddle; 606, heating plate; 607, feed cylinder; 608, discharge long cylinder; 609, coating roller; 610, metering pump; 7, metering valve; 8, transmission part; 801, first gear; 802, second gear; 803, rotating shaft; 804, first bevel gear; 805, second bevel gear; 806, connecting rod; 807, rotating cylinder; 808, mounting rod; 901, mounting plate; 902, scraper; 903, rotating rod; 904, synchronous pulley; 905, synchronous belt; 906, third gear; 907, fourth gear; 908, spring shaft; 909, scraping box; 910, feeding port; 1001, recycling box; 1002, rubber rod; 1003, return pipe; 1004, liquid pump; 1005, manifold; 1006, diversion groove; 11, dryer; 12, rubber roller; 13, gluing machine. Detailed implementation manners

[0036] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention are further described, but the present invention is not limited to these embodiments.

[0037] Example 1 The environmentally friendly high flame-retardant multi-layer composite polyurethane synthetic leather includes a composite fiber base fabric, a flame-retardant intermediate layer, and a wear-resistant surface layer that are sequentially laminated from bottom to top. The flame-retardant intermediate layer includes a phosphorus-nitrogen-based flame-retardant layer, an inorganic flame-retardant layer, and a nano flame-retardant layer that are sequentially laminated from bottom to top; The phosphorus-nitrogen-based flame-retardant layer is composed of the following raw materials in parts by mass: 110 parts of waterborne polyurethane resin, 8 parts of short glass fiber filaments, 4 parts of nano-silica, 1.5 parts of silane coupling agent, 3 parts of foaming agent, 1.5 parts of stabilizer, 0.8 part of thickener, 8 parts of bio-based plasticizer, 12 parts of ammonium polyphosphate, and 8 parts of melamine cyanurate; The inorganic flame retardant layer is composed of the following raw materials in parts by mass: 110 parts of waterborne polyurethane resin, 8 parts of short cut glass fiber, 4 parts of nano-silica, 1.5 parts of silane coupling agent, 3 parts of foaming agent, 1.5 parts of stabilizer, 0.8 part of thickener, 8 parts of bio-based plasticizer, 25 parts of aluminum hydroxide, and 12 parts of magnesium hydroxide; The nano flame retardant layer is composed of the following raw materials in parts by mass: 110 parts of waterborne polyurethane resin, 8 parts of short cut glass fiber, 4 parts of nano-silica, 1.5 parts of silane coupling agent, 3 parts of foaming agent, 1.5 parts of stabilizer, 0.8 part of thickener, 8 parts of bio-based plasticizer, and 4 parts of nano-layered double hydroxide.

[0038] An environmentally friendly adhesive layer is bonded between the composite fiber base fabric, the phosphorus-nitrogen based flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer and the wear-resistant surface layer. The environmentally friendly adhesive layer is composed of the following raw materials in parts by mass: 110 parts of waterborne polyurethane resin, 4 parts of crosslinking agent, 0.7 part of wetting agent, and 16 parts of deionized water.

[0039] The wear-resistant surface layer is composed of the following raw materials in parts by mass: 110 parts of waterborne polyurethane resin, 8 parts of short cut glass fiber, 4 parts of nano-silica, 1.5 parts of silane coupling agent, 3 parts of foaming agent, 1.5 parts of stabilizer, 0.8 part of thickener, 8 parts of bio-based plasticizer, 4 parts of organosilicon wear-resistant agent, 3 parts of polytetrafluoroethylene particles, 0.6 part of carbon nanotube, 1.8 parts of matting agent, 1.3 parts of hand feel agent, 0.8 part of leveling agent, 1.5 parts of ultraviolet absorber, 1.2 parts of antistatic agent, 1.8 parts of antibacterial agent, 2.8 parts of nano-aluminum oxide, and 2.4 parts of nano-silicon oxide.

[0040] The preparation method of the above-mentioned environmentally friendly high flame retardant multi-layer composite polyurethane synthetic leather includes the following steps: S1. Weigh waterborne polyurethane resin, crosslinking agent, wetting agent and deionized water in proportion, mix them evenly to obtain an environmentally friendly polyurethane adhesive. The composite fiber base fabric is successively cleaned, dried and then wound up, and is installed on the production line and coated with the environmentally friendly polyurethane adhesive to obtain a base fabric with adhesive; S2. Weigh waterborne polyurethane resin, short cut glass fiber, nano-silica, silane coupling agent, foaming agent, stabilizer, thickener, bio-based plasticizer in proportion, foam to obtain a basic slurry and transport it to each production unit of each layer on the production line; S3. Simultaneously produce the flame retardant intermediate layer and the wear-resistant surface layer: Add ammonium polyphosphate and melamine cyanurate into 1 / 7 of the basic slurry in proportion, fully heat, stir and mix evenly to obtain a phosphorus-nitrogen based flame retardant slurry, and roll-coat it on the base fabric with adhesive to obtain the basis of the phosphorus-nitrogen based flame retardant layer, and at the same time recover the excess phosphorus-nitrogen based flame retardant slurry; S4. Add aluminum hydroxide and magnesium hydroxide into 2 / 3 of the base slurry in proportion. After fully heating, stirring and mixing evenly, an inorganic flame retardant slurry is obtained, which is roll-coated on the release paper to obtain the base of the inorganic flame retardant layer. Meanwhile, the excess inorganic flame retardant slurry is recycled. S5. Add nanolayered double hydroxide into 1 / 7 of the base slurry in proportion. After fully heating, stirring and mixing evenly, a nano flame retardant slurry is obtained, which is roll-coated on the release paper to obtain the base of the nano flame retardant layer. Meanwhile, the excess nano flame retardant slurry is recycled. S6. Add organosilicon wear-resistant agent, polytetrafluoroethylene particles, carbon nanotubes, matting agent, hand feel agent, leveling agent, ultraviolet absorber, antistatic agent, antibacterial agent, nano alumina and nano silica into 1 / 7 of the base slurry in proportion. After fully heating, stirring and mixing evenly, a surface layer slurry is obtained, which is roll-coated on the release paper to obtain the base of the surface layer. Meanwhile, the excess surface layer slurry is recycled. S7. Dry the phosphorus-nitrogen based flame retardant layer base, inorganic flame retardant layer base, nano flame retardant layer base and surface layer base simultaneously. During the transmission process, the release paper is recycled by the rubber roller to obtain the phosphorus-nitrogen based flame retardant layer, inorganic flame retardant layer, nano flame retardant layer and wear-resistant surface layer. Apply environmentally friendly polyurethane glue on the surfaces of the phosphorus-nitrogen based flame retardant layer, inorganic flame retardant layer and nano flame retardant layer, dry after pressing to obtain an environmentally friendly high flame retardant multi-layer composite polyurethane synthetic leather.

[0041] The thickness of the phosphorus-carbon based flame retardant layer is 0.18 mm, the inorganic flame retardant layer is 1.6 mm, the nano flame retardant layer is 0.2 mm, and the surface layer base is 0.25 mm. The roll coating speed is 11 m / min, the roll coating pressure is 0.3 MPa, the drying temperature is 110 °C, and the drying time is 8 min.

[0042] For the preparation method of the environmentally friendly high flame retardant multi-layer composite polyurethane synthetic leather in the first embodiment, the equipment used is all existing conventional equipment.

[0043] Embodiment 2 An environmentally friendly high flame retardant multi-layer composite polyurethane synthetic leather, comprising a composite fiber base fabric, a flame retardant intermediate layer and a wear-resistant surface layer which are laminated in sequence from bottom to top. The flame retardant intermediate layer includes a phosphorus-nitrogen based flame retardant layer, an inorganic flame retardant layer and a nano flame retardant layer which are laminated in sequence from bottom to top. The phosphorus-nitrogen based flame retardant layer is composed of the following raw materials in parts by mass: 110 parts of waterborne polyurethane resin, 8 parts of short glass fiber filaments, 4 parts of nano silica, 1.5 parts of silane coupling agent, 3 parts of foaming agent, 1.5 parts of stabilizer, 0.8 part of thickening agent, 8 parts of bio-based plasticizer, 12 parts of ammonium polyphosphate, and 8 parts of melamine cyanurate. The inorganic flame retardant layer is composed of the following raw materials in parts by mass: 110 parts of waterborne polyurethane resin, 8 parts of short cut glass fiber, 4 parts of nano-silica, 1.5 parts of silane coupling agent, 3 parts of foaming agent, 1.5 parts of stabilizer, 0.8 part of thickener, 8 parts of bio-based plasticizer, 25 parts of aluminum hydroxide, and 12 parts of magnesium hydroxide; The nano flame retardant layer is composed of the following raw materials in parts by mass: 110 parts of waterborne polyurethane resin, 8 parts of short cut glass fiber, 4 parts of nano-silica, 1.5 parts of silane coupling agent, 3 parts of foaming agent, 1.5 parts of stabilizer, 0.8 part of thickener, 8 parts of bio-based plasticizer, and 4 parts of nano-layered double hydroxide.

[0044] An environment-friendly adhesive layer is bonded between the composite fiber base fabric, the phosphorus-nitrogen based flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer and the wear-resistant surface layer. The environment-friendly adhesive layer is composed of the following raw materials in parts by mass: 110 parts of waterborne polyurethane resin, 4 parts of crosslinking agent, 0.7 part of wetting agent, and 16 parts of deionized water.

[0045] The wear-resistant surface layer is composed of the following raw materials in parts by mass: 110 parts of waterborne polyurethane resin, 8 parts of short cut glass fiber, 4 parts of nano-silica, 1.5 parts of silane coupling agent, 3 parts of foaming agent, 1.5 parts of stabilizer, 0.8 part of thickener, 8 parts of bio-based plasticizer, 4 parts of organosilicon wear-resistant agent, 3 parts of polytetrafluoroethylene particles, 0.6 part of carbon nanotube, 1.8 parts of matting agent, 1.3 parts of hand feel agent, 0.8 part of leveling agent, 1.5 parts of ultraviolet absorber, 1.2 parts of antistatic agent, 1.8 parts of antibacterial agent, 2.8 parts of nano-aluminum oxide, and 2.4 parts of nano-silicon oxide.

[0046] The preparation method of the above-mentioned environment-friendly high flame retardant multi-layer composite polyurethane synthetic leather includes the following steps: S1. Weigh waterborne polyurethane resin, crosslinking agent, wetting agent and deionized water in proportion, mix them evenly to obtain an environment-friendly polyurethane glue. The composite fiber base fabric is successively cleaned, dried and then wound up, and is installed on the production line and coated with the environment-friendly polyurethane glue to obtain a glue-coated base fabric; S2. Weigh waterborne polyurethane resin, short cut glass fiber, nano-silica, silane coupling agent, foaming agent, stabilizer, thickener, bio-based plasticizer in proportion, foam to obtain a basic slurry and transport it to each production unit of each layer on the production line; S3. Simultaneously produce the flame retardant intermediate layer and the wear-resistant surface layer: Add ammonium polyphosphate and melamine cyanurate into 1 / 7 of the basic slurry in proportion, fully heat, stir and mix evenly to obtain a phosphorus-nitrogen based flame retardant slurry, and roll-coat it on the glue-coated base fabric to obtain the basis of the phosphorus-nitrogen based flame retardant layer, and at the same time recover the excess phosphorus-nitrogen based flame retardant slurry; S4. Add aluminum hydroxide and magnesium hydroxide to 2 / 3 of the base slurry in proportion. After fully heating, stirring and mixing evenly, an inorganic flame retardant slurry is obtained, which is roll-coated on the release paper to obtain the base of the inorganic flame retardant layer. At the same time, the excess inorganic flame retardant slurry is recycled; S5. Add nanolayered double hydroxides to 1 / 7 of the base slurry in proportion. After fully heating, stirring and mixing evenly, a nano flame retardant slurry is obtained, which is roll-coated on the release paper to obtain the base of the nano flame retardant layer. At the same time, the excess nano flame retardant slurry is recycled; S6. Add organosilicon wear-resistant agent, polytetrafluoroethylene particles, carbon nanotubes, matting agent, hand feel agent, leveling agent, ultraviolet absorber, antistatic agent, antibacterial agent, nanoaluminum oxide and nanosilicon oxide to 1 / 7 of the base slurry in proportion. After fully heating, stirring and mixing evenly, a surface layer slurry is obtained, which is roll-coated on the release paper to obtain the base of the surface layer. At the same time, the excess surface layer slurry is recycled; S7. At the same time, dry the phosphorus-nitrogen-based flame retardant layer base, inorganic flame retardant layer base, nano flame retardant layer base and surface layer base. During the transmission process, the release paper is recycled by the rubber roller to obtain the phosphorus-nitrogen-based flame retardant layer, inorganic flame retardant layer, nano flame retardant layer and wear-resistant surface layer. Apply environmentally friendly polyurethane glue on the surfaces of the phosphorus-nitrogen-based flame retardant layer, inorganic flame retardant layer and nano flame retardant layer, dry after pressing to obtain an environmentally friendly high flame retardant multi-layer composite polyurethane synthetic leather.

[0047] The thickness of the phosphorus-carbon-based flame retardant layer is 0.18 mm, the inorganic flame retardant layer is 1.6 mm, the nano flame retardant layer is 0.2 mm, and the surface layer base is 0.25 mm; The roll coating speed is 11 m / min, the roll coating pressure is 0.3 MPa, the drying temperature is 110 °C, and the drying time is 8 min.

[0048] As Figures 2 - 10 shown, the equipment used in steps S1-S7 is a synthetic leather production device. The synthetic leather production device includes a driving conveyor belt 1. The number of driving conveyor belts 1 is four and they are distributed vertically. A base fabric 2 is arranged on the driving conveyor belt 1 at the lowermost position, and release papers 3 are arranged on the other three driving conveyor belts 1. Coating rollers 609 are arranged on both the release papers 3 and the base fabric 2. An inorganic flame retardant layer, a nano flame retardant layer and a wear-resistant surface layer are sequentially laid on the three release papers 3 from bottom to top. A phosphorus-nitrogen-based flame retardant layer is pasted on the base fabric 2. A rubber roller 12 rolls at the left end below the release paper 3. Gluing machines 13 are arranged on the phosphorus-nitrogen-based flame retardant layer, inorganic flame retardant layer and nano flame retardant layer. The gluing machines 13 are located on the left side of the rubber roller 12. A pressing machine 4 is arranged on the phosphorus-nitrogen-based flame retardant layer, inorganic flame retardant layer, nano flame retardant layer and wear-resistant surface layer, and the phosphorus-nitrogen-based flame retardant layer, inorganic flame retardant layer, nano flame retardant layer and wear-resistant surface layer all pass through the input end of the pressing machine 4. Drying machines 11 are arranged between the right side of the pressing machine 4, the rubber roller 12 and the coating roller 609; In this embodiment, the driving conveyor belt 1, the rubber roller 12, the glue coater 13, the laminating machine 4, and the dryer 11 are all prior arts and are fixedly installed through conventional steel frames. The driving conveyor belt 1 is a structure combined with a conventional motor, a fixed bracket, and a conveying roller, which is a common device for installing a material roll and transporting materials. The rubber roller 12 is a roller body made of silicone rubber with adhesive on its surface, which can stick and wind back one end of the release paper 3 with a prepared phosphorus-nitrogen based flame retardant layer, an inorganic flame retardant layer, a nano flame retardant layer, and a wear-resistant surface layer laid on its surface during rotation, realizing the production without coating the phosphorus-nitrogen based flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer, and the wear-resistant surface layer on the surface of the base fabric 2, and transporting it to the laminating machine 4.

[0049] A foaming machine 501 is placed in front of the base fabric 2. The outlet flange of the foaming machine 501 is connected to a screw pump 502. The output end flange of the screw pump 502 is connected to a manifold 503. The number of outlet ports of the manifold 503 is four, and four mixing tanks 601 are fixed at the outlet ports. A metering valve 7 is flange-connected between the manifold 503 and the mixing tanks 601. The four mixing tanks 601 are distributed vertically and are on the same vertical horizontal line. A motor 602 is fixed on the uppermost mixing tank 601. The output end of the motor 602 is fixedly connected to a main rotating shaft 603 through a coupling. The main rotating shaft 603 vertically penetrates through the left side position inside the four mixing tanks 601. A plurality of transverse blades 604 are fixed on the main rotating shaft 603, and the transverse blades 604 are all located inside the mixing tanks 601. The main rotating shaft 603 is rotationally connected to four longitudinal blades 605 through a transmission part 8, and the four longitudinal blades 605 are all located inside the mixing tanks 601. A heating plate 606 is fixed at the bottom of the inner wall of the mixing tank 601, and a feed cylinder 607 is integrally formed at the front end of the mixing tank 601. An outlet port is arranged at the lower position at the rear end of the mixing tank 601. The outlet port is flange-connected to a metering pump 610. The output end flange of the metering pump 610 is connected to an outlet long cylinder 608. A coating roller 609 rotates at a position below the outlet long cylinder 608; In this embodiment, the foaming machine 501, the screw pump 502, the metering valve 7, the motor 602, the coating roller 609, and the metering pump 610 are all prior arts. The central axis of the coating roller 609 is connected to an external motor to drive its rotation. The same materials required for each layer are poured into the foaming machine 501 for unified foaming to form a base slurry. The screw pump 502 transports the base slurry into the shunt pipe 503. The metering valve 7 takes the extrusion slurry required for each layer in the shunt pipe 503 and enters the mixing tank 601. Then, the different raw materials of the phosphorus-nitrogen-based flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer, and the wear-resistant surface layer are respectively put into the corresponding mixing tank 601 from the feed cylinder 607. After the feeding is completed, the motor 602 is operated to drive the main rotating shaft 603 to rotate. The transverse paddle 604 rotates with the main rotating shaft 603, and the longitudinal paddle 605 further stirs the base slurry and the additives in the mixing tank 601. The heating plate 606 maintains the temperature in the mixing tank 601 during the stirring process to maintain the foaming state of the slurry, realizing the preparation of the slurries for each layer. The metering pump 610 extracts the slurry in the mixing tank 601 and outputs it from the discharge long tube 608 to the roller body of the coating roller 609. The coating roller 609 rotates to evenly roll-coat the slurry on the base fabric 2 or the release paper 3. Each layer uses a single foaming machine 501 and a motor 602 to realize the foaming and mixing of four slurries, and at the same time prepares and coats the three intermediate layers with different flame retardant effects. After the coating is completed, each layer is conveyed to the bottom of the dryer 11 along with the base fabric 2 and the release paper 3 for drying. After drying, the rubber roller 12 recovers the release paper 3 to convey the formed inorganic flame retardant layer, nano flame retardant layer, and wear-resistant surface layer in the direction of the laminating machine 4. Before reaching the laminating machine 4, the coating machine 13 applies an environment-friendly polyurethane glue on the surfaces of the nitrogen-based flame retardant layer, the inorganic flame retardant layer, and the nano flame retardant layer. After the coating is completed, each layer enters the laminating machine 4 to combine the four layers at the same time. After lamination, the glue is dried by the dryer 11 to complete the production of the composite synthetic leather. Subsequent subjective non-essential requirements such as embossing and cutting are realized by external equipment. The production lines of each layer are combined to achieve a longitudinal distribution and combination of the production lines. The composite synthetic leather is produced simultaneously on the same longitudinal production line, and the mixing material equipment overlaps, fundamentally saving production costs and production floor areas, saving production energy consumption and being environmentally friendly, and significantly improving production efficiency.

[0050] On the left side of the discharge long tube 608, a mounting plate 901 is fixed. At the position near the left side of the bottom of the mounting plate 901, a scraping plate 902 is fixed. Two rotating rods 903 distributed left and right are passed through the mounting plate 901. At the bottom of the rotating rod 903, a synchronous pulley 904 is key-connected. A synchronous belt 905 is engaged on the two synchronous pulleys 904. At the top of the rotating rod 903 on the left side, a third gear 906 is key-connected. Four fourth gears 907 are key-connected on the main rotating shaft 603. The four fourth gears 907 are respectively located at the tops of the four mixing tanks 601. The fourth gear 907 is engaged with the third gear 906. A number of spring shafts 908 are uniformly fixed on the synchronous belt 905. At the end of the spring shaft 908 away from the synchronous belt 905, a scraping box 909 is fixed. The scraping box 909 is in contact with the scraping plate 902. A replenishing port 910 is opened on the scraping box 909. At the rear end of the mixing tank 601, a recovery box 1001 is fixed through a reflux pipe 1003. A rubber rod 1002 is vertically fixed in the recovery box 1001. The rubber rod 1002 is in contact with the scraping box 909. The number of the recovery boxes 1001 is two and they are located on the front and rear sides of the base cloth 2. A flow collecting pipe 1005 is communicated between the two recovery boxes 1001, and the flow collecting pipe 1005 is inclined downward and forward. Flow guiding grooves 1006 are communicated on both the left and right sides of the recovery box 1001, and the bottom of the inner wall of the flow guiding groove 1006 is inclined towards the position of the recovery box 1001. A reflux pipe 1003 is connected between the recovery box 1001 and the mixing tank 601. A liquid pump 1004 is fixed between the reflux pipe 1003 and the mixing tank 601.

[0051] In this embodiment, during the transmission process, the coated phosphorus-nitrogen-based flame retardant layer, inorganic flame retardant layer, nano flame retardant layer and wear-resistant surface layer pass through the squeegee 902. The height of the squeegee 902 is the specific height required for each layer. The slurry on the surface of the base fabric 2 or the release paper 3 is leveled to the required thickness by the squeegee 902. At the same time, the fourth gear 907 rotates with the main rotating shaft 603, the third gear 906 rotates with the fourth gear 907, the rotating rod 903 rotates with the third gear 906, the synchronous pulley 904 rotates with the rotating rod 903, the synchronous belt 903 rotates with the synchronous pulley 904, and the scraping box 909 rotates with the synchronous belt 903. When the scraping box 909 contacts the squeegee 902, the slurry intercepted by the squeegee 909 is scraped into the box. During the rotation of the scraping box 909 with the synchronous belt 903, if there is a gap between the slurry and the scraping box 909, the slurry in the scraping box 909 flows through the replenishing port 910 to the surface with insufficient slurry. When the scraping box 909 rotates to the area above the recovery box 1001, it contacts the rubber rod 1002. Both the rubber rod 1002 and the spring shaft 908 are affected by the change in the counter force during contact. The spring shaft 908 rotates to drive the scraping box 909 to rotate downward. During the downward rotation of the scraping box 909, the slurry inside it is poured into the recovery box 1001. The rubber rod 1002 deforms to enable the scraping box 909 to continue rotating with the synchronous belt 905. After the scraping box 909 leaves the rubber rod 1002, the spring shaft 908 resets, and the angle of the scraping box 909 resets to repeat the above scraping and pouring operations. During the coating and drying processes, the slurry overflowing from the front and rear edges of the base fabric 2 or the release paper 3 flows into the diversion groove 1006. The slurry in the diversion groove 1006 flows into the recovery box 1001 along the angle of its bottom. The slurry in the rear recovery box 1001 flows into the front recovery box 1001 through the collecting pipe 1005. The slurry in the front recovery box 1001 is pumped into the mixing tank 601 by the liquid pump 1004 through the reflux pipe 1003 (the output end of the liquid pump 1004 is fixed to the mixing tank 601, and the input end of the liquid pump 1004 is fixed to the reflux pipe 1003). The liquid pump 1004 prevents the slurry in the mixing tank 601 from flowing back into the diversion groove 1006. The above process realizes the limitation of the coating thickness, and uses the rotation of the motor for mixing each layer to drive the parts used in the slurry recovery process. Moreover, the parts used for slurry recovery in each layer and the parts used for mixing the mixed materials in each layer are all driven by one motor, which greatly realizes the synchronous production of each layer of synthetic leather and the sharing of equipment, saves production costs, and the recovery of excess and overflowing slurry avoids the situation of slurry falling and mixing during the longitudinal synchronous production of each layer. It not only recovers the slurry to save costs but also realizes isolation to prevent the upper layer of slurry from falling to the lower layer. The slurry does not flow to the ground, which can maintain the workshop environment, is environmentally friendly, and ensures the uniform thickness of the synthetic leather and improves the quality of the synthetic leather.

[0052] The transmission part 8 includes a first gear 801 key-connected to the main rotating shaft 603. A rotating shaft 803 is rotatably connected in the mixing tank 601. A second gear 802 and a first bevel gear 804 are key-connected to the rotating shaft 803. The second gear 802 meshes with the first gear 801. A connecting rod 806 is fixed in the mixing tank 601. A rotating cylinder 807 is fixed to the bottom of the connecting rod 806. A mounting rod 808 is rotatably connected in the rotating cylinder 807. A second bevel gear 805 is key-connected to the left end of the mounting rod 808. The longitudinal paddle 605 is fixed to the right end of the mounting rod 808.

[0053] In this embodiment, the gears located in the mixing tank 601 are wrapped with a sealing housing (this means is a conventional technology, so it is not shown in the drawings). The first gear 801 rotates with the main rotating shaft 603, the second gear 802 rotates with the first gear 801, the rotating shaft 803 rotates with the second gear 802, the first bevel gear 804 rotates with the rotating shaft 803, the second bevel gear 805 rotates with the first bevel gear 804, the mounting rod 808 rotates with the second bevel gear 805, and the longitudinal paddle 605 rotates with the mounting rod 805 to realize the change of the rotation direction. Through the transmission part 8, a single motor 602 is used to drive the horizontal and vertical rotations in four mixing tanks 601 at the same time, so as to improve the stirring uniformity by complicating the mixing direction. The eight rotational operations in the four mixing tanks 601 are all realized by one motor 602, which not only saves costs but also improves production efficiency at the same time.

[0054] Embodiment III The environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather includes a composite fiber base fabric, a flame-retardant intermediate layer, and a wear-resistant surface layer that are laminated in sequence from bottom to top. The flame-retardant intermediate layer includes a phosphorus-nitrogen-based flame-retardant layer, an inorganic flame-retardant layer, and a nano flame-retardant layer that are laminated in sequence from bottom to top; The phosphorus-nitrogen-based flame-retardant layer is composed of the following raw materials in parts by mass: 100 parts of waterborne polyurethane resin, 10 parts of short glass fiber filaments, 3 parts of nano-silica, 2 parts of silane coupling agent, 2 parts of foaming agent, 2 parts of stabilizer, 0.5 part of thickener, 10 parts of bio-based plasticizer, 10 parts of ammonium polyphosphate, and 10 parts of melamine cyanurate; The inorganic flame-retardant layer is composed of the following raw materials in parts by mass: 100 parts of waterborne polyurethane resin, 10 parts of short glass fiber filaments, 3 parts of nano-silica, 2 parts of silane coupling agent, 2 parts of foaming agent, 2 parts of stabilizer, 0.5 part of thickener, 10 parts of bio-based plasticizer, 20 parts of aluminum hydroxide, and 15 parts of magnesium hydroxide; The nano flame-retardant layer is composed of the following raw materials in parts by mass: 100 parts of waterborne polyurethane resin, 10 parts of short glass fiber filaments, 3 parts of nano-silica, 2 parts of silane coupling agent, 2 parts of foaming agent, 2 parts of stabilizer, 0.5 part of thickener, 10 parts of bio-based plasticizer, and 3 parts of nano-layered double hydroxide.

[0055] An environmentally friendly adhesive layer is bonded between the composite fiber base fabric, the phosphorus-nitrogen-based flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer and the wear-resistant surface layer. The environmentally friendly adhesive layer is composed of the following raw materials in parts by mass: 80 parts of waterborne polyurethane resin, 5 parts of crosslinking agent, 0.5 part of wetting agent, and 20 parts of deionized water.

[0056] The wear-resistant surface layer is composed of the following raw materials in parts by mass: 100 parts of waterborne polyurethane resin, 10 parts of short glass fiber filaments, 3 parts of nano-silica, 2 parts of silane coupling agent, 2 parts of foaming agent, 2 parts of stabilizer, 0.5 part of thickening agent, 10 parts of bio-based plasticizer, 3 parts of organosilicon wear-resistant agent, 4 parts of polytetrafluoroethylene particles, 0.5 part of carbon nanotubes, 3 parts of matting agent, 1 part of hand feel agent, 1 part of leveling agent, 1 part of ultraviolet absorber, 2 parts of antistatic agent, 1 part of antibacterial agent, 4 parts of nano-aluminum oxide, and 1 part of nano-silica.

[0057] The preparation method of the above-mentioned environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather includes the following steps: S1. Weigh waterborne polyurethane resin, crosslinking agent, wetting agent and deionized water in proportion, mix them evenly to obtain an environmentally friendly polyurethane adhesive. The composite fiber base fabric is sequentially cleaned, dried and then wound up, and installed on the production line and coated with the environmentally friendly polyurethane adhesive to obtain a base fabric with adhesive. S2. Weigh waterborne polyurethane resin, short glass fiber filaments, nano-silica, silane coupling agent, foaming agent, stabilizer, thickening agent, and bio-based plasticizer in proportion, foam them to obtain a basic slurry and transport it to each production unit on the production line. S3. Simultaneously produce the flame retardant intermediate layer and the wear-resistant surface layer: Add ammonium polyphosphate and melamine cyanurate to 1 / 7 of the basic slurry in proportion, heat and stir them evenly to obtain a phosphorus-nitrogen-based flame retardant slurry, and roll-coat it on the base fabric with adhesive to obtain the basis of the phosphorus-nitrogen-based flame retardant layer, and at the same time recycle the excess phosphorus-nitrogen-based flame retardant slurry. S4. Add aluminum hydroxide and magnesium hydroxide to 2 / 3 of the basic slurry in proportion, heat and stir them evenly to obtain an inorganic flame retardant slurry, and roll-coat it on the release paper to obtain the basis of the inorganic flame retardant layer, and at the same time recycle the excess inorganic flame retardant slurry. S5. Add nano-layered double hydroxides to 1 / 7 of the basic slurry in proportion, heat and stir them evenly to obtain a nano flame retardant slurry, and roll-coat it on the release paper to obtain the basis of the nano flame retardant layer, and at the same time recycle the excess nano flame retardant slurry. S6. Add organosilicon wear-resistant agent, polytetrafluoroethylene particles, carbon nanotubes, matting agent, hand feel agent, leveling agent, ultraviolet absorber, antistatic agent, antibacterial agent, nano-aluminum oxide and nano-silica to 1 / 7 of the basic slurry in proportion, heat and stir them evenly to obtain a surface layer slurry, and roll-coat it on the release paper to obtain the basis of the surface layer, and at the same time recycle the excess surface layer slurry. S7. Simultaneously dry the phosphorus-nitrogen-based flame retardant layer base, inorganic flame retardant layer base, nano flame retardant layer base and surface layer base. During the transmission process, the release paper is recycled by the rubber roller to obtain the phosphorus-nitrogen-based flame retardant layer, inorganic flame retardant layer, nano flame retardant layer and wear-resistant surface layer. Apply environmentally friendly polyurethane glue on the surfaces of the phosphorus-nitrogen-based flame retardant layer, inorganic flame retardant layer and nano flame retardant layer, dry it after pressing to obtain the environmentally friendly high flame retardant multi-layer composite polyurethane synthetic leather.

[0058] The thickness of the phosphorus-carbon-based flame retardant layer is 0.1 mm, the inorganic flame retardant layer is 2.0 mm, the nano flame retardant layer is 0.1 mm, and the surface layer base is 0.3 mm. The roll coating speed is 5 m / min, the roll coating pressure is 0.5 MPa, the drying temperature is 80 °C, and the drying time is 10 min.

[0059] The preparation method of the environmentally friendly high flame retardant multi-layer composite polyurethane synthetic leather in Example 3 uses the same processing equipment as in Example 2, with the difference being the formulation ratio and processing conditions.

[0060] Example 4

[0061] The environmentally friendly high flame retardant multi-layer composite polyurethane synthetic leather includes a composite fiber base fabric, a flame retardant intermediate layer and a wear-resistant surface layer that are laminated in sequence from bottom to top. The flame retardant intermediate layer includes a phosphorus-nitrogen-based flame retardant layer, an inorganic flame retardant layer and a nano flame retardant layer that are laminated in sequence from bottom to top. The phosphorus-nitrogen-based flame retardant layer is composed of the following raw materials in parts by mass: 120 parts of waterborne polyurethane resin, 5 parts of short glass fiber filaments, 5 parts of nano-silica, 1 part of silane coupling agent, 5 parts of foaming agent, 1 part of stabilizer, 1 part of thickener, 5 parts of bio-based plasticizer, 15 parts of ammonium polyphosphate, 5 parts of melamine cyanurate. The inorganic flame retardant layer is composed of the following raw materials in parts by mass: 120 parts of waterborne polyurethane resin, 5 parts of short glass fiber filaments, 5 parts of nano-silica, 1 part of silane coupling agent, 5 parts of foaming agent, 1 part of stabilizer, 1 part of thickener, 5 parts of bio-based plasticizer, 30 parts of aluminum hydroxide, 10 parts of magnesium hydroxide. The nano flame retardant layer is composed of the following raw materials in parts by mass: 120 parts of waterborne polyurethane resin, 5 parts of short glass fiber filaments, 5 parts of nano-silica, 1 part of silane coupling agent, 5 parts of foaming agent, 1 part of stabilizer, 1 part of thickener, 5 parts of bio-based plasticizer, 5 parts of nano-layered double hydroxide.

[0062] An environmentally friendly adhesive layer is bonded between the composite fiber base fabric, the phosphorus-nitrogen-based flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer and the wear-resistant surface layer. The environmentally friendly adhesive layer is composed of the following raw materials in parts by mass: 100 parts of waterborne polyurethane resin, 3 parts of crosslinking agent, 1 part of wetting agent, 10 parts of deionized water.

[0063] The wear-resistant surface layer is composed of the following raw materials in parts by mass: 120 parts of waterborne polyurethane resin, 5 parts of short cut glass fibers, 5 parts of nano-silica, 1 part of silane coupling agent, 5 parts of foaming agent, 1 part of stabilizer, 1 part of thickener, 5 parts of bio-based plasticizer, 5 parts of silicone wear-resistant agent, 2 parts of polytetrafluoroethylene particles, 1 part of carbon nanotubes, 1 part of matting agent, 2 parts of feel agent, 0.5 part of leveling agent, 2 parts of ultraviolet absorber, 1 part of antistatic agent, 2 parts of antibacterial agent, 2 parts of nano-aluminum oxide, and 3 parts of nano-silicon oxide.

[0064] The preparation method of the above-mentioned environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather includes the following steps: S1. Weigh waterborne polyurethane resin, crosslinking agent, wetting agent, and deionized water in proportion, mix them evenly to obtain an environmentally friendly polyurethane adhesive. The composite fiber base fabric is successively washed, dried, and then wound up, and installed on the production line and coated with the environmentally friendly polyurethane adhesive to obtain an adhesive-based fabric. S2. Weigh waterborne polyurethane resin, short cut glass fibers, nano-silica, silane coupling agent, foaming agent, stabilizer, thickener, and bio-based plasticizer in proportion, foam to obtain a basic slurry, and transport it to each production unit on the production line. S3. Simultaneously produce the flame-retardant intermediate layer and the wear-resistant surface layer: Add ammonium polyphosphate and melamine cyanurate to 1 / 7 of the basic slurry in proportion, heat, stir, and mix them evenly to obtain a phosphorus-nitrogen-based flame-retardant slurry, and roll-coat it on the adhesive-based fabric to obtain the basis of the phosphorus-nitrogen-based flame-retardant layer, and simultaneously recover the excess phosphorus-nitrogen-based flame-retardant slurry. S4. Add aluminum hydroxide and magnesium hydroxide to 2 / 3 of the basic slurry in proportion, heat, stir, and mix them evenly to obtain an inorganic flame-retardant slurry, and roll-coat it on the release paper to obtain the basis of the inorganic flame-retardant layer, and simultaneously recover the excess inorganic flame-retardant slurry. S5. Add nano-layered double hydroxides to 1 / 7 of the basic slurry in proportion, heat, stir, and mix them evenly to obtain a nano flame-retardant slurry, and roll-coat it on the release paper to obtain the basis of the nano flame-retardant layer, and simultaneously recover the excess nano flame-retardant slurry. S6. Add silicone wear-resistant agent, polytetrafluoroethylene particles, carbon nanotubes, matting agent, feel agent, leveling agent, ultraviolet absorber, antistatic agent, antibacterial agent, nano-aluminum oxide, and nano-silicon oxide to 1 / 7 of the basic slurry in proportion, heat, stir, and mix them evenly to obtain a surface layer slurry, and roll-coat it on the release paper to obtain the basis of the surface layer, and simultaneously recover the excess surface layer slurry. S7. Simultaneously dry the basis of the phosphorus-nitrogen-based flame-retardant layer, the inorganic flame-retardant layer, the nano flame-retardant layer, and the surface layer. During the transmission process, the release paper is recovered by the rubber roller to obtain the phosphorus-nitrogen-based flame-retardant layer, the inorganic flame-retardant layer, the nano flame-retardant layer, and the wear-resistant surface layer. Apply the environmentally friendly polyurethane adhesive on the surfaces of the phosphorus-nitrogen-based flame-retardant layer, the inorganic flame-retardant layer, and the nano flame-retardant layer, press and dry to obtain the environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather.

[0065] The thickness of the phosphorus-carbon-based flame-retardant layer is 0.3 mm, the inorganic flame-retardant layer is 0.5 mm, the nano flame-retardant layer is 0.3 mm, and the surface layer base is 0.1 mm; The roll coating speed is 20 m / min, the roll coating pressure is 0.2 MPa, the drying temperature is 120 °C, and the drying time is 3 min.

[0066] For the preparation method of the environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather in Example 4, the processing equipment used is the same as that in Example 2, except for the formulation ratio and processing conditions.

[0067] Experimental Example For the synthetic leather prepared according to Examples 1 to 4, relevant test experiments were carried out, and the results are shown in Figure 11 : The tensile load was measured according to GB / T38612—2020 and is expressed in N / cm 2 ; The elongation at break was measured according to GB / T38612—2020 and is expressed in %; The horizontal burning rate was measured according to QB / T2729-2005 and is expressed in mm / min; The vertical burning rate was measured according to QB / T2729-2005 and is expressed in mm / min.

[0068] In Examples 1 and 2, the preparation devices for the synthetic leather are different, but in Example 2, the tensile load, elongation at break, horizontal burning rate, and vertical burning rate of the synthetic leather are all better than those in Example 1. Therefore, using the synthetic leather production device in the present invention can improve the performance of the synthetic leather such as tensile load, elongation at break, horizontal burning rate, and vertical burning rate.

[0069] In Examples 3, 4 and 2, the preparation process conditions and formulation ratios of the synthetic leather are different, but in Example 2, the tensile load, elongation at break, horizontal burning rate, and vertical burning rate of the synthetic leather are all better than those in Examples 3 and 4. Therefore, different process conditions will also affect the performance of the synthetic leather such as tensile load, elongation at break, horizontal burning rate, and vertical burning rate.

[0070] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. An environmentally friendly, highly flame-retardant multi-layer composite polyurethane synthetic leather, characterized in that, It includes a composite fiber base fabric, a flame-retardant intermediate layer, and a wear-resistant surface layer that are laminated in sequence from bottom to top. The flame-retardant intermediate layer includes a phosphorus-nitrogen-based flame-retardant layer, an inorganic flame-retardant layer, and a nano flame-retardant layer that are laminated in sequence from bottom to top; The phosphorus-nitrogen-based flame-retardant layer is composed of the following raw materials in parts by mass: 100-120 parts of waterborne polyurethane resin, 5-10 parts of short glass fiber filaments, 3-5 parts of nano-silica, 1-2 parts of silane coupling agent, 2-5 parts of foaming agent, 1-2 parts of stabilizer, 0.5-1 part of thickener, 5-10 parts of bio-based plasticizer, 10-15 parts of ammonium polyphosphate, and 5-10 parts of melamine cyanurate; The inorganic flame-retardant layer is composed of the following raw materials in parts by mass: 100-120 parts of waterborne polyurethane resin, 5-10 parts of short glass fiber filaments, 3-5 parts of nano-silica, 1-2 parts of silane coupling agent, 2-5 parts of foaming agent, 1-2 parts of stabilizer, 0.5-1 part of thickener, 5-10 parts of bio-based plasticizer, 20-30 parts of aluminum hydroxide, and 10-15 parts of magnesium hydroxide; The nano flame-retardant layer is composed of the following raw materials in parts by mass: 100-120 parts of waterborne polyurethane resin, 5-10 parts of short glass fiber filaments, 3-5 parts of nano-silica, 1-2 parts of silane coupling agent, 2-5 parts of foaming agent, 1-2 parts of stabilizer, 0.5-1 part of thickener, 5-10 parts of bio-based plasticizer, and 3-5 parts of nano-layered double hydroxide; 2. An environmentally friendly high flame-retardant multi-layer composite polyurethane synthetic leather according to claim 1, characterized in that, An environment-friendly adhesive layer is bonded between the composite fiber base fabric, the phosphorus-nitrogen-based flame-retardant layer, the inorganic flame-retardant layer, the nano flame-retardant layer, and the wear-resistant surface layer. The environment-friendly adhesive layer is composed of the following raw materials in parts by mass: 80-100 parts of waterborne polyurethane resin, 3-5 parts of cross-linking agent, 0.5-1 part of wetting agent, and 10-20 parts of deionized water.

3. An environmentally friendly high flame-retardant multi-layer composite polyurethane synthetic leather according to claim 1, characterized in that The wear-resistant surface layer is composed of the following raw materials in parts by mass: 100-120 parts of waterborne polyurethane resin, 5-10 parts of short glass fiber filaments, 3-5 parts of nano-silica, 1-2 parts of silane coupling agent, 2-5 parts of foaming agent, 1-2 parts of stabilizer, 0.5-1 part of thickener, 5-10 parts of bio-based plasticizer, 3-5 parts of organosilicon wear-resistant agent, 2-4 parts of polytetrafluoroethylene microparticles, 0.5-1 part of carbon nanotubes, 1-3 parts of matting agent, 1-2 parts of hand feel agent, 0.5-1 part of leveling agent, 1-2 parts of ultraviolet absorber, 1-2 parts of antistatic agent, 1-2 parts of antibacterial agent, 2-4 parts of nano-aluminum oxide, and 1-3 parts of nano-silica.

4. A preparation method of the environmentally friendly high flame-retardant multi-layer composite polyurethane synthetic leather as described in claims 1-3, characterized in that, It includes the following steps: S1. Weigh waterborne polyurethane resin, cross-linking agent, wetting agent, and deionized water in proportion, mix them evenly to obtain an environment-friendly polyurethane adhesive, wash, dry the composite fiber base fabric in sequence, then wind it up, install it on the production line, and apply the environment-friendly polyurethane adhesive to obtain a base fabric with adhesive; S2. Weigh waterborne polyurethane resin, short glass fiber filaments, nano-silica, silane coupling agent, foaming agent, stabilizer, thickener, and bio-based plasticizer in proportion, foam to obtain a basic slurry, and transport it to each production unit of each layer on the production line; S3. Simultaneously produce a flame-retardant intermediate layer and a wear-resistant surface layer: Add ammonium polyphosphate and melamine cyanurate in proportion to 1 / 7 of the base slurry, heat and stir well until evenly mixed to obtain a phosphorus-nitrogen-based flame-retardant slurry, roll-coat it on the adhesive base fabric to obtain the basis of the phosphorus-nitrogen-based flame-retardant layer, and simultaneously recover the excess phosphorus-nitrogen-based flame-retardant slurry; S4. Add aluminum hydroxide and magnesium hydroxide in proportion to 2 / 3 of the base slurry, heat and stir well until evenly mixed to obtain an inorganic flame-retardant slurry, roll-coat it on the release paper to obtain the basis of the inorganic flame-retardant layer, and simultaneously recover the excess inorganic flame-retardant slurry; S5. Add nanolayered double hydroxides in proportion to 1 / 7 of the base slurry, heat and stir well until evenly mixed to obtain a nano flame-retardant slurry, roll-coat it on the release paper to obtain the basis of the nano flame-retardant layer, and simultaneously recover the excess nano flame-retardant slurry; S6. Add organosilicon wear-resistant agent, polytetrafluoroethylene particles, carbon nanotubes, matting agent, hand feel agent, leveling agent, ultraviolet absorber, antistatic agent, antibacterial agent, nanoaluminum oxide and nanosilicon oxide in proportion to 1 / 7 of the base slurry, heat and stir well until evenly mixed to obtain a surface layer slurry, roll-coat it on the release paper to obtain the basis of the surface layer, and simultaneously recover the excess surface layer slurry; S7. Simultaneously dry the basis of the phosphorus-nitrogen-based flame-retardant layer, inorganic flame-retardant layer, nano flame-retardant layer and surface layer. During the transmission process, the release paper is recovered by the rubber roller to obtain the phosphorus-nitrogen-based flame-retardant layer, inorganic flame-retardant layer, nano flame-retardant layer and wear-resistant surface layer. Apply environmentally friendly polyurethane glue on the surfaces of the phosphorus-nitrogen-based flame-retardant layer, inorganic flame-retardant layer and nano flame-retardant layer, dry after pressing to obtain an environmentally friendly high-flame-retardant multi-layer composite polyurethane synthetic leather.

5. An environmentally friendly high flame-retardant multi-layer composite polyurethane synthetic leather and its preparation method according to claim 4, characterized in that, The thickness of the phosphorus-carbon-based flame-retardant layer is 0.1 - 0.3 mm, the inorganic flame-retardant layer is 0.5 - 2.0 mm, the nano flame-retardant layer is 0.1 - 0.3 mm, and the basis of the surface layer is 0.1 - 0.3 mm.

6. An environmentally friendly high flame-retardant multi-layer composite polyurethane synthetic leather according to claim 4 and a preparation method thereof, characterized in that, The roll-coating speed is 5 - 20 m / min, the roll-coating pressure is 0.2 - 0.5 MPa, the drying temperature is 80 - 120 °C, and the drying time is 3 - 10 min.

7. The preparation method of the environmentally friendly high flame-retardant multi-layer composite polyurethane synthetic leather according to claim 4, characterized in that, The equipment used in the steps S1-S7 is a synthetic leather production device. The synthetic leather production device includes a driving conveyor belt (1). The number of driving conveyor belts (1) is four and they are distributed vertically. A base fabric (2) is arranged on the lowermost driving conveyor belt (1), and release papers (3) are arranged on the remaining three driving conveyor belts (1). Coating rollers (609) are arranged on both the release papers (3) and the base fabric (2). An inorganic flame retardant layer, a nano flame retardant layer, and a wear-resistant surface layer are sequentially laid on the three release papers (3) from bottom to top. A phosphazene flame retardant layer is pasted on the base fabric (2). A rubber roller (12) rolls below the left end of the release paper (3). Coating machines (13) are arranged on the phosphazene flame retardant layer, the inorganic flame retardant layer, and the nano flame retardant layer. The coating machines (13) are located on the left side of the rubber roller (12). A laminating machine (4) is arranged on the phosphazene flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer, and the wear-resistant surface layer, and the phosphazene flame retardant layer, the inorganic flame retardant layer, the nano flame retardant layer, and the wear-resistant surface layer all pass through the input end of the laminating machine (4). Drying machines (11) are arranged between the right side of the laminating machine (4), the rubber roller (12), and the coating roller (609); A foaming machine (501) is placed in front of the base fabric (2). The outlet flange of the foaming machine (501) is connected to a screw pump (502). The output end flange of the screw pump (502) is connected to a shunt pipe (503). The number of outlet ports of the shunt pipe (503) is four, and mixing tanks (601) are fixed to all four outlet ports. A metering valve (7) is flange-connected between the shunt pipe (503) and the mixing tanks (601). The four mixing tanks (601) are distributed vertically and are on the same vertical horizontal line. A motor (602) is fixed to the uppermost mixing tank (601). The output end of the motor (602) is fixed to a main rotating shaft (603) through a coupling. The main rotating shaft (603) vertically passes through the position on the left side inside the four mixing tanks (601). A number of transverse paddle blades (604) are fixed to the main rotating shaft (603). The transverse paddle blades (604) are all located inside the mixing tanks (601). The main rotating shaft (603) is rotationally connected to four longitudinal paddle blades (605) through a transmission part (8). The four longitudinal paddle blades (605) are all located inside the mixing tanks (601). A heating plate (606) is fixed to the bottom of the inner wall of the mixing tank (601), and a feed cylinder (607) is integrally formed at the front end of the mixing tank (601). An outlet port is arranged at the lower position at the rear end of the mixing tank (601). The outlet port is flange-connected to a metering pump (610). The output end flange of the metering pump (610) is connected to a discharge long cylinder (608). The coating roller (609) rotates at the position below the discharge long cylinder (608); On the left side of the discharge long tube (608), a mounting plate (901) is fixed. At the position near the left side of the bottom of the mounting plate (901), a scraper (902) is fixed. Two rotating rods (903) distributed left and right are penetrated through the mounting plate (901). A synchronous pulley (904) is key-connected to the bottom of the rotating rod (903). A synchronous belt (905) is engaged on the two synchronous pulleys (904). At the top end of the rotating rod (903) on the left side, a third gear (906) is key-connected. Four fourth gears (907) are key-connected to the main rotating shaft (603). The four fourth gears (907) are respectively located at the top ends of the four mixing tanks (601). The fourth gear (907) is engaged with the third gear (906). A number of spring shafts (908) are uniformly fixed on the synchronous belt (905). At one end of the spring shaft (908) away from the synchronous belt (905), a scraping box (909) is fixed. The scraping box (909) is in contact with the scraper (902). A replenishing port (910) is opened on the scraping box (909). At the rear end of the mixing tank (601), a recovery box (1001) is fixed through a reflux pipe (1003). A rubber rod (1002) is vertically fixed in the recovery box (1001). The rubber rod (1002) is in contact with the scraping box (909). The number of the recovery boxes (1001) is two and they are located on the front and rear sides of the base fabric (2). A collecting pipe (1005) is communicated between the two recovery boxes (1001), and the collecting pipe (1005) inclines downward and forward. Flow guiding grooves (1006) are communicated on the left and right sides of the recovery box (1001), and the bottom of the inner wall of the flow guiding groove (1006) inclines towards the position of the recovery box (1001). A reflux pipe (1003) is connected between the recovery box (1001) and the mixing tank (601). A liquid pump (1004) is fixed between the reflux pipe (1003) and the mixing tank (601).

8. A synthetic leather production device according to claim 7, characterized in that, The transmission part (8) includes a first gear (801) key-connected to the main rotating shaft (603). A rotating shaft (803) is rotatably connected in the mixing tank (601). A second gear (802) and a first bevel gear (804) are key-connected to the rotating shaft (803). The second gear (802) is engaged with the first gear (801). A connecting rod (806) is fixed in the mixing tank (601). A rotating cylinder (807) is fixed at the bottom of the connecting rod (806). A mounting rod (808) is rotatably connected in the rotating cylinder (807). A second bevel gear (805) is key-connected to the left end of the mounting rod (808). A longitudinal paddle (605) is fixed at the right end of the mounting rod (808).

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