CN113234868A - Fur tanning method based on bio-based epoxy active tanning agent - Google Patents
Fur tanning method based on bio-based epoxy active tanning agent Download PDFInfo
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- CN113234868A CN113234868A CN202110537019.XA CN202110537019A CN113234868A CN 113234868 A CN113234868 A CN 113234868A CN 202110537019 A CN202110537019 A CN 202110537019A CN 113234868 A CN113234868 A CN 113234868A
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- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
- C14C1/00—Chemical treatment prior to tanning
- C14C1/08—Deliming; Bating; Pickling; Degreasing
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- C—CHEMISTRY; METALLURGY
- C14—SKINS; HIDES; PELTS; LEATHER
- C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
- C14C3/00—Tanning; Compositions for tanning
- C14C3/02—Chemical tanning
- C14C3/08—Chemical tanning by organic agents
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Abstract
The invention provides a fur tanning method based on a bio-based epoxy active tanning agent, which comprises softening, pickling and tanning processes or softening and tanning processes and comprises the following steps: (1) putting the pretreated fur into softening liquid in a paddle vat for softening; pickling and tanning after softening, or directly tanning after softening; (2) pickling, namely adding organic acid and inorganic acid into the softening liquid in the paddle to form pickling liquid for pickling; (3) adjusting the pH value of the pickled or softened bath lotion to 2.0-5.0, adding a tanning aid and a biological epoxy active tanning agent, scratching for 20-40 min, then intermittently scratching for 6-8 h, standing for 12-15 h, adding an alkalizer into the bath lotion to extract alkali, adjusting the temperature of the bath lotion to 35-50 ℃, intermittently scratching for 2-3 h, standing for 12-15 h, and peeling. The method can solve the problems of chromium and formaldehyde residue and pollution existing in the existing fur tanning method, and can improve the quality of the tanned fur on the fur plate and the fur quilt.
Description
Technical Field
The invention belongs to the field of fur tanning processing, and relates to a fur tanning method based on a biological epoxy active tanning agent.
Background
In recent years, Chinese woolThe leather industry is rapidly developed, but the fur tanning technology is still relatively laggard, and the tanning of a large number of furs, such as sheep fur, sheep shorn, beach lamb skin, lamb skin and the like, still mainly adopts the tanning process of formaldehyde or formaldehyde-aluminum or formaldehyde-chromium salt. Although these tanning processes are characterized by low cost, mature process, easy operation and white fur, they have the problems of affecting the health of operators and environmental pollution, and more seriously, the skins and products tanned by these methods have a large amount of free formaldehyde, which cannot be effectively removed even if formaldehyde removing agents are added during the later finishing, and the products release formaldehyde continuously during the use or storage process, thus causing potential harm to the health of consumers. In addition, the chromium compound added in the main tanning or retanning causes problems of chromium emission and environmental pollution, and Cr3+May be converted into Cr under certain conditions6+And Cr6+Both compounds and formaldehyde are listed by the world health organization as strongly carcinogenic substances.
In recent years, great amount of research on chrome-free and aldehyde-free tanning processes is carried out by tanning researchers, and methods for replacing chrome tanning or/and aldehyde tanning are continuously searched for. According to research, the problems that other metal tanning agents except chrome tanning have the same or similar problems when the metal tanning agents are used for tanning pelts independently, such as the problems that aluminum tanning cannot resist washing, titanium tanning causes fuzz and yellowing, zirconium tanning causes leather boards to be too compact, iron tanning causes products to be not resistant to storage, and the like. Although the use of aluminum tanning is relatively more common, the tanning capability is weaker, and the tanned fur plates have poor wet and heat stability (low shrinkage temperature), and are easy to be subjected to retanning particularly when meeting water, so the aluminum tanning and other tanning agents are generally adopted to perform combined tanning so as to meet the requirement of improving the tanning performance. Glutaraldehyde has good tanning performance, but easily causes serious yellowing of the fur quilt, and the use of the glutaraldehyde is limited. At present, organic phosphonium salt tanning is applied to sheep shorn velvet products, but the tanning agent can release formaldehyde in the tanning process, and hydrogen peroxide is required to be used for oxidation in the later stage of tanning, so that wool fibers can be damaged.
CN102329899A discloses a formaldehyde-free fur tanning method based on oxazolidine, but the probability of skin rot of oxazolidine in the tanning process is high, and the problem of formaldehyde release also exists, so that it is difficult to apply industrially. CN104561395A discloses a process for tanning light-colored skins based on a chrome-free tanning agent TWT, which tanning skins with a formaldehyde content below 75ppm but still having a certain formaldehyde residue.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a fur tanning method based on a bio-based epoxy active tanning agent, so as to solve the problems of chromium and formaldehyde residues and pollution existing in the existing fur tanning method and improve the quality of a pelt board and a fur quilt of tanned furs.
In order to achieve the purpose, the invention adopts the following technical scheme:
a fur tanning method based on bio-based epoxy active tanning agent comprises softening, pickling and tanning processes, or comprises softening and tanning processes, and comprises the following steps:
(1) softening
Putting the pretreated fur into softening liquid in a paddle vat, controlling the using amount of the softening liquid to be 6-10 times of the dry weight of the fur, controlling the temperature of the softening liquid to be 33-35 ℃, paddle the paddle vat for 20-40 min, and then intermittently paddle the paddle vat for 3-8 h; the softening liquid is prepared from sodium chloride, protease and water, the pH value of the softening liquid is adjusted to be 25-55 g/L, when the protease is acid protease, the pH value of the softening liquid is adjusted to be 3.0-3.5, the concentration of the acid protease is 0.08-0.12 g/L, when the protease is neutral protease, the pH value of the softening liquid is adjusted to be 7.0-7.5, and the concentration of the neutral protease is 0.8-1.0 g/L;
pickling and tanning after softening, or directly tanning after softening;
(2) pickling
Adding organic acid and inorganic acid into the softening liquid in the paddle to form a pickling liquid with the pH value of 1.6-2.0, controlling the concentration of the organic acid in the pickling liquid to be 1.5-2.5 g/L and the concentration of the inorganic acid to be 1.5-2.5 g/L, controlling the temperature of the pickling liquid to be room temperature, stroking the paddle for 20-40 min, then stroking the paddle for 3-6 h intermittently, and standing for 12-15 h;
(3) tanning
Adjusting the pH value of the pickled or softened bath lotion to 2.0-5.0, adding a tanning aid into the bath lotion to enable the concentration of the tanning aid to be 0.5-1.0 g/L, scratching a sliding groove for 30-60 min, stopping scratching for 30-60 min, scratching the sliding groove for 0-30 min, adding a bio-based epoxy active tanning agent to enable the concentration to be 8.0-12.0 g/L, controlling the temperature of the bath lotion to be 15-33 ℃, scratching the sliding groove for 20-40 min, intermittently scratching the sliding groove for 6-8 h, standing for 12-15 h, adding an alkalizer into the bath lotion to adjust the pH value of the bath lotion to 8.0-10.0, adjusting the temperature of the bath lotion to 35-50 ℃, intermittently scratching the sliding groove for 2-3 h, standing for 12-15 h, and peeling;
the structure of the bio-based epoxy active tanning agent is shown as a formula (I),
the pretreated fur is the fur subjected to soaking, fleshing and degreasing, or the fur subjected to soaking and fleshing.
In the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, in the formula (I), n is 0-15, preferably 1-6.
In the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, the bio-based epoxy active tanning agent shown in the formula (I) is obtained by performing epoxidation modification on a chitosan degradation product, wherein the chitosan degradation product is obtained by degrading chitosan through an acid degradation method, the epoxidation modification refers to reacting the chitosan degradation product with epoxy chloropropane under a neutral condition, the amount of the epoxy chloropropane is 20-80 wt% of the chitosan degradation product, and the amount of the epoxy chloropropane is preferably 30-50 wt% of the chitosan degradation product. The bio-based epoxy active tanning agent shown in the formula (I) can be synthesized by self or by entrusted professional institutions or commercial companies.
According to the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, chitosan is degraded by an acid degradation method to obtain a chitosan degradation product, the chitosan degradation product is prepared by hydrolyzing chitosan by utilizing the characteristic that glycosidic bonds in the chitosan are unstable to acid, the degradation degree of the chitosan is related to the type, the using amount and the reaction temperature of the acid, and the type, the using amount and the reaction temperature of the acid can be determined according to the molecular weight of the required chitosan degradation product by referring to the prior art. Generally, hydrochloric acid, sulfuric acid, nitric acid, or Lewis acids may be used to degrade chitosan. The chitosan degradation product contains hydroxyl and amino, when the epichlorohydrin reacts with the chitosan degradation product, the amino of the chitosan degradation product reacts with the epichlorohydrin under the condition that the pH value is 7.0-8.0 (neutral or alkalescent) to form the bio-based epoxy active tanning agent with the structure shown in the formula (I), the content of epoxy groups in the bio-based epoxy active tanning agent shown in the formula (I) can be influenced by the dosage of the epichlorohydrin, the dosage of the epichlorohydrin can be controlled to be 20-80 wt% of the chitosan degradation product according to the difference and the requirement of a tanning object and a tanning target, and preferably, the dosage of the epichlorohydrin is controlled to be 30-50 wt% of the chitosan degradation product.
In the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, the tanning assistant agent is melamine, triethylamine, triethanolamine, hexamethylenetetramine, zirconium chloride or aluminum chloride.
In the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, the alkalization agent is added into the bath lotion for multiple times to adjust the pH value of the bath lotion to 8.0-10.0, namely, the alkalization adjusting agent is added into the bath lotion once every 15-30 min, and the pH value of the bath lotion is adjusted to 8.0-10.0.
In the tanning step of the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, the pH value of the bath liquid needs to be controlled within the range of 8.0-10.0 before the fur is produced. Namely, after standing for 12-15 hours before peeling, the pH value of the bath liquid needs to be detected, if the pH value of the bath liquid is within the range of 8.0-10.0, peeling is directly performed, and if the pH value of the bath liquid is not within the range of 8.0-10.0, the pH value of the bath liquid needs to be adjusted to be within the range of 8.0-10.0, and then peeling is performed.
In the tanning step of the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, when the alkalizer is added into the bath lotion for multiple times to adjust the pH value of the bath lotion, the pH value of the bath lotion is preferably adjusted to 8.5-9.5, and before skin stripping, the pH value of the bath lotion is preferably controlled to be within the range of 8.5-9.5, and then the skin stripping is carried out.
In the tanning step of the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, when a scheme of tanning after pickling after softening is adopted, the pH value of a bath solution after pickling is adjusted to 2.0-5.0 in the tanning step, and then a tanning assistant and the bio-based epoxy active tanning agent are added into the bath solution for tanning; when the scheme of directly tanning after softening is adopted, the pH value of the softened bath solution is adjusted to 2.0-5.0 in the tanning step, and then the tanning assistant and the biological epoxy active tanning agent are added into the bath solution for tanning. Preferably, the tanning step is to adjust the pH value of the bath solution after pickling or softening to 3.5-4.0, and then add the tanning assistant and the bio-based epoxy active tanning agent into the bath solution for tanning.
In the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, the protease is 537 acid protease, Angellzym HA protease, sumoylase or DOWELLZYM OS protease. Furthermore, the enzyme activity unit of the adopted acid protease is 2000-3000U/L, and the enzyme activity unit of the adopted neutral protease is 1000-1200U/L.
According to the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, when the scheme that tanning is carried out after pickling after softening is adopted, the concentration of sodium chloride in the pickling liquid in the step (1) is controlled to be 25-55 g/L, and when the scheme that tanning is directly carried out after softening is adopted, the concentration of sodium chloride in the pickling liquid in the step (1) is controlled to be 25-30 g/L.
In the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, the organic acid is formic acid, acetic acid or lactic acid, the inorganic acid is sulfuric acid, and the alkalizer is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, sodium hydroxide and potassium hydroxide.
In the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, the intermittent scratching of the scratch groove means scratching for 5-10 min and stopping scratching for 50-55 min every hour, namely scratching for 5-10 min first and then stopping scratching for 55-50 min.
According to the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, before leather is produced in a tanning step, water washing operation is required, then the leather is produced, and water is dripped.
In the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, if the pretreated fur is not subjected to degreasing operation before being softened, the degreasing operation needs to be carried out after the tanning is finished. Except for the above-mentioned softening, pickling and tanning processes, the conditions of the other processes are the same as those of the corresponding processes in the existing industrial production. In addition to the pretreatment, softening, pickling and tanning of the raw fur material, the subsequent processing operations may be carried out in other procedures in a conventional manner in the existing industrial production, depending on the product requirements and the characteristics of the fur.
In the technical scheme of the fur tanning method based on the bio-based epoxy active tanning agent, the fur is sheep skin, Tan sheep skin, mink skin, fox skin, rabbit skin, lamb skin or ski skin.
Compared with the prior art, the technical scheme of the invention has the following beneficial technical effects:
1. the invention provides a fur tanning method based on a bio-based epoxy active tanning agent, which adopts the bio-based epoxy active tanning agent, namely a macromolecular tanning agent containing a plurality of epoxy active groups, wherein chitosan is degraded to a low polymer containing hydroxyl and amino groups with certain molecular size, and then the low polymer is reacted with epoxy chloropropane to prepare the macromolecular tanning agent, the water solubility of the macromolecular tanning agent is enhanced by the hydroxyl groups in a molecular structure, and the epoxy groups and the amino groups on collagen can be promoted to generate chemical crosslinking action by alkali extraction in the later tanning period, so that the tanning effect is improved, and the harmless tanning of fur and the greening of a tanned product are realized. The method of the invention adopts the bio-based epoxy active tanning agent to carry out fur tanning, uses and discharges chromium-free and aldehyde substances in the production and processing process, does not bring environmental problems, and does not contain chromium and aldehyde substances in the product. Compared with the prior tanning process of chrome tanning, aldehyde tanning, chrome-free tanning and aldehyde-free tanning fur, the method and the tanned product thereof of the invention meet the requirements of environmental protection and safety better.
2. The softening, pickling and tanning processes of the fur tanning method based on the bio-based epoxy active tanning agent provided by the invention are all carried out in the same bath lotion, and the composition of the bath lotion can be adjusted by adding chemical materials into the bath lotion according to different processes without replacing the bath lotion in the softening, pickling and tanning processes. The method can effectively reduce the consumption of water and sodium chloride, not only saves the cost, but also reduces the emission, and has the advantages of reducing the cost of fur tanning processing and being green and environment-friendly.
3. Experiments prove that the shrinkage temperature of skins tanned by the method of the invention, such as beach sheep skins, cashmere skins and rex rabbit skins, reaches more than 83 ℃, the skins have good strength and plumpness and softness, the requirements of subsequent dyeing and printing can be met, and meanwhile, the color of the tanned product fur quilt is not affected and the color is natural. The method of the invention can solve the problems that the fur plate tanned by the existing fur tanning method has poor heat and humidity resistance stability, is easy to cause the yellowing of fur and can cause the damage of fur fibers, and can further improve the quality of tanned fur on the basis of no chromium and no aldehyde residue.
4. The bio-based epoxy active tanning agent adopted by the fur tanning method based on the bio-based epoxy active tanning agent is prepared by modifying a chitosan degradation product as a base, on one hand, the molecular weight of the chitosan degradation product is adjustable, and the molecular chain size of the bio-based epoxy active tanning agent can be flexibly adjusted according to the compactness of different animal skin fibers and the requirements of tanning leather blank performance so as to realize better tanning effect; on the other hand, the chitosan has certain antibacterial property, and the tanning obtained by modifying the chitosan as the basis is adopted for tanning the fur, so that the tanned product can have certain antibacterial property and filling property.
Detailed description of the invention
The tanning process for skins based on bio-based epoxy active tanning agents provided by the present invention is further illustrated by the following examples. It should be noted that the following 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 based on the above disclosure and still fall within the scope of the present invention.
In the following embodiments, the bio-based epoxy active tanning agent with the structure shown as the formula (I) is obtained by reacting amino of chitosan degradation product formed by degrading chitosan by hydrochloric acid, sulfuric acid, nitric acid or Lewis acid through an acid degradation method with epichlorohydrin under neutral or weakly alkaline conditions. When the chitosan is degraded by acid, the chitosan is hydrolyzed to prepare the chitosan oligomer (namely chitosan degradation product) by utilizing the characteristic that glycosidic bonds in the chitosan are unstable to acid, the chitosan degradation product contains hydroxyl and amino, the degradation degree of the chitosan is related to the type, the dosage and the like of the acid, and the type and the dosage of the acid can be determined according to the molecular weight of the required chitosan degradation product by referring to the prior art. When the amino group of the chitosan degradation product reacts with epichlorohydrin, the content of the epichlorohydrin can influence the content of epoxy groups in the bio-based epoxy active tanning agent shown in the formula (I), and the content of the epichlorohydrin is usually 20-80 wt% of the chitosan degradation product.
In the formula (I), n is 0 to 15, preferably 1 to 6.
Example 1
In the embodiment, the method is adopted to tanne the Tan sheep fur, the adopted raw material leather is salt-dried Tan sheep second fur, the raw material leather is batched and retanned according to the principle that the size of the leather and the quality of the fur quilt are similar according to the size of the leather and the quality of the fur quilt, and the wool fiber of the raw material leather is longer and in a spike shape, so that the liquid coefficient of the processing process is larger and is generally controlled to be about 18L/piece in order to prevent the wool from knotting in the tanning process. The method comprises the following specific steps:
(1) softening
The raw material skin is subjected to soaking, fleshing and degreasing operations according to the conventional process.
Adding water and sodium chloride into the scratch groove, scratching the scratch groove for 10min, adding formic acid to adjust the pH value to 3.5 after the sodium chloride is dissolved, adding Angellzym HA protease (Tianjin Triumph, the enzyme activity is 2000-3000U/L), scratching the scratch groove for 30min to form softening liquid, wherein the concentration of the sodium chloride in the softening liquid is 50g/L, and the concentration of the Angellzym HA protease is 0.2 g/L. And putting the soaked, fleshed and degreased fur into the softening liquid in the scoring groove, controlling the using amount of the softening liquid to be 8 times of the dry weight of the fur, controlling the temperature of the softening liquid to be 35 ℃, scoring the scoring groove for 30min, then intermittently scoring the scoring groove, checking the softening degree at intervals, after 4h of intermittent scoring, slightly pushing the part between the ribs with fingers to find that the fur slightly falls off, and then finishing softening.
(2) Pickling
After the softening in the step (1) is finished, adding formic acid and sulfuric acid into the softening liquid in the paddle to form pickle liquor, wherein the concentration of the formic acid in the pickle liquor is 1.5g/L, the concentration of the sulfuric acid in the pickle liquor is 2.2g/L, and the pH value of the pickle liquor is 1.6-2.0. Controlling the temperature of the pickling solution to be room temperature, scratching the scratching groove for 30min, then intermittently scratching the scratching groove for 6h, stopping scratching, and standing for 12 h.
(3) Tanning
Adding a baking soda solution into the bath lotion after the pickling in the step (2) to adjust the pH value of the bath lotion to 3.5-4.0, adding a tanning agent melamine into the bath lotion to enable the concentration of the tanning agent to be 0.5g/L, scratching a scratch groove for 30min, stopping scratching for 30min, scratching the scratch groove for 30min, then adding a biological epoxy active tanning agent to enable the concentration to be 10.0g/L, controlling the temperature of the bath lotion to be room temperature, scratching the scratch groove for 30min, then intermittently scratching for 6h, stopping scratching, standing for 12h, then adding a baking soda solution into the bath lotion every 20min until the pH value of the bath lotion is adjusted to 8.5-9.0, heating the bath lotion to 40 ℃, scratching the scratch groove for 2h, standing for 12h, measuring the pH value, and if the pH value of the bath lotion is lower than 8.5, adding a baking soda solution to adjust the pH value of the bath lotion to 8.5-9.0, then peeling off the bath lotion, and standing for 12h, if the pH value of the bath lotion is lower than 8.5-0, then directly peeling, washing with water, and standing.
In the step (3), the structure of the bio-based epoxy active tanning agent is shown as a formula (I),
in the formula (I), n is 6, the bio-based epoxy active tanning agent shown in the formula (I) is obtained by reacting amino of chitosan degradation product formed by degrading chitosan by hydrochloric acid with epichlorohydrin under neutral condition, and the dosage of the epichlorohydrin is 50 wt% of the chitosan degradation product.
In the steps (1) - (3), the intermittent scratching refers to scratching for 5min and stopping scratching for 55min every hour, namely, stopping scratching for 55min after scratching for 5 min.
The shrinkage temperature of the tanned Tan sheep fur in the embodiment is 84 ℃, the fur is white, the fur is naturally bent, and the skin plate is soft.
Example 2
In the embodiment, the method is adopted to tanne the shorn sheepskin, the adopted raw material leather is salted merino sheep leather, and the shorn sheepskin is dry. Adult merino sheep has large skin, and is sheared before processing, so the wet processing process is not easy to cause hair formation problem, the skin can be tanned in a rotary drum or a scratch groove, and the liquid coefficient is usually controlled to be about 20L/sheet when the skin is tanned in the scratch groove. The method comprises the following specific steps:
(1) softening
The raw material skin is subjected to soaking, fleshing and degreasing operations according to the conventional process.
Adding water and sodium chloride into the scratch groove, scratching the scratch groove for 10min, adding formic acid to adjust the pH value to 3.5 after the sodium chloride is dissolved, then adding 537 acid protease (the enzyme activity is 2000-3000U/L), scratching the scratch groove for 30min to form softening liquid, wherein the concentration of the sodium chloride in the softening liquid is 45g/L, and the concentration of the 537 acid protease is 0.11 g/L. And putting the soaked, fleshed and degreased fur into the softening liquid in the scoring groove, controlling the using amount of the softening liquid to be 10 times of the dry weight of the fur, controlling the temperature of the softening liquid to be 35 ℃, scoring the scoring groove for 30min, then intermittently scoring the scoring groove, checking the softening degree at intervals, after 4h of intermittent scoring, slightly pushing the part between the ribs with fingers to find that the fur slightly falls off, and then finishing softening.
(2) Pickling
After the softening in the step (1) is finished, adding formic acid and sulfuric acid into the softening liquid in the paddle to form pickle liquor, wherein the concentration of the formic acid in the pickle liquor is 1.5g/L, the concentration of the sulfuric acid in the pickle liquor is 2.0g/L, and the pH value of the pickle liquor is 1.8-2.0. Controlling the temperature of the pickling solution to be room temperature, scratching the scratching groove for 30min, intermittently scratching the scratching groove for 6h, stopping scratching, and standing for 12 h.
(3) Tanning
Adding a sodium carbonate solution into the bath liquid after the pickling in the step (2) to adjust the pH value of the bath liquid to 3.5-4.0, adding triethylamine serving as a tanning agent into the bath liquid to enable the concentration of the tanning agent to be 0.7g/L, scratching a scratch groove for 30min, stopping scratching for 60min, scratching the scratch groove for 15min, adding a bio-based epoxy active tanning agent to enable the concentration to be 9.0g/L, controlling the temperature of the bath liquid to be room temperature, scratching the scratch groove for 30min, then intermittently scratching for 6h, stopping scratching, standing for 15h, then adding the sodium carbonate solution into the bath liquid every 20min until the pH value of the bath liquid is adjusted to 9.0-9.2, heating the bath liquid to 40 ℃, intermittently scratching the scratch groove for 2h, standing for 15h, measuring the pH value of the bath liquid, if the pH value of the bath liquid is lower than 9.0, supplementing the sodium carbonate solution to adjust the pH value of the bath liquid to 9.0-9.2, then peeling, standing, and if the pH value of the bath liquid is between 9.0-2, then directly peeling, washing with water, and standing.
In the step (3), the structure of the bio-based epoxy active tanning agent is shown as a formula (I),
in the formula (I), n is 5, the bio-based epoxy active tanning agent shown in the formula (I) is obtained by reacting amino of chitosan degradation product formed by degrading chitosan by hydrochloric acid with epichlorohydrin under neutral condition, and the dosage of the epichlorohydrin is 40 wt% of the chitosan degradation product.
In the steps (1) - (3), the intermittent scratching refers to scratching for 5min and stopping scratching for 55min every hour, namely, stopping scratching for 55min after scratching for 5 min.
The shrinkage temperature of the shorn sheepskin fur tanned by the embodiment is 83 ℃, the fur color is natural, and the skin plate is soft.
Example 3
In the embodiment, the method is adopted to tanne the shorn sheepskin, the adopted raw material leather is salted merino sheep leather, and the shorn sheepskin is dry. Adult merino sheep has large skin, and is sheared before processing, so the wet processing process is not easy to cause hair formation problem, the skin can be tanned in a rotary drum or a scratch groove, and the liquid coefficient is usually controlled to be about 20L/sheet when the skin is tanned in the scratch groove. The method comprises the following specific steps:
(1) softening
The raw material skin is subjected to soaking, fleshing and degreasing operations according to the conventional process.
Adding water and sodium chloride into the groove, scratching the groove for 10min, adding formic acid to adjust the pH value to about 7.0 after the sodium chloride is dissolved, then adding DOWELLZYM OS protease (the enzyme activity is 1000-1200U/L), scratching the groove for 30min to form a softening solution, wherein in the softening solution, the concentration of the sodium chloride is 25g/L, and the concentration of the DOWELLZYM OS protease is 1.0 g/L. And (3) putting the soaked, fleshed and degreased fur into the softening liquid in the groove, controlling the using amount of the softening liquid to be 10 times of the dry weight of the fur, controlling the temperature of the softening liquid to be 35 ℃, scratching the groove for 30min, then scratching the groove intermittently, checking the softening degree at intervals, after scratching for 3h intermittently, slightly pushing the part between the ribs with fingers to find that the fur slightly falls off, and then finishing softening.
(2) Tanning
Adding formic acid into the bath liquid after the pickling in the step (2) to adjust the pH value of the bath liquid to 3.5-4.0, adding triethanolamine serving as a tanning aid into the softening liquid to enable the concentration of the tanning aid to be 0.8g/L, scratching a scratch groove for 30min, stopping for 60min, scratching the scratch groove for 20min, then adding a biological epoxy active tanning agent to enable the concentration to be 12.0g/L, controlling the temperature of the bath liquid to be room temperature, scratching the scratch groove for 30min, intermittently scratching the scratch groove for 6h, standing for 12h, then adding sodium bicarbonate solution into the bath liquid every 20min until the pH value of the bath liquid is adjusted to 9.0-9.2, heating the bath liquid to 40 ℃, scratching the scratch groove for 2h, standing for 12h, then measuring the pH value of the bath liquid, if the pH value of the bath liquid is lower than 9.0, adding sodium bicarbonate solution to adjust the pH value of the bath liquid to 9.0-9.2, then peeling, standing for washing the bath liquid, and if the pH value of the bath liquid is between 9.0-2.2, then directly peeling, washing with water, and standing.
In the step (2), the structure of the bio-based epoxy active tanning agent is shown as a formula (I),
in the formula (I), n is 15, the bio-based epoxy active tanning agent shown in the formula (I) is obtained by reacting amino of chitosan degradation product formed by degrading chitosan by hydrochloric acid with epichlorohydrin, and the dosage of the epichlorohydrin is 80 wt% of the chitosan degradation product.
In the steps (1) - (2), the intermittent scratching refers to scratching for 5min and stopping scratching for 55min every hour, namely, stopping scratching for 55min after scratching for 5 min.
The shrinkage temperature of the shorn sheepskin fur tanned by the embodiment is 85 ℃, the fur color is natural, and the skin plate is soft.
Example 4
In the embodiment, the method is adopted to tanne the rex rabbit fur, and the adopted raw material leather is salted rex rabbit leather. Can be tanned in a rotary drum or a scratch groove, the liquid coefficient is usually controlled to be about 2L/piece when the leather is tanned in the scratch groove, in order to reduce hair falling, the leather is directly tanned after being not independently degreased and softened before being tanned, and the softness of the leather plate is improved after being degreased. The method comprises the following specific steps:
(1) softening
And (3) soaking and fleshing the raw fur according to a conventional process to obtain the pretreated fur.
Adding water and sodium chloride into the scratch groove, scratching the scratch groove for 10min, adding formic acid to adjust the pH value to about 3.8 after the sodium chloride is dissolved, then adding 537 acid protease (the enzyme activity is 2000-3000U/L), scratching the scratch groove for 30min to form softening liquid, wherein the concentration of the sodium chloride in the softening liquid is 25g/L, and the concentration of the 537 acid protease is 0.12 g/L. Putting the pretreated fur into the softening liquid in the scratching groove, controlling the using amount of the softening liquid to be 6 times of the dry weight of the fur, controlling the temperature of the softening liquid to be 32 ℃, scratching the scratching groove for 30min, then intermittently scratching the scratching groove, checking the softening degree at intervals, after 4h of intermittent scratching, slightly pushing the part between the ribs with fingers, and finding that the fur slightly falls off, thereby finishing softening.
(2) Tanning
Adding a baking soda solution into the bath liquid after the pickling in the step (2) to adjust the pH value of the bath liquid to 3.5-4.0, adding a tanning aid hexamethylenetetramine into the softening liquid to enable the concentration of the tanning aid to be 0.5g/L, scratching a scratching groove for 30min, stopping the bath for 60min, then adding a biological epoxy active tanning agent to the concentration of 9.0g/L, controlling the temperature of the bath liquid to be room temperature, scratching the scratching groove for 30min, then intermittently scratching the scratching groove for 6h, standing for 12h, then adding the baking soda solution into the bath liquid every 20min until the pH value of the bath liquid is adjusted to 8.5-8.8, heating the bath liquid to 40 ℃, intermittently scratching the scratching groove for 2h, standing for 12h, measuring the pH value of the bath liquid, if the pH value of the bath liquid is lower than 8.5, supplementing the baking soda solution to adjust the pH value of the bath liquid to 8.5-8.8, then peeling, washing the bath liquid with water, and standing if the pH value of the bath liquid is between 8.5-8.8.8, then directly peeling, washing with water, and standing.
In the step (2), the structure of the bio-based epoxy active tanning agent is shown as a formula (I),
in the formula (I), n is 1, the bio-based epoxy active tanning agent shown in the formula (I) is obtained by reacting amino of chitosan degradation product formed by degrading chitosan by hydrochloric acid with epichlorohydrin, and the dosage of the epichlorohydrin is 30 wt% of the chitosan degradation product.
In the steps (1) - (2), the intermittent scratching refers to scratching for 5min and stopping scratching for 55min every hour, namely, stopping scratching for 55min after scratching for 5 min.
And (3) degreasing is carried out after the tanning in the step (2) is finished, the shrinkage temperature of the finally obtained tanned rex rabbit fur is 85 ℃, the fur color is white, and the fur is soft.
Claims (10)
1. A fur tanning method based on bio-based epoxy active tanning agent is characterized by comprising softening, pickling and tanning processes or softening and tanning processes, and comprises the following steps:
(1) softening
Putting the pretreated fur into softening liquid in a paddle vat, controlling the using amount of the softening liquid to be 6-10 times of the dry weight of the fur, controlling the temperature of the softening liquid to be 33-35 ℃, paddle the paddle vat for 20-40 min, and then intermittently paddle the paddle vat for 3-8 h; the softening liquid is prepared from sodium chloride, protease and water, the pH value is adjusted, and the concentration of the sodium chloride in the softening liquid is 25-55 g/L; when the protease is acid protease, adjusting the pH value of the softening liquid to 3.0-3.5, wherein the concentration of the acid protease is 0.08-0.12 g/L, and when the protease is neutral protease, adjusting the pH value of the softening liquid to 7.0-7.5, and the concentration of the neutral protease is 0.8-1.0 g/L;
pickling and tanning after softening, or directly tanning after softening;
(2) pickling
Adding organic acid and inorganic acid into the softening liquid in the paddle to form a pickling liquid with the pH value of 1.6-2.0, controlling the concentration of the organic acid in the pickling liquid to be 1.5-2.5 g/L and the concentration of the inorganic acid to be 1.5-2.5 g/L, controlling the temperature of the pickling liquid to be room temperature, stroking the paddle for 20-40 min, then stroking the paddle for 3-6 h intermittently, and standing for 12-15 h;
(3) tanning
Adjusting the pH value of the pickled or softened bath lotion to 2.0-5.0, adding a tanning aid into the bath lotion to enable the concentration of the tanning aid to be 0.5-1.0 g/L, scratching a sliding groove for 30-60 min, stopping scratching for 30-60 min, scratching the sliding groove for 0-30 min, adding a bio-based epoxy active tanning agent to enable the concentration to be 8.0-12.0 g/L, controlling the temperature of the bath lotion to be 15-33 ℃, scratching the sliding groove for 20-40 min, intermittently scratching the sliding groove for 6-8 h, standing for 12-15 h, adding an alkalizer into the bath lotion to adjust the pH value of the bath lotion to 8.0-10.0, adjusting the temperature of the bath lotion to 35-50 ℃, intermittently scratching the sliding groove for 2-3 h, standing for 12-15 h, and peeling;
the structure of the bio-based epoxy active tanning agent is shown as a formula (I),
the pretreated fur is the fur subjected to soaking, fleshing and degreasing, or the fur subjected to soaking and fleshing.
2. The method for tanning skins based on bio-based epoxy active tanning agent according to claim 1, wherein in the formula (I), n is 0-15.
3. The method for tanning skins based on bio-based epoxy active tanning agent according to claim 2, characterized in that in formula (I), n is 1-6.
4. The method for tanning skins based on bio-based epoxy active tanning agents according to any one of claims 1 to 3, characterized in that the bio-based epoxy active tanning agent represented by the formula (I) is obtained by epoxidizing and modifying a chitosan degradation product obtained by degrading chitosan through an acid degradation method, wherein the epoxidizing and modifying are carried out by reacting the chitosan degradation product with epoxy chloropropane under the condition that the pH value is 7.0-8.0, and the amount of the epoxy chloropropane is 20-80 wt% of the chitosan degradation product.
5. The method for tanning skins based on bio-based epoxy active tanning agent according to claim 4 characterized in that the amount of epichlorohydrin is 30-50 wt.% of chitosan degradation product when the chitosan degradation product is modified by epoxidation.
6. A process for tanning skins based on bio-based epoxy active tanning agents according to any of claims 1 to 3 characterized in that said tanning aid is melamine, triethylamine, triethanolamine, hexamethylenetetramine, zirconium chloride or aluminium chloride.
7. A process for tanning skins based on bio-based epoxy activated tanning agents according to any of claims 1 to 3 characterized in that the pH value of the bath is controlled in the range of 8.0 to 10.0 before the skins are delivered in the tanning step.
8. A process for tanning skins based on bio-based epoxy active tanning agents according to any of claims 1 to 3 characterized in that said protease is 537 acid protease, angelzym HA protease, sumoylase or DOWELLZYM OS protease.
9. A process for tanning skins based on bio-based epoxy activated tanning agent according to any of claims 1 to 3 characterized in that said organic acid is formic acid, acetic acid or lactic acid, said inorganic acid is sulfuric acid and said alkalizing agent is at least one of sodium carbonate, potassium carbonate, sodium bicarbonate, sodium hydroxide, potassium hydroxide.
10. A process for tanning skins based on bio-based epoxy active tanning agents according to anyone of claims 1 to 3 characterized in that said skins are sheepskins, beachns, mink, fox, rabbit, lamb or runner skins.
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| CN115216565A (en) * | 2022-05-16 | 2022-10-21 | 宁夏羊博士皮草科技有限公司 | Integrative chrome-free tanning method for Tan lamb fur leather |
| CN116103451A (en) * | 2023-03-30 | 2023-05-12 | 精艺裘皮制品股份有限公司 | Multi-working-procedure effective synergistic beach sheepskin harmless tanning method |
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| CN115216565A (en) * | 2022-05-16 | 2022-10-21 | 宁夏羊博士皮草科技有限公司 | Integrative chrome-free tanning method for Tan lamb fur leather |
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