Preparation method of waterproof imitation leather microfiber base cloth with three-layer structure

Abstract

The invention belongs to the technical field of material preparation, and relates to a preparation method of waterproof imitation leather microfiber base cloth with a three-layer structure. Two sides of a sea-island fiber non-woven fabric are impregnated with three kinds of solvent type polyurethane slurry step by step, the penetration depth and the liquid carrying rate of each slurry are accurately controlled, and the microfiber base fabric with a three-layer structure sequentially comprising a waterproof layer, a compact layer and a macroporous layer is prepared after solidification and post-treatment. The waterproof function is achieved, meanwhile, the soft hand feeling and breathability of the base cloth are considered, the problem that in the prior art, performance balance is poor is broken through, the problem that the hand feeling, breathability and waterproofness of microfiber base cloth are difficult to consider is solved, and technical support is provided for the high-end application field.

Description

Technical Field

[0001] The invention belongs to the technical field of material preparation and relates to a method for preparing a three-layer waterproof imitation leather microfiber base cloth. Background Art

[0002] Microfiber fabrics (abbreviated as "microfiber fabrics") have attracted much attention due to their excellent physical properties and wide application in many fields. Their internal structure plays a key role in the presentation of simulated leather effects and the realization of waterproof performance. Currently, the structural design of microfiber fabrics is mainly divided into two types:

[0003] The first is the coating structure of a homogeneous base fabric. That is, when the base fabric is a homogeneous layer, functional materials need to be coated layer by layer through post-processing. However, the multi-layer structure of existing technologies mostly adopts a post-coating process, which bonds the layers together through adhesives or curing treatments. However, this process can make the material feel stiff, significantly reduce breathability (due to poor adhesion between the coating layer and the fiber surface, hindering air circulation), and increase the risk of interlayer delamination (insufficient bonding strength between the surface coating layer and the base fabric layer). At the same time, due to the high complexity of post-processing, it can also lead to a decrease in product qualification rate and an increase in cost.

[0004] The second is the preparation method of the heterogeneous layer base fabric. In comparison, this method has improved on the above-mentioned problems, but it still has the short board of performance balance. For example, the patent application disclosed in the publication number CN111764177A discloses a method for preparing all-water-based microfiber synthetic leather. As a typical representative of heterogeneous layer preparation, its core steps include dipping the microfiber non-woven fabric in a modified polyvinyl alcohol aqueous solution and drying it, dipping it again in an aqueous polyurethane slurry A and applying an aqueous polyurethane slurry B on one side, then dipping it in an oxalic acid aqueous solution for solidification, washing and drying it, and then opening it with an alkali solution, and finally performing a post-finishing process. This method is better than the homogeneous layer coating structure in terms of interlayer bonding (fiber and slurry form a more stable composite structure), process simplification (reducing the back-end processing steps) and cost yield (improving the pass rate and reducing costs), but it is still difficult to take into account excellent feel, breathability and waterproofness at the same time. For example, the feel and breathability may be limited due to improper slurry curing degree, or the improvement of waterproof performance is at the expense of breathability.

[0005] Therefore, the existing technology has not yet been able to completely solve the balance problem between the feel, breathability and waterproofness of microfiber-based fabrics. Developing a microfiber-based fabric with excellent feel, breathability and waterproof performance has become a technical direction that the current industry urgently needs to break through. Summary of the Invention

[0006] The purpose of the present invention is to solve the deficiencies in the prior art and to provide a method for preparing a three-layer waterproof imitation leather microfiber base fabric.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a three-layer waterproof imitation leather microfiber base fabric comprises the steps of impregnating a sea-island fiber non-woven fabric with a polyurethane slurry, wherein the polyurethane slurry is a solvent-based slurry and is divided into three types, namely polyurethane slurry 1, polyurethane slurry 2, and polyurethane slurry 3.

[0009] Polyurethane slurry 1 is a foaming polyurethane slurry with a resin solid content of 13-15%; polyurethane slurry 2 is a defoaming polyurethane slurry with a resin solid content of 21-24% and contains silicone resin (a waterproof material, the recommended concentration range of silicone resin in polyurethane slurry 2 is 4-6wt%); polyurethane slurry 3 is a foaming polyurethane slurry with a resin solid content of 5-7%;

[0010] In the present invention, the foamed polyurethane slurry is a conventional polyurethane slurry used for non-woven fabric impregnation. This type of polyurethane slurry is understood to be any conventional polyurethane slurry that can contribute to the pore structure. To distinguish it from the defoaming polyurethane slurry, the present invention specifically names the conventional polyurethane slurry as foamed polyurethane slurry.

[0011] In the present invention, defoaming polyurethane slurry refers to a polyurethane slurry that is further endowed with defoaming properties compared to foaming polyurethane slurry, so that the final material cannot produce bubbles during processing. Generally, foaming polyurethane slurry can be converted into defoaming polyurethane slurry by adding a defoaming agent (typically such as silicone resin); this type of polyurethane slurry has the defoaming property and cannot produce bubbles, so it is usually not used as a base fabric impregnation slurry. To distinguish it from conventional polyurethane slurry, this invention specifically names this type of defoaming-modified polyurethane slurry as defoaming polyurethane slurry;

[0012] The two sides of the island-in-the-sea fiber nonwoven fabric are respectively denoted as side A and side B, and the thickness of the island-in-the-sea fiber nonwoven fabric is denoted as d;

[0013] When impregnating the sea-island fiber non-woven fabric with polyurethane slurry, first impregnate the A side of the sea-island fiber non-woven fabric with polyurethane slurry 1 until the penetration depth of polyurethane slurry 1 is d1, so that the liquid-carrying rate 1 of the sea-island fiber non-woven fabric (the percentage of the mass of polyurethane slurry 1 carried by the sea-island fiber non-woven fabric in the dry weight of the sea-island fiber non-woven fabric itself) is 52-58%, d1 < d. Then impregnate the A side of the sea-island fiber non-woven fabric with polyurethane slurry 2 until the penetration depth of polyurethane slurry 2 is d2, so that the liquid-carrying rate 2 of the sea-island fiber non-woven fabric (the percentage of the mass of polyurethane slurry 2 carried by the sea-island fiber non-woven fabric in the dry weight of the sea-island fiber non-woven fabric itself) is 8-12%, d2 < d1. Then impregnate the B side of the sea-island fiber non-woven fabric with polyurethane slurry 3 until the penetration depth of polyurethane slurry 3 is d3, so that the liquid-carrying rate 3 of the sea-island fiber non-woven fabric (the percentage of the mass of polyurethane slurry 3 carried by the sea-island fiber non-woven fabric in the dry weight of the sea-island fiber non-woven fabric itself) is 15-30%, d3 = d - d1;

[0014] d is 2.43-2.57 mm, d1 is 1.71-2.00 mm, and d2 is 0.28-0.43 mm.

[0015] The waterproof artificial leather superfine fiber base fabric of the present invention has a three-layer structure, which are a waterproof layer, a dense layer, and a macroporous layer in sequence.

[0016] The key to the process control of the present invention lies in the selection of polyurethane slurry in the first and second steps and the process control of impregnation. It is necessary to meet the requirements of both the dense layer and the waterproof layer, which is a technical difficulty. If the control is improper, not only the ideal waterproof layer cannot be obtained, but the dense layer will also fail.

[0017] The dense layer is formed by the solidification of polyurethane slurry 1 impregnated into the sea-island fiber non-woven fabric. Since the resin solid content of polyurethane slurry 1 is medium, while forming relatively large pores, it still has good structural properties, making the dense layer have good softness and a structure that can support the base fabric, and can simulate the characteristics of the dermis layer.

[0018] If the resin solid content of polyurethane slurry 1 is too high, it will affect the formation of the subsequent waterproof layer; if the resin solid content of polyurethane slurry 1 is too low, it will cause the base fabric to collapse, the overall base fabric to be too soft, and unable to maintain the elasticity of the base fabric.

[0019] In the prior art, the dense layer only needs to be considered when selecting the processing parameters for polyurethane slurry 1. In the present invention, the waterproof layer is the result of both polyurethane slurry 1 (the first step) and polyurethane slurry 2 (the second step) being impregnated into the island-in-the-sea fiber nonwoven fabric. Therefore, unlike the prior art, the present invention uses polyurethane slurry 1 with a relatively low resin solids content to impregnate the island-in-the-sea fiber nonwoven fabric, creating processing conditions for the subsequent immersion of polyurethane slurry 2. Consequently, polyurethane slurry 1 must be impregnated into the island-in-the-sea fiber nonwoven fabric before polyurethane slurry 2.

[0020] The present invention controls the liquid carrying rate 1 of the sea-island fiber nonwoven fabric to be 52-58%. If it is too high, the softness and air permeability of the base fabric will be affected, resulting in low softness and poor air permeability; if it is too low, the entire base fabric will be too soft and the elasticity of the base fabric cannot be maintained.

[0021] The waterproof layer is used to simulate the protective properties of the epidermis. In order to obtain the target waterproof layer, it is necessary to control the resin solid content of the polyurethane slurry 2 to be appropriate. Under the conditions of allowable resin solid content, the liquid carrying rate 2 of the sea island fiber non-woven fabric is controlled to be higher, so that the polyurethane slurry 2 can be fully immersed in the gap, thereby making the waterproof layer have a higher density, which can give the waterproof imitation leather microfiber base fabric excellent waterproof performance.

[0022] If the resin solid content of the polyurethane slurry 2 is too high, the fluidity of the slurry will be poor, resulting in a too low rate of penetration into the base cloth, making it difficult to apply to industrialization; if the resin solid content of the polyurethane slurry 2 is too low, it will affect the density of the waterproof layer, resulting in poor waterproof effect.

[0023] The present invention controls the liquid carrying rate 2 of the sea-island fiber nonwoven fabric to be 8-12%. If it is too high, it will cause air permeability problems; if it is too low, it will not be able to obtain ideal waterproof properties.

[0024] The macroporous layer is formed by the solidification of a polyurethane slurry 3 impregnated into the island-in-the-sea fiber nonwoven fabric. Because the polyurethane slurry 3 has a low resin solids content and good fluidity, it quickly penetrates into the base fabric. This results in larger pores in the macroporous layer, simulating the subcutaneous layer and providing excellent breathability and softness. The polyurethane content in the macroporous layer is determined by the resin solids content of the polyurethane slurry 3 and the liquid pick-up rate 3 of the island-in-the-sea fiber nonwoven fabric. Given a certain resin solids content, if the liquid pick-up rate 3 of the island-in-the-sea fiber nonwoven fabric is too high, the base fabric will be too soft and unable to maintain its elasticity. If it is too low, the base fabric thickness will be unbalanced, leading to serious quality issues.

[0025] The present invention adopts the design of the three-layer pore structure to make the ultrafine fiber material closer to genuine leather in appearance and feel, thus meeting people's demand for high-quality synthetic leather.

[0026] In the present invention, the values ​​of d1 and d2 are set within a reasonable range. Setting d1 in this way is conducive to ensuring the overall elasticity of the base fabric, avoiding the base fabric being too soft, the structure collapsing, and lacking elasticity due to d1 being too small, and avoiding the base fabric being too small in proportion due to d1 being too large, thereby causing the air permeability of the base fabric to decrease; setting d2 in this way can avoid the poor waterproofness of the base fabric due to d2 being too small, and can also avoid the poor feel of the base fabric and poor air permeability due to d2 being too large.

[0027] As the preferred technical solution:

[0028] The preparation method of the three-layer waterproof imitation leather microfiber base fabric as described above, the density of the sea island fiber non-woven fabric is 0.25-0.29g / cm 3 , usually choosing non-woven fabrics with this density can ensure that the base fabric has suitable mechanical properties.

[0029] The preparation method of the three-layer waterproof imitation leather microfiber base fabric is as follows: after impregnating the sea island fiber non-woven fabric with polyurethane slurry, it is also sequentially coagulated, washed, reduced (using toluene), and dried (temperature is 125-130°C).

[0030] The preparation method of the three-layer waterproof imitation leather microfiber base fabric as described above comprises the steps of: coagulating the sea island fiber non-woven fabric impregnated with polyurethane slurry and dipping the entire fabric into a DMF solution;

[0031] The DMF solution consists of DMF (purity greater than 99.5%) and water in a mass ratio of 1:0.8-1.2.

[0032] The preparation method of the three-layer waterproof imitation leather microfiber base fabric as described above comprises the steps of: coagulating the sea island fiber non-woven fabric impregnated with polyurethane slurry and dipping the entire fabric into a DMF solution;

[0033] The DMF solution consists of DMF (purity greater than 99.5%) and water in a mass ratio of 1:2.5-3.5.

[0034] The preparation method of the three-layer waterproof imitation leather microfiber base fabric as described above comprises the steps of: firstly partially immersing the island-in-sea fiber non-woven fabric after being impregnated with the polyurethane slurry into a DMF solution 1, so that the polyurethane slurry 1 is converted into a gel state, and then the entire island-in-sea fiber non-woven fabric after being impregnated with the polyurethane slurry is immersed in a DMF solution 2;

[0035] DMF solution 1 is composed of DMF (purity greater than 99.5%) and water in a mass ratio of 1:0.8-1.2; DMF solution 2 is composed of DMF (purity greater than 99.5%) and water in a mass ratio of 1:2.5-3.5; the mass proportion of DMF in DMF solution 1 and DMF solution 2 is relatively appropriate, which can avoid incomplete solidification due to excessively large proportions and large solidified resin pores due to too small proportions.

[0036] The present invention first partially immerses the island-in-the-sea fiber nonwoven fabric, which has been impregnated with polyurethane slurry, into a high-concentration DMF solution 1, transforming the polyurethane slurry 1 into a gel state. This is then followed by conventional coagulation. Compared to direct coagulation using conventional processes, this results in smaller cells formed during the resin coagulation process on the surface, creating a material structure with a gradient of density from the inside out. This further optimizes the waterproofness of the microfiber base fabric surface while maintaining breathability.

[0037] The preparation method of the three-layer waterproof imitation leather microfiber base fabric as described above, wherein the water penetration of the three-layer waterproof imitation leather microfiber base fabric is ≤0.2mg, the softness is above 5.0, and the water vapor permeability is>0.8mg / (cm 2 ·h).

[0038] Beneficial effects:

[0039] There are significant technical difficulties in developing a non-homogeneous multi-layer structure with waterproof function for the base fabric itself. The existing technology has only achieved a two-layer structure (dense layer and macroporous layer) without waterproof function. Although it has advantages such as simple processing flow, low energy consumption and better product performance compared with post-processing (such as dry method and printing processing), its application scenarios are still limited to basic functions.

[0040] The present invention develops a three-layer structure (dense layer, waterproof layer and macroporous layer) through a special impregnation process, which significantly expands the application range of the material in special environments (such as high humidity and liquid contact scenarios). However, the realization of this three-layer structure requires strict control of the impregnation and curing process parameters. Improper control may lead to problems such as the inability to form a waterproof layer or substandard performance, failure of the dense layer structure, and stiff feel of the base fabric. Despite the process challenges, the present invention still takes into account the soft feel and breathability of the base fabric while achieving the waterproof function by optimizing the impregnation process, breaking through the functional limitations of the existing two-layer structure and providing technical support for the high-end application of microfiber base fabrics (such as outdoor equipment and medical protection). BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic diagram of the impregnation process in Example 1;

[0042] Figure 2This is a physical picture of the three-layer waterproof imitation leather microfiber base fabric of Example 1, wherein the black and red mixed color area is the waterproof layer, the red area is the dense layer, and the white area is the macroporous layer. DETAILED DESCRIPTION

[0043] Below in conjunction with specific embodiment, further elaborate 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 present invention.

[0044] The detection methods of the relevant indicators in the embodiments and comparative examples are as follows:

[0045] Liquid carryover rate: measured according to QB / T 4044-2010 standard;

[0046] Water penetration: measured according to QB / T 4044-2010 standard;

[0047] Softness: measured according to ISO 17235:2015, using a leather softness tester (GT-303);

[0048] Water vapor permeability: measured according to QB / T 4044-2010 standard.

[0049] Example 1

[0050] A method for preparing a three-layer waterproof imitation leather microfiber base fabric, the specific steps are as follows:

[0051] (1) Material preparation:

[0052] Sea island fiber nonwoven fabric: density 0.25g / cm 3 , thickness d is 2.57 mm;

[0053] Polyurethane slurry 1: a foamed polyurethane slurry with a resin solid content of 13%, obtained by diluting a product of Shanghai Huide Technology Co., Ltd., brand HDD-3060HTD, with DMF;

[0054] Polyurethane slurry 2: Defoaming polyurethane slurry, prepared by diluting product 4050 (manufactured by Jiangsu Huafeng Microfiber Materials Co., Ltd.) with DMF, and then adding silicone resin (manufactured by Zhejiang Jinglian Chemical Co., Ltd., brand JS-MS) and defoamer (manufactured by Jiangsu Jianyu Additives Technology Co., Ltd., brand GPE-30); polyurethane slurry 2 had a resin solids content of 21%, a silicone resin content of 5wt%, and a defoamer content of 0.5wt%;

[0055] Polyurethane slurry 3: a foamed polyurethane slurry with a resin solid content of 6%, obtained by diluting a product of Shanghai Huide Technology Co., Ltd., brand HDD-3060HTD, with DMF;

[0056] DMF solution 1: composed of DMF and water in a mass ratio of 1:0.8;

[0057] DMF solution 2: composed of DMF and water in a mass ratio of 1:2.5;

[0058] Toluene;

[0059] (2) Impregnation treatment:

[0060] The two sides of the sea island fiber nonwoven fabric are marked as side A and side B respectively. Figure 1 As shown in a, the A side of the sea island fiber nonwoven fabric is first impregnated with polyurethane slurry 1 until the penetration depth of the polyurethane slurry 1 is 1.71 mm, so that the liquid carrying rate 1 of the sea island fiber nonwoven fabric is 52%. Figure 1 As shown in b, the polyurethane slurry 2 is then used to impregnate the A side of the sea island fiber nonwoven fabric to a penetration depth of 0.28 mm, so that the liquid carrying rate 2 of the sea island fiber nonwoven fabric is 8%. Figure 1 As shown in c, the polyurethane slurry 3 is then used to impregnate the B side of the sea-island fiber nonwoven fabric to a penetration depth of 0.86 mm, so that the liquid carrying rate 3 of the sea-island fiber nonwoven fabric is 29%;

[0061] After the impregnation treatment, the Figure 1 Layers shown in c; wherein, layer I is the area impregnated with polyurethane slurry 1, which will subsequently form a dense layer; layer II is the area impregnated with polyurethane slurry 1 and polyurethane slurry 2, which will subsequently form a waterproof layer; layer III is the area impregnated with polyurethane slurry 3, which will subsequently form a macroporous layer;

[0062] (3) Solidification treatment:

[0063] The impregnated island fiber nonwoven fabric is partially immersed in DMF solution 1 to convert the polyurethane slurry 1 into a gel state, and then the entire fabric is immersed in DMF solution 2;

[0064] (4) Post-processing:

[0065] The sea island fiber nonwoven fabric after coagulation treatment was washed, reduced in weight, and dried (at a temperature of 125° C.) in sequence.

[0066] The final three-layer waterproof imitation leather microfiber base fabric (such as the actual Figure 2 The water penetration of the material is 0.18 mg, the softness is 5.1, and the water vapor permeability is 1.3 mg / (cm2 ·h).

[0067] Comparative Example 1

[0068] A method for preparing a microfiber-based cloth is different from that of Example 1 in that the resin solid content of the polyurethane slurry 1 is 10%.

[0069] Since the solid content of the resin in the polyurethane slurry 1 is too low, the structure of the microfiber base fabric collapses.

[0070] Comparative Example 2

[0071] A method for preparing a microfiber base fabric differs from Example 1 only in that: the resin solid content of the polyurethane slurry 1 is 17%, and when the polyurethane slurry 2 is used to impregnate the A side of the sea-island fiber non-woven fabric, the penetration depth of the polyurethane slurry 2 can only reach 0.17 mm, and the liquid carrying rate 2 of the sea-island fiber non-woven fabric can only reach 5%.

[0072] The water penetration of the final microfiber base fabric is 0.71mg, the softness is 5.2, and the water vapor permeability is 1.8mg / (cm 2 ·h).

[0073] Compared with Example 1, the water penetration of the microfiber base cloth in Comparative Example 2 is significantly increased. This is because the resin solid content in the polyurethane slurry 1 is too high. When the polyurethane slurry 2 is used to impregnate the A side of the island fiber non-woven fabric, the penetration depth of the polyurethane slurry 2 is limited, and the liquid carrying rate 2 of the island fiber non-woven fabric is too low, which affects the formation of the subsequent waterproof layer.

[0074] Comparative Example 3

[0075] A method for preparing a microfiber-based cloth is different from that of Example 1 in that the resin solid content of the polyurethane slurry 2 is 20%.

[0076] The water penetration of the final microfiber base fabric is 0.23mg, the softness is 5.3, and the water vapor permeability is 1.5mg / (cm 2 ·h).

[0077] Compared with Example 1, the water penetration of the microfiber base cloth in Comparative Example 3 is significantly increased. This is because the resin solid content in the polyurethane slurry 2 is too low, which affects the density of the waterproof layer.

[0078] Comparative Example 4

[0079] A method for preparing a microfiber-based cloth is different from that of Example 1 in that the resin solid content of the polyurethane slurry 3 is 4%.

[0080] Since the solid content of the resin in the polyurethane slurry 3 is too low, the thickness of the base fabric is unbalanced.

[0081] Comparative Example 5

[0082] A method for preparing a microfiber-based cloth is different from that of Example 1 in that the resin solid content of the polyurethane slurry 3 is 10%.

[0083] The water penetration of the final microfiber base fabric is 0.18mg, the softness is 4.8, and the water vapor permeability is 0.6mg / (cm 2 ·h).

[0084] Compared with Example 1, the water vapor permeability of the microfiber base cloth in Comparative Example 5 is significantly reduced. This is because the resin solid content in the polyurethane slurry 3 is too high and the fluidity is poor, making it difficult to quickly and evenly penetrate into the B side of the island fiber non-woven fabric, resulting in a reduction in the size and number of pores formed in the macroporous layer, and the connectivity between the pores deteriorates, compressing the water vapor transmission channel.

[0085] Comparative Example 6

[0086] A method for preparing a microfiber base fabric, which differs from Example 1 only in that: when the A side of the island fiber non-woven fabric is impregnated with polyurethane slurry 1, the penetration depth of polyurethane slurry 1 is 1.6 mm, and the liquid carrying rate 1 of the island fiber non-woven fabric is 48%; when the B side of the island fiber non-woven fabric is impregnated with polyurethane slurry 3, the penetration depth of polyurethane slurry 3 is 0.97 mm, and the liquid carrying rate is 34%.

[0087] Since the penetration depth of the polyurethane slurry 1 is too small, the base fabric is too soft and the structure collapses.

[0088] Comparative Example 7

[0089] A method for preparing a microfiber base fabric differs from Example 1 only in that: when the A side of the island fiber non-woven fabric is impregnated with polyurethane slurry 1, the penetration depth of polyurethane slurry 1 is 2.2 mm, and the liquid carrying rate 1 of the island fiber non-woven fabric is 69%; when the B side of the island fiber non-woven fabric is impregnated with polyurethane slurry 3, the penetration depth of polyurethane slurry 3 is 0.37 mm, and the liquid carrying rate is 13%.

[0090] The water penetration of the final microfiber base fabric is 0.07mg, the softness is 5, and the water vapor permeability is 0.6mg / (cm 2 ·h).

[0091] Compared with Example 1, the water vapor permeability of the microfiber base cloth in Comparative Example 7 is significantly reduced. This is because the penetration depth of the polyurethane slurry 1 is too large, resulting in too small a proportion of the macroporous layer, which in turn leads to a decrease in the air permeability of the base cloth.

[0092] Example 2

[0093] A method for preparing a three-layer waterproof imitation leather microfiber base fabric, the specific steps are as follows:

[0094] (1) Material preparation:

[0095] Sea island fiber nonwoven fabric: density 0.27g / cm 3 , thickness d is 2.5 mm;

[0096] Polyurethane slurry 1: a foamed polyurethane slurry with a resin solid content of 14%, obtained from Shanghai Huide Technology Co., Ltd., brand HDD-3060HTD, and diluted with DMF;

[0097] Polyurethane slurry 2: A defoaming polyurethane slurry was prepared by diluting a product (brand 4050, produced by Jiangsu Huafeng Microfiber Materials Co., Ltd.) with DMF, followed by the addition of a silicone resin (produced by Zhejiang Jinglian Chemical Co., Ltd., brand JS-MS) and a defoamer (produced by Jiangsu Jianyu Additives Technology Co., Ltd., brand GPE-30). The polyurethane slurry had a resin solids content of 24%, a silicone resin content of 5 wt%, and a defoamer content of 0.5 wt%.

[0098] Polyurethane slurry 3: a foamed polyurethane slurry with a resin solid content of 5%, obtained by diluting a product of Shanghai Huide Technology Co., Ltd., brand HDD-3060HTD, with DMF;

[0099] DMF solution 1: composed of DMF and water in a mass ratio of 1:1;

[0100] DMF solution 2: composed of DMF and water in a mass ratio of 1:3;

[0101] Toluene;

[0102] (2) Impregnation treatment:

[0103] The two sides of the island fiber non-woven fabric are respectively designated as side A and side B. The A side of the island fiber non-woven fabric is first impregnated with polyurethane slurry 1 to a penetration depth of 1.86 mm, so that the liquid carrying rate 1 of the island fiber non-woven fabric is 54%. The A side of the island fiber non-woven fabric is then impregnated with polyurethane slurry 2 to a penetration depth of 0.35 mm, so that the liquid carrying rate 2 of the island fiber non-woven fabric is 10%. The B side of the island fiber non-woven fabric is then impregnated with polyurethane slurry 3 to a penetration depth of 0.64 mm, so that the liquid carrying rate 3 of the island fiber non-woven fabric is 22%.

[0104] (3) Solidification treatment:

[0105] The impregnated island fiber nonwoven fabric is partially immersed in DMF solution 1 to convert the polyurethane slurry 1 into a gel state, and then the entire fabric is immersed in DMF solution 2;

[0106] (4) Post-processing:

[0107] The sea island fiber nonwoven fabric after coagulation treatment was washed, reduced in weight, and dried (at a temperature of 128° C.) in sequence.

[0108] The final three-layer waterproof imitation leather microfiber fabric has a water penetration of 0.12 mg, a softness of 5.5, and a water vapor permeability of 1.1 mg / (cm 2 ·h).

[0109] Comparative Example 8

[0110] A method for preparing a microfiber base fabric, which differs from Example 2 only in that: when the A side of the island fiber non-woven fabric is impregnated with polyurethane slurry 1, the liquid pick-up rate 1 of the island fiber non-woven fabric is 59%, and when the A side of the island fiber non-woven fabric is impregnated with polyurethane slurry 2, the penetration depth of polyurethane slurry 2 is 0.21 mm, and the liquid pick-up rate is 6%.

[0111] The water penetration of the final microfiber base fabric is 0.27mg, the softness is 5.5, and the water vapor permeability is 1.2mg / (cm 2 ·h).

[0112] Compared with Example 2, the water penetration of the microfiber base cloth in Comparative Example 8 is significantly increased. This is because when the A side of the island fiber non-woven fabric is impregnated with the polyurethane slurry 1, the liquid carrying rate 1 of the island fiber non-woven fabric is too high, which compresses the immersion space of the subsequent polyurethane slurry 2, making it difficult for the slurry 2 to be fully filled, resulting in a decrease in the density of the waterproof layer and an inability to form a continuous and high-density protective structure.

[0113] Comparative Example 9

[0114] A method for preparing a microfiber base fabric differs from Example 2 only in that: when the A side of the island fiber non-woven fabric is impregnated with polyurethane slurry 1, the liquid pick-up rate 1 of the island fiber non-woven fabric is 51%, and when the A side of the island fiber non-woven fabric is impregnated with polyurethane slurry 2, the penetration depth of polyurethane slurry 2 is 0.5 mm, and the liquid pick-up rate is 14%.

[0115] The water penetration of the final microfiber base fabric is 0.05mg, the softness is 5.3, and the water vapor permeability is 0.5mg / (cm 2 ·h).

[0116] Compared with Example 2, the water vapor permeability of the microfiber base cloth in Comparative Example 9 is significantly reduced. This is because when the A side of the island fiber non-woven fabric is impregnated with the polyurethane slurry 1, the liquid carrying rate 1 of the island fiber non-woven fabric is too low, resulting in insufficient filling of the polyurethane slurry 1 and weakened structural support of the dense layer, which leads to excessive penetration depth of the subsequently impregnated polyurethane slurry 2 and excessive thickness of the waterproof layer. The high density characteristics of the waterproof layer block the channel for water vapor transmission.

[0117] Example 3

[0118] A method for preparing a three-layer waterproof imitation leather microfiber base fabric, the specific steps are as follows:

[0119] (1) Material preparation:

[0120] Sea island fiber nonwoven fabric: density 0.29g / cm 3 , thickness d is 2.43 mm;

[0121] Polyurethane slurry 1: a foamed polyurethane slurry with a resin solid content of 15%, obtained by diluting a product of Shanghai Huide Technology Co., Ltd., brand HDD-3060HTD, with DMF;

[0122] Polyurethane slurry 2: Defoaming polyurethane slurry, prepared by diluting product 4050 (manufactured by Jiangsu Huafeng Microfiber Materials Co., Ltd.) with DMF, and then adding silicone resin (manufactured by Zhejiang Jinglian Chemical Co., Ltd., brand JS-MS) and defoamer (manufactured by Jiangsu Jianyu Additives Technology Co., Ltd., brand GPE-30); polyurethane slurry 2 had a resin solids content of 22%, a silicone resin content of 5wt%, and a defoamer content of 0.5wt%;

[0123] Polyurethane slurry 3: a foamed polyurethane slurry with a resin solid content of 7%, obtained by diluting a product of Shanghai Huide Technology Co., Ltd., brand HDD-3060HTD, with DMF;

[0124] DMF solution 1: composed of DMF and water in a mass ratio of 1:1.2;

[0125] DMF solution 2: composed of DMF and water in a mass ratio of 1:3.5;

[0126] Toluene;

[0127] (2) Impregnation treatment:

[0128] The two sides of the island fiber non-woven fabric are respectively designated as side A and side B. The A side of the island fiber non-woven fabric is first impregnated with polyurethane slurry 1 to a penetration depth of 2 mm, so that the liquid carrying rate 1 of the island fiber non-woven fabric is 58%. The A side of the island fiber non-woven fabric is then impregnated with polyurethane slurry 2 to a penetration depth of 0.43 mm, so that the liquid carrying rate 2 of the island fiber non-woven fabric is 12%. The B side of the island fiber non-woven fabric is then impregnated with polyurethane slurry 3 to a penetration depth of 0.43 mm, so that the liquid carrying rate 3 of the island fiber non-woven fabric is 15%.

[0129] (3) Solidification treatment:

[0130] The impregnated island fiber nonwoven fabric is partially immersed in DMF solution 1 to convert the polyurethane slurry 1 into a gel state, and then the entire fabric is immersed in DMF solution 2;

[0131] (4) Post-processing:

[0132] The sea island fiber nonwoven fabric after coagulation treatment was washed, reduced in weight, and dried (at a temperature of 130° C.) in sequence.

[0133] The final three-layer waterproof imitation leather microfiber fabric has a water penetration of 0.07 mg, a softness of 5.8, and a water vapor permeability of 0.9 mg / (cm 2 ·h).

[0134] Example 4

[0135] A method for preparing a three-layer waterproof imitation leather microfiber base fabric is different from Example 1 only in that: during the coagulation treatment, only one step is performed, that is, the impregnated sea-island fiber non-woven fabric is entirely immersed in the DMF solution 2.

[0136] The final three-layer waterproof imitation leather microfiber fabric has a water penetration of 0.2 mg, a softness of 5.2, and a water vapor permeability of 1.5 mg / (cm 2 ·h).

[0137] Example 5

[0138] A method for preparing a three-layer waterproof imitation leather microfiber base fabric is different from Example 1 only in that: during the coagulation treatment, only one step is performed, that is, the sea-island fiber non-woven fabric after the impregnation treatment is entirely immersed in the DMF solution 1.

[0139] The water penetration of the three-layer waterproof imitation leather microfiber fabric was 0.06 mg, the softness was 5, and the water vapor permeability was 0.8 mg / (cm 2 ·h).

[0140] Comparing Example 1 with Examples 4-5, it can be seen that the island-in-the-sea fiber nonwoven fabric, after being impregnated with polyurethane slurry, is first partially immersed in a high-concentration DMF solution 1, causing the polyurethane slurry 1 to transform into a gel state, followed by conventional coagulation. Compared to direct coagulation using conventional methods, this results in smaller cells formed during the resin coagulation process on the surface, thereby creating a material structure with a gradient of density from the inside out. While maintaining breathability, this further optimizes the waterproofness of the microfiber base fabric surface.

Claims

1. A method for preparing a three-layer waterproof imitation leather microfiber base fabric, comprising the steps of impregnating a sea-island fiber nonwoven fabric with a polyurethane slurry, characterized in that: The polyurethane sizing agents are solvent-based sizing agents, with a total of 3 types, respectively denoted as polyurethane sizing agent 1, polyurethane sizing agent 2, and polyurethane sizing agent 3; Polyurethane sizing agent 1 is a foaming polyurethane sizing agent with a resin solid content of 13 - 15%; polyurethane sizing agent 2 is a defoaming polyurethane sizing agent with a resin solid content of 21 - 24% and contains silicone resin; polyurethane sizing agent 3 is a foaming polyurethane sizing agent with a resin solid content of 5 - 7%; The two sides of the sea-island fiber non-woven fabric are respectively denoted as side A and side B, and the thickness of the sea-island fiber non-woven fabric is denoted as d; When impregnating the sea-island fiber non-woven fabric with the polyurethane sizing agent, first impregnate side A of the sea-island fiber non-woven fabric with polyurethane sizing agent 1 until the penetration depth of polyurethane sizing agent 1 is d1, so that the liquid pick-up rate 1 of the sea-island fiber non-woven fabric is 52 - 58%, d1 < d. Then impregnate side A of the sea-island fiber non-woven fabric with polyurethane sizing agent 2 until the penetration depth of polyurethane sizing agent 2 is d2, so that the liquid pick-up rate 2 of the sea-island fiber non-woven fabric is 8 - 12%, d2 < d1. Then impregnate side B of the sea-island fiber non-woven fabric with polyurethane sizing agent 3 until the penetration depth of polyurethane sizing agent 3 is d3, so that the liquid pick-up rate 3 of the sea-island fiber non-woven fabric is 15 - 30%, d3 = d - d1; d is 2.43 - 2.57 mm, d1 is 1.71 - 2.00 mm, and d2 is 0.28 - 0.43 mm.

2. The method for preparing a three-layer waterproof imitation leather microfiber fabric according to claim 1, characterized in that: The density of sea island fiber nonwoven fabric is 0.25-0.29g / cm 3 .

3. The method for preparing a three-layer waterproof imitation leather microfiber fabric according to claim 1, characterized in that: After impregnating the sea-island fiber non-woven fabric with the polyurethane sizing agent, coagulation, water washing, weight reduction, and drying are successively carried out.

4. The method for preparing a three-layer waterproof imitation leather microfiber fabric according to claim 3, characterized in that: Coagulation means immersing the entire sea-island fiber non-woven fabric impregnated with the polyurethane sizing agent into the DMF solution; The DMF solution is composed of DMF and water with a mass ratio of 1:0.8 - 1.

2.

5. The method for preparing a three-layer waterproof leather-like microfiber fabric according to claim 3, characterized in that: Coagulation means immersing the entire sea-island fiber non-woven fabric impregnated with the polyurethane sizing agent into the DMF solution; The DMF solution is composed of DMF and water with a mass ratio of 1:2.5 - 3.

5.

6. The method for preparing a three-layer waterproof leather-like microfiber fabric according to claim 3, characterized in that: Coagulation means first partially immersing the sea-island fiber non-woven fabric impregnated with the polyurethane sizing agent into DMF solution 1 to make polyurethane sizing agent 1 turn into a gel state, and then immersing the entire sea-island fiber non-woven fabric impregnated with the polyurethane sizing agent into DMF solution 2; DMF solution 1 is composed of DMF and water with a mass ratio of 1:0.8 - 1.2; DMF solution 2 is composed of DMF and water with a mass ratio of 1:2.5 - 3.

5.

7. The method for preparing a three-layer waterproof leather-like microfiber fabric according to any one of claims 1 to 6, characterized in that: The water penetration of the three-layer waterproof imitation leather microfiber base fabric is ≤0.2mg, the softness is above 5.0, and the water vapor permeability is>0.8mg / (cm 2 ·h).

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