Electromagnetic shielding chromium-free leather prepared through in-situ polypyrrole pretreatment and method thereof

Abstract

The invention discloses a preparation method of in-situ polypyrrole pretreated electromagnetic shielding chromium-free leather, which specifically comprises the following steps: step 1, carrying out polypyrrole in-situ polymerization pretreatment on pickled leather to obtain a pretreated leather blank and a main tanning bath containing the pretreated leather blank; and 2, tanning the pretreated leather blank to obtain the in-situ polypyrrole pretreated electromagnetic shielding chromium-free leather. A stable built-in conductive network is constructed, meanwhile, the porosity of the material is improved, and the problems that when a conductive coating is constructed on leather through polypyrrole, interface bonding is weak, a conductive path is discontinuous, and the shielding effectiveness durability is poor are solved. The invention further discloses the in-situ polypyrrole pretreated electromagnetic shielding chromium-free leather and application.

Description

Technical Field

[0001] This invention belongs to the field of leather chemicals and functional leather manufacturing technology, and relates to a method for preparing electromagnetic shielding chromium-free leather with in-situ polypyrrole pretreatment. This invention also relates to electromagnetic shielding chromium-free leather and its applications. Background Technology

[0002] With the increasing prevalence of advanced electronic devices, electromagnetic interference (EMI) has become a growing concern. EMI originates from natural phenomena (such as solar radiation and lightning) or the use of electronic equipment and power transmission lines. It can not only affect the normal operation of precision electronic instruments but also pose a potential threat to human health. Therefore, the development of efficient and flexible electromagnetic shielding materials is particularly urgent. Currently, synthetic polymer composite materials or metal-coated fabrics are commonly used as electromagnetic shielding materials. While these materials offer some shielding effectiveness, they often suffer from inherent limitations such as high material rigidity, poor biodegradability, and insufficient wearing comfort.

[0003] As a natural and renewable material, leather possesses a natural three-dimensional collagen fiber network, giving it excellent flexibility and mechanical strength. It can also attenuate electromagnetic waves through multiple internal reflections and dipole-mediated absorption by its own carboxyl and amino groups. Currently, strategies for imparting functionality to leather mainly focus on applying conductive surface coatings after tanning. However, such post-treatment methods often suffer from poor adhesion between the coating and the leather interface, insufficient coating durability, and mostly still rely on traditional processes such as chrome tanning, which brings potential ecological and health burdens.

[0004] Polypyrrole (PPy), as a typical conductive polymer material, possesses advantages such as intrinsic conductivity, structural designability, good environmental stability, and multiple interactions with collagen fibers, making it an ideal substrate for constructing flexible electromagnetic shielding materials. However, when polypyrrole is used to construct conductive coatings on leather, problems still exist, including weak interfacial bonding, discontinuous conductive pathways, and poor shielding effectiveness and durability. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment, which solves the problems of weak interfacial bonding, discontinuous conductive pathways, and poor shielding effectiveness and durability in the prior art when polypyrrole is used to construct a conductive coating on leather.

[0006] A second objective of this invention is to provide electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole, obtained by the above-described method for preparing electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole.

[0007] A third objective of this invention is to provide an application for in-situ polypyrrole pretreated electromagnetic shielding chromium-free leather.

[0008] The technical solution adopted in this invention is a method for preparing electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment, which specifically includes the following steps: Step 1 involves pretreating the pickled hides with in-situ polypyrrole polymerization to obtain pretreated hide blanks and a main tanning bath containing the pretreated hide blanks. Step 1 is specifically implemented according to the following steps: Step 1.1, prepare the pyrrole treatment solution; Step 1.2: Prepare the oxidizing agent solution; Step 1.3: Pre-treat the pickled hides to obtain pre-treated hide blanks and a main tanning bath containing the pre-treated hide blanks; Step 2 involves tanning the pretreated leather to obtain in-situ polypyrrole pretreated electromagnetic shielding chromium-free leather. Step 2 is implemented specifically according to the following steps: Step 2.1: Main tanning is carried out using zirconium sulfate (Zr(SO4)2) tanning agent; Step 2.2, control the osmotic pH and binding pH; Step 2.3, Tanning; Step 2.4, post-tanning treatment, to obtain electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole.

[0009] The invention is further characterized by: In step 1.1, the pyrrole treatment solution is composed of pyrrole monomer and hydrochloric acid solution mixed at a volume ratio of 1:(20-25), and the concentration of hydrochloric acid solution is 0.2~0.6mol / L.

[0010] In step 1.2, the oxidant solution is a solution of ferric chloride in hydrochloric acid solution, with the concentration of ferric chloride in the oxidant solution being 330~340 g / L and the concentration of hydrochloric acid solution being 0.2~0.6 mol / L; The oxidant solution should be sonicated for 10-30 minutes before use.

[0011] The mass ratio of the total liquid phase composed of pyrrole treatment solution and oxidant solution to the mass of pickled leather is (4.5-5):1.

[0012] In step 1.3, the pickled hide is immersed in a pyrrole treatment solution and magnetically stirred at 16-22°C for 60 minutes. Then, an oxidant solution is added dropwise using a syringe to initiate the in-situ polymerization of pyrrole. The in-situ polymerization reaction continues for 40-70 minutes. After the reaction is completed, the pretreated hide blank and the main tanning bath containing the pretreated hide blank are obtained. The drip rate for adding the product drop by drop is 1-2 drops per second.

[0013] In step 2.1, 4-6% of Zr(SO4)2 tanning agent based on the hide weight is added to the main tanning bath containing the pretreated hide.

[0014] In step 2.2, the permeation pH of the main tanning bath containing the pretreated hides is controlled at 0.5, and then sodium bicarbonate is used to adjust the binding pH to 1.0.

[0015] In step 2.3, the pretreated hides after pH adjustment are tanned under magnetic stirring for 4 hours.

[0016] In step 2.4, after the pretreated leather blanks are left to stand in the main tanning bath for 10 to 12 hours, the pretreated leather blanks are taken out, washed with water, and air-dried naturally to obtain in-situ polypyrrole pretreated electromagnetic shielded chromium-free leather.

[0017] The second technical solution adopted in this invention is electromagnetic shielding chromium-free leather pretreated with in-situ polypyrrole, which is prepared by the same method as the electromagnetic shielding chromium-free leather pretreated with in-situ polypyrrole.

[0018] The third technical solution adopted in this invention is the application of in-situ polypyrrole pretreated electromagnetic shielding chromium-free leather, and the application of in-situ polypyrrole pretreated electromagnetic shielding chromium-free leather in electromagnetic shielding.

[0019] The beneficial effects of this invention are: (1) The method for preparing electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment disclosed in this invention adopts an innovative strategy of in-situ deposition of polypyrrole in the pre-tanning stage. This fully utilizes the intrinsic conductivity, structural designability, and multiple interactions of polypyrrole with collagen fibers. First, polypyrrole is directly introduced into the collagen fiber network through in-situ polymerization, followed by tanning with Zr(SO4)2. By allowing conductive PPy to grow and anchor in the three-dimensional collagen matrix, a stable built-in conductive network is constructed, fundamentally enhancing the interfacial bonding strength between the conductive layer and the leather matrix. This not only synergistically optimizes the conductivity, mechanical properties, and long-term durability of the material but also increases the material porosity, avoiding the problems of weak interfacial bonding, easy detachment, and insufficient durability common in traditional external coatings. This invention provides a new path for developing high-performance chromium-free eco-friendly electromagnetically shielded leather that meets the requirements of green manufacturing.

[0020] (2) The leather disclosed in this invention, which combines electromagnetic shielding, photothermal conversion, and antibacterial properties, exhibits excellent comprehensive performance: the shrinkage temperature reaches 78.8°C, the electromagnetic shielding effectiveness is as high as 27.3dB, and it still maintains above 20dB after 5000 cycles of friction, demonstrating excellent durability; its solar absorption rate is 97%, and at 1000W / m 2 It can achieve a temperature rise of 40°C under light irradiation; at the same time, it has improved air and moisture permeability and service durability, and the antibacterial rate against Staphylococcus aureus and Escherichia coli reaches 99.9%, giving it self-cleaning and biological protection functions. Attached Figure Description

[0021] Figure 1 The untanned control leather, polypyrrole-treated leather, and in-situ polypyrrole-pretreated electromagnetically shielded chromium-free leather in Example 1 of this invention are compared at 50 mV·s. - ¹Comparison of cyclic voltammetry curves at different scan rates; Figure 2 This is a comparison of the electrochemical impedance spectroscopy curves of untanned control leather, polypyrrole-treated leather, and in-situ polypyrrole-pretreated electromagnetically shielded chromium-free leather in Example 1 of this invention. Detailed Implementation

[0022] The following detailed description is provided in conjunction with specific implementation methods.

[0023] The preparation method of electromagnetic shielding chromium-free leather with in-situ polypyrrole pretreatment specifically includes the following steps: Step 1: The pickled leather is pretreated by in-situ polypyrrole polymerization to obtain pretreated leather blanks and a main tanning bath containing the pretreated leather blanks.

[0024] Step 1.1: Prepare the pyrrole treatment solution.

[0025] The pyrrole treatment solution is composed of pyrrole monomer and hydrochloric acid solution mixed at a volume ratio of 1:(20-25), and the concentration of hydrochloric acid solution is 0.2~0.6mol / L.

[0026] Step 1.2: Prepare the oxidant solution.

[0027] The oxidizing agent solution is a solution of ferric chloride (FeCl3·6H2O) in hydrochloric acid solution. The concentration of FeCl3 in the oxidizing agent solution is 330~340 g / L, and the concentration of hydrochloric acid solution is 0.2~0.6 mol / L.

[0028] The oxidant solution should be sonicated for 10-30 minutes before use.

[0029] Step 1.3: Pre-treat the pickled hides to obtain pre-treated hide blanks and a main tanning bath containing the pre-treated hide blanks.

[0030] The pickled hides are immersed in a pyrrole treatment solution and magnetically stirred for 60 minutes at 16-22°C to ensure full penetration. Then, an oxidizing agent solution is added dropwise using a syringe to initiate in-situ polymerization of pyrrole. The in-situ polymerization reaction continues for 40-70 minutes. After the reaction is complete, pretreated hide blanks and a main tanning bath containing the pretreated hide blanks are obtained.

[0031] The drip rate for adding the product drop by drop is 1-2 drops per second.

[0032] The mass ratio of the total liquid phase composed of pyrrole treatment solution and oxidant solution to the mass of pickled leather is (4.5-5):1.

[0033] Step 2: Tanning the pretreated leather blanks to obtain in-situ polypyrrole pretreated electromagnetic shielded chromium-free leather.

[0034] Step 2.1: Main tanning is performed using Zr(SO4)2 tanning agent.

[0035] Add 4-6% Zr(SO4)2 tanning agent based on the weight of the hide to the main tanning bath containing the pretreated hide.

[0036] Step 2.2: Control the osmotic pH and binding pH.

[0037] The permeation pH of the main tanning bath containing the pretreated hides was controlled at 0.5, and then the binding pH was adjusted to 1.0 using sodium bicarbonate.

[0038] Step 2.3, Tanning.

[0039] The pretreated hides, after pH adjustment, were tanned for 4 hours under magnetic stirring.

[0040] Step 2.4, post-tanning treatment, to obtain electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole.

[0041] After the pretreated leather blanks are left to stand in the main tanning bath for 10 to 12 hours, the pretreated leather blanks are taken out, washed with water, and air-dried naturally to obtain electromagnetic shielded chromium-free leather with in-situ polypyrrole pretreatment.

[0042] Example 1 The preparation method of electromagnetic shielding chromium-free leather with in-situ polypyrrole pretreatment specifically includes the following steps: Step 1: The pickled leather is pretreated by in-situ polypyrrole polymerization to obtain pretreated leather blanks and a main tanning bath containing the pretreated leather blanks.

[0043] Step 1.1: Prepare the pyrrole treatment solution.

[0044] The pyrrole treatment solution is composed of pyrrole monomer and hydrochloric acid solution at a volume ratio of 1:25, and the concentration of hydrochloric acid solution is 0.42 mol / L.

[0045] Step 1.2: Prepare the oxidant solution.

[0046] The oxidizing agent solution is FeCl3·6H2O in hydrochloric acid solution, with the concentration of FeCl3 in the oxidizing agent solution being 340 g / L and the concentration of hydrochloric acid solution being 0.42 mol / L.

[0047] The oxidant solution should be sonicated for 15 minutes before use.

[0048] The mass ratio of the total liquid phase composed of pyrrole treatment solution and oxidant solution to the mass of pickled leather is 4.5:1.

[0049] Step 1.3: Pre-treat the pickled hides to obtain pre-treated hide blanks and a main tanning bath containing the pre-treated hide blanks.

[0050] The pickled hides were immersed in a pyrrole treatment solution and magnetically stirred at 20°C for 60 minutes to ensure full penetration. Then, an oxidizing agent solution was added dropwise using a syringe to initiate in-situ polymerization of pyrrole. The in-situ polymerization reaction continued for 60 minutes. After the reaction was completed, pretreated hide blanks and a main tanning bath containing the pretreated hide blanks were obtained.

[0051] The dropwise addition rate is 1 drop / second.

[0052] Step 2: Tanning the pretreated leather blanks to obtain in-situ polypyrrole pretreated electromagnetic shielded chromium-free leather.

[0053] Step 2.1: Main tanning is performed using Zr(SO4)2 tanning agent.

[0054] Zr(SO4)2 tanning agent, based on 6% of the hide weight, was added to the main tanning bath containing the pretreated hides.

[0055] Step 2.2: Control the osmotic pH and binding pH.

[0056] The permeation pH of the main tanning bath containing the pretreated hides was controlled at 0.5, and then the binding pH was adjusted to 1.0 using sodium bicarbonate.

[0057] Step 2.3, Tanning.

[0058] The pretreated hides, after pH adjustment, were tanned for 4 hours under magnetic stirring.

[0059] Step 2.4, post-tanning treatment, to obtain electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole.

[0060] After the pretreated leather blanks are left to stand in the main tanning bath for 12 hours, the pretreated leather blanks are taken out, washed with water, and air-dried naturally to obtain electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment.

[0061] Table 1 shows the electromagnetic shielding performance test results of the untanned control group, zirconium sulfate tanned raw leather, and in-situ polypyrrole pretreated chromium-free electromagnetic shielding leather.

[0062] Table 1. Comparison of electromagnetic shielding performance of chromium-free leather pretreated with in-situ polypyrrole.

[0063] Data shows that the overall electromagnetic shielding effectiveness of the control group was 1.5–2.0 dB, that of zirconium sulfate tanned leather was 6.3–7.8 dB, while the electromagnetic shielding effectiveness of in-situ polypyrrole pretreated chromium-free leather was significantly better than the former two, reaching 25.1–27.3 dB. The improved electromagnetic shielding performance of in-situ polypyrrole pretreated chromium-free leather is mainly due to the formation of a richer multi-point network structure within the leather. This structure causes electromagnetic waves to undergo more reflections between collagen fibers, lengthening the propagation path and enhancing absorption loss. In addition, the introduction of polypyrrole enriches the π-π conjugated system in collagen fibers, improving charge transport capacity, thereby further enhancing the electromagnetic shielding effect.

[0064] Figure 1 The study showcased an untanned control sample, polypyrrole-treated leather, and in-situ polypyrrole-pretreated electromagnetically shielded chromium-free leather (PPy-Zr) at 50 mV·s. -1 Cyclic voltammetry curves at scan rate were used to study the redox properties of tanned leather. The curves show that the areas enclosed by the curves for both polypyrrole-treated leather and in-situ polypyrrole-pretreated electromagnetically shielded chromium-free leather are significantly larger than the control group, indicating that polypyrrole can enhance the charge transport capacity of these two types of leather. This improvement may stem from the fact that charge carriers generated within the polypyrrole segments construct channels, promoting charge transfer between molecular chains. Simultaneously, the π-π conjugated structure of polypyrrole also enhances the overall conductivity.

[0065] Figure 2 Electrochemical impedance spectroscopy (EIS) curves of the control group, polypyrrole-treated leather, and in-situ polypyrrole-pretreated electromagnetically shielded chromium-free leather are presented. The equivalent series resistance (ESR) of the control group was 17.4 Ω, that of the polypyrrole-treated leather was 6.5 Ω, while that of the in-situ polypyrrole-pretreated electromagnetically shielded chromium-free leather decreased to 4.3 Ω. This indicates that, compared with the control group, the introduction of polypyrrole significantly reduced the internal resistance of the leather, thereby improving its charge transport capability. By comparing the impedance data of the polypyrrole-treated leather and the in-situ polypyrrole-pretreated electromagnetically shielded chromium-free leather, it can be found that the latter has a lower ESR, further confirming its superior charge transfer characteristics.

[0066] Example 2 The preparation method of electromagnetic shielding chromium-free leather with in-situ polypyrrole pretreatment specifically includes the following steps: Step 1: The pickled leather is pretreated by in-situ polypyrrole polymerization to obtain pretreated leather blanks and a main tanning bath containing the pretreated leather blanks.

[0067] Step 1.1: Prepare the pyrrole treatment solution.

[0068] The pyrrole treatment solution is composed of pyrrole monomer and hydrochloric acid solution at a volume ratio of 1:20, and the concentration of hydrochloric acid solution is 0.42 mol / L.

[0069] Step 1.2: Prepare the oxidant solution.

[0070] The oxidizing agent solution is FeCl3·6H2O in hydrochloric acid solution, with the concentration of FeCl3 in the oxidizing agent solution being 330 g / L and the concentration of hydrochloric acid solution being 0.42 mol / L.

[0071] The oxidant solution should be sonicated for 15 minutes before use.

[0072] The mass ratio of the total liquid phase composed of pyrrole treatment solution and oxidant solution to the mass of pickled leather is 4.5:1.

[0073] Step 1.3: Pre-treat the pickled hides to obtain pre-treated hide blanks and a main tanning bath containing the pre-treated hide blanks.

[0074] The pickled hides were immersed in a pyrrole treatment solution and magnetically stirred at 18°C ​​for 60 minutes to ensure full penetration. Then, an oxidizing agent solution was added dropwise using a syringe to initiate in-situ polymerization of pyrrole. The in-situ polymerization reaction continued for 40 minutes. After the reaction, pretreated hide blanks and a main tanning bath containing the pretreated hide blanks were obtained.

[0075] The dropwise addition rate is 1 drop / second.

[0076] Step 2: Tanning the pretreated leather blanks to obtain in-situ polypyrrole pretreated electromagnetic shielded chromium-free leather.

[0077] Step 2.1: Main tanning is performed using Zr(SO4)2 tanning agent.

[0078] Add 4% Zr(SO4)2 tanning agent based on the weight of the hide to the main tanning bath containing the pretreated hide.

[0079] Step 2.2: Control the osmotic pH and binding pH.

[0080] The permeation pH of the main tanning bath containing the pretreated hides was controlled at 0.5, and then the binding pH was adjusted to 1.0 using sodium bicarbonate.

[0081] Step 2.3, Tanning.

[0082] The pretreated hides, after pH adjustment, were tanned for 4 hours under magnetic stirring.

[0083] Step 2.4, post-tanning treatment, to obtain electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole.

[0084] After the pretreated leather blanks are left to stand in the main tanning bath for 10 hours, the pretreated leather blanks are taken out, washed with water, and air-dried naturally to obtain in-situ polypyrrole pretreated electromagnetic shielded chromium-free leather.

[0085] Example 3 The preparation method of electromagnetic shielding chromium-free leather with in-situ polypyrrole pretreatment specifically includes the following steps: Step 1: The pickled leather is pretreated by in-situ polypyrrole polymerization to obtain pretreated leather blanks and a main tanning bath containing the pretreated leather blanks.

[0086] Step 1.1: Prepare the pyrrole treatment solution.

[0087] The pyrrole treatment solution is composed of pyrrole monomer and hydrochloric acid solution at a volume ratio of 1:20, and the concentration of hydrochloric acid solution is 0.40 mol / L.

[0088] Step 1.2: Prepare the oxidant solution.

[0089] The oxidizing agent solution is FeCl3·6H2O in hydrochloric acid solution, with the concentration of FeCl3 in the oxidizing agent solution being 330 g / L and the concentration of hydrochloric acid solution being 0.40 mol / L.

[0090] The oxidant solution should be sonicated for 20 minutes before use.

[0091] The mass ratio of the total liquid phase consisting of pyrrole treatment solution and oxidant solution to the mass of the pickled leather is 5:1.

[0092] Step 1.3: Pre-treat the pickled hides to obtain pre-treated hide blanks and a main tanning bath containing the pre-treated hide blanks.

[0093] The pickled hides were immersed in a pyrrole treatment solution and magnetically stirred at 20°C for 60 minutes to ensure full penetration. Then, an oxidizing agent solution was added dropwise using a syringe to initiate in-situ polymerization of pyrrole. The in-situ polymerization reaction continued for 55 minutes. After the reaction was completed, pretreated hide blanks and a main tanning bath containing the pretreated hide blanks were obtained.

[0094] The dropwise addition rate is 2 drops / second.

[0095] Step 2: Tanning the pretreated leather blanks to obtain in-situ polypyrrole pretreated electromagnetic shielded chromium-free leather.

[0096] Step 2.1: Main tanning is performed using Zr(SO4)2 tanning agent.

[0097] Add 5% Zr(SO4)2 tanning agent based on the weight of the hide to the main tanning bath containing the pretreated hide.

[0098] Step 2.2: Control the osmotic pH and binding pH.

[0099] The permeation pH of the main tanning bath containing the pretreated hides was controlled at 0.5, and then the binding pH was adjusted to 1.0 using sodium bicarbonate.

[0100] Step 2.3, Tanning.

[0101] The pretreated hides, after pH adjustment, were tanned for 4 hours under magnetic stirring.

[0102] Step 2.4, post-tanning treatment, to obtain electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole.

[0103] After the pretreated leather blanks are left to stand in the main tanning bath for 12 hours, the pretreated leather blanks are taken out, washed with water, and air-dried naturally to obtain electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment.

[0104] Example 4 The preparation method of electromagnetic shielding chromium-free leather with in-situ polypyrrole pretreatment specifically includes the following steps: Step 1: The pickled leather is pretreated by in-situ polypyrrole polymerization to obtain pretreated leather blanks and a main tanning bath containing the pretreated leather blanks.

[0105] Step 1.1: Prepare the pyrrole treatment solution.

[0106] The pyrrole treatment solution is composed of pyrrole monomer and hydrochloric acid solution at a volume ratio of 1:25, and the concentration of hydrochloric acid solution is 0.42 mol / L.

[0107] Step 1.2: Prepare the oxidant solution.

[0108] The oxidizing agent solution is FeCl3·6H2O in hydrochloric acid solution, with the concentration of FeCl3 in the oxidizing agent solution being 340 g / L and the concentration of hydrochloric acid solution being 0.42 mol / L.

[0109] The oxidant solution should be sonicated for 30 minutes before use.

[0110] The mass ratio of the total liquid phase consisting of pyrrole treatment solution and oxidant solution to the mass of the pickled leather is 5:1.

[0111] Step 1.3: Pre-treat the pickled hides to obtain pre-treated hide blanks and a main tanning bath containing the pre-treated hide blanks.

[0112] The pickled hides were immersed in a pyrrole treatment solution and magnetically stirred at 22°C for 60 minutes to ensure full penetration. Then, an oxidizing agent solution was added dropwise using a syringe to initiate in-situ polymerization of pyrrole. The in-situ polymerization reaction continued for 60 minutes. After the reaction, pretreated hide blanks and a main tanning bath containing the pretreated hide blanks were obtained.

[0113] The dropwise addition rate is 2 drops / second.

[0114] Step 2: Tanning the pretreated leather blanks to obtain in-situ polypyrrole pretreated electromagnetic shielded chromium-free leather.

[0115] Step 2.1: Main tanning is performed using Zr(SO4)2 tanning agent.

[0116] Zr(SO4)2 tanning agent, based on 6% of the hide weight, was added to the main tanning bath containing the pretreated hides.

[0117] Step 2.2: Control the osmotic pH and binding pH.

[0118] The permeation pH of the main tanning bath containing the pretreated hides was controlled at 0.5, and then the binding pH was adjusted to 1.0 using sodium bicarbonate.

[0119] Step 2.3, Tanning.

[0120] The pretreated hides, after pH adjustment, were tanned for 4 hours under magnetic stirring.

[0121] Step 2.4, post-tanning treatment, to obtain electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole.

[0122] After the pretreated leather blanks are left to stand in the main tanning bath for 12 hours, the pretreated leather blanks are taken out, washed with water, and air-dried naturally to obtain electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment.

[0123] Example 5 Electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole was prepared using the same method as for electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole.

[0124] Example 6 Application of in-situ polypyrrole pretreated chromium-free electromagnetic shielding leather.

Claims

1. A method for preparing electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole, characterized in that, Specifically, the following steps are included: Step 1 involves pretreating the pickled hides with in-situ polypyrrole polymerization to obtain pretreated hide blanks and a main tanning bath containing the pretreated hide blanks. Step 1 is specifically implemented according to the following steps: Step 1.1, prepare the pyrrole treatment solution; Step 1.2: Prepare the oxidizing agent solution; Step 1.3: Pre-treat the pickled hides to obtain pre-treated hide blanks and a main tanning bath containing the pre-treated hide blanks; Step 2 involves tanning the pretreated leather to obtain in-situ polypyrrole pretreated electromagnetic shielding chromium-free leather. Step 2 is implemented specifically according to the following steps: Step 2.1: Main tanning is carried out using Zr(SO4)2 tanning agent; Step 2.2, control the osmotic pH and binding pH; Step 2.3, Tanning; Step 2.4, post-tanning treatment, to obtain electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole.

2. The method for preparing electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment according to claim 1, characterized in that, In step 1.1, the pyrrole treatment solution is composed of pyrrole monomer and hydrochloric acid solution mixed at a volume ratio of 1:(20-25), and the concentration of hydrochloric acid solution is 0.2~0.6mol / L.

3. The method for preparing electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment according to claim 1, characterized in that, In step 1.2, the oxidant solution is a solution of ferric chloride in hydrochloric acid solution, the concentration of ferric chloride in the oxidant solution is 330~340g / L, and the concentration of hydrochloric acid solution is 0.2~0.6mol / L; The oxidant solution should be sonicated for 10-30 minutes before use.

4. The method for preparing electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment according to claim 1, characterized in that, In step 1.3, the pickled hide is immersed in a pyrrole treatment solution and magnetically stirred at 16-22°C for 60 minutes. Then, an oxidant solution is added dropwise using a syringe to initiate the in-situ polymerization of pyrrole. The in-situ polymerization reaction continues for 40-70 minutes. After the reaction is completed, the pretreated hide blank and the main tanning bath containing the pretreated hide blank are obtained. The dripping rate is 1-2 drops / second when added drop by drop; The mass ratio of the total liquid phase composed of pyrrole treatment solution and oxidant solution to the mass of pickled leather is (4.5-5):

1.

5. The method for preparing electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment according to claim 1, characterized in that, In step 2.1, Zr(SO4)2 tanning agent, at 4-6% of the hide weight, is added to the main tanning bath containing the pretreated hide.

6. The method for preparing electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment according to claim 1, characterized in that, In step 2.2, the permeation pH of the main tanning bath containing the pretreated hide is controlled at 0.5, and then sodium bicarbonate is used to adjust the binding pH to 1.

0.

7. The method for preparing electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment according to claim 1, characterized in that, In step 2.3, the pretreated hides after pH adjustment are tanned under magnetic stirring for 4 hours.

8. The method for preparing electromagnetically shielded chromium-free leather with in-situ polypyrrole pretreatment according to claim 1, characterized in that, In step 2.4, after the pretreated leather blank is left to stand in the main tanning bath for 10 to 12 hours, the pretreated leather blank is taken out, washed with water, and air-dried naturally to obtain in-situ polypyrrole pretreated electromagnetic shielded chromium-free leather.

9. Electromagnetically shielded chromium-free leather pretreated with in-situ polypyrrole, characterized in that, The chromium-free electromagnetic shielding leather is prepared using the method described in any one of claims 1-8 for in-situ polypyrrole pretreatment.

10. The application of in-situ polypyrrole pretreated electromagnetic shielding chromium-free leather, characterized in that, Application of in-situ polypyrrole pretreated chromium-free leather in electromagnetic shielding.

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