CN108359752B - Animal skin cleaning and tanning method based on epoxy compound - Google Patents
Animal skin cleaning and tanning method based on epoxy compound Download PDFInfo
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- CN108359752B CN108359752B CN201810227626.4A CN201810227626A CN108359752B CN 108359752 B CN108359752 B CN 108359752B CN 201810227626 A CN201810227626 A CN 201810227626A CN 108359752 B CN108359752 B CN 108359752B
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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
- C14C3/22—Chemical tanning by organic agents using polymerisation products
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Abstract
The invention discloses an animal skin cleaning and tanning method based on epoxy compounds. The method is characterized in that a polyoxyethylene diepoxy ether compound with good water solubility, adjustable molecular chain length and double epoxy groups is used as a tanning agent, the tanning is carried out under neutral conditions in the initial stage, pickling operation is not needed, the use and discharge of neutral salt are avoided, and the reaction of the epoxy groups and collagen molecules and the formation of cross-linked bonds are promoted by adding a catalyst, increasing the pH value and the temperature in the later stage and the like. By adopting the technical scheme, the tanning effect of the epoxy tanning agent is improved, and clean and efficient tanning is realized. The method is suitable for tanning in the process of making leather and fur coat from various animal skins, can obtain soft and white leather with the shrinkage temperature close to 85 ℃, has the integral sensory property similar to that of glutaraldehyde tanned leather, and can meet the requirement of chrome-free tanning of the leather.
Description
Technical Field
The invention relates to a leather tanning technology, in particular to a tanning method which takes a diepoxy compound as a tanning agent and does not use neutral salt, aldehyde, chromium and other substances in tanning, belonging to the technical field of leather clean production. .
Background
Tanning is a very important process in leather making, and chrome tanning is the most important tanning method at present due to the traditional habit, the production cost, the leather-forming performance, the leather-forming diversity and the like. The traditional chrome tanning method adopts a pickling-chrome tanning process, in the pickling process, more than 7 percent of common salt is usually used for preventing the acid swelling of the skins, and the content of chloride ions in the waste liquid is up to 30000 mg/L. The chromium content in the waste liquid after chrome tanning is greatly beyond the national standard due to the incomplete utilization of chromium in the chrome tanning process, and a large amount of chromium-containing solid waste is generated, thereby bringing great pressure to the environment. In recent years, with the increasing demand for environmental protection and the change of consumption concept, it is necessary to develop a new tanning method to replace chrome tanning.
Chrome-free tanning is largely divided into non-chrome metal tanning and organic tanning depending on the type of tanning agent. Because the precipitation point of the non-chromium metal salt tanning agent is low, pickling operation is generally needed, a large amount of salt is needed to be added, and the problems that the shrinkage temperature of tanned leather is not high, the performance of leather has a large difference with that of chromium tanned leather and the like exist. Organic tanning is the main development direction of the non-chrome tanning technology. At present, the chrome-free tanning technology adopted industrially is mainly aldehyde tanning, such as glutaraldehyde, oxazolidine, organic phosphorus tanning agent and the like. The shrinkage temperature of glutaraldehyde tanned leather can reach 85 ℃, the leather has better comprehensive performance, is the most main tanning method of chrome-free tanned automobile cushion leather at present, but the tanned leather has yellow color, needs a pickling process, and still generates a large amount of neutral salt emission. The tanning agent such as oxazolidine, organic phosphorus and the like has the problem of excessive formaldehyde, and is difficult to be industrially adopted. Therefore, there is a need to develop new salt-free, chromium-free and formaldehyde-free leather tanning processes.
The epoxy compound is a compound containing one or more epoxy groups in a molecule, and the epoxy group in the structure can react with various groups such as hydroxyl, amino, carboxyl and the like in a side chain of a protein molecule in a wider pH range (pH 3-9). Polyepoxy compounds are capable of generating cross-linking between collagen molecular chains and, therefore, may be applied to tanning leather. Zeeman et al treated collagen with 1,4-butanediol glycidyl ether gave a product with a contraction temperature of 63 ℃ (Zeeman R, Dijkstra P J, Van Wachem P B, et al Crosslinking and modification of dermalsheep collagen using 1, 4-butyl diol ether Journal of biomedical materials Research Part B Applied Biomaterials 2015,46(3): 424-433). Masuoka et al tanned with ethylene glycol glycidyl ether in a methanol and ammonia reaction system and The shrinkage temperature of The Leather rose to 80 deg.C (Masuoka M, Makamura M. The application of catalysts and other additives oxygen precursors of Leather. Journal of The Society of Leather technologies and chemists, 1987,71: 127-133). The shrinkage temperature of Leather tanned in the organic phase is higher with the aromatic epoxy compounds of Heath et al, and tanning is carried out under alkaline conditions, the shrinkage temperature of the Leather reaching 90 deg.C (Heath R J, Di Y, Hudson A. optimization of epoxide-based tanning systems: an initial study. Journal of Society of Leather technologies and Chemists, 2005, 89(5): 186-193). Gao Jing et al studied the combination of epoxy compounds and vegetable tanning agents to tanne bayberry extract with glycerol triglycidyl ether at pH4.5 and 50 ℃ with the shrinkage temperature of the leather reaching 93 ℃ (Gao Jing, Li Jing, Liao products, Shibi. vegetable tanning agent-epoxy resin combination study, Chinese leather 2012,03: 8-12).
The above studies show that epoxy compounds have potential as tanning agents, but the tanning performance is still far from the actual requirements of leather, and therefore, no industrial scale application has been reported. The main reasons for this are the small variety of water-soluble polyepoxy compounds and the short molecular chain. The commonly used water-soluble aliphatic polyepoxy compounds, such as 1,4-butanediol glycidyl ether, glycerol triglycidyl ether and the like, have slow reaction rate of epoxy groups and collagen molecules in an aqueous medium at a low temperature (below 40 ℃) and low crosslinking rate, so that the tanning property is low and the shrinkage temperature of tanned leather is below 70 ℃. Polyepoxy compounds with rigid structure, such as TEPIC and aromatic epoxy compounds, are tanned in an organic phase, and under the action of a catalyst, the shrinkage temperature of leather can reach more than 80 ℃, but the tanning in an organic phase system is difficult to be applied industrially. Therefore, there is a need to develop a novel epoxy compound tanning agent and tanning method having good tanning effect in aqueous medium for tanning.
Disclosure of Invention
The invention aims to provide an animal skin cleaning and tanning method based on epoxy compounds aiming at the defects of the prior art, so as to solve the problems of neutral salt and chromium pollution in the leather tanning process, slow reaction rate, low crosslinking rate, low shrinkage temperature of tanned leather and the like in the existing epoxy compound tanning method in an aqueous medium.
The method is basically characterized in that polyoxyethylene diepoxy ether compounds with good water solubility, adjustable molecular chain length and double epoxy groups are used as tanning agents, polyoxyethylene groups in molecules of the tanning agents provide good water solubility, tanning can be carried out in a water medium, the length of molecular chains can be regulated and controlled by regulating the number of Ethoxy (EO), the size requirement of the molecules of the tanning agents on cross-linking of collagen fibers and the requirements of different animal skins are met, and the double epoxy groups can be cross-linked in the collagen molecules to generate tanning property; by utilizing the characteristics of stability and low reaction activity of the epoxy group under a neutral condition, the tanning initial stage is carried out under the neutral condition without pickling operation, so that the use and discharge of neutral salt are avoided; the reaction process is accelerated by adding a catalyst, increasing the pH value and the temperature in the later period and the like, and the reaction of the epoxy group and the collagen molecule and the formation of a cross-linking bond are promoted. By adopting the technical scheme, the tanning effect of the epoxy tanning agent is improved, clean and efficient tanning is realized, and the requirement of leather on chrome-free tanning is met.
The method for cleaning and tanning the animal skin based on the epoxy compound, which can realize the aim of the invention, comprises the following operation steps, wherein the materials used in each operation step are calculated according to the parts by mass except for the specific description:
(1) various animal skins such as sheepskins, oxhide and pigskins serving as leather raw material skins are subjected to the processes of soaking, unhairing, liming, deliming and softening, or various animal skins such as sheepskins, fox skins and mink skins serving as fur raw material skins are subjected to the processes of soaking, degreasing, softening and the like, and then are tanned according to the following steps;
(2) tanning: 100 parts of softened bare leather (based on the mass of leather-tanned grey leather, the amount of leather tanned into 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 200-1000 parts of water (based on the mass of fur tanned into raw material leather) are added, the temperature is adjusted to 15-30 ℃, a proper amount of acid is added, the pH value of bath foam is adjusted to be in a range of 6.0-7.5, 2-10 parts of bis-epoxy tanning agent is added, the rotary drum is rotated for 2-6 hours, 0.1-3 parts of catalyst is added into the rotary drum after the tanning agent is completely permeated into the leather, an appropriate amount of alkali extracting agent is added for 0.5-5 hours in a rotating mode for multiple times, the pH value of the bath foam is adjusted to be in a range of 8-10, 50-200 parts of water is added after the. Or in the above-mentioned operation sequence, firstly adding 0.1-3 portions of catalyst, rotating for 0.5-5 hr, then adding 2-10 portions of diepoxy tanning agent, rotating for 3-6 hr, and making other operation be unchanged. 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 technical scheme, the diepoxy tanning agent is polyoxyethylene bis-epoxy ether and derivatives thereof, has double-end epoxy groups, a main chain is a polyoxyethylene unit, and the main structure is shown in figure 1, wherein n has a value range of 1-25; preferably, n has a value of 2 to 15.
In the technical scheme, the catalyst is a tertiary amine substance, and preferably, hexamethylenetetramine is used.
In the above technical solution, the adding manner of the catalyst includes adding the catalyst before or after the epoxy tanning agent, preferably, adding the catalyst before the epoxy tanning agent.
In the technical scheme, the tanning pH control comprises the steps of controlling the pH value in the initial stage of tanning within the range of 6.0-7.5, not requiring an pickling process, and preferably controlling the pH value within the range of 6.5-7.0; the pH value at the final stage of tanning is controlled within the range of 8-10 and 8.5-9.5.
In the above technical solution, the alkali extracting agent is at least one of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, magnesium oxide, ethanolamine, diethanolamine, triethanolamine and ethylenediamine, and preferably, sodium carbonate or triethanolamine is used.
In the technical scheme, the tanning temperature control comprises controlling the temperature in the early stage of tanning within the range of 15-30 ℃, preferably, controlling the temperature to be 10-25 ℃; the temperature at the end of tanning is controlled in the range of 35-50 c, preferably 40-55 c.
In the technical scheme, the animal skin cleaning and tanning method based on the epoxy compound can be suitable for tanning in the tanning and fur making processes of various animal skins.
The invention also adopts other technical measures.
The invention has the following advantages:
the invention provides a method for tanning leather by using epoxy compounds in an aqueous medium, the polyoxyethylene diepoxy ether tanning agent has good water solubility and adjustable molecular chain length, and can meet the requirements of tanning on the molecular size of the tanning agent in tanning different animal skins.
The invention provides a clean animal skin tanning method, the tanning agent is nontoxic, the tanning initial stage is carried out under neutral condition, the pickling operation is not needed, and the use and discharge of neutral salt are avoided.
The invention provides an efficient chrome-free tanning method by taking an epoxy compound as a tanning agent, which can obtain soft and white leather with the shrinkage temperature close to 85 ℃, has the integral sensory property similar to that of glutaraldehyde tanned leather, and can meet the requirement of chrome-free tanning of the leather.
Drawings
FIG. 1 is a molecular structural formula of a polyoxyethylene bis-epoxy ether compound tanning agent.
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 invention.
Example 1: tanning of goat leather
The sheep raw leather is tanned after being treated by leather-making procedures such as soaking, unhairing, liming, deliming, softening, washing and the like according to the conventional process. Softening 100kg of naked skin (mass of grey skin), adding 100kg of water, adjusting the temperature to 25 ℃, adding a proper amount of acid, such as 1:10 diluted formic acid solution, rotating for 60 minutes, adjusting the pH of bath liquid to be 6.5-7.0, adding 5kg of polyoxyethylene diepoxy ether agent with the molecular weight of about 300, rotating for 120 minutes, adding 0.4kg of hexamethylenetetramine after tanning agent is completely permeated into the skin, rotating for 60 minutes, adding a proper amount of sodium carbonate solution (dissolved by 10 times of water) for 2-4 times at intervals of 30 minutes each time, adjusting the pH of bath liquid to be 8.9-9.1, adding 100kg of hot water at 50 ℃, heating to 40 ℃, continuing to rotate for 60 minutes, stopping the drum overnight after the drum is stopped, rotating for 30 minutes next day, discharging the drum, and standing for 2 days. The results show that the shrinkage temperature of the leather reaches 85 ℃ by adopting the method of the invention.
Example 2: tanning of cow leather
The leather raw material leather is tanned after being treated by leather-making procedures such as soaking, unhairing, liming, deliming, softening, washing and the like according to the conventional process. Softening 100kg of naked skin (mass of the grey skin), adding 50kg of water, adjusting the temperature to 20 ℃, adding a proper amount of acid, such as a 1:10 diluted non-expansive aromatic sulfonic acid solution, rotating for 90 minutes, adjusting the pH value of a bath solution to be 6.5-7.0, adding 0.2kg of hexamethylenetetramine, rotating for 60 minutes, adding 7.5kg of polyoxyethylene bis-epoxy ether tanning agent with the molecular weight of about 200, rotating for 180 minutes, adding 0.5kg of hexamethylenetetramine after the tanning agent is completely permeated into the skin, rotating for 60 minutes, adding a proper amount of sodium carbonate solution (dissolved by 10 times of water) 3-5 times, each time at intervals of 30 minutes, adjusting the pH value of the bath solution to be 8.5-9.0, adding 150kg of hot water at 50 ℃, heating to 35 ℃, continuing to rotate for 120 minutes, stopping the drum, standing overnight, rotating for 30 minutes next day, and standing for 2 days. The results show that the shrinkage temperature of the leather reaches 83 ℃ by adopting the method of the invention.
Example 3: tanning sheep fur
The sheep raw material leather for fur production is treated by soaking, degreasing and softening processes according to the conventional process, and then tanned. 100kg of degreased or neutral enzyme softened fur is put into a paddle vat, 500kg of water is added, the temperature is adjusted to 30 ℃, a proper amount of acid is added, such as a 1:10 diluted non-swelling aromatic sulfonic acid solution, the mixture is rotated for 90 minutes, after the pH of a bath solution is adjusted to be 6.5-7.0, 10kg of polyoxyethylene bis-epoxy ether tanning agent with the molecular weight of about 600 is added, the mixture is rotated for 240 minutes, after the tanning agent is completely permeated into the skin, 0.8kg of hexamethylenetetramine is added, the mixture is rotated for 120 minutes, a proper amount of sodium carbonate solution (dissolved by 10 times of water) is added 3-5 times, the pH of the bath solution is adjusted to be 8.5-9.0 at intervals, after the bath solution is continuously rotated for 180 minutes, the mixture is intermittently rotated, the mixture is rotated for 10 minutes per hour, the mixture is taken out of a drum, and. The results show that the shrinkage temperature of the leather reaches 84 ℃ by the method of the invention.
Claims (6)
1. An animal skin cleaning and tanning method based on epoxy compounds is characterized by comprising the following steps, wherein materials used in each operation step are calculated according to parts by mass unless specified:
(1) the animal skin as the leather tanning raw material skin is tanned according to the following steps after the processes of soaking, unhairing, liming, deliming and softening, or the animal skin as the fur tanning raw material skin is soaked, degreased and softened;
(2) tanning: softening bare leather, calculating the mass of the ash bending leather when the leather is tanned by 100 parts, calculating the mass of the leather converted into the mass of the leather of 100 parts when the fur is tanned, placing the leather in a rotary drum or a scratch groove, adding 30-150 parts of water when tanning leather, adding 200-1000 parts of water when tanning fur, adjusting the temperature to 15-30 ℃, adding a proper amount of acid, adjusting the pH value of bath solution to be stabilized in the range of 6.0-7.5, adding 2-10 parts of polyoxyethylene bis-epoxy ether tanning agent, rotating for 2-6 hours, after the tanning agent is completely penetrated into the skin, 0.1 to 3 parts of catalyst is added into the rotary drum, the rotary drum is rotated for 0.5 to 5 hours, adding appropriate amount of alkali extracting agent for several times, adjusting pH value of the bath liquid to 8-10, rotating for 1-3 hr, adding 50-200 parts of water, controlling the temperature of the bath liquid to be 30-50 ℃, 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, neutralizing, dyeing and fatliquoring are carried out.
2. The method for cleaning and tanning animal skin based on epoxy compound as claimed in claim 1, wherein the polyoxyethylene bis epoxy ether tanning agent used is polyoxyethylene bis epoxy ether and its derivatives, having double epoxy groups and polyoxyethylene unit as main chain
3. The method for cleaning and tanning animal skin based on epoxy compound as claimed in claim 1, characterized in that said catalyst is hexamethylenetetramine.
4. The method of claim 1, wherein the animal skin is selected from the group consisting of cow skin, pig skin, and sheep skin.
5. The method for clean tanning of animal skin based on epoxy compound as claimed in claim 1, characterized in that the animal skin as fur tanning raw material skin is one of sheepskin, fox skin, mink skin.
6. The method for cleaning and tanning animal skin based on epoxy compound as claimed in claim 1, wherein the alkali extracting agent is at least one of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, magnesium oxide, ethanolamine, diethanolamine, triethanolamine and ethylenediamine.
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| CN110628968B (en) * | 2019-10-26 | 2021-09-24 | 辛集市凌爵皮革有限责任公司 | Processing technology of chrome-free tanning of sheep leather, sheep white wet leather and sheep leather |
| CN111154030B (en) * | 2020-02-07 | 2021-04-27 | 四川大学 | Preparation and application of polyoxyalkylene-containing epoxy acrylate polymer active fatliquor |
| CN115011742A (en) * | 2022-06-29 | 2022-09-06 | 陕西科技大学 | Epoxy modified collagen polypeptide-based organic chromium-free tanning agent, preparation method and application |
| 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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| CN101544621A (en) * | 2009-02-26 | 2009-09-30 | 山东轻工业学院 | Epoxidation maleic-acid monoester and compounding method thereof |
| CN101629218B (en) * | 2009-08-12 | 2013-04-10 | 成都凯特有机硅新材料科技有限公司 | Water-soluble self-emulsifying coupled modified silicone oil composite and application in pickling, tanning and dyeing of leather making |
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