阅读说明：本技术 一种氧化石墨烯原位还原制备高物性皮革的方法 (Method for preparing high-physical-property leather by in-situ reduction of graphene oxide ) 是由 李彦春 杨新乐 杨茂 于 2021-10-15 设计创作，主要内容包括：本发明一种氧化石墨烯原位还原制备高物性皮革的方法,属于皮革功能材料应用技术领域,具体为在酸化后的酸皮中加入纳米氧化石墨烯分散液进行分散,分散后加入一定量的铬粉进行铬鞣,铬鞣完成后加入还原剂进行纳米氧化石墨烯的原位还原。本发明在铬鞣工序中加入纳米氧化石墨烯渗透进入皮革后,再加入还原剂原位还原氧化石墨烯,可以使成革的抗张强度、撕裂强度明显提高,提高了鞣制时对铬的吸收,导热率提高,显著提升皮革的物理性能,具有操作简单、用量少、污染小、效果显著的特点。(The invention discloses a method for preparing high-physical-property leather by in-situ reduction of graphene oxide, belongs to the technical field of application of leather functional materials, and particularly relates to a method for preparing high-physical-property leather by adding nano graphene oxide dispersion liquid into acidified leather for dispersion, adding a certain amount of chromium powder for chrome tanning after dispersion, and adding a reducing agent for in-situ reduction of nano graphene oxide after chrome tanning is completed. According to the invention, after nano graphene oxide is added into the leather to permeate into the leather in the chrome tanning process, the reducing agent is added to reduce the graphene oxide in situ, so that the tensile strength and the tearing strength of the finished leather are obviously improved, the absorption of chrome during tanning is improved, the thermal conductivity is improved, the physical performance of the leather is obviously improved, and the method has the characteristics of simplicity in operation, less dosage, less pollution and obvious effect.)

1. The method for preparing the high-physical-property leather by in-situ reduction of the graphene oxide is characterized in that nano graphene oxide dispersion liquid is added into the acidified acid leather for dispersion, a certain amount of chromium powder is added for chrome tanning after the dispersion, and a reducing agent is added for in-situ reduction of the nano graphene oxide after the chrome tanning is finished.

2. The method according to claim 1, wherein the preparation method of the nano graphene oxide dispersion liquid comprises the following steps: ultrasonically dispersing nano graphene oxide water liquid with the mass percentage concentration of 0.05-0.2% for 1-1.5 h, adding a dispersing agent with the mass percentage concentration of 0.5-2% of the nano graphene oxide water liquid, and ultrasonically treating for 1-2 h to obtain nano graphene oxide dispersion liquid.

3. The method according to claim 2, wherein the dispersant is one or more of dodecylbenzene sulfonic acid, penetrant JFC, peregal O-25, and citric acid.

4. The method of claim 1, wherein the reducing agent is one or more of ascorbic acid, reducing sugar, sodium bisulfite, sodium thiosulfate, and sodium sulfite.

5. The method of claim 4, wherein the reducing agent is ascorbic acid.

6. The method according to claim 1, wherein the chromium powder is added in an amount of 6% by mass of the pickled Chinese cabbage skin.

7. The method of claim 1 wherein said chromium powder is basic chromium sulfate.

8. The method according to claim 1, wherein the reducing agent is added in an amount of 3-10% by mass of the nano graphene oxide dispersion liquid.

Technical Field

The invention belongs to the technical field of leather functional material application, and particularly relates to a method for preparing high-physical-property leather by in-situ reduction of graphene oxide.

Background

The leather is made from fresh hide through several dozens of processes of soaking, degreasing, unhairing, pickling, tanning, neutralizing, fatliquoring finishing and the like, wherein the most critical process is tanning, tanning is a process of adding a tanning agent to convert the hide into cooked skin with moisture, the leather tanning agent reacts with skin collagen fibers to form chemical bonding, and a cross-linking structure is formed among natural protein fibers, so that the leather has low antimicrobial effect, good mechanical property and proper elasticity and softness. Currently, the main tanning processes are: 1) inorganic salt tanning, such as metal salts of chromium, aluminum and the like form coordinate bonds with carboxyl groups on protein fibers; 2) organic tanning, such as aldehyde compounds and phenolic compounds, forming covalent bonds with amino groups and hydroxyl groups on protein fibers; 3) vegetable tanning, which utilizes the action of high molecular weight substances in vegetable juice with protein fibers through hydrogen bonds and ionic bonds.

In the method, the content of aldehyde tanning formaldehyde is high, leather is not resistant to yellowing, and a vegetable tanning leather blank has poor whiteness and yellowing. Due to the special electronic layer structure of chromium, tanned leather has the characteristics of good flexibility, extensibility, heat-resistant stability and water vapor permeability, and is widely applied to leather production and always dominates the production due to the excellent properties of softness, fullness, high humidity and heat resistance and the like. However, since the utilization rate of chromium salt in the current chrome tanning method is low, a large amount of trivalent chromium is discharged without being absorbed, causing serious environmental pollution. The main way to reduce the amount of chromium solvent is to increase the absorption rate of the chrome tanning agent and thus reduce the emission of chromium containing pollutants, but at present the effect is limited.

Graphene is an ideal two-dimensional crystal, and has a perfect crystal structure, extremely high electrical and thermal conductivity, excellent optical and mechanical properties and the like. Graphene Oxide (GO) serving as a graphene derivative also has good physical properties, the graphene oxide aqueous dispersion has good stability, active groups capable of reacting with leather collagen fibers such as hydroxyl, carboxyl and carbonyl are contained on the surface and the edge of the nanosheet layer, and a nano-size effect and a small-size effect are also contained between the collagen fibers, so that the nano-graphene oxide can be used in the leather production process. Graphene can be obtained after reduction of graphene oxide, but oxygen-containing functional groups in graphene oxide cannot be completely removed, and a conjugated structure cannot be completely restored, so that the graphene oxide is generally called Reduced Graphene Oxide (RGO). The higher the degree of reduction, the closer to the original properties of graphene.

Disclosure of Invention

The invention provides a method for preparing high-physical-property leather by in-situ reduction of graphene oxide, aiming at the problems of small chromium absorption amount and poor leather physical property in the chrome tanning process in the prior art. The invention is realized by the following technical scheme:

a method for preparing high-physical-property leather by in-situ reduction of graphene oxide comprises the steps of adding nano graphene oxide dispersion liquid into acidified acid leather for dispersion, adding a certain amount of chromium powder for chrome tanning after dispersion, and adding a reducing agent for in-situ reduction of nano graphene oxide after the chrome tanning is finished.

Further, the preparation method of the nano graphene oxide dispersion liquid comprises the following steps: ultrasonically dispersing nano graphene oxide water liquid with the mass percentage concentration of 0.05-0.2% for 1-1.5 h, adding a dispersing agent with the mass percentage concentration of 0.5-2% of the nano graphene oxide water liquid, and ultrasonically treating for 1-2 h to obtain nano graphene oxide dispersion liquid.

Furthermore, the dispersant is more than one of dodecyl benzene sulfonic acid, penetrant JFC, peregal O-25 and citric acid.

The reducing agent is one or more of ascorbic acid, reducing sugar, sodium bisulfite, sodium thiosulfate and sodium sulfite.

Further, the reducing agent is ascorbic acid.

Further, the addition amount of the chromium powder is 6% of the mass of the pickled Chinese cabbage skin.

Further, the chromium powder is basic chromium sulfate.

Further, the addition amount of the reducing agent is 3-10% of the mass of the nano graphene oxide dispersion liquid.

The nano graphene oxide can be reduced to obtain graphene, but oxygen-containing functional groups in the graphene oxide cannot be completely removed, and a conjugated structure cannot be completely recovered, so that the nano graphene oxide is generally called Reduced Graphene Oxide (RGO). The higher the degree of reduction, the closer to the original properties of graphene. According to the invention, under the action of ultrasonic waves and a dispersing agent, the graphene oxide sheet layer is reduced in size and is uniformly dispersed in an aqueous solution, so that the graphene oxide sheet layer can penetrate into leather collagen fibers. The surface and the edge of the nano graphene oxide sheet layer contain active groups such as hydroxyl, carboxyl, carbonyl and the like which can react with collagen fibers of leather, and a nano size effect and a small size effect are achieved between the collagen fibers, so that the nano graphene oxide can generate a gain effect on the leather after penetrating into the leather. After the graphene oxide permeates into the skin, a reducing agent is added, so that oxygen-containing functional groups which are not combined with the graphene oxide in the skin are removed, the graphene oxide is reduced in situ, a conjugated structure is recovered, the performance of the graphene oxide is improved, and the performance of the leather is further improved.

Advantageous effects

(1) The invention reduces the size of the graphene oxide lamella by the action of ultrasonic waves and a dispersing agent, the surface and the edge of the nano graphene oxide lamella contain active groups which can react with the collagen fiber, such as hydroxyl, carboxyl, carbonyl and the like, and the nano graphene oxide lamella has a nano size effect and a small size effect among the collagen fibers, thereby generating a gain effect on the leather; (2) according to the invention, after nano graphene oxide is added into the leather to permeate into the leather in the chrome tanning process, the reducing agent is added to reduce the graphene oxide in situ, so that the tensile strength and the tearing strength of the finished leather are obviously improved, the absorption of chrome during tanning is improved, the thermal conductivity is improved, the physical performance of the leather is obviously improved, and the method has the characteristics of simplicity in operation, less dosage, less pollution and obvious effect.

Drawings

FIG. 1 is a grain and flesh map of the pickled skins of example 2 before and after reduction and of conventional chrome tanned skins.

Detailed Description

In order to make the technical solutions of the present invention better understood, the following description is provided clearly and completely, and other similar embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present application based on the embodiments in the present application.

The parts described in the following examples are parts by weight, and the kraft pickled hides used in examples 1 to 3 and comparative example 1 are kraft pickled hides of the same specification.

Example 1

(1) Preparing a nano graphene oxide dispersion liquid: taking 100 parts of nano graphene oxide dispersion liquid with the mass fraction of 0.1%, carrying out ultrasonic treatment for 1 hour, then adding 0.5 part of dispersing agent (the dispersing agent is sodium dodecyl sulfate and citric acid with the mass ratio of 5: 2), and carrying out ultrasonic treatment for 2 hours to obtain the nano graphene oxide dispersion liquid;

(2) chrome tanning and graphene oxide infiltration: adding 7% of salt into a rotary drum, adjusting the liquid ratio to be 1, the water temperature to be 33 ℃ and the pH value to be 2.5-3.0, rotating for 15 minutes, putting cowhide pickled skin, adding the nano graphene oxide dispersion liquid obtained in the step (1), rotating for 1.5 hours, adding basic chromium sulfate accounting for 6% of the mass of the pickled skin, and rotating for 1.5 hours; adjusting the pH value to 3.5-4.0 by using sodium formate and sodium bicarbonate, rotating for 1 hour, and standing overnight;

(3) in-situ reduction of graphene oxide: adjusting the liquid ratio to be 1 in a rotary drum, adding the cowhide treated in the step (2) at the water temperature of 45 ℃, adding 5 parts of sodium bisulfite, rotating for 10 hours, stopping the drum, staying overnight, neutralizing and fatting by adopting a conventional process, taking out, standing and airing.

Example 2

(1) Preparing a nano graphene oxide dispersion liquid: taking 100 parts of nano graphene oxide water solution with the mass fraction of 0.15%, carrying out ultrasonic treatment for 1 hour, then adding 0.5 part of dispersing agent (the dispersing agent is sodium dodecyl sulfate, peregal-O25 and citric acid with the mass ratio of 10:1: 2), and carrying out ultrasonic treatment for 1.5 hours to obtain nano graphene oxide dispersion liquid;

(2) chrome tanning and graphene oxide infiltration: adding 7% of salt into a rotary drum, adjusting the liquid ratio to be 1, the water temperature to be 33 ℃ and the pH value to be 2.5-3.0, rotating for 15 minutes, then adding cow leather to soak acid skin, adding the nano graphene oxide dispersion liquid obtained in the step (1), rotating for 1.5 hours, adding basic chromium sulfate accounting for 6% of the mass of the acid skin, and rotating for 1.5 hours; adjusting pH to 3.5-4.0 with sodium formate and sodium bicarbonate, rotating for 1 hr, standing overnight, and showing grain and meat surface of cow hide as shown in fig. 1 (before Go reduction);

(3) in-situ reduction of graphene oxide: adjusting the liquid ratio to be 1 in a rotary drum, adding the cowhide treated in the step (2) at the water temperature of 50 ℃, adding 10 parts of ascorbic acid, rotating for 10 hours, stopping the drum, standing overnight, neutralizing and fatting by adopting a conventional process, taking out, standing and airing, wherein the grain surface and flesh surface of the obtained cowhide leather are shown in fig. 1 (after Go reduction).

Example 3

(1) Preparing a nano graphene oxide dispersion liquid: taking 200 parts of nano graphene oxide dispersion liquid with the mass fraction of 0.2%, carrying out ultrasonic treatment for 1 hour, then adding 1 part of dispersing agent (the dispersing agent is sodium dodecyl sulfate and penetrating agent JFC with the mass ratio of 2: 1), and carrying out ultrasonic treatment for 2 hours to obtain the nano graphene oxide dispersion liquid;

(2) chrome tanning and graphene oxide infiltration: adding 7% of salt into a rotary drum, adjusting the liquid ratio to be 1, the water temperature to be 33 ℃ and the pH value to be 2.5-3.0, rotating for 15 minutes, then adding cow leather to soak acid skin, adding the nano graphene oxide dispersion liquid obtained in the step (1), rotating for 1.5 hours, adding basic chromium sulfate accounting for 6% of the mass of the acid skin, and rotating for 1.5 hours; adjusting the pH value to 3.5-4.0 by using sodium formate and sodium bicarbonate, rotating for 1 hour, and standing overnight;

(3) in-situ reduction of graphene oxide: adjusting the liquid ratio to be 1 in a rotary drum, adding the cowhide treated in the step (2) at the water temperature of 50 ℃, adding 20 parts of reducing sugar, rotating for 10 hours, stopping the drum, staying overnight, neutralizing and fatting by adopting a conventional process, taking out, standing and airing.

Comparative example 1

(1) Preparing a nano graphene oxide dispersion liquid: taking 100 parts of nano graphene oxide dispersion liquid with the mass fraction of 0.1%, carrying out ultrasonic treatment for 1 hour, then adding 0.5 part of dispersing agent (the dispersing agent is sodium dodecyl sulfate, peregal-O25 and citric acid with the mass ratio of 10:1:2, and carrying out ultrasonic treatment for 1.5 hours to obtain the nano graphene oxide dispersion liquid;

(2) chrome tanning and graphene oxide infiltration: adding salt into a rotary drum, adjusting the liquid ratio, the water temperature and the pH value, rotating for 15 minutes, then adding cowhide and pickling acid skin, adding the nano graphene oxide dispersion liquid obtained in the step (1), rotating for 1.5 hours, adding 6% chromium powder, and rotating for 1.5 hours; adjusting the pH value to 3.5-4.0 by using sodium formate and sodium bicarbonate, rotating for 1 hour, standing overnight, neutralizing by adopting a conventional process, adding fat, taking out, standing and airing.

Application examples

The physical properties (shrinkage temperature, tensile strength, elongation at break, tear strength and thermal conductivity) and the intracutaneous Gr content of the cowhide leather treated in the embodiments 1-3 and the comparative example 1 are detected, sampling detection is carried out according to national and industrial standards QB/T2710-. As can be seen from tables 1 and 2, the method of the application can obviously improve the physical properties of the finished leather, improve the heat conductivity coefficient of the leather, increase the absorption of chromium during tanning and reduce the discharge of chromium-polluted wastewater.

Table 1 shows the physical properties of the treated leathers of conventional chrome tanned leathers of examples 1 to 3 and comparative example 1

TABLE 2 results of thermal conductivity test of treated cow leather of conventional chrome tanned leather, example 2 and comparative example 1

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