Polylysine-based chrome-free tanning agent with fragrance slow-release behavior as well as preparation method and application of polylysine-based chrome-free tanning agent

Abstract

The invention discloses a polylysine-based chrome-free tanning agent with an aromatic slow-release behavior and a preparation method and application thereof, and belongs to the technical field of green biomass materials and ecological leather, the method comprises the following steps: carrying out epoxy modification on polylysine to obtain an epoxy modified polylysine cross-linking agent, then adding aromatic aldehyde to carry out a cross-linking reaction, and carrying out vacuum drying to obtain the polylysine-based chrome-free tanning agent with the aromatic slow-release behavior. And carrying out heating and stirring reaction, dialysis, freeze drying and grinding to obtain the polylysine-based chrome-free tanning agent with the aromatic slow-release behavior. The method is applied to a leather tanning process, and biomass green ecological leather with fragrance slow release is obtained. Powerful crosslinking is formed with leather collagen fibers, so that the physical properties of the leather are remarkably improved; meanwhile, the leather is endowed with pleasant unique fragrance, and unpleasant amine odor generated in traditional leather making is effectively neutralized and eliminated. And double breakthrough of ecological leather manufacturing in performance improvement and sensory experience improvement is realized. The preparation route is simple, and a thought is provided for design of a novel green chrome-free tanning agent and manufacturing of aromatic leather.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of green biomass materials and ecological leather, and particularly relates to a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, a preparation method and application. BACKGROUND

[0002] Leather products have special odors such as fishy and rancid odors inherent to fur. Although these unpleasant odors are improved to some extent during leather processing, they cannot be completely removed. In addition, certain chemicals are inevitably added during leather chemical production, which also produces a large amount of unpleasant odor. The main components of leather are collagen and fat, which are good sources of nutrition for bacteria and provide a good living environment for the growth and reproduction of bacteria, breeding a harmful odor of mold.

[0003] Currently, in the leather production process, essence is introduced to effectively mask the inherent odor while ensuring good tanning performance. However, direct addition of essence molecules has problems such as easy volatilization and easy oxidation under light and heat conditions, which may lead to odor deterioration and make it difficult to ensure the stability and long-lasting fragrance effect of the essence. In addition, although microcapsule encapsulation technology has become the mainstream method for leather perfuming, it still has technical bottlenecks such as complex preparation process and low encapsulation efficiency. At the same time, the method of impregnating leather with essence capsules also cannot achieve the effect of long-lasting and stable retention of fragrance, and the fragrance retention time still needs to be further improved.

[0004] Therefore, in view of the problems of fast volatilization, easy oxidation, short fragrance retention time and complex microcapsule process in the existing leather odor control and perfuming technology, an improved leather perfuming technical solution is needed, and a new perfuming method needs to be developed urgently. On the basis of maintaining the excellent tanning performance and physical properties of leather, the new perfuming method can achieve the effect of mild, long-lasting and stable retention of fragrance, thereby effectively masking the inherent odor of leather and improving the sensory quality and use experience of the product. SUMMARY

[0005] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, a preparation method and application, to solve the technical problems of fast volatilization, easy oxidation, short fragrance retention time and complex microcapsule process in the existing leather perfuming technology.

[0006] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: The present application discloses a preparation method of a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising: The polylysine is subjected to epoxy modification to obtain an epoxy modified polylysine crosslinking agent; the epoxy modified polylysine crosslinking agent is added with furfural to perform crosslinking reaction, and through heating and stirring reaction, dialysis, freeze drying and grinding, the polylysine based chrome-free tanning agent with aromatic slow release behavior is obtained.

[0007] Preferably, the conditions for epoxy modification of the polylysine include: after mixing glycerol triglycidyl ether, polylysine and hexamethylenetetramine, the pH value is adjusted to 6-9.5; after stirring reaction, the epoxy modified polylysine crosslinking agent is obtained; the epoxy of the epoxy modified polylysine crosslinking agent is from the glycerol triglycidyl ether.

[0008] Further preferably, the molar ratio of the polylysine to the glycerol triglycidyl ether is 1: (3-9).

[0009] Further preferably, the temperature of the stirring reaction is 30-50 DEG C; and the time of the stirring reaction is 2-6 h.

[0010] Preferably, the mass of the epoxy modified polylysine crosslinking agent is 8%-15% of the mass of the furfural; and the mass concentration of the epoxy modified polylysine crosslinking agent is 0.1-1 g / L.

[0011] Preferably, the conditions for the crosslinking reaction include: stirring reaction at 25-55 DEG C for 2-6 h.

[0012] Preferably, the temperature of the dialysis is 25-45 DEG C, the time of the dialysis is 24-72 h; the temperature of the freeze drying is -60 DEG C to -80 DEG C, and the time of the freeze drying is 24-72 h.

[0013] The application discloses a polylysine based chrome-free tanning agent with aromatic slow release behavior.

[0014] Preferably, the structural formula of the polylysine based chrome-free tanning agent with aromatic slow release behavior is: .

[0015] The application further discloses application of the polylysine based chrome-free tanning agent with aromatic slow release behavior prepared by the preparation method of the polylysine based chrome-free tanning agent with aromatic slow release behavior to leather processing.

[0016] Compared with the prior art, the application has the following beneficial effects: The application discloses a preparation method of a polylysine-based chrome-free tanning agent with fragrance slow-release behavior.

[0017] Further, the mass concentration of the epoxy-modified polylysine crosslinking agent is 0.15-0.20 g / mL, so that the overcrosslinking reaction caused by excessively high concentration or the insufficient chain extension caused by excessively low concentration can be avoided, and the uniformity of the chain extension reaction is ensured. The furfural is selected to perform further chain extension reaction, so that the odor problem caused by the chrome-free tanning agent tanned leather can be improved, and the epoxy group can be reacted to ensure the stability of the subsequent reaction.

[0018] Further, the epoxy group in the epoxy-modified polylysine crosslinking agent is derived from glycerol triglycidyl ether, the molar mass of the glycerol triglycidyl ether is 10%-30% of the molar mass of the polylysine in the epoxy-modified polylysine crosslinking agent, and the glycerol triglycidyl ether contains three units of epoxy groups, so that the average number of epoxy groups that can be carried by each molecular chain of the polylysine in the grafting reaction is ensured, which directly affects the ability of forming a crosslinking network.

[0019] Further, the molar ratio of the epoxy-modified polylysine crosslinking agent to the furfural is 1:1-1:12, so that the ratio between the epoxy groups and the aldehyde groups is balanced, and the mechanical properties, the thermal stability and the fragrance retention of the tanned leather are adjusted; if the ratio is too low, the fragrance retention of the leather is insufficient, and if the ratio is too high, the tanning performance is excessively high, and the phenomenon of over-tanning is caused; the ratio can introduce sufficient tanning groups to achieve good tanning performance, and can also maintain the long-lasting fragrance retention of the leather.

[0020] Further, the chain extension reaction is performed at a stirring temperature of 25-55 DEG C for 2-6 h, so that the epoxy groups and the aldehyde groups can be fully reacted, the unreacted groups are avoided to be left, and the incomplete reaction caused by the ring opening of the epoxy groups at high temperature is avoided, and the structural stability of the polylysine chrome-free tanning agent with fragrance slow-release behavior is ensured.

[0021] Further, the obtained aromatic slow-release behavior polylysine chrome-free tanning agent solution is left to room temperature to obtain a final sample; the dialysis conditions are 25-45 DEG C, and the time is 24-72 h; the freeze-drying conditions are -60 to -80 DEG C, and the time is 24-72 h. The unreacted small molecules are removed to avoid the influence of residues on the performance, and the purity of the material is ensured. The vacuum drying conditions are mild, which will not damage the structure of the aromatic polylysine chrome-free tanning agent and will not affect the performance in the application of leather.

[0022] The polylysine-based chrome-free tanning agent with aromatic slow-release behavior disclosed in the application introduces vanillin, epoxy group and polylysine into the structure of the chrome-free tanning agent by combining chemical modification and physical crosslinking, and the synthesis method is simple. The abundant amino groups of polylysine, the high reactivity of the epoxy group and the aromatic characteristics of vanillin together endow the tanned leather material with good mechanical properties, thermal stability and persistent fragrance, and realize the transformation from bad smell to suitable fragrance of the traditional tanned leather material.

[0023] Further, the structure of the epoxy-modified polylysine crosslinking agent is determined to ensure that the amino groups in the molecule can react with the epoxy groups; the molecular stability of the crosslinking agent is improved to provide a structural basis for the introduction of the aldehyde groups in vanillin and improve the tanning performance and thermal stability.

[0024] The application of the polylysine-based chrome-free tanning agent with aromatic slow-release behavior disclosed in the application in leather processing. By introducing the epoxy-modified polylysine crosslinking agent, the epoxy groups in the tanning agent can effectively react with the collagen fibers of the leather to form a stable crosslinking network, significantly improve the mechanical properties of the leather, and avoid the poor tanning performance of the traditional chrome-free tanning agent. At the same time, by controlling the reaction ratio, the "over-tanning" phenomenon is prevented. The formation of the crosslinking structure improves the thermal stability of the leather, so that the leather is not easy to deform or degrade under high-temperature processing or use conditions, and the service life of the leather product is prolonged. The introduction of vanillin provides the leather with persistent fragrance retention characteristics, effectively masks the odor during leather processing, and realizes the transformation from bad smell to suitable fragrance. By adjusting the proportion of vanillin, the fragrance retention and tanning performance can be balanced to ensure slow release and persistent pleasant fragrance. As a chrome-free tanning agent, it avoids the heavy metal pollution and health risks caused by chrome tanning agents, and meets the green tanning requirements. At the same time, the unreacted small molecules are removed by dialysis and freeze-drying during the preparation process to ensure the purity of the tanning agent and avoid the influence of residues on the performance of the leather. By combining chemical modification and physical crosslinking, the route is simple, the conditions are mild, and the production is easy to scale up, which provides a new idea for the innovative design of the aromatic chrome-free tanning agent. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The synthesis route of the polylysine-based chrome-free tanning agent with aromatic slow-release behavior disclosed in the application is shown in the figure; Figure 2 Infrared absorption spectrum of aromatic aldehyde, epoxy modified polylysine crosslinking agent and polylysine based chrome-free tanning agent with aromatic slow release behavior in Example 2 of the present application; Figure 3 Electronic scanning spectrum of polylysine based chrome-free tanning agent with aromatic slow release behavior and tanned leather in Example 2 of the present application; wherein (a) is aromatic aldehyde; (b) is polylysine chrome-free tanning agent PGV-2 with aromatic slow release behavior prepared by the method in Example 2; (c) is raw hide; (d) is leather tanned by PGV-2 tanning agent prepared by the method in Example 2; Figure 4 Shrinkage temperature spectrum of polylysine based chrome-free tanning agent with aromatic slow release behavior in leather in Example 2 of the present application; wherein PS is raw hide, PGV-1 is leather tanned by chrome-free tanning agent prepared by the method in Example 1, PGV-2 is leather tanned by chrome-free tanning agent prepared by the method in Example 2, PGV-3 is leather tanned by chrome-free tanning agent prepared by the method in Example 3, and PGV-4 is leather tanned by chrome-free tanning agent prepared by the method in Example 4. DETAILED DESCRIPTION

[0026] The technical solutions of the present application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0027] In the present application, all the embodiments and preferred embodiments mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0028] In the present application, all the technical features and preferred features mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0029] In the present application, percentage (%) or part refers to weight percentage or weight part of the composition, if not otherwise specified.

[0030] In the present application, all the components or preferred components mentioned in the present application can be combined to form new technical solutions, if not otherwise specified.

[0031] In the present application, unless otherwise specified, the numerical range “a~b” represents a shorthand notation of any real number combination between a and b, wherein a and b are both real numbers. For example, the numerical range “6~22” represents that all the real numbers between “6~22” have been listed herein, and “6~22” is only a shorthand notation of these numerical combinations.

[0032] The ranges disclosed herein below the lower limit and above the upper limit of the range can each be independently one or more of the lower limit and one or more of the upper limit.

[0033] In the present invention, the term "and / or" as used herein means any combination of one or more of the associated listed items as well as all possible combinations and includes these combinations.

[0034] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in accordance with the sequence. Preferably, the reaction method herein is carried out sequentially.

[0035] Unless otherwise specified, the professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equivalent to that described can also be applied in the present invention.

[0036] The present invention provides a preparation method of a polylysine-based chromium-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Dissolve the epoxy-modified polylysine solution in water to prepare an epoxy-modified polylysine crosslinking agent; 2) Add vanillin to the epoxy-terminated polylysine-based crosslinking agent to carry out crosslinking reaction, and after heating and stirring reaction, a crosslinked solution is obtained. The crosslinked solution is subjected to dialysis, freeze-drying, and grinding to obtain a polylysine-based chromium-free tanning agent with fragrance slow-release behavior.

[0037] In step 2), the structure of the polylysine-based chromium-free tanning agent with fragrance slow-release behavior is: ; In step 1), the epoxy group source is glycerol triglycidyl ether, and the molar mass of the epoxy-modified polylysine crosslinking agent is 10% to 30% of the molar mass of the polylysine in the epoxy-modified polylysine crosslinking agent. The concentration of the epoxy-modified polylysine crosslinking agent is 0.15 to 0.20 g / mL.

[0038] In step 1), the preparation conditions of the crosslinking agent include pH = 9, temperature 35-50℃, and stirring reaction for 2-6 h.

[0039] In step 2), the fragrance source in the aromatic polylysine-based chromium-free tanning agent is vanillin, and the mass of vanillin is 8% to 15% of the mass of the epoxy-modified chromium-free tanning agent crosslinking agent. The dialysis conditions are 25-45℃ for 24-72 h, and the freeze-drying conditions include vacuum drying at -60 to -80℃ for 48-72 h.

[0040] The application innovatively carries out a chemical cross-linking reaction between epoxy-modified polylysine and vanillin, and successfully prepares an epoxy-modified aromatic slow-release polylysine-based chrome-free tanning agent. The tanning agent is applied to the leather tanning process, and an excellent performance biomass green ecological leather can be obtained. Compared with traditional leather, this new type of leather effectively breaks through the problems of unpleasant odor and poor physical performance commonly existing in traditional tanned leather. It not only has the characteristics of long-acting fragrance retention and can continuously emit natural fragrance, but also has higher tanning performance, can inhibit the growth of microorganisms, and significantly prolong the service life of leather products. It has great advantages in the preparation process. The whole process only involves basic operation steps such as solution mixing, blending cross-linking, dialysis purification and drying forming, and does not need to rely on complex and expensive special equipment, which is easy to operate and can realize large-scale production. It effectively fills the functional gap of chrome-free tanning agent, highly meets the current environmental protection development trend, provides strong technical support for the transformation of the leather industry to green and ecological direction, and has important industry application value.

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0042] Embodiment 1 A preparation method of a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Preparation of an epoxy-modified polylysine cross-linking agent After 6.67 g of glycerol triglycidyl ether, 10.00 g of polylysine with a relative molecular weight of 3500 Da, and 0.1 g of hexamethylenetetramine are mixed, the pH is adjusted to 6, and the reaction is carried out in a 30℃ oil bath for 6 h to obtain an epoxy-modified polylysine cross-linking agent.

[0043] 2) Preparation of a polylysine-based chrome-free tanning agent with fragrance slow-release behavior The furfural is dissolved in aqueous solution, the pH is adjusted to 8, the obtained solution is added to the epoxy modified polylysine crosslinking agent obtained in step 1), and the crosslinking is carried out in an oil bath at 25℃ for 6 h. The crosslinking blended solution is poured into a dialysis bag with a molecular weight of 1000 Da, dialysis is carried out in a shaking box at 25℃ for 72 h, then it is placed in a freezer for 24 h, dried in a freeze dryer at -60℃ for 72 h, and finally ground to obtain the polylysine-based chrome-free tanning agent with fragrance slow-release behavior.

[0044] Example 2 A method for preparing a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Preparation of an epoxy modified polylysine crosslinking agent After mixing 6.67 g of glycerol triglycidyl ether, 10.00 g of polylysine with a relative molecular weight of 3500 Da and 0.1 g of hexamethylenetetramine, the pH is adjusted to 6.5, and the reaction is carried out in an oil bath at 35℃ for 5 h to obtain the epoxy modified polylysine crosslinking agent.

[0045] 2) Preparation of a polylysine-based chrome-free tanning agent with fragrance slow-release behavior The furfural is dissolved in aqueous solution, the pH is adjusted to 8, the obtained solution is added to the epoxy modified polylysine crosslinking agent obtained in step 1), and the crosslinking is carried out in an oil bath at 30℃ for 5 h. The crosslinking blended solution is poured into a dialysis bag with a molecular weight of 1000, dialysis is carried out in a shaking box at 30℃ for 60 h, then it is placed in a freezer for 24 h, dried in a freeze dryer at -65℃ for 60 h, and finally ground to obtain the polylysine-based chrome-free tanning agent with fragrance slow-release behavior.

[0046] See Figure 1 It is a synthetic route diagram of the polylysine-based chrome-free tanning agent with fragrance slow-release behavior disclosed in the present application. As can be seen from the diagram, the entire preparation process is simple, and the polylysine-based chrome-free tanning agent with fragrance slow-release behavior can be obtained.

[0047] See Figure 2 It is an infrared absorption diagram of the aromatic aldehyde, the epoxy modified polylysine crosslinking agent and the polylysine-based chrome-free tanning agent with fragrance slow-release behavior in Example 2 of the present application. As can be seen from the diagram, compared with the epoxy modified polylysine crosslinking agent, the polylysine chrome-free tanning agent with fragrance slow-release has an aldehyde group peak at the same position as the aromatic aldehyde at 2735 cm -1 , which means that the aldehyde group structure has been successfully introduced into the epoxy modified polylysine crosslinking agent, indicating the successful construction of the aromatic chrome-free tanning agent.

[0048] See Figure 3Electronic scanning diagram of polylysine-based chrome-free tanning agent with fragrance slow-release behavior in Example 2 of the present application and tanned leather; wherein (a) is vanillin; (b) is the polylysine chrome-free tanning agent PGV with fragrance slow-release behavior prepared by the method of Example 2; (c) is raw hide; (d) is the leather tanned by the PGV tanning agent prepared by the method of Example 2; it can be seen from the diagram that the polylysine-based chrome-free tanning agent with fragrance slow-release behavior is successfully prepared and attached to the epoxy-modified polylysine crosslinking agent, and the dispersion of collagen fibers of the leather tanned by the tanning agent is larger than that of the raw hide, and the leather presents a state of individual fiber bundles.

[0049] Reference is made to Figure 4 Shrinkage temperature diagram of the polylysine chrome-free tanning agent with fragrance slow-release behavior in Example 2 of the present application after application in leather; wherein PS is raw hide, PGV-1 is the leather tanned by the chrome-free tanning agent prepared according to the method of Example 1, PGV-2 is the leather tanned by the chrome-free tanning agent prepared according to the method of Example 2, PGV-3 is the leather tanned by the chrome-free tanning agent prepared according to the method of Example 3, and PGV-4 is the leather tanned by the chrome-free tanning agent prepared according to the method of Example 4. It can be seen from the diagram that the shrinkage temperature of the leather tanned by the chrome-free tanning agent prepared in Example 2 is higher than 80℃, and the heat resistance stability of the leather is improved compared with the raw hide, which indicates that the tanning effect of the polylysine chrome-free tanning agent with fragrance slow-release behavior prepared in the present application is improved. This means that the polylysine chrome-free tanning agent with fragrance slow-release behavior prepared in the present application has strong crosslinking effect and heat stability.

[0050] Example 3 A preparation method of a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Preparation of epoxy-modified polylysine crosslinking agent 6.67 g of glycerol triglycidyl ether, 10.00 g of polylysine with a relative molecular weight of 3500 and 0.1 g of hexamethylenetetramine are mixed, the pH is adjusted to 7, and the mixture is reacted at 40℃ for 5 h to obtain the epoxy-modified polylysine crosslinking agent.

[0051] 2) Preparation of polylysine-based chrome-free tanning agent with fragrance slow-release behavior Vanillin is dissolved in an aqueous solution, the pH of the solution is adjusted to 8, and the obtained solution is added to the epoxy-modified polylysine crosslinking agent obtained in step 1), and the mixture is crosslinked in an oil bath at 35℃ for 4 h. The crosslinked and blended solution is poured into a dialysis bag with a molecular weight of 1000, dialyzed in a 35℃ shaking box for 48 h, then placed in a freezer for 24 h, dried in a freeze dryer at -70℃ for 48 h, and finally ground to obtain the polylysine-based chrome-free tanning agent with fragrance slow-release behavior.

[0052] Example 4 A method for preparing a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Preparation of an epoxy-modified polylysine crosslinking agent After mixing 6.67 g of glycerol triglycidyl ether, 10.00 g of polylysine with a relative molecular weight of 3500 and 0.1 g of hexamethylenetetramine, the pH is adjusted to 7.5, and the reaction is carried out at 45°C for 4 h to obtain the epoxy-modified polylysine crosslinking agent.

[0053] 2) Preparation of a polylysine-based chrome-free tanning agent with fragrance slow-release behavior Fragrant aldehyde is dissolved in an aqueous solution, the pH is adjusted to 8, and the obtained solution is added to the epoxy-modified polylysine crosslinking agent obtained in step 1). The crosslinking is carried out in an oil bath at 40°C for 3 h, the crosslinking blended solution is poured into a dialysis bag with a molecular weight of 1000, dialysis is carried out in a shaking box at 40°C for 36 h, then it is placed in a freezer for 24 h, dried in a freeze dryer at -75°C for 36 h, and finally ground to obtain a polylysine-based chrome-free tanning agent with fragrance slow-release behavior.

[0054] Example 5 A method for preparing a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Preparation of an epoxy-modified polylysine crosslinking agent After mixing 6.67 g of glycerol triglycidyl ether, 10.00 g of polylysine with a relative molecular weight of 3500 and 0.1 g of hexamethylenetetramine, the pH is adjusted to 8, and the reaction is carried out at 50°C for 3 h to obtain the epoxy-modified polylysine crosslinking agent.

[0055] 2) Preparation of a polylysine-based chrome-free tanning agent with fragrance slow-release behavior Fragrant aldehyde is dissolved in an aqueous solution, the pH is adjusted to 8, and the obtained solution is added to the epoxy-modified polylysine crosslinking agent obtained in step 1). The crosslinking is carried out in an oil bath at 45°C for 2 h, the crosslinking blended solution is poured into a dialysis bag with a molecular weight of 1000, dialysis is carried out in a shaking box at 45°C for 24 h, then it is placed in a freezer for 24 h, dried in a freeze dryer at -80°C for 24 h, and finally ground to obtain a polylysine-based chrome-free tanning agent with fragrance slow-release behavior.

[0056] Example 6 A method for preparing a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Preparation of an epoxy-modified polylysine crosslinking agent Mix 6.67 g of glycerol triglycidyl ether, 10.00 g of polylysine with relative molecular weight of 3500 and 0.1 g of hexamethylenetetramine, adjust pH to 8.5, and react at 50°C for 2 h first to obtain the epoxy-modified polylysine crosslinking agent.

[0057] 2) Preparation of polylysine-based chrome-free tanning agent with fragrance slow-release behavior Dissolve the vanillin in an aqueous solution, adjust the pH to 8, and add the obtained solution to the epoxy-modified polylysine crosslinking agent obtained in step 1) to crosslink in an oil bath at 50°C for 2 h. Pour the crosslinked blended solution into a dialysis bag with a molecular weight of 1000, dialyze in a shaking box at 45°C for 24 h, then stand in a freezer for 24 h, dry in a freeze dryer at -80°C for 24 h, and finally grind to obtain the polylysine-based chrome-free tanning agent with fragrance slow-release behavior.

[0058] Example 7 A method for preparing a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Preparation of epoxy-modified polylysine crosslinking agent Mix 6.67 g of glycerol triglycidyl ether, 10.00 g of polylysine with relative molecular weight of 3500 and 0.1 g of hexamethylenetetramine, adjust pH to 9.5, and react at 45°C for 2 h first to obtain the epoxy-modified polylysine crosslinking agent.

[0059] 2) Preparation of polylysine-based chrome-free tanning agent with fragrance slow-release behavior Dissolve the vanillin in an aqueous solution, adjust the pH to 8, and add the obtained solution to the epoxy-modified polylysine crosslinking agent obtained in step 1) to crosslink in an oil bath at 45°C for 2 h. Pour the crosslinked blended solution into a dialysis bag with a molecular weight of 1000, dialyze in a shaking box at 35°C for 72 h, then stand in a freezer for 24 h, dry in a freeze dryer at -60°C for 72 h, and finally grind to obtain the polylysine-based chrome-free tanning agent with fragrance slow-release behavior.

[0060] Example 8 A method for preparing a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Preparation of epoxy-modified polylysine crosslinking agent Mix polylysine and glycerol triglycidyl ether at a molar ratio of 1:6 (10.00 g of 3500 Da polylysine corresponds to 13.34 g of glycerol triglycidyl ether), add 0.1 g of hexamethylenetetramine, adjust the pH to 7, and react in an oil bath at 40°C for 4 h to obtain the epoxy-modified polylysine crosslinking agent. Prepare a 0.1 g / L aqueous solution of the crosslinking agent.

[0061] 2) Preparation of polylysine-based chrome-free tanning agent with fragrance slow-release behavior Take 100 g of aqueous furfural solution, add 8 g of the above epoxy-modified polylysine crosslinking agent, adjust the pH value of the mixed solution to 8, and crosslink in an oil bath at 55°C for 4 h; pour the crosslinked blended solution into a 1000 Da dialysis bag, dialyze in a 35°C shaking box for 48 h, and then place in a freezer for 24 h; finally, dry in a freeze dryer at -70°C for 48 h, and grind to obtain the product.

[0062] Example 9 A method for preparing a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Preparation of epoxy-modified polylysine crosslinking agent Take 10.00 g of polylysine with a relative molecular weight of 5000 Da, and mix with 20.01 g of glycerol triglycidyl ether at a molar ratio of 1:9, then add 0.1 g of hexamethylenetetramine, adjust the pH value to 8, and react in an oil bath at 45°C for 3 h to obtain the epoxy-modified polylysine crosslinking agent; prepare a 1 g / L aqueous solution of the crosslinking agent.

[0063] 2) Preparation of polylysine-based chrome-free tanning agent with fragrance slow-release behavior Take 100 g of aqueous furfural solution, add 15 g of the above epoxy-modified polylysine crosslinking agent, adjust the pH value of the mixed solution to 8, and crosslink in an oil bath at 40°C for 3 h; pour the crosslinked blended solution into a 1000 Da dialysis bag, dialyze in a 30°C shaking box for 36 h, and then place in a freezer for 24 h; finally, dry in a freeze dryer at -75°C for 36 h, and grind to obtain the product.

[0064] Example 10 A method for preparing a polylysine-based chrome-free tanning agent with fragrance slow-release behavior, comprising the following steps: 1) Preparation of epoxy-modified polylysine crosslinking agent Mix 10.00 g of 3500 Da polylysine with 13.34 g of glycerol triglycidyl ether at a molar ratio of 1:6, add 0.1 g of hexamethylenetetramine, adjust the pH value to 9, and react in an oil bath at 48°C for 2.5 h to obtain the crosslinking agent; prepare a 0.55 g / L aqueous solution of the crosslinking agent.

[0065] 2) Preparation of polylysine-based chrome-free tanning agent with fragrance slow-release behavior Take 100 g of aqueous furfural solution, add 11.5 g of the above crosslinking agent (mass ratio 11.5%), adjust the pH value to 8, and crosslink in an oil bath at 50°C for 2.5 h; dialysis conditions: 38°C, 40 h; freeze-drying temperature: -72°C, 40 h; and grind to obtain the product.

[0066] In summary, the polylysine-based chromium-free tanning agent with fragrance slow-release behavior, preparation method and application of the present application, the epoxy modified polylysine is crosslinked by furfural to obtain the epoxy modified fragrance slow-release polylysine-based chromium-free tanning agent, and the product obtained after crosslinking is applied to the leather tanning process to obtain the biomass green ecological leather with fragrance slow-release. The innovative technology can not only form strong crosslinking with skin collagen fibers and significantly improve the physical properties of leather, but also can give the leather a unique pleasant fragrance, effectively neutralize and eliminate the unpleasant amine odor generated in traditional tanning. The preparation route of the present application is simple, and on the basis of maintaining the excellent tanning performance and physical properties of leather, the mild, long-lasting and stable retention effect of fragrance can be realized, thereby effectively covering the inherent odor of leather and improving the sensory quality and use experience of the product.

[0067] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A process for the preparation of polylysine based chrome-free tanning agents with slow aromatic release behavior, characterized by, The application relates to a preparation method of a polylysine-based chrome-free tanning agent with aromatic slow-release behavior. The polylysine is subjected to epoxy modification to obtain an epoxy-modified polylysine crosslinking agent; furfural is added to the epoxy-modified polylysine crosslinking agent to perform a crosslinking reaction; and after heating and stirring reaction, dialysis, freeze drying and grinding, the polylysine-based chrome-free tanning agent with aromatic slow-release behavior is obtained. The conditions for epoxy modification of the polylysine include: mixing glycerol triglycidyl ether, polylysine and hexamethylenetetramine, adjusting the pH value to 6-9.5; and after stirring reaction, the epoxy-modified polylysine crosslinking agent is obtained; and the epoxy of the epoxy-modified polylysine crosslinking agent is from the glycerol triglycidyl ether.

2. A process for the preparation of polylysine-based chrome-free tanning agents with slow aromatic release according to claim 1, characterized by the fact that, The molar ratio of the polylysine to the glycerol triglycidyl ether is 1: (3-9).

3. A process for the preparation of polylysine-based chrome-free tanning agents with slow aromatic release behavior according to claim 2, characterized by the fact that, The stirring reaction is performed at a temperature of 30-50 DEG C for 2-6 hours.

4. A process for the preparation of polylysine-based chrome-free tanning agents with slow aromatic release according to claim 2, characterized by the fact that, The mass of the epoxy-modified polylysine crosslinking agent is 8%-15% of the mass of the furfural; and the mass concentration of the epoxy-modified polylysine crosslinking agent is 0.1-1 g / L.

5. A process for the preparation of polylysine-based chrome-free tanning agents with slow aromatic release behavior according to claim 1, characterized by, The crosslinking reaction is performed at a temperature of 25-55 DEG C for 2-6 hours.

6. A process for the preparation of polylysine-based chrome-free tanning agents with slow aromatic release according to claim 1, characterized by the fact that, The dialysis is performed at a temperature of 25-45 DEG C for 24-72 hours; and the freeze drying is performed at a temperature of -60 DEG C to -80 DEG C for 24-72 hours.

7. A process for the preparation of polylysine-based chrome-free tanning agents with slow aromatic release behavior according to claim 1, characterized by, The polylysine-based chrome-free tanning agent with aromatic slow-release behavior is prepared by the preparation method of any one of claims 1-7.

8. A polylysine-based chrome-free tanning agent having a slow aromatic release behavior, characterized in that, The polylysine-based chrome-free tanning agent with aromatic slow-release behavior has the structural formula:

9. Polylysine-based chrome-free tanning agent with slow aromatic release behavior according to claim 8, characterized by the fact that, 10. The polylysine-based chrome-free tanning agent with aromatic slow-release behavior is prepared by the preparation method of any one of claims 1-7. 。 The polylysine-based chrome-free tanning agent with aromatic slow-release behavior is prepared by the preparation method of any one of claims 1-7.

Images