Preparation method and application of microfiber base cloth with low oligomer urethane content

Abstract

The application relates to a preparation method and application of a microfiber base fabric with low oligomer urethane content, and the preparation method is as follows: sequentially laying a first island fiber web, a woven fabric and a second island fiber web from bottom to top, carrying out needle punching to prepare a composite non-woven fabric; then carrying out heating and ironing treatment on the obtained composite non-woven fabric to realize complete shrinkage of the composite non-woven fabric; then immersing the ironed composite non-woven fabric in a water-based polyurethane preparation solution, and then carrying out drying; and then carrying out a fiber opening process to prepare a product, wherein the polyurethane content in the base fabric is greater than or equal to 10 wt% and less than 25%; and the application is that the product is subjected to dyeing treatment to prepare low-color-migration microfiber leather; the method is simple, the prepared product has lower polyurethane content and small deformation, and has good dimensional stability; and the product is applied to dyeing, and has good dyeing effect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water-based microfiber suede, and relates to a preparation method and application of a microfiber base cloth with low oligomeric urethane content. BACKGROUND

[0002] When polyester microfiber leather is dyed, it is difficult to remove the dyes adsorbed by the polyurethane, which is the main reason for the migration of dyes to the surface of other materials in the subsequent application process. In order to remove the dyes in the polyurethane and gaps to improve color migration, multiple reduction treatments are required, which will bring a large amount of wastewater, and the COD of the wastewater is very high, which brings great trouble to wastewater treatment. Alternatively, the amount of polyurethane can be reduced to facilitate the removal of dyes (in addition, there may be other design requirements to reduce the amount of polyurethane), but too little polyurethane will have weak binding to the fibers and will not play a supporting role, resulting in poor dimensional stability of the microfiber leather.

[0003] Patent CN1625626A discloses a composite sheet for artificial leather with low elongation and good softness, which provides a new design for reducing the amount of polyurethane impregnation, uses a textile fabric as a reinforcing material, inserts a non-woven microfiber fabric layer, and uses a needle to puncture and mechanically combine the microfibers of the non-woven fabric layer and the yarn of the fabric layer. However, this method only relies on the shape of the textile fabric being more rigid than the non-woven fabric to improve the dimensional stability of the fabric by replacing a portion of the non-woven fabric, but this method does not fundamentally change the deformability of the single-structure microfiber leather, and the improvement effect is minimal, and a large amount of polyurethane (25wt%) is still required, which will still cause the polyurethane to adsorb more dyes, which will migrate to the surface of other materials in the subsequent application process.

[0004] Therefore, it is of great significance to study a preparation method and application of a microfiber base cloth with lower polyurethane content, small deformation, and good dimensional stability. SUMMARY

[0005] To solve the problems in the prior art, the application provides a preparation method and application of a microfiber base cloth with low oligomeric urethane content.

[0006] To achieve the above-mentioned purposes, the application adopts the following solutions:

[0007] A preparation method of a microfiber base cloth with low oligomeric urethane content, comprising the following steps:

[0008] (1) Preparation of a composite non-woven fabric;

[0009] The first island fiber web, the woven fabric and the second island fiber web are sequentially laid from bottom to top, and a composite nonwoven fabric is prepared by needling to obtain a composite nonwoven fabric composed of a first island fiber layer, a woven fabric layer and a second island fiber layer; the first island fiber and the second island fiber pass through the pores of the woven fabric layer under the driving of the needles, and the two fiber webs are intertwined to form cross-linking points and are integrated into one;

[0010] (2) heat shrinkage ironing process;

[0011] The composite nonwoven fabric obtained in step (1) is subjected to heat ironing treatment, and complete shrinkage of the composite nonwoven fabric is realized in this stage to obtain an ironed composite nonwoven fabric; in the ironed composite nonwoven fabric, the thickness ratio of the second island fiber layer to the first island fiber layer is 1:1.5-2:1; the thickness of the woven fabric accounts for 10-20% of the total thickness of the ironed composite nonwoven fabric; the smaller the thickness of the first island fiber layer, the more intensive the planar distribution of polyurethane, but too small thickness will lead to stiff hand feeling of the first island fiber layer, so it is desirable to have a smaller thickness of the first island fiber layer under the premise of maintaining hand feeling, therefore, the suitable thickness ratio control range is 1:1.5-2:1. If the thickness of the woven fabric accounts for too small a proportion of the total thickness of the composite nonwoven fabric, on the one hand, it has little effect on improving the entanglement of fibers and the straightness of island fibers, and on the other hand, it cannot buffer the shrinkage difference between the upper and lower island fiber layers, which is easy to cause uneven base fabric, and too large thickness of the woven fabric will lead to stiff hand feeling of the composite nonwoven fabric; the fibers passing through the pores of the woven fabric after heat shrinkage fixation are like "pillars" penetrating the upper and lower three layers, which makes the base fabric full and upright;

[0012] (3) impregnation and curing process;

[0013] The ironed composite nonwoven fabric after step (2) is immersed in a water-based polyurethane preparation solution (the water-based polyurethane preparation solution is a conventional immersion solution prepared from a water-based polyurethane solution, a thickening agent and a defoaming agent), and then dried to completely cure the polyurethane resin;

[0014] (4) fiber opening process;

[0015] The composite nonwoven fabric after immersion and drying in step (3) is subjected to fiber opening to dissolve the sea phase in the island fibers to obtain a super fiber base fabric with low polyurethane content; the polyurethane content in the super fiber base fabric with low polyurethane content is ≥10wt% and <25wt%, and the polyurethane content in the final super fiber base fabric is controlled within this range by controlling the concentration and liquid carrying rate of polyurethane in the water-based polyurethane preparation solution in step (3);

[0016] The concentration of polyurethane in the aqueous polyurethane preparation solution can be, for example, 10 wt%, 13 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 22 wt%, 24 wt%, etc. The selection of the concentration of polyurethane in the preparation solution and the wet-out rate is not particularly limited, and can be controlled according to the desired content of polyurethane in the final microfiber base fabric and the specifications of the impregnated non-woven fabric, to set a reasonable polyurethane concentration and wet-out rate. The amount of polyurethane adhered to the non-woven fabric is controlled by adjusting the concentration of polyurethane. The resin content is at least 10%, and the polyurethane is mainly adhered to the "struts" and fiber cross-linking points described above, serving to tighten the "struts" and better maintain the upright, non-collapsed, and non-deformable nature of the base fabric during subsequent fiber splitting. Compared to the prior art, which requires at least 25% or more polyurethane, the present application can ensure that the microfiber leather is not easily deformed by changing the fiber architecture of the non-woven fabric, even with a low amount of polyurethane. However, it is necessary to ensure at least 10% polyurethane content (polyurethane content / weight ratio of microfiber base fabric), and too little resin will still cause the microfiber leather to deform. The upper limit of the specific polyurethane content can be determined according to specific needs, for example, to solve the problem of color migration, the resin content is controlled at 10-15% which is appropriate.

[0017] The fiber splitting process is a conventional method in the industry, and the choice of splitting method and post-treatment method can be determined according to specific needs. For example, if the sea phase of the island fiber is water-soluble fiber, a water reduction method such as that disclosed in CN113862931A should be selected; if LDPE is selected as the sea phase, a toluene reduction method can be selected. For environmental considerations, it is preferred to use a water-soluble polymer as the sea phase.

[0018] The above microfiber base fabric can further undergo conventional post-treatment processes to obtain microfiber leather, such as skin grinding, dyeing, and wrinkle processing, to obtain an aqueous microfiber leather with low polyurethane content.

[0019] As described above, in the preparation method of a microfiber base fabric with low polyurethane content, the shrinkage rate of the island fibers laid above the woven fabric is σ1, the shrinkage rate of the fibers constituting the woven fabric is σ2, and the shrinkage rate of the bottom layer of island fibers laid below the woven fabric is σ3, σ2-σ1 is 4-6%, and σ3-σ2 is 4-6%.

[0020] Using three layers of fibers with different shrinkage rates, the shrinkage rate increases progressively, ensuring the maximum density difference between the upper and lower layers while controlling the smoothness of the nonwoven fabric. If only a two-layer structure of one layer of high-shrinkage island fiber and one layer of low-shrinkage island fiber is used, the shrinkage rate difference between the upper and lower layers needs to be deliberately increased to maximize the density difference. If the shrinkage difference at the boundary between the two layers is too large during shrinkage, wrinkles are likely to appear on the surface of the nonwoven fabric. In addition, if only a two-layer structure of one layer of island fiber and one layer of woven fabric is used, the woven fabric layer often needs to be made of special microfibers; otherwise, the woven fabric layer will have a stiff feel, which is significantly different from the nonwoven fabric layer. Moreover, due to the limited thickness of the woven fabric layer, the actual effect of increasing the polyurethane distribution density on the same plane through shrinkage difference is not significant.

[0021] The selection of σ1 and σ3 should be based on the setting of σ2, with σ1 < σ2 < σ3, to obtain a gradient distribution of the composite nonwoven fabric along the fiber thickness direction. σ2-σ1≥4%, σ3-σ2≥4%, so that the composite nonwoven fabric obtained in this way exhibits a sufficient gradient change trend in fabric density along the fiber thickness direction after heat shrinkage, which allows polyurethane to have sufficient driving force to deposit in the lower layer during the impregnation and curing process, thereby increasing the polyurethane distribution density on the same plane and further improving the uprightness of the "support fibers"; σ2-σ1≤6%, σ3-σ2≤6%, the values ​​of σ2-σ1 and σ3-σ2 should not be too high, otherwise the excessive difference in fiber shrinkage rate will cause the nonwoven fabric to be uneven overall, producing a wrinkled appearance.

[0022] As described above, in the preparation method of a low polyurethane content microfiber base fabric, the shrinkage rate σ2 of the fibers constituting the woven fabric is 8-12%. During the needle punching process, the fibers of the upper and lower layers are inserted into the pores of the middle layer. The middle layer with a high shrinkage rate is selected in order to tighten the pores after the heat shrinking and ironing process, so that the fibers in the pores are more tightly entangled, and the resulting composite fabric is also more rigid.

[0023] As described above, in the preparation method of a low-polyurethane content microfiber base fabric, the pore diameter between the fibers constituting the woven fabric is 800-1200 μm. During needle punching, the fibers lying flat in the upper and lower layers move along the thickness direction under the action of the needle and become upright. When the needle passes through the woven fabric layer, the warp and weft fibers slide under force, allowing the needle to pass through the "well" shaped holes formed by the warp and weft fibers. The driven fibers are orderly inserted into the "well" shaped holes of the woven fabric layer like chopsticks. The size of the pores of different woven fabrics determines the distribution density of "support fibers" per unit area. Too small a pore size will cause excessive resistance to the needle passage, which is not conducive to the passage of fibers and causes the fiber bundles inserted into the woven fabric yarn to become entangled with the fibers of the woven fabric. This will result in an uneven fabric surface and a rough and stiff feel, especially after shrinkage. Too large a pore size will reduce the binding of the "well" shaped holes of the woven fabric to the fibers.

[0024] In the preparation method of the low polyurethane content microfiber base fabric described above, the needle punching density in step (1) is 3000-4000 needles / cm. 2 In the nonwoven fabric processing, an appropriate needle punching density should be selected. Too high a needle punching density will damage the fibers of the woven fabric, while too low a needle punching density will result in too few "support fibers" distributed in the "well" shaped holes, which is not conducive to obtaining a stable fiber skeleton structure.

[0025] The present invention also provides an application of a low polyurethane content microfiber base fabric prepared by the method described in any of the preceding claims, characterized in that: the low polyurethane content microfiber base fabric is dyed to prepare low color migration microfiber leather.

[0026] As a preferred technical solution:

[0027] The application of a low polyurethane content microfiber base fabric as described above, wherein the polyurethane content in the low polyurethane content microfiber base fabric is 10-15 wt%.

[0028] Invention principle:

[0029] Existing designs typically use a single-structure needle-punched nonwoven fabric as a skeleton, with polyurethane resin filling the gaps between the nonwoven fibers or adhering to the fiber surface to create a microfiber base fabric. Under external forces, the relative positions of the fibers in the nonwoven fabric, built with a fiber skeleton, undergo significant changes, making the nonwoven fabric prone to deformation. Cured polyurethane helps to fix the fibers, particularly the "pillar fibers" formed by the needle punches. These "pillar fibers" are the core structure of the nonwoven fabric skeleton and are crucial for forming fiber entanglement points. If there is insufficient polyurethane, the microfiber base fabric is still prone to deformation due to insufficient fixation points. Therefore, a certain amount of polyurethane needs to be added to obtain sufficient fixation points to improve the deformation of the microfiber base fabric.

[0030] In general, microfiber base fabrics require at least 25% polyurethane (polyurethane content / weight ratio of microfiber base fabric) to obtain a microfiber base fabric that is not easily deformed. However, as described in the background art, some problems with the prior art need to be improved by reducing the polyurethane content. Therefore, this invention, from the perspective of nonwoven fabric structural design, combines the adjustment of polyurethane distribution to obtain a microfiber base fabric that can achieve the effect of not being easily deformed even under relatively low polyurethane content conditions.

[0031] The present application improves in the following two aspects: first, the woven cloth is introduced as an intermediate layer, the "supporting fibers" of the non-woven fabric are fixed in the pores of the woven cloth, and the large shrinkage of the pores can effectively fasten the "supporting fibers", replacing the original effect of fixing the "supporting fibers" by polyurethane; second, by using the feature that the curing process of water-based polyurethane makes it easier to deposit on the surface of high-density fibers, the design with a density gradient distribution can be combined to make the water-based polyurethane more concentrated on one side. Compared with the uniform distribution of water-based polyurethane, under the same polyurethane content, there is a region with higher water-based polyurethane distribution density in the direction perpendicular to the "supporting fibers", which is used to pin the "supporting fibers". Thus, the present application can ensure that the microfiber leather does not deform while greatly reducing the polyurethane content (less than 15wt%).

[0032] Regarding the first aspect, the present application introduces a three-layer structure on the basis of the original needle-punched non-woven fabric design, with the upper and lower layers being fiber webs of non-woven fabric and the middle layer being a woven cloth woven with warp and weft. During needle punching, the fibers of the upper and lower layers will pass through the pores between the warp and weft fibers in the middle layer of woven cloth, and the pores in the middle layer of woven cloth play a role in fixing the relative positions of the fibers of the upper and lower layers of non-woven fabric. Further, by using the high shrinkage of the fibers in the middle layer, complete shrinkage is achieved under heat treatment process, so that the fibers interpenetrating the upper and lower layers are tightened and more upright, and the relative positions of the fibers are not easily changed under external force. By adjusting the shrinkage, microfiber leather with different angle resistance to deformation can be obtained. On the one hand, in the direction perpendicular to the base cloth, the woven cloth plays a role in inhibiting the laying of fibers in the interior of the non-woven fabric, and the interpenetration and cross-linking of fibers in the pores thereof more effectively improve the uprightness of such "supporting fibers";

[0033] Regarding the second aspect, by selecting fibers with different shrinkage abilities, the composite non-woven fabric obtains a gradient change in fabric density along the thickness direction of the fabric after the heat shrinkage ironing process. When impregnated with polyurethane, the polyurethane is easily deposited on the side with high fabric density. By changing the fabric density distribution, the deposition distribution of polyurethane is changed. Compared with uniform deposition in the three-layer fabric, the deposition is biased towards the lower layer of fibers, which is beneficial to relatively increase the distribution density of polyurethane in the plane, so that the bonding points of polyurethane are more, which is more conducive to fixing the "supporting fibers" and supporting the entire fiber framework to be less prone to collapse.

[0034] Advantages

[0035] (1) The present application is a method for preparing a microfiber base cloth with low polyurethane content, which uses woven cloth as a support point, and the shrinkage of the woven cloth to improve the upright stability of the "supporting fibers" and strengthen the density of the support points, thereby reducing the content of polyurethane resin while maintaining the non-deformability of the microfiber base cloth.

[0036] (2) The superfiber base cloth with low oligomer urethane content of the application has low color migration during dyeing. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 Schematic diagram of the process of inserting island fibers in the gap of woven cloth. DETAILED DESCRIPTION

[0038] The application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the application and not to limit the scope of the application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the application after reading the content taught by the application, and these equivalent forms also fall within the scope defined by the appended claims.

[0039] The test methods involved in the detailed description are as follows:

[0040] (1) Fiber shrinkage rate: Take 50 fibers, measure their length L1, place them in an oven at 140℃ for 10 min, measure their length L2 after cooling, and the shrinkage rate is (L1-L2) / L1*100%. The average value is measured.

[0041] (2) Pore diameter between fibers: Randomly take 100 pores of the woven cloth, measure the side length of each square hole, and define the average value as the pore diameter.

[0042] (3) Determination standard of complete shrinkage of non-woven fabric: Randomly take three samples of the non-woven fabric after shrinkage and ironing, measure the length L3, place them in an oven at 140℃ for 30 min, measure the length L4 after cooling, and when (L3-L4) / L3*100%≤0.5%, it is considered that the non-woven fabric is completely shrunk. If one of the samples is abnormal, it should be retested. If the retest is still abnormal, it is determined that the non-woven fabric is not completely shrunk.

[0043] (4) Elongation rate: The elongation rate is the static elongation rate, which is a material physical property index for measuring whether the superfiber base cloth with low oligomer urethane content is easy to deform under external force. The test is carried out according to the PV3909 standard with a load of 50N.

[0044] (5) Test method of color migration: Refer to ISO 15701 / IUF 442.

[0045] In the embodiments, the island fibers in both the first and second island fiber webs are WSPET / PET island fibers, with an island ratio of 30 / 70, 19 islands, and a fineness of 4.0 dtex. The island fibers in the first and second island fiber webs are selected from WSPET / PET island fibers with different shrinkage rates. Since the preparation of WSPET / PET island fibers with different shrinkage rates is not the focus of this application, it will not be elaborated here. The desired shrinkage rate can be adjusted by referring to conventional spinning processes, such as adjusting the drafting temperature and multiple during fiber preparation to achieve a large elastic strain within the fiber, and then relaxing the accumulated elastic strain through shrinkage at high temperatures. Typically, the island ratio can be 50:50 to 20:80, the number of islands can be 6 or more, and the fineness can be 3.0 to 6.0 dtex. Within the range of island fibers commonly used for preparing microfiber leather materials, changes in the island ratio, number of islands, and fineness do not affect the achievement of the invention's objective.

[0046] The control of polyurethane impregnation amount is a prior art technique, and the corresponding calculation process will not be elaborated in subsequent embodiments. Specifically, the weight of the composite nonwoven fabric after deducting the island phase content is obtained by using the island-to-island ratio of the island fibers in the first and second island fiber webs and the actual amount of each layer used in the preparation of the composite nonwoven fabric. By inputting the liquid carry-over rate and the polyurethane content in the microfiber base fabric with low polyurethane content, the weight ratio of polyurethane in the aqueous polyurethane formulation can be calculated. Based on different composite nonwoven fabrics, the polyurethane content in the microfiber base fabric can be controlled to be ≥10wt% and <25wt% by controlling the liquid carry-over rate and the weight ratio of polyurethane in the aqueous polyurethane formulation.

[0047] Example 1

[0048] A method for preparing a microfiber base fabric with low polyurethane content, the specific steps of which are as follows:

[0049] (1) Preparation of raw materials;

[0050] The second island fiber web laid on top of the woven fabric: the shrinkage rate of the island fibers in the second island fiber web is 6%;

[0051] Woven fabric: made of PET, with a shrinkage rate of 10%; the pore diameter between the fibers constituting the woven fabric is 800μm;

[0052] The first island fiber web laid under the woven fabric: the shrinkage rate of the island fibers in the first island fiber web is 14%;

[0053] (2) Preparation of composite nonwoven fabric;

[0054] like Figure 1As shown, the first island fiber web, the woven cloth and the second island fiber web are laid in turn from bottom to top, and are needled by using a single hook needle type (model: R100) with a needling density of 3000 needles / cm 2 ; a composite nonwoven fabric composed of the first island fiber layer, the woven cloth layer and the second island fiber layer is prepared; wherein the grammage of the second island fiber web is 200 g / m 2 , the grammage of the woven cloth is 80 g / m 2 , and the grammage of the first island fiber web is 315 g / m 2 ;

[0055] (3) a heat shrinkage ironing process;

[0056] The composite nonwoven fabric obtained in step (2) is subjected to a heating treatment to realize complete shrinkage of the composite nonwoven fabric, and then is ironed to prepare an ironed composite nonwoven fabric; in the ironed composite nonwoven fabric, the thickness ratio of the second island fiber layer to the first island fiber layer is 1:1.5; the thickness of the woven cloth accounts for 10% of the total thickness of the composite nonwoven fabric;

[0057] The composite nonwoven fabric after the heat shrinkage ironing process has no wrinkles on the surface;

[0058] (4) an impregnation and curing process;

[0059] The composite nonwoven fabric after ironing in step (3) is impregnated with a water-based polyurethane preparation liquid, and then is dried to completely cure the polyurethane resin; the water-based polyurethane preparation liquid is prepared by mixing a water-based polyurethane emulsion (manufacturer: Zhejiang Huafeng Synthetic Resin Co., Ltd., brand: JF-PDY-516HY, polyurethane resin content 50wt%), deionized water, a thickening agent (manufacturer: Dow Chemical, brand: ACRYSOL TT-615) and a defoaming agent (manufacturer: Dow Corning, brand: AFE-1247) to prepare a water-based polyurethane preparation liquid with a polyurethane concentration of 6wt%; wherein the amounts of the deionized water, the thickening agent and the defoaming agent are 723 parts, 10 parts and 0.1 part respectively by weight fraction;

[0060] The liquid retention rate is controlled to be 140%;

[0061] (5) a fibrillation process;

[0062] After the composite nonwoven fabric after impregnation and drying in step (4) is fibrillated, the islands in the island fibers are dissolved out to prepare a low polyurethane content super fiber base cloth.

[0063] The static elongation of the prepared low polyurethane content super fiber base cloth is 10% in the radial direction and 15% in the weft direction, and the polyurethane content in the low polyurethane content super fiber base cloth is 10wt%.

[0064] The low color transfer microfiber base cloth with oligomeric urethane content is subjected to dyeing treatment to prepare low color transfer microfiber leather, and the specific process is as follows:

[0065] The low color transfer microfiber base cloth with oligomeric urethane content is placed in water under the condition of bath ratio of 1:15, and then dispersed dyes are added, the dispersed dyes are 6wt% of the low color transfer microfiber base cloth with oligomeric urethane content, then the temperature is raised to 90℃ at a speed of 2℃ / min, and then the temperature is raised to 135℃ at a speed of 1℃ / min, and the dyeing is kept for 40 minutes, after the dyeing is finished, the temperature is lowered to 60℃, and then washing, reduction, neutralization, washing and drying are carried out.

[0066] The color transfer of the prepared low color transfer microfiber base cloth is 4.5 levels.

[0067] Comparative Example 1

[0068] A preparation method of a low color transfer microfiber base cloth with oligomeric urethane content, which is basically the same as Example 1, except that in step (2), the first island fiber web and the second island fiber web are sequentially laid from bottom to top to prepare a composite non-woven fabric composed of a first island fiber layer and a second island fiber layer (i.e. an inorganic woven cloth layer).

[0069] The low color transfer microfiber base cloth with oligomeric urethane content cannot be successfully prepared, and after the heat shrinkage ironing process in step (3), the surface of the composite non-woven fabric is wrinkled and scrapped.

[0070] Comparing the composite non-woven fabric after the heat shrinkage process of Comparative Example 1 and Example 1, it can be found that in Comparative Example 1, when the intermediate 10% shrinkage rate woven cloth layer is lacking, the first island fiber and the second island fiber with a shrinkage rate difference of 8% exist a huge shrinkage difference at the interweaving interface, and in order to resist the shrinkage difference, wrinkles occur on the surface of the cloth.

[0071] Comparative Example 2

[0072] A preparation method of a low color transfer microfiber base cloth with oligomeric urethane content, which is basically the same as Example 1, except that in step (2), the first island fiber web and the woven cloth are sequentially laid from bottom to top to prepare a composite non-woven fabric composed of a first island fiber layer and a woven cloth layer (i.e. without a second island fiber layer), and the thickness of the first island fiber layer is the sum of the thicknesses of the first island fiber layer and the second island fiber layer in Example 1.

[0073] The static elongation rate of the prepared low color transfer microfiber base cloth with oligomeric urethane content is 26% in the radial direction and 30% in the weft direction.

[0074] Comparing Comparative Example 2 and Example 1, it can be found that the microfiber base cloth prepared by the two-layer structure of the composite non-woven fabric in Comparative Example 2 has a much larger static elongation rate under the same oligomeric urethane content (10wt%), that is, the base cloth is very easy to deform, and has lost its usability.

[0075] Comparative Example 3

[0076] A preparation method of the oligomeric urethane content super fiber base cloth, the specific steps are basically the same as those of Example 1, the difference is only that the shrinkage of the fibers in the woven cloth in step (1) is 6%, the shrinkage of the island fibers in the first island fiber web is 10%, and the shrinkage of the island fibers in the second island fiber web is 2%.

[0077] The static elongation of the prepared oligomeric urethane content super fiber base cloth is 12% in the radial direction and 18% in the weft direction.

[0078] Comparing Comparative Example 3 with Example 1, it can be found that the static elongation of the oligomeric urethane content super fiber base cloth of Comparative Example 3 increases obviously, that is, the fibers are relatively easier to deform under external force. It is speculated that the decrease in the shrinkage of the woven cloth makes the "pillar fibers" that tighten the pores of the woven cloth relatively loose, and the fibers in the base cloth are prone to collapse after being stressed, which causes the base cloth to be easily deformed with external force.

[0079] Comparative Example 4

[0080] A preparation method of the oligomeric urethane content super fiber base cloth, the specific steps are basically the same as those of Example 1, the difference is only that the shrinkage of the fibers in the woven cloth in step (1) is 10%, the shrinkage of the island fibers in the first island fiber web is 13%, and the shrinkage of the island fibers in the second island fiber web is 9%.

[0081] The static elongation of the prepared oligomeric urethane content super fiber base cloth is 12% in the radial direction and 17% in the weft direction.

[0082] Comparing Comparative Example 4 with Example 1, it can be found that the static elongation of the oligomeric urethane content super fiber base cloth of Comparative Example 4 increases obviously, that is, the fibers are relatively easier to deform under external force. Since the shrinkage of the fibers is changed, the density difference between the composite non-woven cloth layers after shrinkage is not obvious, the distribution gradient of the polyurethane is not significant during the polyurethane impregnation stage, which further leads to less concentrated distribution of the polyurethane and weakened fixing effect, resulting in that the material is prone to deformation.

[0083] Comparative Example 5

[0084] A preparation method of the oligomeric urethane content super fiber base cloth, the specific steps are basically the same as those of Example 1, the difference is only that the shrinkage of the fibers in the woven cloth in step (1) is 10%, the shrinkage of the island fibers in the first island fiber web is 17%, and the shrinkage of the island fibers in the second island fiber web is 3%.

[0085] The oligomeric urethane content super fiber base cloth cannot be successfully prepared, and the surface of the composite non-woven cloth is wrinkled after the heat shrinkage ironing process in step (3), which is scrapped.

[0086] Comparing Comparative Example 5 with Example 1, it can be found that too large shrinkage difference can cause wrinkles on the cloth surface.

[0087] Example 2

[0088] A preparation method of a super fiber base cloth with low oligomeric urethane content, the specific steps are as follows:

[0089] (1) Preparation of raw materials;

[0090] The second island fiber web laid above the woven cloth: the shrinkage rate of the island fibers in the second island fiber web is 6%;

[0091] Woven cloth: the material is PET, and the shrinkage rate is 12%; the pore diameter between the fibers constituting the woven cloth is 1000 μm;

[0092] The first island fiber web laid below the woven cloth: the shrinkage rate of the island fibers in the first island fiber web is 18%;

[0093] (2) Preparation of the composite non-woven fabric;

[0094] The first island fiber web, the woven cloth and the second island fiber web are sequentially laid from bottom to top, and are needled by using a single hook needle type (model: R100), and the needling density is 3500 strokes / cm 2 ; a composite non-woven fabric composed of a first island fiber layer, a woven cloth layer and a second island fiber layer is prepared; wherein the grammage of the second island fiber web is 250 g / m 2 , the grammage of the woven cloth is 100 g / m 2 , and the grammage of the first island fiber web is 263 g / m 2 ;

[0095] (3) Heat shrinkage and ironing process;

[0096] The composite non-woven fabric obtained in step (2) is subjected to heat treatment to realize complete shrinkage of the composite non-woven fabric, and then ironing is performed to obtain an ironed composite non-woven fabric; in the ironed composite non-woven fabric, the thickness ratio of the second island fiber layer to the first island fiber layer is 1:1; the thickness of the woven cloth accounts for 15% of the total thickness of the composite non-woven fabric.

[0097] (4) Impregnation and curing process;

[0098] The composite non-woven fabric after ironing in step (3) is immersed in an aqueous polyurethane solution, and then dried to completely cure the polyurethane resin; the aqueous polyurethane solution is prepared by mixing an aqueous polyurethane emulsion (manufacturer: Zhejiang Huafeng Synthetic Resin Co., Ltd., model: JF-PDY-516HY, polyurethane resin content: 50wt%), deionized water, thickener (manufacturer: Dow Chemical, model: ACRYSOL TT-615), and defoaming agent (manufacturer: Dow Corning, model: AFE-1247) to prepare an aqueous polyurethane solution with a polyurethane concentration of 8wt%; wherein the amounts of deionized water, thickener, and defoaming agent are 520 parts, 6 parts, and 0.1 part, respectively, by weight fraction;

[0099] The liquid retention rate is controlled to be 140%;

[0100] (5) a fiber opening process;

[0101] The composite non-woven fabric after immersion and drying in step (4) is opened to dissolve the sea phase in the sea-island fibers to obtain a low-polyurethane-content microfiber base fabric.

[0102] The static elongation of the obtained low-polyurethane-content microfiber base fabric is 9% in the radial direction and 13% in the weft direction, and the polyurethane content in the low-polyurethane-content microfiber base fabric is 13wt%.

[0103] The low-polyurethane-content microfiber base fabric is subjected to dyeing treatment to prepare a low-color-transfer microfiber leather, and the specific process is as follows:

[0104] Under the condition of a bath ratio of 1:15, the low-polyurethane-content microfiber base fabric is placed in water, and then dispersed dyes are added, the amount of the dispersed dyes being 6wt% of the low-polyurethane-content microfiber base fabric, and then the temperature is raised to 90℃ at a rate of 2℃ / min, and then the temperature is raised to 135℃ at a rate of 1℃ / min, and the dyeing is performed for 40 minutes, after which the temperature is lowered to 60℃, and then washing, reduction, neutralization, and washing are performed, and drying is performed.

[0105] The color transfer of the obtained low-color-transfer microfiber base fabric is 4.5 levels.

[0106] Example 3

[0107] A method for preparing a low-polyurethane-content microfiber base fabric, and the specific steps are as follows:

[0108] (1) preparation of raw materials;

[0109] The second sea-island fiber web laid above the woven fabric: the shrinkage rate of the sea-island fibers in the second sea-island fiber web is 8%;

[0110] The woven fabric: the material is PET, and the shrinkage rate is 12%; the pore diameter between the fibers constituting the woven fabric is 1200μm;

[0111] The first island-in-the-sea fiber web laid under the woven fabric: the shrinkage of the island-in-the-sea fibers in the first island-in-the-sea fiber web is 16%;

[0112] (2) Preparation of the composite nonwoven fabric;

[0113] The first island-in-the-sea fiber web, the woven fabric and the second island-in-the-sea fiber web are laid in sequence from bottom to top, and are needled by using a single hook needle type (model: R100) at a needling density of 4000 strokes / cm 2 ; a composite nonwoven fabric composed of a first island-in-the-sea fiber layer, a woven fabric layer and a second island-in-the-sea fiber layer is prepared; wherein the grammage of the second island-in-the-sea fiber web is 350 g / m 2 , the grammage of the woven fabric is 120 g / m 2 , and the grammage of the first island-in-the-sea fiber web is 184 g / m 2 ;

[0114] (3) Heat shrinkage and ironing process;

[0115] The composite nonwoven fabric obtained in step (2) is subjected to a heating treatment to realize complete shrinkage of the composite nonwoven fabric, and then is ironed to obtain an ironed composite nonwoven fabric; in the ironed composite nonwoven fabric, the thickness ratio of the second island-in-the-sea fiber layer to the first island-in-the-sea fiber layer is 2:1; the thickness of the woven fabric accounts for 20% of the total thickness of the composite nonwoven fabric.

[0116] (4) Impregnation and curing process;

[0117] The composite nonwoven fabric after ironing in step (3) is impregnated with an aqueous polyurethane preparation liquid, and then is dried to completely cure the polyurethane resin; the aqueous polyurethane preparation liquid is prepared by mixing an aqueous polyurethane emulsion (manufacturer: Zhejiang Huafeng Synthetic Resin Co., Ltd., brand: JF-PDY-516HY, polyurethane resin content 50 wt%), deionized water, thickening agent (manufacturer: Dow Chemical, brand: ACRYSOL TT-615) and defoaming agent (manufacturer: Dow Corning, brand: AFE-1247) to prepare an aqueous polyurethane preparation liquid with a polyurethane concentration of 9 wt%; wherein the amounts of deionized water, thickening agent and defoaming agent are 450 parts, 5 parts and 0.1 part, respectively, by weight fraction;

[0118] The liquid retention rate is controlled to be 140%;

[0119] (5) Fiber opening process;

[0120] After the composite nonwoven fabric after impregnation and drying in step (4) is opened, the sea phase in the island-in-the-sea fibers is dissolved out, and a superfiber base fabric with low polyurethane content is prepared.

[0121] The elongation of the prepared microfiber base cloth with oligomeric urethane content is 8.5% in the radial direction and 12% in the weft direction, and the polyurethane content in the microfiber base cloth with oligomeric urethane content is 15 wt%.

[0122] The microfiber base cloth with oligomeric urethane content is subjected to dyeing treatment to prepare a low-color-transfer microfiber leather, and the specific process is as follows:

[0123] The microfiber base cloth with oligomeric urethane content is placed in water under the condition of a bath ratio of 1:15, and then a disperse dye is added, the disperse dye being 6 wt% of the microfiber base cloth with oligomeric urethane content, and then the temperature is raised to 90°C at a rate of 2°C / min, and then the temperature is raised to 135°C at a rate of 1°C / min, and the dyeing is kept for 40 minutes, and then the temperature is lowered to 60°C, and then washing, reduction, neutralization, and washing are performed, and drying is performed.

[0124] The color transfer of the prepared microfiber base cloth with low color transfer is 4.0 levels.

[0125] Example 4

[0126] A preparation method of a microfiber base cloth with oligomeric urethane content, and the specific steps are as follows:

[0127] (1) Preparation of raw materials;

[0128] The second island fiber web laid above the woven cloth: the shrinkage rate of the island fibers in the second island fiber web is 7%;

[0129] Woven cloth: the material is PET, and the shrinkage rate is 11%; the pore diameter between the fibers constituting the woven cloth is 800 μm;

[0130] The first island fiber web laid below the woven cloth: the shrinkage rate of the island fibers in the first island fiber web is 17%;

[0131] (2) Preparation of composite non-woven fabric;

[0132] The first island fiber web, the woven cloth, and the second island fiber web are sequentially laid from bottom to top, and needle punching is performed using a single hook needle type (model: R100) at a needle punching density of 3000 pokes / cm 2 ; a composite non-woven fabric composed of a first island fiber layer, a woven cloth layer, and a second island fiber layer is prepared; wherein the grammage of the second island fiber web is 200 g / m 2 , the grammage of the woven cloth is 80 g / m 2 , and the grammage of the first island fiber web is 315 g / m 2 ;

[0133] (3) Heat shrinkage ironing process;

[0134] The composite nonwoven fabric obtained in step (2) is subjected to heat treatment to achieve complete shrinkage of the composite nonwoven fabric, and then is ironed to obtain an ironed composite nonwoven fabric; in the ironed composite nonwoven fabric, the thickness ratio of the second island-in-sea fiber layer to the first island-in-sea fiber layer is 1:1.5; the thickness of the woven fabric accounts for 10% of the total thickness of the composite nonwoven fabric.

[0135] (4) impregnation and curing step;

[0136] The ironed composite nonwoven fabric after step (3) is immersed in an aqueous polyurethane preparation solution, and then is dried to completely cure the polyurethane resin; the aqueous polyurethane preparation solution is prepared by mixing an aqueous polyurethane emulsion (manufacturer: Zhejiang Huafeng Synthetic Resin Co., Ltd., brand: JF-PDY-516HY, polyurethane resin content: 50wt%), deionized water, a thickening agent (manufacturer: Dow Chemical, brand: ACRYSOL TT-615), and a defoaming agent (manufacturer: Dow Corning, brand: AFE-1247) to obtain an aqueous polyurethane preparation solution with a polyurethane concentration of 11wt%; wherein the amounts of deionized water, the thickening agent, and the defoaming agent are 352 parts, 3 parts, and 0.1 part, respectively, by weight fraction;

[0137] The liquid retention rate is controlled to be 140%;

[0138] (5) fiber opening step;

[0139] After the composite nonwoven fabric after step (4) is immersed and dried, the island-in-sea fibers are dissolved out after fiber opening to obtain a low-polyurethane-content super fiber base cloth.

[0140] The static elongation of the obtained low-polyurethane-content super fiber base cloth is 8% in the radial direction and 11% in the weft direction, and the polyurethane content in the low-polyurethane-content super fiber base cloth is 18wt%.

[0141] The low-polyurethane-content super fiber base cloth is subjected to dyeing treatment to prepare a low-color-transfer super fiber leather, and the specific process is as follows:

[0142] Under the condition of a bath ratio of 1:15, the low-polyurethane-content super fiber base cloth is placed in water, and then a disperse dye is added, the disperse dye being 6wt% of the low-polyurethane-content super fiber base cloth, and then the temperature is raised to 90℃ at a rate of 2℃ / min, and then the temperature is raised to 135℃ at a rate of 1℃ / min, and the dyeing is kept for 40 minutes, after which the temperature is lowered to 60℃, and then washing, reduction, neutralization, and washing are performed, and drying is performed.

[0143] The color transfer of the obtained low-color-transfer super fiber base cloth is 3.5 levels.

[0144] Example 5

[0145] A method for preparing a low-polyurethane-content super fiber base cloth, and the specific steps are as follows:

[0146] (1) Preparation of raw materials;

[0147] Second island-in-the-sea fiber web laid above the woven fabric: the shrinkage of the island-in-the-sea fibers in the second island-in-the-sea fiber web is 5%;

[0148] Woven fabric: the material is PET, and the shrinkage is 10%; the pore diameter between the fibers constituting the woven fabric is 1000 μm;

[0149] First island-in-the-sea fiber web laid below the woven fabric: the shrinkage of the island-in-the-sea fibers in the first island-in-the-sea fiber web is 15%;

[0150] (2) Preparation of the composite nonwoven fabric;

[0151] The first island-in-the-sea fiber web, the woven fabric, and the second island-in-the-sea fiber web are laid in sequence from bottom to top, and are needled using a single hook needle type (model: R100) at a needling density of 3500 strokes / cm 2 ; a composite nonwoven fabric composed of a first island-in-the-sea fiber layer, a woven fabric layer, and a second island-in-the-sea fiber layer is prepared; the grammage of the second island-in-the-sea fiber web is 250 g / m 2 , the grammage of the woven fabric is 100 g / m 2 , and the grammage of the first island-in-the-sea fiber web is 263 g / m 2 ;

[0152] (3) Heat shrinkage and ironing process;

[0153] The composite nonwoven fabric obtained in step (2) is subjected to a heating treatment to achieve complete shrinkage of the composite nonwoven fabric, and then is ironed to obtain an ironed composite nonwoven fabric; in the ironed composite nonwoven fabric, the thickness ratio of the second island-in-the-sea fiber layer to the first island-in-the-sea fiber layer is 1:1; the thickness of the woven fabric accounts for 15% of the total thickness of the composite nonwoven fabric.

[0154] (4) Impregnation and curing process;

[0155] The composite nonwoven fabric after ironing in step (3) is impregnated with an aqueous polyurethane preparation liquid, and then is dried to completely cure the polyurethane resin; the aqueous polyurethane preparation liquid is prepared by mixing an aqueous polyurethane emulsion (manufacturer: Zhejiang Huafeng Synthetic Resin Co., Ltd., brand: JF-PDY-516HY, polyurethane resin content 50 wt%), deionized water, thickener (manufacturer: Dow Chemical, brand: ACRYSOL TT-615), and defoaming agent (manufacturer: Dow Corning, brand: AFE-1247) to prepare an aqueous polyurethane preparation liquid with a polyurethane concentration of 13 wt%; wherein the amounts of deionized water, thickener, and defoaming agent are 284 parts, 1.5 parts, and 0.1 part, respectively, by weight fraction;

[0156] The liquid retention rate is controlled to be 140%;

[0157] (5) opening process;

[0158] The composite nonwoven fabric after impregnation and drying in step (4) is opened to dissolve the sea phase in the island fibers, thereby obtaining the microfiber base fabric with low oligomeric urethane content.

[0159] The static elongation of the obtained microfiber base fabric with low oligomeric urethane content is 6% in the radial direction and 9% in the weft direction, and the polyurethane content in the microfiber base fabric with low oligomeric urethane content is 20 wt%.

[0160] The microfiber base fabric with low oligomeric urethane content is subjected to dyeing treatment to prepare a low-color-migration microfiber leather, and the specific process is as follows:

[0161] Under the condition of bath ratio of 1:15, the microfiber base fabric with low oligomeric urethane content is placed in water, and then dispersed dyes are added, the dispersed dyes being 6 wt% of the microfiber base fabric with low oligomeric urethane content, and then the temperature is raised to 90°C at a speed of 2°C / min, and then the temperature is raised to 135°C at a speed of 1°C / min, and the dyeing is kept for 40 minutes, and then the temperature is lowered to 60°C, and then washing, reduction, neutralization, and washing are performed, and then drying is performed.

[0162] The color migration of the obtained low-color-migration microfiber base fabric is 3.5 levels.

[0163] Example 6

[0164] A preparation method of a microfiber base fabric with low oligomeric urethane content, and the specific steps are as follows:

[0165] (1) Preparation of raw materials;

[0166] The second island fiber web laid above the woven fabric: the shrinkage rate of the island fibers in the second island fiber web is 4%;

[0167] Woven fabric: the material is PET, and the shrinkage rate is 8%; the pore diameter between the fibers constituting the woven fabric is 1200 μm;

[0168] The first island fiber web laid below the woven fabric: the shrinkage rate of the island fibers in the first island fiber web is 14%;

[0169] (2) Preparation of composite nonwoven fabric;

[0170] The first island fiber web, the woven fabric, and the second island fiber web are sequentially laid from bottom to top, and are needled by using a single hook needle type (model: R100) at a needling density of 4000 stabs / cm 2 ; thereby obtaining a composite nonwoven fabric composed of a first island fiber layer, a woven fabric layer, and a second island fiber layer; wherein the grammage of the second island fiber web is 350 g / m 2 , and the grammage of the woven fabric is 120 g / m 2, the first island-in-sea fiber web has a grammage of 184 g / m 2 ;

[0171] (3) heat-shrinking and ironing process;

[0172] The composite nonwoven fabric obtained in step (2) is subjected to heat treatment to achieve complete shrinkage of the composite nonwoven fabric, and then ironing is performed to obtain an ironed composite nonwoven fabric; in the ironed composite nonwoven fabric, the thickness ratio of the second island-in-sea fiber layer to the first island-in-sea fiber layer is 2:1; the thickness of the woven fabric accounts for 20% of the total thickness of the composite nonwoven fabric.

[0173] (4) impregnation and curing process;

[0174] The composite nonwoven fabric after ironing in step (3) is impregnated with an aqueous polyurethane preparation solution, and then dried to completely cure the polyurethane resin; the aqueous polyurethane preparation solution is prepared by mixing an aqueous polyurethane emulsion (manufacturer: Zhejiang Huafeng Synthetic Resin Co., Ltd., brand: JF-PDY-516HY, polyurethane resin content: 50wt%), deionized water, thickening agent (manufacturer: Dow Chemical, brand: ACRYSOL TT-615), and defoaming agent (manufacturer: Dow Corning, brand: AFE-1247) to prepare an aqueous polyurethane preparation solution with a polyurethane concentration of 15wt%; wherein the amounts of deionized water, thickening agent, and defoaming agent are 232 parts, 1.2 parts, and 0.1 part, respectively, by weight fraction;

[0175] The liquid retention rate is controlled to be 140%;

[0176] (5) fiber opening process;

[0177] After the composite nonwoven fabric after impregnation and drying in step (4) is subjected to fiber opening, the island phase in the island-in-sea fibers is dissolved out, and a low-polyurethane-content superfiber base cloth is prepared.

[0178] The static elongation of the prepared low-polyurethane-content superfiber base cloth is 5% in the radial direction and 8% in the weft direction, and the polyurethane content in the low-polyurethane-content superfiber base cloth is 23wt%.

[0179] The low-polyurethane-content superfiber base cloth is subjected to dyeing treatment to prepare a low-color-migration superfiber leather, and the specific process is as follows:

[0180] Under the condition of a bath ratio of 1:15, the low-polyurethane-content superfiber base cloth is placed in water, and then dispersed dye is added, the amount of which is 6wt% of the low-polyurethane-content superfiber base cloth, and then the temperature is raised to 90℃ at a rate of 2℃ / min, and then the temperature is raised to 135℃ at a rate of 1℃ / min, and the dyeing is kept for 40 minutes, after which the temperature is lowered to 60℃, and then washing, reduction, neutralization, and washing are performed, and drying is performed.

[0181] The color migration of the prepared low-color-migration superfiber base cloth is 3 levels.

[0182] From the comparison of the above examples, it can be found that when the polyurethane content in the microfiber base cloth with low oligomer urethane content is 10-15wt%, the desired color migration resistance effect can be obtained, and the color migration level reaches level 4 and above.

Claims

1. A method for preparing a microfiber base fabric with low polyurethane content, characterized in that... Includes the following steps: (1) Preparation of composite nonwoven fabric; A first island fiber web, a woven fabric, and a second island fiber web are sequentially laid from bottom to top, and then needle-punched to prepare a composite nonwoven fabric, resulting in a composite nonwoven fabric composed of a first island fiber layer, a woven fabric layer, and a second island fiber layer. The shrinkage rate of the island fibers laid on top of the woven fabric is σ1, the shrinkage rate of the fibers constituting the woven fabric is σ2, and the shrinkage rate of the bottom layer island fibers laid below the woven fabric is σ3. σ2 is 8~12%, σ2-σ1 is 4~6%, and σ3-σ2 is 4~6%. (2) Heat shrinking and ironing process; The composite nonwoven fabric obtained in step (1) is subjected to heat ironing to achieve complete shrinkage of the composite nonwoven fabric, thus obtaining an ironed composite nonwoven fabric; in the ironed composite nonwoven fabric, the thickness ratio of the second island fiber layer to the first island fiber layer is 1:1.5~2:1; the thickness of the woven fabric layer accounts for 10~20% of the total thickness of the ironed composite nonwoven fabric; (3) Impregnation and curing process; The composite nonwoven fabric that has been ironed in step (2) is impregnated with water-based polyurethane formulation and then dried. (4) Fiber opening process; After the composite nonwoven fabric impregnated and dried in step (3) is opened, the marine phase in the island fiber is dissolved to obtain a microfiber base fabric with low polyurethane content; the polyurethane content in the microfiber base fabric with low polyurethane content is ≥10wt% and <25wt%.

2. The method for preparing a low-polyurethane-content microfiber base fabric according to claim 1, characterized in that, In step (1), the pore diameter between the fibers constituting the woven fabric is 800~1200μm.

3. The method for preparing a low-polyurethane-content microfiber base fabric according to claim 1, characterized in that, In step (1), the needle density is 3000~4000 needles / cm². 2 .

4. The application of a low-polyurethane-content microfiber base fabric prepared by the method according to any one of claims 1 to 3, characterized in that: Low-color-migration microfiber leather is prepared by dyeing the microfiber base fabric with low polyurethane content.

5. The application of the low polyurethane content microfiber base fabric according to claim 4, characterized in that, The polyurethane content in the low polyurethane content microfiber base fabric is 10~15wt%.

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