1. The preparation method and the application of the polyethylene glycol s-triazine derivative tanning agent are characterized by comprising the following steps of:

synthesis of tanning agent: dissolving 5-10 parts of s-triazine compound in 300 parts of 100-one aprotic solvent, fully stirring, adding 2-4 parts of acid-binding agent after the s-triazine compound is dissolved, dropwise adding 10-30 parts of polyethylene glycol into the mixed solution at 0-50 ℃, and carrying out heat preservation reaction for 2-10 hours; after the reaction is finished, distilling and recovering the solvent, adding a proper amount of water for dissolving, and adjusting the pH value to 5-7 by using alkali to obtain the polyethylene glycol s-triazine derivative tanning agent;

the application of the tanning agent comprises the following steps: directly tanning the softened leather prepared by the conventional leather making process; softening 100 parts of naked leather (by the mass of leather tanning ash-folding leather and by the mass of fur tanning raw material leather), placing the naked leather in a rotary drum or a scoring tanning device, adding 30-150 parts of water (by leather tanning) or 200 parts of water (by fur tanning) 1000 parts, adjusting the temperature to 15-30 ℃, adding a proper amount of acid, adjusting the pH value of bath solution to be in a range of 5-9, adding 3-20 parts of polyethylene glycol sym-triazine derivative tanning agent, rotating for 2-6 hours, adding a proper amount of alkali extracting agent for multiple times, adjusting the pH value of the bath solution to be in a range of 5-9, adding 50-200 parts of water, controlling the temperature of the bath solution to be 35-50 ℃, and continuing to rotate for 1-6 hours; the tanned leather is aged for more than 1 day, and then the subsequent procedures of shaving, retanning, neutralization, dyeing, fatliquoring and the like are carried out.

2. The preparation method and the application of the polyethylene glycol s-triazine derivative tanning agent according to claim 1, wherein the s-triazine compound is at least one of cyanuric chloride and trichloroisocyanuric acid.

3. The preparation method and the application of the polyethylene glycol s-triazine derivative tanning agent as claimed in claim 1, wherein the molecular weight of the polyethylene glycol is in the range of 200-2000, preferably 500-1000.

4. The preparation method and the application of the polyethylene glycol s-triazine derivative tanning agent according to claim 1, wherein the weight ratio of s-triazine: polyethylene glycol: acid binding agent: the solvent (mass ratio) is 0-50 ℃, and the reaction temperature is 0-10 = (5-10): 10-30): 2-4): 100-.

5. The preparation method and the application of the polyethylene glycol s-triazine derivative tanning agent according to claim 1, characterized in that the softened skins are directly tanned without a pickling process, the pH value in the early stage of tanning is controlled to be 6-9, and the preferred pH value is 6; controlling the pH value to be 5-7 by alkali extraction operation at the final stage of tanning; the temperature in the initial stage of tanning is controlled within the range of 15-30 ℃, and the temperature in the final stage of tanning is controlled within the range of 35-50 ℃.

6. A process for preparing the polyglycol s-triazine derivative tanning agent and its application according to claims 1-5 are characterized in that the tanning method is suitable for tanning in the tanning and fur making process of various animal skins.

Background

The traditional tanning method is to use chromium to tan the raw leather, wherein the chromium has the most excellent tanning performance in a plurality of metal tanning agents, but the method has larger demand for chromium, the global chromium resource is very limited, the utilization rate of the chromium in the tanning process is only about 70 percent, the direct discharge of the unused chromium can cause pressure to the environment and damage to vegetation, and the tail end treatment difficulty of the chromium waste liquid is large, and the cost is high. Although there are many studies to improve the absorption of chromium into the skin and thus to increase the utilization of chromium, these methods require a large cost and are difficult to be applied industrially.

From the structural design of the tanning agent, the tanning agent required for tanning firstly needs at least 2 binding sites capable of stably binding with skin collagen, so that a 'cross-linked network' required for tanning is realized, the reaction speed of binding with the skin collagen is moderate, if the binding speed with the collagen is too slow, the tanning period is prolonged and cannot be accepted by the industry, and if the binding speed with the collagen is too fast, the excessive binding on the surface of the leather is easily caused, and the penetration of the tanning agent is influenced [ the LIAO LONG PROCENTOLOGY ] and the tanning technology [ M ] scientific Press, 2001 ]; secondly, the selected tanning agent needs to have good water solubility and can be combined with skin collagen under a tanning water system; furthermore, the selected tanning agent needs to have proper molecular weight, the excessive molecular weight is difficult to enter the interior of the protein, and the small molecular weight is difficult to form effective cross-linking between peptide chains; finally, the raw materials used in the syntan are readily available and of low toxicity, and the prohibitively high raw material prices and high toxicity are unacceptable to the industry.

Polyethylene glycol is mainly synthesized by ethylene glycol and ethylene oxide, is a compound with wide application, and is widely applied to a plurality of fields of drug research and development, material modification and the like due to low toxicity and amphiphilic property. The polyethylene glycol derivative is used as a leather tanning agent, and has the following main advantages: 1) the polyethylene glycol has good water solubility, and can meet the requirements of a tanning water system; 2) the synthesis process of the polyethylene glycol is mature, the price is low, and the production requirement can be met; 3) it is non-toxic and has good biocompatibility, can be used for collagen modification and satisfies the current concept of green products [ Antonnen K.P. Hoffman A, et al. Water structure of PEG solutions by differential Chemistry science measurements [ J ]. Topics in Applied Chemistry Poly (ethylene Glycol) Chemistry: Biotechnical and biological applications. plenum Press, New York, 1992:15-28 ]; 4) the long chain structure of the fat group can control the length of a molecular chain and adjust the molecular weight according to requirements; 5) the tanning agent has terminal hydroxyl groups, and can introduce various tanning groups through modification to generate a tanning effect; 6) simple structure and easy control. However, the current research on the tanning agent still has the following problems: 1) the end aldehyde group product obtained by direct oxidation has low reaction efficiency and high cost; 2) the lack of rigidity in the simple chain structure leads to poor cross-linking stability [ Zhou, Yongxiang, Ma, Jianzhong, et al, Modification of collagen with thread novel ligands, sulfonated calix [4] olefins [ J ]. International Journal of Biological macromolecules, 2018.04: 169. 173 ].

Cyanuric chloride (cyanic chloride), chemical name 2,4, 6-trichloro-1, 3, 5-triazine, molecular formula C₃N₃Cl₃Or trichloro-s-triazine, also known as cyanuric chloride. The s-triazine ring of cyanuric chloride is quite stable and can be decomposed only in concentrated sulfuric acid and heated to more than 150 ℃. It can be considered as the acid chloride of cyanuric acid. The influence of C = N unsaturated bonds on three chlorine atoms is enhanced, and the reaction is easy; meanwhile, the activity of three chlorine atoms is quite large, and the three chlorine atoms can be replaced by functional groups such as-OH, -NH, -SH, -NHR and the like in stages, so that the application of sym-triazine containing derivatives [ Fuyebin, cyanuric chloride ] with different properties and purposes in the field of fine chemical industry is formed [ J]Chengdu textile advanced specialty school bulletin 2002, 19(2):19-22.]. In addition, three chlorine atoms on the 1,3, 5-triazine ring respectively have different reactivity at different temperatures. At about 0 ℃, the chlorine atom at the 1 position can be substituted; at about 30 ℃, the chlorine atom at the 3 position can be substituted; around 80 ℃ and the chlorine atom in the 5 position may be substituted [ Namazi H, Adeli M. Synthesis of barrel-like triblock copolymers, dendritic triazine-block-poly (ethylene glycol) -block-dendritic triazine and ionization of the resin absorption derivatives [ J]. Polymer, 2005, 46(24):10788-10799.]. Therefore, the cyanuric chloride has good reaction controllability. In addition, the active chlorine atom in the cyanuric chloride structure is capable of covalent bonding with the amino group in the collagen structure of the hide and is therefore largely used for the development of reactive dyes [ Gotoh Y, Tsukada M, Minoura N. Chemical modification of a silk fibre with cyclic chlorine-activated poly (ethylene glycol): analysis of reaction site by proton NMR spectroscopy and transformation of the same [ J ] dye]. Bioconjugate Chemistry, 1993, 4(6):554-559.]。

In summary, most of the current studies on polyethylene glycol derivatives at home and abroad are limited to the research and development of collagen modified materials, and the purpose of improving the physicochemical properties of collagen materials is achieved by coupling polyethylene glycol with the collagen materials. However, tanning, a specific means of collagen modification, requires the introduction of a large number of robust crosslinks between the collagen of the skin and the reaction in a relatively mild aqueous phase, which is not achievable with current polyethylene glycol derivatives.

Based on the problems, the invention provides a preparation method and an application method of a polyethylene glycol s-triazine derivative tanning agent. The synthetic tanning agent has the advantages of simple and quick synthetic process, controllable molecular weight through the length of the polyethylene glycol chain, light product color and good water solubility, the shrinkage temperature of the white wet leather tanned by the synthetic tanning agent is higher than 78 ℃, the white wet leather does not contain aldehyde and chromium, and the clean production in the leather making process can be realized.

Disclosure of Invention

The invention aims to provide a preparation method and application of a polyethylene glycol s-triazine derivative tanning agent for tanning leather, the method can simply and rapidly prepare the water-soluble polyethylene glycol s-triazine derivative tanning agent, the prepared tanning agent does not contain aldehyde and chromium, and is a clean chromium-free tanning agent which is used for producing wet white leather and can finish tanning within 12h without pickling, and the shrinkage temperature of the wet white leather exceeds 78 ℃.

The preparation method and the application of the tanning agent based on the polyethylene glycol s-triazine derivative, which can realize the aim of the invention, comprise the following operation steps, wherein the materials used in each operation step are calculated according to the parts by mass except the specific description:

synthesis of tanning agent: dissolving 10 parts of s-triazine compound in an aprotic solvent, fully stirring the solution until the s-triazine compound is dissolved, adding 2-4 parts of an acid-binding agent, dropwise adding 10-30 parts of polyethylene glycol into the mixed solution at 0-50 ℃, and reacting for 2-10 hours under heat preservation. And after the reaction is finished, distilling to recover the solvent, adding a proper amount of water for dissolving, and adjusting the pH value to 5-7 by using alkali to obtain the polyethylene glycol s-triazine derivative tanning agent.

The application of the tanning agent comprises the following steps: the softened leather prepared by the conventional leather-making process is directly tanned. 100 parts of softened bare leather (based on the mass of leather-tanned grey leather, and the amount of leather-tanned raw material leather) are placed in tanning equipment such as a rotary drum or a groove, 30-150 parts of water (based on the mass of leather-tanned grey leather) or 1000 parts of water (based on the mass of fur-tanned raw material leather) is added, the temperature is adjusted to 15-30 ℃, a proper amount of acid is added, the pH value of bath liquid is adjusted to be in a range of 5-9, 3-20 parts of polyethylene glycol sym-triazine derivative tanning agent is added, the bath liquid is rotated for 2-6 hours, a proper amount of alkali extracting agent is added for multiple times during the period, the pH value of the bath liquid is adjusted to be in a range of 5-9, 50-200 parts of water is added, the temperature of the bath liquid is controlled to be 35-50 ℃, and the bath liquid is continuously rotated for 1-6 hours. The tanned leather is aged for more than 1 day, and then the subsequent procedures of shaving, retanning, neutralization, dyeing, fatliquoring and the like are carried out.

In the above method for synthesizing the tanning agent, the s-triazine compound is at least one of cyanuric chloride and trichloroisocyanuric acid.

In the above-mentioned method for synthesizing the tanning agent, the molecular weight of the polyethylene glycol is in the range of 200-2000, preferably 500-1000.

In the above method for synthesizing tanning agent, the feed ratio is s-triazine: polyethylene glycol: acid binding agent: the solvent (mass ratio) is 0-50 ℃, and the reaction temperature is 0-10 = (5-10): 10-30): 2-4): 100-.

In the application method of the tanning agent, the tanning pH control comprises the steps of not needing a pickling process before tanning, and controlling the pH value at the initial stage of tanning to be 6; the pH value is controlled at 5-7, preferably 6, by alkali extraction at the end of tanning.

In the application method of the tanning agent, the tanning temperature control comprises controlling the temperature in the early stage of tanning at 15-30 ℃, preferably, 15-25 ℃; the temperature at the end of tanning is controlled at 35-50 deg.C, preferably at 45 deg.C.

The tanning method in the technical scheme is suitable for the production of various leathers and furs.

Compared with the prior art, the method has the beneficial effects that the polyethylene glycol and cyanuric chloride are adopted as raw materials to be synthesized by adopting a one-step method, the synthesis method is simple, the product does not contain chromium and aldehyde, has better water solubility and white color, when the product is used as a tanning agent to tanne softened leather, pickling operation is not needed, neutral salt is not introduced, the production period is short, the prepared wet-white leather is obviously thickened, the hand feeling is full, the shrinkage temperature is higher (more than 78 ℃), the requirements of various leathers and fur leathers can be met, and the wet-white leather is free of aldehyde and chromium and conforms to the environment-friendly concept of clean leather making.

Detailed Description

The present invention is described in detail below by way of examples, it should be noted that the examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and those skilled in the art can make modifications and adaptations of the present invention without essential to the present invention.

Synthesis example of tanning agent

Example 1

Adding 200ml of acetone into a three-neck flask with a tetrafluoro stirring rod, weighing 23.9g of cyanuric chloride, adding the cyanuric chloride into the three-neck flask, stirring and dissolving in a cold water bath (0-5 ℃), adding 8.8g of dried anhydrous sodium carbonate while stirring, weighing 14.1g of dried polyethylene glycol 200, adding the polyethylene glycol 200 into a constant-pressure separating funnel, adjusting the dropping speed to 30min, completely dropping the stirred reaction liquid, reacting for 7.5h, pouring out the reaction mother liquid, performing suction filtration, concentrating the filtrate on a rotary evaporator with the vacuum degree of 0.08MPa and the temperature of 20 ℃ to remove the solvent, adding a proper amount of water for dissolving, and adjusting the pH value to 5-7 with alkali to obtain the polyethylene glycol s-triazine derivative tanning agent.

Example 2

Adding 200ml of acetone into a three-neck flask with a tetrafluoro stirring rod, weighing 23.9g of cyanuric chloride, adding the cyanuric chloride into the three-neck flask, stirring and dissolving in a cold water bath (0-5 ℃), then adding 8.8g of dried anhydrous sodium carbonate, weighing 42.1g of polyethylene glycol 600 subjected to drying operation, adding the polyethylene glycol 600 into a constant-pressure separating funnel, adjusting the dropping speed to be 30min, completely dropping the stirred reaction liquid, introducing nitrogen for protection, pouring out the reaction mother liquid after reacting for 8.5h, filtering, concentrating the filtrate on a rotary evaporator with the vacuum degree of 0.08MPa and the temperature of 20 ℃ to remove the solvent, adding a proper amount of water for dissolving, and adjusting the pH value to 5-7 by using alkali to obtain the polyethylene glycol sym-triazine derivative tanning agent.

Example 3

Adding 250ml of toluene into a three-neck flask with a tetrafluoro stirring rod, weighing 23.9g of cyanuric chloride, adding the cyanuric chloride into the three-neck flask, stirring and dissolving in a cold water bath (0-5 ℃), then adding 6.1g of dried sodium hydroxide, weighing 56.2g of polyethylene glycol 800 subjected to drying operation, adding the polyethylene glycol 800 into a constant-pressure separating funnel, adjusting the dropping speed to be completely dropped into the stirring reaction liquid within 30min, introducing nitrogen for protection, pouring out the reaction mother liquid after reacting for 8.5h, filtering, concentrating the filtrate on a rotary evaporator with the vacuum degree of 0.08MPa and the temperature of 20 ℃ to remove the solvent, adding a proper amount of water for dissolving, and adjusting the pH value to 5-7 with alkali to obtain the polyethylene glycol s-triazine derivative tanning agent.

Example 4

Adding 250ml of toluene into a three-neck flask with a tetrafluoro stirring rod, weighing 23.9g of cyanuric chloride, adding the cyanuric chloride into the three-neck flask, stirring and dissolving the cyanuric chloride in a cold water bath (0-5 ℃), then adding 6.1g of dried sodium hydroxide, weighing 70.2g of dried polyethylene glycol 1000, adding the polyethylene glycol 1000 into a constant-pressure separating funnel, adjusting the dropping speed to 30min, completely dropping the stirred reaction solution, introducing nitrogen for protection, pouring out the reaction mother solution after reaction for 10h, filtering, concentrating the filtrate on a rotary evaporator with the vacuum degree of 0.08MPa and the temperature of 20 ℃ to remove the solvent, adding a proper amount of water for dissolving, and adjusting the pH value to 5-7 by using alkali to obtain the polyethylene glycol s-triazine derivative tanning agent.

Example 5

Adding 400ml of dried benzene into a three-neck flask with a tetrafluoro stirring rod, weighing 23.9g of cyanuric chloride, adding the cyanuric chloride into the three-neck flask, stirring and dissolving in a cold water bath (0-5 ℃), then adding 6.1g of dried sodium hydroxide, weighing 140.4g of polyethylene glycol 2000 subjected to drying operation, adding the polyethylene glycol 2000 into a constant-pressure separating funnel, adjusting the dropping speed to completely drop into the stirring reaction liquid within 30min, introducing nitrogen for protection, pouring out the reaction mother liquid after reacting for 10h, filtering, concentrating the filtrate on a rotary evaporator with the vacuum degree of 0.08MPa and the temperature of 20 ℃ to remove the solvent, adding a proper amount of water for dissolving, and adjusting the pH value to 5-7 with alkali to obtain the polyethylene glycol s-triazine derivative tanning agent.

Examples of the use of tanning agents

Tanning of cow leather garment

Taking the tanning process of the first layer cow leather clothing leather as an example, the application process is shown in table 1.

Table 1 tanning process of the polyethylene glycol s-triazine derivative tanning agent cow leather.

The polyethylene glycol s-triazine derivative tanning agent obtained in the embodiment is used for tanning cowhide according to the process in the table 1, the tanned leather is stored for 2 days, and then the subsequent procedures of shaving, retanning, neutralizing, fatliquoring and the like are carried out according to a conventional method, and the final crust leather effect is shown in the table 2.

Table 2 tanning effect of polyglycol s-triazine derivative tanning agent.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the technical solutions of the present invention in any way. Any simple modification, equivalent change and modification made to the above embodiments according to the technical spirit of the present invention still fall within the scope of the technical solution of the present invention.