A preparation method of an antibacterial fatliquoring agent for dry-hardened leather cultural relics

Abstract

The application relates to the field of cultural relic protection, and discloses a preparation method of an antibacterial fatliquoring agent for dry and hardened leather cultural relics, which comprises the following steps: step 1): mixing water, nano titanium dioxide and polyethylene glycol 400 to obtain a mixed solution; step 2): modifying the mixed solution by using a silane coupling agent to obtain silane coupling agent modified nano titanium dioxide powder; step 3): reacting coconut oil and polyethylene glycol-400 to obtain modified coconut oil; step 4): adding maleic anhydride to the modified coconut oil and reacting, and adding the silane coupling agent modified nano titanium dioxide powder; step 5): adding sodium metabisulfite solution and reacting; and step 6): blending to obtain the antibacterial fatliquoring agent. The antibacterial fatliquoring agent has excellent permeability and filling property for dry and hardened leather cultural relics, the leather cultural relics have high antibacterial property after protection treatment, the softness of the leather cultural relics is improved, and the leather cultural relics are not damaged.

Description

Technical Field

[0001] This invention relates to the field of cultural relic protection, and in particular to a method for preparing an antibacterial fatliquoring agent for dried and hardened leather cultural relics. Background Technology

[0002] Because leather's main component is natural collagen, it provides an ideal environment for the growth and reproduction of many microorganisms. Therefore, leather artifacts are highly susceptible to erosion by various microorganisms (including mold, yeast, and bacteria) during preservation. Traditional antibacterial and antifungal measures can only create a sterile preservation environment for leather artifacts by using antifungal agents, but these methods also cause some damage to the leather artifacts themselves. Currently, there is very little research on the antibacterial and antifungal properties of leather artifacts themselves.

[0003] Therefore, in order to better preserve and protect dried and hardened leather artifacts, it is urgent to research a protective agent with excellent antibacterial and fatliquoring properties that is harmless to the leather artifacts themselves. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a method for preparing an antibacterial fatliquoring agent for dried and hardened leather artifacts. The antibacterial fatliquoring agent prepared by this method simultaneously contains hydrophilically modified coconut oil and silane coupling agent-modified nano-titanium dioxide. This antibacterial fatliquoring agent exhibits excellent penetration and filling properties for dried and hardened leather artifacts. After protective treatment, the leather artifacts possess extremely high antibacterial properties, resisting the erosion of various bacterial colonies, while also achieving a certain degree of improved softness without causing damage to the leather artifacts.

[0005] The specific technical solution of this invention is as follows: a method for preparing an antibacterial fatliquoring agent for dried and hardened leather artifacts, comprising the following steps:

[0006] Step 1): Add nano-titanium dioxide and polyethylene glycol 400 to water, and then stir and ultrasonically disperse them to obtain a mixture; the mass ratio of water, nano-titanium dioxide and polyethylene glycol 400 is 90-110:0.3-0.7:0.02-0.1.

[0007] Nano-titanium dioxide is known to possess unique properties such as UV resistance, antibacterial activity, and self-cleaning. The free radicals it generates under UV irradiation exhibit strong chemical activity. When encountering bacteria, these free radicals can directly attack the bacterial cell wall and cell membrane, or inhibit the replication of intracellular components, thereby affecting cell metabolism. Therefore, adding it to fatliquoring agents can achieve excellent antibacterial effects when treating leather artifacts. However, nano-titanium dioxide is prone to aggregation in aqueous media. To address this, this invention adds polyethylene glycol 400 to water. The hydrophobic groups of polyethylene glycol 400 adsorb onto the surface of the nano-titanium dioxide particles, forming an adsorption layer. The hydrophilic groups are suspended in the aqueous medium. When two nanoparticles approach each other, the adsorption layer is compressed, reducing the number of polyethylene glycol molecular chains. The adsorption layers overlap and interpenetrate, generating repulsive forces to stabilize the nanoparticles.

[0008] Step 2): Heat the mixture obtained in Step 1) to 50-70℃, add 0.3-0.7wt% of KH550 silane coupling agent to the mixture, adjust the pH of the system to 3-5, react at a constant temperature for 0.5-1.5h, centrifuge, take the precipitate and redisperse it in water, ultrasonically treat to remove excess silane coupling agent, dry, and vacuum cool to obtain silane coupling agent modified nano titanium dioxide powder;

[0009] This invention reveals that unmodified nano-titanium dioxide has a large specific surface area and high surface free energy, which is unfavorable for its dispersion in non-polar media and prone to aggregation in polar media. Therefore, further organic modification of nano-titanium dioxide is necessary. Silane coupling agents are bifunctional substances; one end can react physically or chemically with organic groups, while the other end can react with hydroxyl groups on the surface of nanoparticles to form strong chemical bonds, enabling nano-titanium dioxide to better integrate with polymers in the system.

[0010] Step 3): Mix coconut oil and polyethylene glycol-400 at a mass ratio of 1:1-6, add sodium methoxide as catalyst, and react at 125-135℃ for 2-4 hours to obtain modified coconut oil.

[0011] Coconut oil possesses excellent antifungal and antimicrobial properties. The primary antibacterial and antifungal component in coconut oil is lauric acid, which achieves its antibacterial effect by disrupting the signal transduction of pathogens, thereby affecting the normal physiological metabolic activities of cells. It also exhibits certain emulsifying properties. Furthermore, since medium-chain fatty acid monoglycerides have good antibacterial properties, and coconut oil contains over 60% medium-chain fatty acids, this invention utilizes a transesterification reaction between polyethylene glycol 400 and coconut oil to generate fatty acid monoglycerides, thereby further enhancing the antibacterial properties of coconut oil.

[0012] Step 4): Add maleic anhydride to the modified coconut oil at a mass ratio of 1-2:1, stir and react at 80-100℃ for 2-4 hours, then add 1-4 wt% of silane coupling agent modified nano-titanium dioxide dispersion to the system, and continue to keep warm for 0.5-1.5 hours.

[0013] Using the hydroxyl-modified coconut oil from step 3) as the starting material, it is esterified with maleic anhydride to obtain maleic anhydride ester. In the maleic anhydride molecule, the electron-withdrawing properties of the two carbonyl groups in the conjugated ring increase the positive charge of the carbonyl carbon, thereby improving the activity of the acylation reaction. Therefore, the esterification reaction of maleic anhydride alcohols is relatively easy to proceed. This reaction does not produce water or other small molecule condensates, so it is irreversible. After the reaction, an unsaturated double bond is introduced into the modified coconut oil, which is beneficial to the subsequent sulfonation reaction. At the same time, a carboxyl group is introduced, giving the product a certain degree of hydrophilicity. Step 5): The reaction product from step 4) is cooled to 70-80℃, and 20-30wt% of the reaction product is added to a 15-20wt% sodium metabisulfite solution. After reacting for 0.5-1.5h, the pH is adjusted to 6-8, and the reaction is maintained at a constant temperature for 1-3h.

[0014] The double bond is reduced by sodium metabisulfite and accompanied by sulfonation. During sulfonation, the sulfonic acid group is mainly attached to the carbon near the carboxyl group, which introduces hydrophilic sulfonic acid group into the molecular structure of the product, which can improve the emulsifying properties of fatliquoring agents.

[0015] Step 6): Add water to adjust the solid content of the system obtained in step 5), stir at a constant temperature, and obtain the antibacterial fatliquoring agent.

[0016] Preferably, in step 1), the mixture is stirred for 20-40 minutes and ultrasonically dispersed for 20-40 minutes.

[0017] Preferably, in step 2), the centrifugation process lasts for 15-25 minutes at a speed of 8000-12000 r / min.

[0018] Preferably, in step 2), the ultrasonic treatment lasts for 10-20 minutes.

[0019] Preferably, in step 3), the amount of sodium methoxide catalyst used is 0.5-1.5 wt% of coconut oil.

[0020] Preferably, in step 6), the solid content of the water-added system is adjusted to 35-45%.

[0021] Preferably, in step 6), the temperature of the constant temperature stirring is 70-80℃, and the time is 35-45 minutes.

[0022] Compared with the prior art, the present invention has the following technical effects: The antibacterial fatliquoring agent prepared by the method of the present invention contains both hydrophilically modified coconut oil and silane coupling agent modified nano titanium dioxide. This antibacterial fatliquoring agent has excellent penetration and filling properties for dried and hardened leather artifacts. After the leather artifacts are protected, they have extremely high antibacterial properties and can resist the erosion of various bacterial colonies. At the same time, their softness is also improved to a certain extent. Moreover, the main raw materials are natural, non-toxic, and inexpensive, and will not damage the leather artifacts. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments.

[0024] Example 1

[0025] Step 1): Add nano TiO2 and polyethylene glycol-400 to a certain amount of deionized water. The mass ratio of deionized water, nano TiO2 and polyethylene glycol-400 is 100:0.5:0.04. Stir with a magnetic stirrer for 30 minutes and then disperse with ultrasound for 30 minutes.

[0026] Step 2): Transfer the solution obtained in Step 1) into a 250 mL three-necked flask, raise the temperature to 60 °C, add 0.5 wt% KH550 silane coupling agent, adjust the pH of the system to 4 with ammonia, and react at a constant temperature for 1 h.

[0027] Step 3): Then, centrifuge at 10000 r / min for 20 min, take the precipitate and redisperse it in deionized water, continue to sonicate for 15 min, dry in an oven at 100℃ for 24 h, and vacuum cool for 1 h to obtain silane coupling agent modified nano titanium dioxide powder.

[0028] Step 4): Weigh coconut oil and polyethylene glycol-400 in a 1:4 mass ratio and add them to a three-necked flask equipped with a stirrer. Add 1 wt% sodium methoxide of coconut oil as a catalyst and react at 130°C for 3 hours.

[0029] Step 5) Add maleic anhydride at a mass ratio of 1:1.5 with the obtained modified coconut oil, stir and react at 90℃ for 3h, then add 4% KH550-TiO2 powder and keep warm for 1h.

[0030] Step 6): Cool to 75℃, add 25wt% sodium metabisulfite solution with a concentration of 17wt%, react for 1 hour, adjust the pH value to 7 with ammonia water, and react at a constant temperature for 2 hours.

[0031] Step 7): Add purified water to adjust the solid content of the system to 40%, and continue stirring at a constant temperature of 75℃ for 40 minutes.

[0032] Example 2

[0033] Step 1): Add nano TiO2 and polyethylene glycol-400 to a certain amount of deionized water. The mass ratio of deionized water, nano TiO2 and polyethylene glycol-400 is 100:0.5:0.02. Stir with a magnetic stirrer for 20 minutes and then disperse with ultrasound for 20 minutes.

[0034] Step 2): Transfer the solution obtained in Step 1) into a 250 mL three-necked flask, raise the temperature to 50 °C, add 0.3 wt% KH550 silane coupling agent, adjust the pH of the system to 3 with ammonia, and react at a constant temperature for 0.5 h.

[0035] Step 3): Then, centrifuge at 10000 r / min for 15 min, take the precipitate and redisperse it in deionized water, continue to sonicate for 10 min, dry in an oven at 100℃ for 24 h, and vacuum cool for 1 h to obtain silane coupling agent modified nano titanium dioxide powder.

[0036] Step 4): Weigh coconut oil and polyethylene glycol-400 in a 1:1 mass ratio and add them to a three-necked flask equipped with a stirrer. Add 0.5 wt% sodium methoxide of coconut oil as a catalyst and react at 125°C for 4 hours.

[0037] Step 5) Add maleic anhydride at a mass ratio of 1:1 with the obtained modified coconut oil, stir and react at 80℃ for 4h, then add 2% KH550-TiO2 powder and keep warm for 1.5h.

[0038] Step 6): Cool down to 70°C, add 20wt% of a 17wt% sodium metabisulfite solution, react for 1 hour, adjust the pH to 6 with ammonia, and react at a constant temperature for 1 hour.

[0039] Step 7): Add purified water to adjust the solid content of the system to 35%, and continue stirring at a constant temperature of 70℃ for 35 minutes.

[0040] Example 3

[0041] Step 1): Add nano TiO2 and polyethylene glycol-400 to a certain amount of deionized water. The mass ratio of deionized water, nano TiO2 and polyethylene glycol-400 is 110:0.7:0.1. Stir with a magnetic stirrer for 40 minutes and then disperse with ultrasound for 40 minutes.

[0042] Step 2): Transfer the solution obtained in Step 1) into a 250 mL three-necked flask, raise the temperature to 70 °C, add 0.7 wt% KH550 silane coupling agent, adjust the pH of the system to 5 with ammonia, and react at a constant temperature for 1.5 h.

[0043] Step 3): Then, centrifuge at 10000 r / min for 25 min, take the precipitate and redisperse it in deionized water, continue to sonicate for 20 min, dry in an oven at 100℃ for 24 h, and vacuum cool for 1 h to obtain silane coupling agent modified nano titanium dioxide powder.

[0044] Step 4): Weigh coconut oil and polyethylene glycol-400 in a mass ratio of 1:6 and add them to a three-necked flask equipped with a stirrer. Add 1.5 wt% sodium methoxide of coconut oil as a catalyst and react at 135°C for 2 hours.

[0045] Step 5) Add maleic anhydride at a mass ratio of 1:2 with the obtained modified coconut oil, stir and react at 100℃ for 4h, then add 1% KH550-TiO2 powder and keep warm for 0.5h.

[0046] Step 6): Cool down to 80℃, add 30wt% of a 17wt% sodium metabisulfite solution, react for 1.5h, adjust the pH to 8 with ammonia, and react at a constant temperature for 3h.

[0047] Step 7): Add purified water to adjust the solid content of the system to 45%, and continue stirring at a constant temperature of 80℃ for 45 minutes.

[0048] Comparative Example 1 (using unmodified coconut oil)

[0049] Step 1): Add nano TiO2 and polyethylene glycol-400 to a certain amount of deionized water. The mass ratio of deionized water, nano TiO2 and polyethylene glycol-400 is 100:0.5:0.04. Stir with a magnetic stirrer for 30 minutes and then disperse with ultrasound for 30 minutes.

[0050] Step 2): Transfer the solution obtained in Step 1) into a 250 mL three-necked flask, raise the temperature to 60 °C, add 0.5 wt% KH550 silane coupling agent, adjust the pH of the system to 4 with ammonia, and react at a constant temperature for 1 h.

[0051] Step 3): Then, centrifuge at 10000 r / min for 20 min, take the precipitate and redisperse it in deionized water, continue to sonicate for 15 min, dry in an oven at 100℃ for 24 h, and vacuum cool for 1 h to obtain silane coupling agent modified nano titanium dioxide powder.

[0052] Step 4): Weigh coconut oil and polyethylene glycol-400 in a 1:4 mass ratio and add them to a three-necked flask equipped with a stirrer. Add 1 wt% sodium methoxide of coconut oil as a catalyst and react at 130°C for 3 hours.

[0053] Step 5) After adding 4% KH550-TiO2 powder and keeping it at a constant temperature for 1 hour, the temperature was lowered to 75°C, the pH was adjusted to 7 with ammonia, and the reaction was carried out at a constant temperature for 2 hours.

[0054] Step 6): Add purified water to adjust the solid content of the system to 40%, and stir at a constant temperature of 75℃ for 40 minutes.

[0055] Comparative Example 2 (using unmodified nano-TiO2)

[0056] Step 1): Add nano TiO2 and polyethylene glycol-400 to a certain amount of deionized water. The mass ratio of deionized water, nano TiO2 and polyethylene glycol-400 is 100:0.5:0.04. Stir with a magnetic stirrer for 30 minutes and then disperse with ultrasound for 30 minutes.

[0057] Step 2): Weigh coconut oil and polyethylene glycol-400 and add them to a three-necked flask equipped with a stirrer at a mass ratio of 1:4. Add 1 wt% sodium methoxide of coconut oil as a catalyst and react at 125-135℃ for 3 hours.

[0058] Step 3) Add maleic anhydride at a mass ratio of 1:1.5 with the obtained modified coconut oil, stir and react at 90℃ for 3h, then add 4% of the obtained TiO2 dispersion and keep warm for 1h.

[0059] Step 4): Cool down to 75°C, add 25wt% of a 17wt% sodium metabisulfite solution, react for 1 hour, adjust the pH to 7 with ammonia, and react at a constant temperature for 2 hours.

[0060] Step 5): Add purified water to adjust the solid content of the system to 40%, and continue stirring at a constant temperature of 75℃ for 40 minutes.

[0061] Comparative Example 3 (using unmodified coconut oil and unmodified nano-TiO2)

[0062] Step 1): Add nano TiO2 and polyethylene glycol-400 to a certain amount of deionized water. The mass ratio of deionized water, nano TiO2 and polyethylene glycol-400 is 100:0.5:0.04. Stir with a magnetic stirrer for 30 minutes and then disperse with ultrasound for 30 minutes.

[0063] Step 2): Weigh coconut oil and polyethylene glycol-400 in a mass ratio of 1:4 and add them to a three-necked flask equipped with a stirrer. Add 1 wt% sodium methoxide of coconut oil as a catalyst and react at 130°C for 3 hours.

[0064] Step 3) Add 4% of the obtained TiO2 dispersion to the solution obtained in Step 2) and react for 1 hour. Then, cool down to 75°C, adjust the pH value to 7 with ammonia water, and react at a constant temperature for 2 hours.

[0065] Step 4): Add purified water to adjust the solid content of the system to 40%, and continue stirring at a constant temperature of 75℃ for 40 minutes.

[0066] Performance testing

[0067] Case Antibacterial zone diameter / mm Antibacterial rate / % Softness change rate / % Example 1 42.51 86.79 +15.24 Example 2 30.52 53.48 +9.19 Example 3 27.64 49.92 +7.93 Comparative Example 1 23.37 35.43 +8.72 Comparative Example 2 20.85 33.66 +6.48 Comparative Example 3 11.50 19.82 +2.03

[0068] As can be seen from the table:

[0069] Example 1 shows that the antibacterial fatliquoring agent exhibits excellent antibacterial effects, with the largest inhibition zone diameter. The leather treated with this agent also shows the highest antibacterial rate, while its softness is significantly improved. In Example 2, due to the low dosage of polyethylene glycol 400 during modification, dispersibility was insufficient, leading to the aggregation of nano-TiO2 and failing to achieve good dispersion. Furthermore, the antibacterial properties of coconut oil were not improved. The low dosage of KH550 resulted in insufficient grafting of coupling agent onto the surface of the nano-TiO2 particles, also failing to effectively improve the aggregation phenomenon in the nano-TiO2 dispersion.

[0070] In Example 3, excessive use of polyethylene glycol 400, while effectively dispersing nano-TiO2 due to steric hindrance, caused the polar ends of the polyethylene glycol 400 to become entangled, leading to the re-aggregation of the already dispersed nano-titanium dioxide. Although the formation of glycerol diesters and monoglycerides increases the antibacterial rate of the alcoholysis products with the increase of polyethylene glycol 400, when the amount of polyethylene glycol increases to a certain value and the reaction reaches a certain extent, the monoglycerides gradually become higher fatty acid polyethylene glycol esters, and the antibacterial properties of the products gradually decrease. Excessive hydrolysis of silane coupling agent generates siloxane anions that attack the Si atoms in the silane coupling agent molecules bonded to nano-titanium dioxide, bridging the particles and causing flocculation of the nanoparticles, weakening their stability and causing agglomeration.

[0071] Comparative Example 1 uses unmodified coconut oil, which is insoluble in water, difficult to emulsify, and prone to stratification in solution. The resulting antibacterial fatliquoring agent is extremely unstable, and therefore its antibacterial effect is far inferior to that of Example 1.

[0072] In Comparative Example 2, unmodified nano-TiO2 was used. Although the addition of polyethylene glycol 400 could effectively improve the aggregation phenomenon, it still had some aggregation compared to the modified nano-TiO2 and could not fully penetrate between collagen fibers. Therefore, the antibacterial effect and the rate of change in softness were not as good as in Example 1.

[0073] Comparative Example 3 uses unmodified coconut oil and unmodified nano-TiO2 to form a composite. The unmodified coconut oil separates into layers in the solution, while the unmodified nano-TiO2 agglomerates in the solution. The prepared fatliquoring agent has extremely poor stability, so its antibacterial properties and softness change rate when applied to leather artifacts are not significant.

[0074] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing an antibacterial fatliquoring agent for dried and hardened leather artifacts, characterized in that... Includes the following steps: Step 1): Add nano-titanium dioxide and polyethylene glycol 400 to water, and then stir and ultrasonically disperse them to obtain a mixture; the mass ratio of water, nano-titanium dioxide and polyethylene glycol 400 is 90-110:0.5:0.

04. Step 2): Heat the mixture obtained in Step 1) to 50-70℃, add 0.3-0.7wt% of KH550 silane coupling agent to the mixture, adjust the pH of the system to 3-5, react at a constant temperature for 0.5-1.5h, centrifuge, take the precipitate and redisperse it in water, sonicate to remove excess silane coupling agent, dry, and vacuum cool to obtain silane coupling agent modified nano titanium dioxide powder; Step 3): Mix coconut oil and polyethylene glycol-400 at a mass ratio of 1:1-6, add sodium methoxide as catalyst, and react at 125-135℃ for 2-4 hours to obtain modified coconut oil; Step 4): Add maleic anhydride to the modified coconut oil at a mass ratio of 1-2:1, stir and react at 80-100℃ for 2-4 hours, then add 1-4 wt% of silane coupling agent modified nano titanium dioxide to the system, and continue to keep warm for 0.5-1.5 hours. Step 5): Cool the reaction product from Step 4) to 70-80℃, add 20-30wt% of the reaction product to a 15-20wt% sodium metabisulfite solution, react for 0.5-1.5h, adjust the pH to 6-8, and react at a constant temperature for 1-3h. Step 6): Add water to adjust the solid content of the system obtained in Step 5), stir at a constant temperature, and obtain the antibacterial fatliquoring agent.

2. The preparation method according to claim 1, characterized in that: In step 1), stir for 20-40 minutes and ultrasonically disperse for 20-40 minutes.

3. The preparation method according to claim 1, characterized in that: In step 2), centrifuge for 15-25 minutes at a speed of 8000-12000 r / min.

4. The preparation method according to claim 1, characterized in that: In step 2), ultrasonic treatment is performed for 10-20 minutes.

5. The preparation method according to claim 1, characterized in that: In step 3), the amount of sodium methoxide catalyst used is 0.5-1.5 wt% of coconut oil.

6. The preparation method according to claim 1, characterized in that: In step 6), water is added to adjust the solid content of the system to 35-45%.

7. The preparation method according to claim 1, characterized in that: In step 6), the temperature for constant temperature stirring is 70-80℃, and the time is 35-45 minutes.

8. The application of the antibacterial fatliquoring agent obtained by the preparation method according to any one of claims 1-7 in the temperature protection of dried and hardened leather.