Preparation method of high-property water-based microfiber base fabric and simulated leather suede base fabric

Abstract

The present invention belongs to the field of ultrafine fiber synthetic leather and relates to a method for preparing a high-property water-based ultrafine base fabric and a simulated leather suede base fabric, comprising sequentially performing the following process steps: impregnating a non-woven fabric with an aqueous polyurethane impregnation liquid, drying and solidifying it, drying by reduction, and grinding and raising it to obtain the high-property simulated leather suede base fabric; during drying and solidifying, placing the non-woven fabric impregnated with the aqueous polyurethane impregnation liquid on a sealing plate, with the two sides of the non-woven fabric being designated as side A and side B, with only side B in contact with the sealing plate; the non-woven fabric is a sea-island fiber non-woven fabric, and drying by reduction is performed to remove the sea phase from the non-woven fabric and then dry it; grinding and raising is performed to grind the B side of the non-woven fabric to raise it. The present invention achieves a gradient distribution of polyurethane by drying and solidifying the non-woven fabric impregnated with the aqueous polyurethane on a sealing plate, thereby preparing a simulated leather suede base fabric with high physical properties and a high velvety feel.

Description

Technical Field

[0001] The invention belongs to the field of ultrafine fiber synthetic leather and relates to a method for preparing a high-physical-property water-based ultrafine fiber base cloth and a simulated leather suede base cloth. Background Art

[0002] Microfiber synthetic leather, a highly anticipated alternative to natural leather, has gained widespread market recognition thanks to its unique manufacturing process and superior performance. Its production principle primarily involves creating a nonwoven fabric from island-in-the-sea fibers, which is then impregnated with a polyurethane resin and subjected to a fiber-opening process. This separates each island-in-the-sea fiber into microfiber bundles, creating a three-dimensional interwoven network structure similar to the collagen fibers found in natural leather. This structure not only makes microfiber synthetic leather resemble natural leather in appearance, but also surpasses it in physical properties, making it an ideal choice for high-end leather products.

[0003] Waterborne polyurethane (PU) is attracting significant attention for its environmental friendliness and excellent performance, particularly in the preparation of microfiber suede fabrics. Using water as a dispersion medium, PU avoids the environmental pollution associated with traditional organic solvents, offering a new green solution for industries such as coatings, adhesives, and synthetic leather.

[0004] However, in the preparation of microfiber suede base fabric made of water-based polyurethane, there are two different process routes, each with its own characteristics but also accompanied by some challenges.

[0005] The first process involves adding specific additives to impart thermo-gel properties to water-based polyurethane. Prior to drying, the polyurethane becomes non-fluid, preventing it from migrating with water vapor during the drying process and ensuring a relatively even distribution of the polyurethane throughout the nonwoven fabric. While this method appears effective, it faces a significant practical challenge: the tight bond between the polyurethane and the fibers complicates the subsequent refining and napping process, resulting in a short, sparse nap that makes it difficult to achieve the desired velvety effect.

[0006] In order to solve the problems existing in the first process, researchers developed a second process. This process uses water-based polyurethane microparticles dispersed in solvent water. By heating, the polyurethane microparticles move with the water vapor, forming a relatively concentrated distribution on the upper and lower surfaces of the non-woven fabric, while a fiber layer without polyurethane attachment is formed in the middle. Subsequently, the non-woven fabric is separated from the middle through the skinning process, and the fiber layer is used for raising. Although this method can solve the problem of close bonding between polyurethane and fiber to a certain extent, making raising easier, it also has obvious shortcomings. This process will inevitably destroy the structure of the middle fiber layer during the skinning process, causing some long fibers to shorten, thereby weakening the mechanical properties of the base fabric. Summary of the Invention

[0007] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for preparing a high-physical-property water-based microfiber base fabric and a simulated leather suede base fabric.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a suede base fabric of simulated leather with high physical properties, comprising the following process steps: impregnating a non-woven fabric with an aqueous polyurethane impregnation solution, drying and solidifying the non-woven fabric, drying the non-woven fabric by weight reduction, and grinding and raising the non-woven fabric to obtain the suede base fabric of simulated leather with high physical properties;

[0010] During drying and curing, the non-woven fabric soaked in the aqueous polyurethane impregnation liquid is placed on the sealing plate. The two sides of the non-woven fabric are marked as side A and side B, and only side B is in contact with the sealing plate.

[0011] The non-woven fabric is a sea-island fiber non-woven fabric with a tensile load of 252-872N / 10mm. The reduction drying is to remove the sea phase in the non-woven fabric and then dry it;

[0012] The grinding and raising process is to grind the B side of the non-woven fabric to make it raise the nap.

[0013] When preparing the suede base fabric of simulated leather in the prior art, the non-woven fabric impregnated with water-based polyurethane impregnation liquid is often placed on a trawl with holes or a hollow frame in the drying and curing stage to allow water vapor to quickly dissipate on the upper and lower surfaces. Figure 1 As shown, the upper and lower layers have polyurethane, and the middle layer has no polyurethane. The dried and solidified product is sequentially subjected to peeling (i.e., peeling from the middle layer) and grinding and raising treatment to obtain two suede base fabrics with simulated leather. However, since peeling destroys the entanglement of the fibers in the middle layer and causes some long fibers to become short fibers, the mechanical properties of the suede base fabric deteriorate.

[0014] When the present invention prepares the suede base fabric of artificial leather, Figure 2 As shown, during the drying and curing stage, the nonwoven fabric 2, impregnated with the aqueous polyurethane impregnation liquid, is placed on a sealing plate 1. Because the sealing plate 1 is airtight, moisture in the nonwoven fabric 2, impregnated with the aqueous polyurethane impregnation liquid, can only be removed through the upper surface of the nonwoven fabric 2. The upward directional movement of water vapor drives the polyurethane upward, and after drying and curing, the aqueous polyurethane 3 is distributed from sparse to dense along the lower surface to the upper surface of the nonwoven fabric 2. The dried and cured product can be further processed to obtain a suede base fabric without peeling, and the nonwoven fabric structure is relatively intact, resulting in excellent mechanical properties for the suede base fabric.

[0015] As the preferred technical solution:

[0016] In the method for preparing a suede base fabric of high-physical-property simulated leather as described above, the thickness of the non-woven fabric, the solid content of the aqueous polyurethane impregnation liquid, the liquid saturation of the non-woven fabric after being impregnated with the aqueous polyurethane impregnation liquid, and the drying and curing process parameters are coordinated with each other so that after drying and curing, the aqueous polyurethane is distributed from sparse to dense along the direction from the lower surface of the non-woven fabric to the upper surface of the non-woven fabric.

[0017] Currently, some specialized technologies exist to achieve specialized polyurethane distribution patterns within nonwoven fabrics, such as a gradually decreasing gradient. For example, patent application CN114086401A utilizes chemical reaction foaming to propel polyurethane movement and achieve the desired polyurethane distribution. However, this method's processing is complex and involves numerous control points, making it difficult to implement efficiently on an industrial scale. Furthermore, the addition of inorganic acids and other additives during the preparation process generates certain carbon dioxide emissions. Patent application CN112695516A exploits the charged properties of waterborne polyurethane to induce electrophoretic migration under a certain DC electric field strength, creating regions of varying concentrations. Drying then evaporates the solvent, resulting in a waterborne microfiber fabric with varying densities on both sides. This method is specific to ionic waterborne polyurethanes, requiring a long electric field treatment time and high equipment requirements, making it difficult to implement efficiently on an industrial scale. Patent application CN116005462A utilizes the sedimentation of the polyurethane solution under its own weight during a static process to achieve a gradient concentration distribution within the fabric. This processing method requires a long static process, making it difficult to manufacture on an industrial scale.

[0018] According to the method for preparing a suede base fabric with high physical properties of simulated leather, the thickness of the non-woven fabric is 0.5-1.2 mm, which is lower than the prior art (2.5-4.3 mm).

[0019] The thickness of the non-woven fabric determines the length of the internal heat transfer and mass transfer paths. Heat transfer and mass transfer paths that are too long or too short are not conducive to drying and curing. After drying and curing, the water-based polyurethane is distributed from sparse to dense along the direction from the lower surface to the upper surface of the non-woven fabric.

[0020] In the method for preparing a suede base fabric with high physical properties of simulated leather as described above, the solid content of the aqueous polyurethane impregnation liquid is 25-33%. The preparation process of the aqueous polyurethane impregnation liquid is: using deionized water to dilute the aqueous polyurethane emulsion to obtain an aqueous polyurethane impregnation liquid with a solid content of 25-33%. If necessary, conventional additives such as wetting agents and defoaming agents that are beneficial to the impregnation process can also be added.

[0021] The solid content determines the concentration of polyurethane particles in the waterborne polyurethane impregnation liquid. A solid content of 25-33% is more suitable for the waterborne polyurethane impregnation liquid. At this point, the polyurethane particles precipitate at a moderate rate on the liquid surface, and the ability of water vapor to drive the polyurethane molecules to migrate is moderate, which is conducive to the distribution of the waterborne polyurethane from sparse to dense along the bottom surface to the top surface of the non-woven fabric after drying and curing, giving the suede base fabric a better feel.

[0022] Since the upper surface of the non-woven fabric absorbs a lot of heat, the polyurethane particles near the upper surface of the non-woven fabric are first pushed by the water vapor. If the solid content of the aqueous polyurethane impregnation solution is too high, a thin polyurethane layer will easily form on the upper surface of the non-woven fabric during the drying and curing stage. This polyurethane layer will hinder the overflow of water vapor inside the non-woven fabric, and the internal water vapor will gather. The ability of water molecules to drive the polyurethane to migrate upward increases, thereby causing the polyurethane to gather and distribute on the upper layer of the non-woven fabric (such as Figure 3 If the solid content of the aqueous polyurethane impregnation solution is too low, the feel of the suede base fabric will not be full.

[0023] According to the method for preparing a suede base fabric of high-physical-property simulated leather as described above, the liquid saturation of the non-woven fabric after being impregnated with the aqueous polyurethane impregnation liquid is 65-80%, and the liquid saturation = actual liquid saturation / full impregnation liquid saturation × 100%. The full impregnation liquid saturation is the liquid saturation of the non-woven fabric after full impregnation. The full impregnation process is: after the non-woven fabric is immersed in the aqueous polyurethane impregnation liquid for 5 minutes, it passes through a liquid roller to squeeze out the air in the non-woven fabric, and the operation is repeated until the weight is constant after impregnation, and the aqueous polyurethane impregnation liquid on the surface of the non-woven fabric is removed by scraping or adsorption with a dry cloth; the liquid saturation indirectly represents the number of voids in the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid.

[0024] The present invention controls the liquid saturation of the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid to be 65-80%. At this time, the volatilization rate of water, the precipitation rate of polyurethane particles and the directional movement of water molecules drive the migration speed of the aqueous polyurethane to the upper surface of the non-woven fabric to be appropriate, and the polyurethane forms a stepped distribution in the non-woven fabric. Since the non-woven fabric has a small gram weight and a low thickness, and has fast heat conduction and heat exchange, if the liquid saturation of the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid is high, there are fewer voids in the non-woven fabric, and the polyurethane slurry is relatively more, the ability of water molecules to drive the polyurethane to migrate upward is stronger, and the polyurethane is concentrated and distributed in the upper layer of the non-woven fabric (such as Figure 3 If the non-woven fabric after being impregnated with the water-based polyurethane impregnation liquid has a low liquid saturation rate and there are many voids in the non-woven fabric, water vapor will not only evaporate from the surface of the non-woven fabric, but also easily escape from the voids in the non-woven fabric. The ability of water molecules to drive the polyurethane to migrate upward is weak, and the polyurethane is relatively evenly distributed in the non-woven fabric (as shown). Figure 4 shown).

[0025] In the method for preparing a suede base fabric with high physical properties of simulated leather as described above, the drying and curing is divided into two stages. The temperature of the first stage is lower than the boiling point of water (i.e., the solvent in the aqueous polyurethane impregnation solution), and the temperature of the second stage is higher than the boiling point of water.

[0026] As described above, in the method for preparing a suede base fabric of a high-property simulated leather, during drying and curing, the temperature of the first stage is 80-98°C, and after the first stage, the water content of the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid is 30-50wt% (taking at least 10 minutes), and the temperature of the second stage is 100-140°C. After the second stage, the water content of the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid is within 2wt%, which is considered to be completed by drying and curing.

[0027] The present invention adopts a two-step high- and low-temperature heating process during drying and curing, which avoids the problem of direct high-temperature heating, which would cause the surface to absorb heat too quickly and quickly generate a large amount of hot gas due to the time required for inward heat transfer. This would initially form a thin polyurethane layer, hindering the subsequent volatilization of water vapor. Adjusting the internal and external base temperatures and water content at the low-temperature stage is a necessary condition for achieving an ideal distribution at high temperatures. During the drying process, the polyurethane is driven upward by the water vapor, and the volatile liquid level gradually moves downward toward the interior of the non-woven fabric. As the polyurethane migrates, the internal polyurethane decreases. After drying and curing, the water-based polyurethane is distributed from sparse to dense along the direction from the bottom surface to the top surface of the non-woven fabric.

[0028] The present invention controls the temperature of the first stage to be 80-98° C., and the water content of the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid after the first stage is 30-50wt%. Since the temperature at this time has not reached the boiling point of water, the heat mainly acts on the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid, so that the non-woven fabric reaches a uniform internal and external temperature in the thickness direction, thereby avoiding the formation of a thin polyurethane layer in the early stage due to the generation of a large amount of hot air on the surface, which blocks the subsequent water vapor volatilization channel and causes the internal water vapor to have an excessively strong driving force on the polyurethane, resulting in the polyurethane being accumulated and distributed on the upper layer of the non-woven fabric (such as Figure 3 shown).

[0029] The present invention controls the temperature of the second stage to be 100-140°C. After the second stage, the water content of the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid is within 2wt%, which is considered to have completed drying and curing. In the second stage, the drying temperature exceeds the boiling point of water, the volatilization rate of water at the liquid surface on the upper surface of the non-woven fabric is accelerated, and the precipitation rate of polyurethane is accelerated. By synchronously regulating the water content to 30-50wt% in the first stage, the ability of water to drive the polyurethane particles to move upward is relatively weakened, so that the movement speed of polyurethane is controlled at an ideal level. As the internal polyurethane continues to migrate upward, a stepped distribution is formed with more polyurethane in the upper part and less polyurethane in the lower part. If the water content in the material is too much after the first stage, it is easy to form a polarized distribution in which the upper layer is entirely polyurethane and the lower layer has basically no polyurethane (such as Figure 3 If the water content in the material is too low after the first stage, it will be difficult to form a gradient distribution.

[0030] Different from the present invention, the prior art generally selects a heat treatment temperature greater than 100° C. for the purpose of rapidly drying moisture.

[0031] The method for preparing a suede base fabric with high physical properties of simulated leather as described above, wherein the density of the non-woven fabric is 0.28-0.36 g / cm 3 .

[0032] The density of non-woven fabric is 0.28-0.36g / cm 3 When the capillary effect is present, the polyurethane particles can stably adhere to the gaps between the non-woven fibers without external force.

[0033] In the above-mentioned method for preparing a suede base fabric with high physical properties of simulated leather, drying and curing are performed by heating in a hot box.

[0034] According to any one of the above methods for preparing a suede base fabric for simulated leather with high physical properties, the suede base fabric for simulated leather with high physical properties has a tensile load of 322-894 N / 10 mm and a rebound time of 38-98 s.

[0035] The present invention also provides a high-property water-based microfiber base cloth, which is an intermediate product of the method for preparing the high-property simulated leather suede base cloth as described above.

[0036] Beneficial effects:

[0037] (1) Due to the directional distribution of polyurethane during the drying and curing process of the present invention, the fiber structure of the non-woven fabric is well preserved, avoiding the damage to the fiber structure caused by the skinning process in the traditional process, thereby significantly improving the tensile load, tear strength and other mechanical properties of the suede base fabric.

[0038] (2) The present invention controls the solid content of the aqueous polyurethane impregnation liquid to be between 25-33% and the liquid saturation of the non-woven fabric to be between 65-80%, so that the suede base fabric after drying and curing is neither too thick nor too thin, and has a full feel, thereby meeting the requirements of high-end leather products for the feel.

[0039] (3) The present invention adopts water-based polyurethane as the impregnation liquid, avoiding the use of organic solvents and reducing environmental pollution; at the same time, by optimizing the drying and curing process, the energy utilization efficiency is improved and green production is achieved.

[0040] (4) The method of the present invention is simple and suitable for industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the process of preparing suede base fabric of simulated leather in the prior art;

[0042] Figure 2 This is a schematic diagram of a suede base fabric for preparing simulated leather according to the present invention;

[0043] Figure 3 Schematic diagram of the distribution of polyurethane in the non-woven fabric when the solid content of the aqueous polyurethane impregnation liquid is too high (exceeding 33%), or the liquid saturation of the non-woven fabric after being impregnated with the aqueous polyurethane impregnation liquid is high (exceeding 80%), or the water content of the non-woven fabric after being impregnated with the aqueous polyurethane impregnation liquid after the first stage is too high (exceeding 50wt%), or the temperature of the first stage is too high (exceeding the boiling point of water), or high-temperature drying (exceeding 100°C) is directly used;

[0044] Figure 4 Schematic diagram of the distribution of polyurethane in the non-woven fabric after being impregnated with the aqueous polyurethane impregnation liquid when the liquid saturation of the non-woven fabric is low (less than 65%);

[0045] Figure 5 This is a scanning electron microscope image of the suede base fabric with high physical properties of simulated leather prepared in Example 1;

[0046] Figure 6 This is a scanning electron microscope image of the suede base fabric of high-property simulated leather prepared in Example 7;

[0047] Among them, 1-sealing plate, 2-non-woven fabric, 3-water-based polyurethane. DETAILED DESCRIPTION

[0048] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0049] The following are the test methods for the relevant performance indicators in each embodiment:

[0050] Polyurethane distribution: Using a scanning electron microscope, the gradient distribution effect of polyurethane was observed in the longitudinal section;

[0051] Tensile load: The tensile load of the sample was tested using the test method of GB / T1040.3-2006; the tensile speed was 100 mm / min, the sample width was 10 mm, and the length was 200 mm; the equipment used was a universal tensile testing machine;

[0052] Moisture content: The moisture content of the sample (non-woven fabric impregnated with aqueous polyurethane impregnation liquid) was tested using the textile leather moisture meter AKD-W10S produced by Yangzhou Aikeruide Instrument Co., Ltd.

[0053] Rebound time: Prepare a suede base fabric of high-property simulated leather with a length and width of 1 cm. Fold it in half and load it with a weight of 1 kg. After holding it for 10 minutes, remove the pressure and unfold the suede base fabric. Record the time it takes for the fold mark to completely disappear within 10 minutes. This is the rebound time.

[0054] The calculation formulas for the liquid saturation rate in the following embodiments are as follows:

[0055] Liquid saturation rate = actual liquid saturation rate / full immersion liquid saturation rate × 100%.

[0056] In the formula, the full impregnation liquid rate is the liquid rate of the non-woven fabric after full impregnation. The full impregnation process is: after the non-woven fabric is immersed in the aqueous polyurethane impregnation liquid for 5 minutes, it passes through the liquid roller to squeeze out the air in the non-woven fabric, and repeats the operation until the weight is constant after impregnation. The aqueous polyurethane impregnation liquid on the surface of the non-woven fabric is removed by scraping or adsorption with a dry cloth.

[0057] Example 1

[0058] A method for preparing a suede base fabric with high physical properties of simulated leather, the specific steps are as follows:

[0059] (1) non-woven fabric is impregnated with aqueous polyurethane impregnation liquid;

[0060] The sea-island fiber nonwoven fabric (sea phase is LDPE, island phase is PA, the mass ratio of sea phase to island phase is 70:30, thickness is 0.8 mm, density is 0.34 g / cm 3 , tensile load of 526N / 10mm) was immersed in an aqueous polyurethane impregnation liquid (solid content of 31%, obtained by diluting Dow's aqueous polyurethane dispersion SYNTEGRAYS-3000 with water) until its liquid saturation rate reached 75% and then taken out;

[0061] (2) drying and curing;

[0062] The non-woven fabric impregnated with the aqueous polyurethane impregnation solution was placed on a sealing plate (the two sides of the non-woven fabric were designated as side A and side B, with only side B in contact with the sealing plate), and then dried in a hot box at 95°C to a moisture content of 45 wt%, and then dried and cured at 130°C.

[0063] (3) weight reduction drying (i.e., drying after removing the sea phase in the non-woven fabric);

[0064] (4) Grinding and raising the leather (i.e. grinding and raising the B side of the non-woven fabric) to obtain a suede base fabric with high physical properties of simulated leather.

[0065] The suede base fabric of the high physical property imitation leather finally obtained is as follows Figure 5 As shown, the tensile load of the suede base fabric of high physical property imitation leather is 556N / 10mm, and the rebound time is 98s.

[0066] Example 2

[0067] A method for preparing a suede base fabric of high-physical-property simulated leather is basically the same as that in Example 1, except that the thickness of the sea-island fiber nonwoven fabric in step (1) is 1.5 mm and the tensile load is 872 N / 10 mm.

[0068] The tensile load of the suede base fabric with high physical properties of simulated leather finally obtained is 894N / 10mm, and the rebound time is 51s.

[0069] Example 3

[0070] A method for preparing a suede base fabric of simulated leather with high physical properties is basically the same as that in Example 1, except that the thickness of the sea-island fiber non-woven fabric in step (1) is 0.4 mm and the tensile load is 252 N / 10 mm.

[0071] The tensile load of the suede base fabric with high physical properties of simulated leather finally obtained is 237N / 10mm, and the rebound time is 42s.

[0072] Compared with Example 1, the rebound time of the suede base fabrics of the high-property simulated leather in Examples 2 and 3 was shortened. This is because the thickness of the nonwoven fabrics in Examples 2 and 3 was either too high (Example 2) or too low (Example 3). The thickness of the nonwoven fabric determines the length of the internal heat and mass transfer paths. When the nonwoven fabric is too thick, the heat and mass transfer paths are too long, making it difficult for the polyurethane to form an ideal gradient distribution from sparse to dense during the drying and curing process. When the nonwoven fabric is too thin, the heat and mass transfer paths are too short, which is also not conducive to the gradient distribution of the polyurethane. In both cases, the rebound time of the resulting high-property simulated leather suede base fabric is shortened.

[0073] Example 4

[0074] A method for preparing a suede base fabric of simulated leather with high physical properties is basically the same as that in Example 1, except that the solid content of the aqueous polyurethane impregnation liquid in step (1) is 45%.

[0075] The tensile load of the suede base fabric with high physical properties of simulated leather finally obtained is 551N / 10mm, and the rebound time is 55s.

[0076] Compared with Example 1, the rebound time of the suede base fabric of high physical property imitation leather in Example 4 is shortened. This is because the solid content of the aqueous polyurethane impregnation liquid used in Example 4 is too high, and a thin polyurethane layer is easily formed on the upper surface of the non-woven fabric during the drying and curing stage. The polyurethane layer will hinder the overflow of water vapor inside the non-woven fabric, and the internal water vapor will accumulate. The ability of water molecules to drive the polyurethane to migrate upward is increased, thereby causing the polyurethane to accumulate and distribute on the upper layer of the non-woven fabric (such as Figure 3 As shown), it is not conducive to the gradient distribution of waterborne polyurethane from sparse to dense along the direction from the lower surface of the non-woven fabric to the upper surface of the non-woven fabric after drying and curing, resulting in a shortened rebound time of the base fabric.

[0077] Example 5

[0078] A method for preparing a suede base fabric with high physical properties and simulated leather is basically the same as that in Example 1, except that: in step (1), the sea-island fiber nonwoven fabric is taken out after its liquid saturation reaches 95%.

[0079] The tensile load of the suede base fabric with high physical properties of simulated leather finally obtained is 554N / 10mm, and the rebound time is 49s.

[0080] Compared with Example 1, the rebound time of the suede base fabric of high physical property imitation leather in Example 5 is shortened. This is because the liquid saturation rate of the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid in Example 5 is too high, the voids in the non-woven fabric are relatively small, the polyurethane slurry is relatively large, the ability of water molecules to drive the polyurethane to migrate upward is strong, and the polyurethane is concentrated and distributed in the upper layer of the non-woven fabric (such as Figure 3 As shown), the base fabric rebounds in a shorter time.

[0081] Example 6

[0082] A method for preparing a suede base fabric with high physical properties and simulated leather is basically the same as that in Example 1, except that: in step (1), the sea island fiber nonwoven fabric is taken out after its liquid saturation reaches 30%.

[0083] The tensile load of the suede base fabric with high physical properties of simulated leather finally obtained is 548N / 10mm, and the rebound time is 38s.

[0084] Compared with Example 1, Example 6 has a shorter rebound time of the suede base fabric of the high-property simulated leather. This is because the liquid saturation rate of the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid in Example 6 is too low, and there are many voids in the non-woven fabric. Water vapor not only evaporates from the upper surface of the non-woven fabric, but also easily escapes from the voids in the non-woven fabric. The ability of water molecules to drive the polyurethane to migrate upward is weak, and the polyurethane is relatively evenly distributed in the non-woven fabric (that is, the polyurethane cannot form a gradient distribution from sparse to dense in the non-woven fabric), which leads to a shortened rebound time of the base fabric.

[0085] Example 7

[0086] A method for preparing a suede base fabric of simulated leather with high physical properties is basically the same as that in Example 1, except that: during the drying and curing step (2), the non-woven fabric impregnated with the aqueous polyurethane impregnation liquid is placed on a sealing plate and then directly dried and cured at 130°C.

[0087] The suede base fabric of the high physical property imitation leather finally obtained is as follows Figure 6 As shown, the tensile load of the suede base fabric of high physical property imitation leather is 542N / 10mm, and the rebound time is 47s.

[0088] Compared with Example 1, the rebound time of the suede base fabric of high physical property imitation leather in Example 7 is shortened. This is because Example 7 directly uses high temperature heating (130°C) for drying and curing. It takes a certain amount of time for the temperature to transfer heat inward, resulting in excessive heat absorption on the surface and rapid generation of a large amount of hot air, which is conducive to the rapid precipitation of polyurethane in the surface polyurethane slurry to form a thin film to prevent heat from entering the interior, and also to prevent the overflow of water vapor inside the non-woven fabric. The internal water vapor accumulates, and the ability of water molecules to drive the polyurethane to migrate upward is increased, thereby causing the polyurethane to accumulate and distribute on the upper layer of the non-woven fabric (such as Figure 3 As shown), the rebound time of the base fabric is shortened.

[0089] Example 8

[0090] A method for preparing a suede base fabric of simulated leather with high physical properties is basically the same as that in Example 1, except that: during the drying and curing step (2), the non-woven fabric impregnated with the aqueous polyurethane impregnation liquid is placed on a sealing plate and then dried in a hot box at 95°C to a water content of 54wt%, and then dried and cured at 130°C.

[0091] The tensile load of the final high-physical-property simulated leather suede base fabric is 553N / 10mm, and the rebound time is 65s.

[0092] Example 9

[0093] A method for preparing a suede base fabric with high physical properties of simulated leather, the specific steps are as follows:

[0094] (1) non-woven fabric is impregnated with aqueous polyurethane impregnation liquid;

[0095] The sea-island fiber nonwoven fabric (sea phase is LDPE, island phase is PA, sea-island mass ratio is 70:30, thickness is 0.6 mm, density is 0.28 g / cm 3 , tensile load of 316N / 10mm) was immersed in an aqueous polyurethane impregnation liquid (solid content of 33%, obtained by diluting Dow's aqueous polyurethane dispersion SYNTEGRAYS-3000 with water) until its liquid saturation rate reached 80% and then taken out;

[0096] (2) drying and curing;

[0097] The non-woven fabric impregnated with the aqueous polyurethane impregnation solution was placed on a sealing plate (the two sides of the non-woven fabric were designated as side A and side B, with only side B in contact with the sealing plate), and then dried in a hot box at 80°C to a water content of 30 wt%, and then dried and cured at 140°C.

[0098] (3) weight reduction drying (i.e., drying after removing the sea phase in the non-woven fabric);

[0099] (4) Grinding and raising the leather (i.e. grinding and raising the B side of the non-woven fabric) to obtain a suede base fabric with high physical properties of simulated leather.

[0100] The tensile load of the suede base fabric with high physical properties of simulated leather finally obtained is 322N / 10mm, and the rebound time is 76s.

[0101] Example 10

[0102] A method for preparing a suede base fabric with high physical properties of simulated leather, the specific steps are as follows:

[0103] (1) non-woven fabric is impregnated with aqueous polyurethane impregnation liquid;

[0104] The sea-island fiber nonwoven fabric (sea phase is LDPE, island phase is PA, the mass ratio of sea phase to island phase is 70:30, thickness is 0.9 mm, density is 0.36 g / cm 3 , tensile load of 548N / 10mm) was immersed in an aqueous polyurethane impregnation liquid (solid content of 25%, obtained by diluting Dow's aqueous polyurethane dispersion SYNTEGRAYS-3000 with water) until its liquid saturation rate reached 65% and then taken out;

[0105] (2) drying and curing;

[0106] The non-woven fabric impregnated with the aqueous polyurethane impregnation solution was placed on a sealing plate (the two sides of the non-woven fabric were designated as side A and side B, with only side B in contact with the sealing plate), and then dried in a hot box at 98°C to a water content of 50 wt%, and then dried and cured at 100°C.

[0107] (3) weight reduction drying (i.e., drying after removing the sea phase in the non-woven fabric);

[0108] (4) Grinding and raising the leather (i.e. grinding and raising the B side of the non-woven fabric) to obtain a suede base fabric with high physical properties of simulated leather.

[0109] The tensile load of the suede base fabric with high physical properties of simulated leather finally obtained is 538N / 10mm, and the rebound time is 81s.

[0110] Example 11

[0111] A method for preparing a suede base fabric with high physical properties of simulated leather, the specific steps are as follows:

[0112] (1) non-woven fabric is impregnated with aqueous polyurethane impregnation liquid;

[0113] The sea-island fiber nonwoven fabric (sea phase is LDPE, island phase is PA, the mass ratio of sea phase to island phase is 70:30, thickness is 1.2 mm, density is 0.3 g / cm 3 , tensile load of 734N / 10mm) was immersed in a water-based polyurethane impregnation liquid (solid content of 28%, the manufacturer of water-based polyurethane is Dow Chemical Company, model number YS4000) until the liquid saturation rate reached 72% and then taken out;

[0114] (2) drying and curing;

[0115] The non-woven fabric impregnated with the aqueous polyurethane impregnation solution was placed on a sealing plate (the two sides of the non-woven fabric were designated as side A and side B, with only side B in contact with the sealing plate), and then dried in a hot box at 90°C to a moisture content of 37 wt%, and then dried and cured at 110°C.

[0116] (3) weight reduction drying (i.e., drying after removing the sea phase in the non-woven fabric);

[0117] (4) Grinding and raising the leather (i.e. grinding and raising the B side of the non-woven fabric) to obtain a suede base fabric with high physical properties of simulated leather.

[0118] The tensile load of the suede base fabric with high physical properties of simulated leather finally obtained is 742N / 10mm, and the rebound time is 85s.

Claims

1. A method for preparing a suede base fabric of high physical property simulated leather, characterized in that: The process comprises the following steps: impregnating a non-woven fabric with a water-based polyurethane impregnation liquid, drying and solidifying the non-woven fabric, drying the non-woven fabric with a reduced weight to obtain a water-based microfiber base fabric with high physical properties, and grinding and raising the water-based microfiber base fabric with high physical properties to obtain a suede base fabric with high physical properties imitating leather; During drying and curing, the non-woven fabric soaked in the aqueous polyurethane impregnation liquid is placed on the sealing plate. The two sides of the non-woven fabric are marked as side A and side B, and only side B is in contact with the sealing plate. The non-woven fabric is a sea-island fiber non-woven fabric, and the reduction drying is to remove the sea phase in the non-woven fabric and then dry it; The grinding and raising process is to grind the B side of the non-woven fabric to make it nappy; The thickness of the non-woven fabric, the solid content of the water-based polyurethane impregnation liquid, the liquid saturation of the non-woven fabric after being impregnated with the water-based polyurethane impregnation liquid, and the process parameters of drying and curing are coordinated with each other so that after drying and curing, the water-based polyurethane is distributed from sparse to dense along the direction from the lower surface to the upper surface of the non-woven fabric; The thickness of the non-woven fabric is 0.6-1.2mm; The solid content of the water-based polyurethane impregnation liquid is 25-33%; The liquid saturation of the non-woven fabric after being impregnated with the aqueous polyurethane impregnation liquid is 65-80%, and the liquid saturation = actual liquid impregnation / full impregnation liquid impregnation × 100%. The full impregnation liquid impregnation is the liquid impregnation of the non-woven fabric after full impregnation. The full impregnation process is as follows: after the non-woven fabric is immersed in the aqueous polyurethane impregnation liquid for 5 minutes, it passes through the liquid roller to squeeze out the air in the non-woven fabric, and the operation is repeated until the weight is constant after impregnation, and the aqueous polyurethane impregnation liquid on the surface of the non-woven fabric is removed; Drying and curing is divided into two stages. The temperature of the first stage is lower than the boiling point of water, and the temperature of the second stage is higher than the boiling point of water. During drying and curing, the temperature of the first stage is 80-98°C, and the water content of the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid after the first stage is 30-50wt%. The temperature of the second stage is 100-140°C, and the water content of the non-woven fabric after being immersed in the aqueous polyurethane impregnation liquid after the second stage is within 2wt%.

2. The method for preparing a suede base fabric of high physical property imitation leather according to claim 1, characterized in that: The density of non-woven fabric is 0.28-0.36g / cm 3 .

3. A high-property water-based microfiber base cloth, characterized in that: It is an intermediate product of the method for preparing a suede base fabric of high-physical-property simulated leather as described in any one of claims 1 to 2.

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