CN114231672A - Leather pickling-free, salt-free and high-absorption chrome tanning process method - Google Patents
Leather pickling-free, salt-free and high-absorption chrome tanning process method Download PDFInfo
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- CN114231672A CN114231672A CN202111433656.9A CN202111433656A CN114231672A CN 114231672 A CN114231672 A CN 114231672A CN 202111433656 A CN202111433656 A CN 202111433656A CN 114231672 A CN114231672 A CN 114231672A
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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
- C14C1/04—Soaking
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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
- C14C3/04—Mineral tanning
- C14C3/06—Mineral tanning using chromium compounds
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Abstract
The invention provides a leather pickling-free salt-free high-absorption chrome tanning process method, which comprises the following steps: step 1, weighing and metering; step 2, soaking in water; step 3, liming; step 4, washing with water; step 5, pre-deliming; step 6, deashing and softening: adding 0.5-1 time of 30 ℃ water, adding 0.8% of deliming agent and 0.2% of degreasing agent, adding sulfuric acid to adjust the pH value to 3.5, and adding 0.5% of softened complex enzyme and 0.5% of auxiliary agent; step 7, washing with water; step 8, performing chrome tanning; step 9, adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.4-0.5% of the tare weight of the raw materials; step 10, adding acid for several times; the method has the characteristics of saving the production cost, reducing the environmental pollution and ensuring that the quality index of the finished product is not reduced by promoting the absorption of chrome tanning.
Description
Technical Field
The invention relates to the technical field of leather clean production, in particular to a pickling-free, salt-free and high-absorption chrome tanning process method for leather.
Background
The key process of converting the original leather blank into leather includes the steps of: soaking, unhairing, liming, fleshing, softening, washing, pickling, chrome tanning and other processes, wherein the pickling process is mainly used for reducing the pH value of the naked skin to be close to the pH value of a chrome tanning solution, preventing the surface from being over tanned, further dispersing collagen fibers, increasing the reactive groups of collagen, further removing non-fibrous protein in the skin, dehydrating the collagen part, enlarging the gaps among the collagen fibers and facilitating the penetration and combination of tanning agent molecules. In the traditional chrome tanning process, pickling is generally carried out firstly, namely the pH value of the pelts is adjusted to 2.0-3.0 by formic acid and sulfuric acid, which is beneficial to the penetration of chrome tanning agent. In order to prevent the skin from acid swelling, neutral salt such as sodium chloride and the like accounting for 6% -10% of the weight of the skin is required to be added in pickling, then chrome tanning agent accounting for 6% -8% of the weight of the skin (accounting for 1.0% -1.8% of the amount of chromium) is added, the chrome tanning is carried out, alkali is extracted by alkaline substances such as sodium bicarbonate and the like at the end stage of the chrome tanning, the pH value of tanning liquid is increased to 3.8-4.2, and the combination of the chromium and the skin is promoted.
In the traditional pickling-chrome tanning process, the absorption rate of the chrome tanning agent is only 60% -70%, and about 30% -40% of chrome is not utilized, so that the waste of chrome resources is caused, and if the chrome tanning agent is directly discharged, the greater environmental pollution is caused: meanwhile, the neutral salt added for preventing the leather from swelling is also discharged along with the tanning waste liquid, thereby further bringing harm to the environment. The pickling process increases the use of materials, increases the difficulty of process control and has adverse effect on the environment. The pickling requires the use of large amounts of neutral salts, otherwise the skins "acid" and swell, which is neither favourable for penetration of the chrome tanning agent in the early stages of tanning, nor seriously impairs the strength of the skins. If the dosage of the neutral salt is too large, the leather is dehydrated, and the finished leather is flat, thin and not full. In the later stage of tanning, the tanning agent and the skin collagen are combined into a main part, and at the moment, the acid must be neutralized and removed, so that collagen carboxyl is dissociated, the molecules of the chrome tanning agent are enlarged, but the alkali extraction operation is slightly improper, so that quality problems such as grain surface roughness, chrome spots and the like are easily caused.
Disclosure of Invention
The invention aims to solve the technical problem of providing a leather pickling-free salt-free high-absorption chrome tanning process method which saves production cost, reduces environmental pollution and can ensure that the quality index of a finished product is not reduced by promoting chrome tanning absorption.
In order to solve the technical problems, the invention adopts the technical scheme that:
a leather pickling-free salt-free high-absorption chrome tanning process method comprises the following steps:
step 1, weighing and metering: weighing the raw leather as a material counting basis for the subsequent procedures of soaking, liming, washing, pre-deliming, softening, pickling, tanning and the like;
step 2, soaking: adding water to the hide which has been submerged in the hide;
step 3, liming;
step 4, washing with water;
step 5, pre-deliming;
step 6, deashing and softening: adding 0.5-1 time of 30 ℃ water, adding 0.8% of deliming agent and 0.2% of degreasing agent, adding sulfuric acid to adjust the pH value to 3.5, and adding 0.5% of softened complex enzyme and 0.5% of auxiliary agent;
and 7, washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;
step 8, chrome tanning: adding 2-3% chrome tanning agent, rotating for 60-90min, adding 1-1.5% tanning assistant, and rotating for 60-90 min;
step 9, adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.4-0.5% of the tare weight of the raw materials;
step 10, acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, then adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the raw leather: 0.3%, 0.5%;
step 11, adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 0.8-1% of the weight of the raw material peel;
step 12, fractional alkali extraction: adding the baking soda 5 times, rotating for 30min after adding the baking soda each time, then adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging the liquid out of the drum, wherein the use amount of the baking soda added each time is as follows according to the weight percentage of the raw material skin: 0.5%, 0.5%.
Further, in the step 2, after adding water, 0.4% of soaking aid, 0.2% of degreasing agent, 0.15% of bactericide and 0.4% of sodium carbonate are added, and the mixture is rotated for 20-30min and stopped for 40min at normal temperature, then rotated for 10min and stopped for 50min, and the circulation is performed for 12 times to remove meat, dirt, preservative and the like on the raw material skin.
Further, in the step 3, 0.8-1 time of water is added into the rotary drum, 0.5% of liming auxiliary agent and 0.1% of degreasing agent are added, the rotary drum rotates for 30-40min, 0.5% of lime is added, and the rotary drum rotates for 30-40 min; adding 0.5% depilatory enzyme preparation, rotating for 15-20min, stopping for 45min, circulating for three times, and filtering to remove hair; adding 0.5% sodium sulfide and 0.5% lime, rotating for 10-15min, stopping for 50min, adding 0.2% sodium sulfide and 0.5% lime, rotating for 10-20min, stopping for 50min, and rotating for 2 times; adding 1.5-2 times of water, adding 0.5% of liming auxiliary agent and 0.2% of lime, stopping for 50min every 10min, and circulating for 12 times.
Further, in the step 4, the water washing step is to add 1.5-2 times of water into the raw leather and wash for 20-30 min.
Further, in the step 5, the pre-deashing step comprises the steps of adding 0.8-1.2 times of water and 0.5 times of ammonium sulfide, rotating for 50-60min, and draining.
Further, in the step 6, the softening compound enzyme comprises 40 parts by weight of acid protease, 30 parts by weight of saccharifying enzyme and 30 parts by weight of lipase.
Further, in the step 6, the auxiliary agent comprises 30 parts by weight of an enzyme permeation promoter, 20 parts by weight of an enzyme activator and 50 parts by weight of a diluent.
Further, in the step 8, the tanning assistant is an aldehyde acid type polymer leather tanning agent.
Further, in the step 12, the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.
Further, in the step 8, the chrome tanning agent is basic chromium salt.
Adopt the produced beneficial effect of above-mentioned technical scheme to lie in:
the invention improves the process, does not have the pickling process, can not generate leather acid swelling, simultaneously saves the material of salt, avoids the problem of environmental pollution caused by reducing the acid swelling by using the salt, improves the process before tanning, promotes the penetration and combination of tanning agent molecules, and ensures that the quality index of finished products is not lower than that of the conventional process.
The invention improves the soaking step, mainly aims at removing dirt and preservative on the raw hide and degreasing to restore the raw hide to a fresh hide state, prepares for the next process, and then adopts the liming step, wherein the liming step is carried out by adding liming auxiliary agent, degreasing agent and unhairing enzyme preparation, fully dispersing collagen fibers, removing fiber interstitium, degreasing to remove hair and epidermis, cleaning naked hide grains and facilitating the contact absorption and utilization of chromium.
According to the invention, the softening compound enzyme is added in the deashing and softening process, the softening compound enzyme is an acidic softening compound enzyme, wherein the acidic softening compound enzyme comprises acidic protease, saccharifying enzyme and lipase, the acidic protease hydrolyzes collagen fibers, the saccharifying enzyme can mainly and effectively remove residual fibrous interstitials such as dermatan sulfate, mucin and like proteins, the lipase can remove residual fat in the skin, and dirt on the surface of the skin and residual scale and grease in the skin are effectively removed by utilizing the synergistic action of various enzymes and auxiliaries, so that the purpose of further dispersing the collagen fibers is achieved; on the basis of the improvement of the process of the previous process, the invention adds the aldehyde acid type high molecular leather tanning agent as a tanning aid in the tanning process, stores in the absorption and utilization of chromium, achieves the tanning effect and reduces the dosage of the chromium so as to achieve the aim of reducing chromium pollution.
According to the method, after the previous steps of water soaking, liming and deliming are improved, collagen fibers are fully dispersed, interstitial fibers are removed, fur and skins are degreased and removed, naked skin particles are cleaned, skin scales are fully removed, chromium is conveniently absorbed and utilized in a contact mode, a tanning aid and a small amount of chrome tanning agent are added in a chrome tanning step, acid swelling cannot be generated due to the fact that the pickling step is omitted, the steps of acid adding and the like are adopted, firstly, formic acid is added, formic acid molecules are small, permeation is fast, a masking effect is achieved on chrome tanning liquid, uniformity of chrome tanning can be improved, then, sulfuric acid is added in multiple times, rotation is conducted, full contact is achieved, the PH value is slowly reduced, the chrome tanning step is carried out, and a sufficient chrome tanning effect is achieved, but due to the fact that the action time of a strong acid environment is short, acid swelling cannot occur, and the problem that salt is not needed to be added to reduce the skin acid swelling is solved.
According to the invention, sodium thiosulfate and sodium thiosulfate are added as reducing agents, dichromate, hexavalent chromium and the like can be reduced into effective trivalent chromium tanning agents, so that the full utilization of the chromium tanning agents is promoted, the using amount of the chromium tanning agents is reduced, and the chromium pollution is further reduced.
The product obtained by the invention has delicate, light and smooth grain surface, the leather yield is 100%, the quality is not changed after being stored for one month, the high temperature resistance is good, the product quality is not reduced at all compared with the conventional tanning process, but the production cost is saved, and the environmental pollution is reduced.
Detailed Description
The following detailed description will be provided for the embodiments of the present invention with reference to specific embodiments, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented. Unless otherwise indicated, the techniques employed in the examples are conventional and well known to those skilled in the art, and the reagents and products employed are also commercially available. Various procedures and methods not described in detail are conventional methods well known in the art, and the source, trade name, and if necessary, the constituents of the reagents used are indicated at the first appearance.
In the following examples, acidic protease, saccharifying enzyme and lipase can be obtained from enzyme preparations produced by Biotech, Inc. of Hengchanghua, Doning, the enzyme permeation promoter can be polyoxyethylene ether surfactant, the enzyme activator can be calcium salt product, and the diluent can be mixture of starch and anhydrous sodium sulfate. The materials such as the soaking aid, the liming aid, the depilatory enzyme preparation, the deliming agent, the degreasing agent and the like can be purchased and obtained by New chemical materials Co., Ltd, of Foshan city, the chrome tanning agent adopts basic chromium salt, and the active ingredient of the chrome tanning agent is chromium sesquioxide.
Example 1
A leather pickling-free salt-free high-absorption chrome tanning process method comprises the following steps:
step 1, weighing and metering: weighing the raw leather as a material counting basis for the subsequent procedures of soaking, liming, washing, pre-deliming, softening, pickling, tanning and the like;
step 2, soaking: adding water which does not pass through the raw material skin into the raw material skin, adding 0.4% of soaking auxiliary agent, 0.2% of degreasing agent, 0.15% of bactericide and 0.4% of sodium carbonate after adding water, rotating for 20min and stopping for 40min at normal temperature, then rotating for 10min and stopping for 50min, circulating for 12 times, and removing meat, dirt, preservative and the like on the raw material skin;
step 3, liming, namely adding 0.8 time of water into the rotary drum, adding 0.5 percent of liming auxiliary agent and 0.1 percent of degreasing agent, rotating for 30min, adding 0.5 percent of lime, and rotating for 30 min; adding 0.5% depilatory enzyme preparation, rotating for 15min, stopping for 45min, circulating for three times, and filtering to remove hair; adding 0.5% sodium sulfide and 0.5% lime, rotating for 10min, stopping for 50min, adding 0.2% sodium sulfide and 0.5% lime, rotating for 10min, stopping for 50min, and rotating for 2 times; adding 1.5 times of water, adding 0.5% of liming auxiliary agent and 0.2% of lime, stopping for 50min every 10min, and circulating for 12 times;
and 4, washing with water: adding 1.5 times of water into the raw material peel, and washing for 20-30 min;
step 5, pre-deliming: adding 0.8 time of water and 0.5 time of ammonium sulfide, rotating for 50min, and draining;
step 6, deashing and softening: adding 0.5 time of water with the temperature of 30 ℃, adding 0.8% of deliming agent and 0.2% of degreasing agent, adding sulfuric acid to adjust the pH value to 3.5, and adding 0.5% of softened complex enzyme and 0.5% of auxiliary agent, wherein the softened complex enzyme comprises 40 parts by weight of acid protease, 30 parts by weight of saccharifying enzyme and 30 parts by weight of lipase, and the auxiliary agent comprises 30 parts by weight of enzyme permeation promoter, 20 parts by weight of enzyme activator and 50 parts by weight of diluent;
and 7, washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;
step 8, chrome tanning: adding 2% of chrome tanning agent, rotating for 90min, adding 1% of tanning assistant agent, rotating for 90min, wherein the tanning assistant agent is an aldehyde acid type high-molecular leather tanning agent, and the chrome tanning agent is basic chrome salt;
step 9, adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.4% of the tare weight of the raw materials;
step 10, acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, then adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the raw leather: 0.3%, 0.5%;
step 11, adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 0.8% of the weight of the raw material;
step 12, fractional alkali extraction: adding the baking soda 5 times, rotating for 30min after adding the baking soda each time, then adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging the liquid out of the drum, wherein the use amount of the baking soda added each time is as follows according to the weight percentage of the raw material skin: 0.5%, 0.5%.
And in the step 12, the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.
Example 2
A leather pickling-free salt-free high-absorption chrome tanning process method comprises the following steps:
step 1, weighing and metering: weighing the raw leather as a material counting basis for the subsequent procedures of soaking, liming, washing, pre-deliming, softening, pickling, tanning and the like;
step 2, soaking: adding water which does not pass through the raw material skin into the raw material skin, adding 0.4% of soaking auxiliary agent, 0.2% of degreasing agent, 0.15% of bactericide and 0.4% of sodium carbonate after adding water, rotating for 30min and stopping for 40min at normal temperature, then rotating for 10min and stopping for 50min, circulating for 12 times, and removing meat, dirt, preservative and the like on the raw material skin;
step 3, liming, namely adding 0.8-1 time of water into the rotary drum, adding 0.5% of liming auxiliary agent and 0.1% of degreasing agent, rotating for 40min, adding 0.5% of lime, and rotating for 30-40 min; adding 0.5% depilatory enzyme preparation, rotating for 20min, stopping for 45min, circulating for three times, and filtering to remove hair; adding 0.5% sodium sulfide and 0.5% lime, rotating for 15min, stopping for 50min, adding 0.2% sodium sulfide and 0.5% lime, rotating for 20min, stopping for 50min, and rotating for 2 times; adding 1.5-2 times of water, adding 0.5% of liming auxiliary agent and 0.2% of lime, stopping for 50min every 10min, and circulating for 12 times;
and 4, washing with water: adding 1.5-2 times of water into the raw material peel, and washing for 30 min;
step 5, pre-deliming: adding 1.2 times of water and 0.5 times of ammonium sulfide, rotating for 60min, and draining;
step 6, deashing and softening: adding 1 time of water with the temperature of 30 ℃, adding 0.8% of deashing agent and 0.2% of degreasing agent, adding sulfuric acid to adjust the pH value to 3.5, and adding 0.5% of softening compound enzyme and 0.5% of auxiliary agent, wherein the softening compound enzyme comprises 40 parts by weight of acid protease, 30 parts by weight of saccharifying enzyme and 30 parts by weight of lipase, and the auxiliary agent comprises 30 parts by weight of enzyme permeation promoter, 20 parts by weight of enzyme activator and 50 parts by weight of diluent;
and 7, washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;
step 8, chrome tanning: adding 3% of chrome tanning agent, rotating for 60min, adding 1.5% of tanning assistant, rotating for 60min, wherein the tanning assistant is an aldehyde acid type high-molecular leather tanning agent, and the chrome tanning agent is basic chromium salt;
step 9, adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.5 percent of the tare weight of the raw materials;
step 10, acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, then adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the raw leather: 0.3%, 0.5%;
step 11, adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 1% of the weight of the raw material peel;
step 12, fractional alkali extraction: adding the baking soda 5 times, rotating for 30min after adding the baking soda each time, then adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging the liquid out of the drum, wherein the use amount of the baking soda added each time is as follows according to the weight percentage of the raw material skin: 0.5%, 0.5%.
And in the step 12, the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.
Example 3
A leather pickling-free salt-free high-absorption chrome tanning process method comprises the following steps:
step 1, weighing and metering: weighing the raw leather as a material counting basis for the subsequent procedures of soaking, liming, washing, pre-deliming, softening, pickling, tanning and the like;
step 2, soaking: adding water which does not pass through the raw material skin into the raw material skin, adding 0.4% of soaking auxiliary agent, 0.2% of degreasing agent, 0.15% of bactericide and 0.4% of sodium carbonate after adding water, rotating for 25min and stopping for 40min at normal temperature, then rotating for 10min and stopping for 50min, circulating for 12 times, and removing meat, dirt, preservative and the like on the raw material skin;
step 3, liming, namely adding 0.9 time of water into the rotary drum, adding 0.5 percent of liming auxiliary agent and 0.1 percent of degreasing agent, rotating for 35min, adding 0.5 percent of lime, and rotating for 35 min; adding 0.5% depilatory enzyme preparation, rotating for 15min, stopping for 45min, circulating for three times, and filtering to remove hair; adding 0.5% sodium sulfide and 0.5% lime, rotating for 15min, stopping for 50min, adding 0.2% sodium sulfide and 0.5% lime, rotating for 15min, stopping for 50min, and rotating for 2 times; adding 1.5 times of water, adding 0.5% of liming auxiliary agent and 0.2% of lime, stopping for 50min every 10min, and circulating for 12 times;
and 4, washing with water: adding 2 times of water into the raw material peel, and washing for 20-30 min;
step 5, pre-deliming: adding 1 time of water and 0.5 time of ammonium sulfide, rotating for 60min, and draining;
step 6, deashing and softening: adding 1 time of water with the temperature of 30 ℃, adding 0.8% of deashing agent and 0.2% of degreasing agent, adding sulfuric acid to adjust the pH value to 3.5, and adding 0.5% of softening compound enzyme and 0.5% of auxiliary agent, wherein the softening compound enzyme comprises 40 parts by weight of acid protease, 30 parts by weight of saccharifying enzyme and 30 parts by weight of lipase, and the auxiliary agent comprises 30 parts by weight of enzyme permeation promoter, 20 parts by weight of enzyme activator and 50 parts by weight of diluent;
and 7, washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;
step 8, chrome tanning: adding 2-3% of chrome tanning agent, rotating for 80min, adding 1.3% of tanning assistant, rotating for 80min, wherein the tanning assistant is an aldehyde acid type high-molecular leather tanning agent, and the chrome tanning agent is basic chromium salt;
step 9, adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.5 percent of the tare weight of the raw materials;
step 10, acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, then adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the raw leather: 0.3%, 0.5%;
step 11, adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 1% of the weight of the raw material peel;
step 12, fractional alkali extraction: adding the baking soda 5 times, rotating for 30min after adding the baking soda each time, then adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging the liquid out of the drum, wherein the use amount of the baking soda added each time is as follows according to the weight percentage of the raw material skin: 0.5%, 0.5%.
And in the step 12, the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.
Comparative example 1
A leather pickling-free salt-free high-absorption chrome tanning process method comprises the following steps:
step 1, weighing and metering: weighing the raw leather as a material counting basis for the subsequent procedures of soaking, liming, washing, pre-deliming, softening, pickling, tanning and the like;
step 2, soaking: adding water which does not pass through the raw material skin into the raw material skin, adding 0.4% of soaking auxiliary agent, 0.2% of degreasing agent, 0.15% of bactericide and 0.4% of sodium carbonate after adding water, rotating for 20-30min at normal temperature, stopping for 40min, then rotating for 10min, stopping for 50min, circulating for 12 times, and removing meat, dirt, preservative and the like on the raw material skin;
step 3, liming, namely adding 1 time of water into the rotary drum, adding 0.5 percent of liming auxiliary agent and 0.1 percent of degreasing agent, rotating for 40min, adding 0.5 percent of lime, and rotating for 40 min; adding 0.5% depilatory enzyme preparation, rotating for 20min, stopping for 45min, circulating for three times, and filtering to remove hair; adding 0.5% sodium sulfide and 0.5% lime, rotating for 15min, stopping for 50min, adding 0.2% sodium sulfide and 0.5% lime, rotating for 20min, stopping for 50min, and rotating for 2 times; adding 2 times of water, adding 0.5% of liming auxiliary agent and 0.2% of lime, stopping for 50min every 10min, and circulating for 12 times;
and 4, washing with water: adding 2 times of water into the raw material peel, and washing for 20-30 min;
step 5, pre-deliming: adding 1.2 times of water and 0.5 times of ammonium sulfide, rotating for 60min, and draining;
step 6, deashing and softening: adding 1 time of water with the temperature of 30 ℃, adding 0.8% of deashing agent and 0.2% of degreasing agent, adding sulfuric acid to adjust the pH value to 3.5, and adding 0.5% of softening compound enzyme and 0.5% of auxiliary agent, wherein the softening compound enzyme comprises 40 parts by weight of acid protease, 30 parts by weight of saccharifying enzyme and 30 parts by weight of lipase, and the auxiliary agent comprises 30 parts by weight of enzyme permeation promoter, 20 parts by weight of enzyme activator and 50 parts by weight of diluent;
and 7, washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;
step 8, pickling: adding sulfuric acid, adjusting the pH value of the bath liquid to 2.3, and rotating for 4 h;
step 9, chrome tanning: adding 3% chrome tanning agent, rotating for 60min, adding 1.5% tanning assistant, rotating for 60min, wherein the chrome tanning agent is basic chromium salt;
step 10, extracting alkali by times: adding the baking soda 5 times, rotating for 30min after adding the baking soda each time, then adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging the liquid out of the drum, wherein the use amount of the baking soda added each time is as follows according to the weight percentage of the raw material skin: 0.5%, 0.5%.
In the step 10, the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.
The main difference between comparative example 1 and examples 1 to 3 is that the pickling operation was carried out in advance before chrome tanning, but it did not add sodium chloride during pickling.
Comparative example 2
A leather pickling-free salt-free high-absorption chrome tanning process method comprises the following steps:
step 1, weighing and metering: weighing the raw leather as a material counting basis for the subsequent procedures of soaking, liming, washing, pre-deliming, softening, pickling, tanning and the like;
step 2, soaking: adding water which does not pass through the raw material skin into the raw material skin, adding 0.4% of soaking auxiliary agent, 0.2% of degreasing agent, 0.15% of bactericide and 0.4% of sodium carbonate after adding water, rotating for 20-30min at normal temperature, stopping for 40min, then rotating for 10min, stopping for 50min, circulating for 12 times, and removing meat, dirt, preservative and the like on the raw material skin;
step 3, liming, namely adding 0.8-1 time of water into the rotary drum, adding 0.5% of liming auxiliary agent and 0.1% of degreasing agent, rotating for 30-40min, adding 0.5% of lime, and rotating for 30-40 min; adding 0.5% depilatory enzyme preparation, rotating for 15-20min, stopping for 45min, circulating for three times, and filtering to remove hair; adding 0.5% sodium sulfide and 0.5% lime, rotating for 10-15min, stopping for 50min, adding 0.2% sodium sulfide and 0.5% lime, rotating for 10-20min, stopping for 50min, and rotating for 2 times; adding 1.5-2 times of water, adding 0.5% of liming auxiliary agent and 0.2% of lime, stopping for 50min every 10min, and circulating for 12 times;
and 4, washing with water: adding 1.5-2 times of water into the raw material peel, and washing for 20-30 min;
step 5, pre-deliming: adding 0.8-1.2 times of water and 0.5 times of ammonium sulfide, rotating for 50-60min, and draining;
step 6, deashing and softening: adding 0.5-1 time of 30 ℃ water, adding 0.8% of deliming agent and 0.2% of degreasing agent, adding sulfuric acid to adjust the pH value to 3.5, and adding 0.5% of softening compound enzyme and 0.5% of auxiliary agent, wherein the softening compound enzyme comprises 40 parts by weight of acid protease, 30 parts by weight of saccharifying enzyme and 30 parts by weight of lipase, and the auxiliary agent comprises 30 parts by weight of enzyme permeation promoter, 20 parts by weight of enzyme activator and 50 parts by weight of diluent;
and 7, washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;
step 8, pickling: adding sulfuric acid, adding sodium chloride with the amount of 10% of the weight of the ash bark, adjusting the pH value of the bath liquid to 2.3, and rotating for 4 hours;
step 9, chrome tanning: adding 3% chrome tanning agent, rotating for 60min, adding 1.5% tanning assistant, rotating for 60min, wherein the chrome tanning agent is basic chromium salt;
step 10, extracting alkali by times: adding the baking soda 5 times, rotating for 30min after adding the baking soda each time, then adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging the liquid out of the drum, wherein the use amount of the baking soda added each time is as follows according to the weight percentage of the raw material skin: 0.5%, 0.5%.
In the step 10, the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.
The main difference between comparative example 2 and examples 1 to 3 is that pickling work is required in advance before chrome tanning, and sodium chloride is added during pickling.
Comparative example 3
A leather pickling-free salt-free high-absorption chrome tanning process method comprises the following steps:
step 1, weighing and metering: weighing the raw leather as a material counting basis for the subsequent procedures of soaking, liming, washing, pre-deliming, softening, pickling, tanning and the like;
step 2, soaking in water;
step 3, liming;
step 4, washing with water;
step 5, pre-deliming;
step 6, deashing and softening;
and 7, washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;
step 8, chrome tanning: adding 3% of chrome tanning agent, rotating for 90min, adding 1.5% of tanning assistant, rotating for 90min, wherein the tanning assistant is an aldehyde acid type high-molecular leather tanning agent, and the chrome tanning agent is basic chromium salt;
step 9, adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.5 percent of the tare weight of the raw materials;
step 10, acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, then adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the raw leather: 0.3%, 0.5%;
step 11, adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 1% of the weight of the raw material peel;
step 12, fractional alkali extraction: adding the baking soda 5 times, rotating for 30min after adding the baking soda each time, then adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging the liquid out of the drum, wherein the use amount of the baking soda added each time is as follows according to the weight percentage of the raw material skin: 0.5%, 0.5%.
And in the step 12, the semi-finished product after the drum discharging is subjected to shaving, neutralization, dyeing, oiling and finishing to form a final finished product.
The main difference between comparative example 2 and examples 1-3 is that the conventional processes are used for soaking, liming, washing, pre-deliming, softening and the like, and the long-time liming, deliming, protease softening and enzyme assistant treatment modes are not adopted.
The results of the tests on the content of contaminants in the effluents obtained from the tanning process of examples 1-3 and comparative examples 1-3 and the results of the tests on the properties of the leathers obtained are shown below in table 1:
TABLE 1 comparison of test results
| Item | Cl-/（mg/L） | Cr3+（mg/L） | Appearance of the product | Rate of leather formation | Storage of |
| Example 1 | Not detected out | 97 | The grain surface is fine, light and smooth | 100% | Has no change for one month |
| Example 2 | Not detected out | 142 | The grain surface is fine, light and smooth | 100% | Has no change for one month |
| Example 3 | Not detected out | 118 | The grain surface is fine, light and smooth | 100% | Has no change for one month |
| Comparative example 1 | Not detected out | 142 | Surface damage and uneven color | Leather without quality requirement | Has no change for one month |
| Comparative example 2 | 4851 | 124 | Fine, deep blue and smooth grain surface | 100% | Has no change for one month |
| Comparative example 3 | Not detected out | 189 | Grain surface defect with stiff edge and dead wrinkle and uneven color | 62% | Has no change for one month |
As can be seen from the test results in Table 1, leather meeting the product quality requirements can be obtained by adopting the processes in examples 1-3 and comparative example 2, the process in comparative example 1, namely sodium chloride is not added in the pickling process, the crust leather will be damaged by acid swelling collagen, and the leather can not be made any more, and the ideal product can not be obtained, in comparative example 2, a satisfactory product could be obtained due to the addition of sodium chloride during pickling, but it detected a large amount of Cl "residues in the waste liquor from the tanning process, in comparative example 3, since the raw hide was not subjected to the effective pretreatment before the chrome tanning process, there was a problem of grain surface defects at the stiff side and dead-wrinkled portions, the tanning effect is poor, the problem of uneven color exists, the leather yield of the leather which meets the requirements and is produced is only 62%, and the production requirement cannot be met.
In conclusion, the process is improved, the pickling process is omitted, leather acid swelling is avoided, salt materials are saved, the problem of environmental pollution caused by reduction of acid swelling through salt is solved, the process is improved before tanning, permeation and combination of tanning agent molecules are promoted, the quality index of a finished product is guaranteed to be not lower than that of a conventional process, the grain surface of the obtained product is fine, light and smooth, the leather yield is 100%, the product is free of quality change after being stored for one month, the high-temperature resistance is good, the product quality is not reduced compared with that of the conventional tanning process, the production cost is saved, and the environmental pollution is reduced.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. A leather pickling-free salt-free high-absorption chrome tanning process method is characterized by comprising the following steps:
step 1, weighing and metering: weighing the raw leather as a material counting basis for the subsequent procedures of soaking, liming, washing, pre-deliming, softening, pickling, tanning and the like;
step 2, soaking: adding water to the hide which has been submerged in the hide;
step 3, liming;
step 4, washing with water;
step 5, pre-deliming;
step 6, deashing and softening: adding 0.5-1 time of 30 ℃ water, adding 0.8% of deliming agent and 0.2% of degreasing agent, adding sulfuric acid to adjust the pH value to 3.5, and adding 0.5% of softened complex enzyme and 0.5% of auxiliary agent;
and 7, washing with water: adding cold water into the drum, cooling to 20 ℃, and washing with water;
step 8, chrome tanning: adding 2-3% chrome tanning agent, rotating for 60-90min, adding 1-1.5% tanning assistant, and rotating for 60-90 min;
step 9, adding acid: adding formic acid, and rotating for 30min, wherein the use amount of the formic acid is 0.4-0.5% of the tare weight of the raw materials;
step 10, acid is added for several times: adding sulfuric acid for 4 times, rotating for 30min after adding sulfuric acid each time, then adjusting the pH value of bath liquid to 2.3, and rotating for 90min, wherein the dosage of the sulfuric acid added each time is respectively as follows according to the weight percentage of the raw leather: 0.3%, 0.5%;
step 11, adding sodium thiosulfate: adding sodium thiosulfate, and rotating for 40min, wherein the use amount of the sodium thiosulfate is 0.8-1% of the weight of the raw material peel;
step 12, fractional alkali extraction: adding the baking soda 5 times, rotating for 30min after adding the baking soda each time, then adjusting the pH value to 3.8, heating to 36 ℃, rotating for 4h, discharging liquid and discharging the liquid out of the drum, wherein the use amount of the baking soda added each time is as follows according to the weight percentage of the raw material skin: 0.5%, 0.5%.
2. The leather pickling-free, salt-free and high-absorption chrome tanning process method as claimed in claim 1, wherein in the step 2, 0.4% of a pickling auxiliary agent, 0.2% of a degreasing agent, 0.15% of a bactericide and 0.4% of sodium carbonate are added after water is added, and the process is carried out for 20-30min at normal temperature, 40min after stop, 10min after stop for 50min after stop for 12 times of rotation to remove meat, dirt, preservatives and the like on the raw leather.
3. The leather pickling-free, salt-free and high-absorption chrome tanning process method as claimed in claim 1, wherein in the step 3, 0.8-1 time of water, 0.5% of liming auxiliary agent and 0.1% of degreasing agent are added into a rotary drum, the rotary drum is rotated for 30-40min, 0.5% of lime is added, and the rotary drum is rotated for 30-40 min; adding 0.5% depilatory enzyme preparation, rotating for 15-20min, stopping for 45min, circulating for three times, and filtering to remove hair; adding 0.5% sodium sulfide and 0.5% lime, rotating for 10-15min, stopping for 50min, adding 0.2% sodium sulfide and 0.5% lime, rotating for 10-20min, stopping for 50min, and rotating for 2 times; adding 1.5-2 times of water, adding 0.5% of liming auxiliary agent and 0.2% of lime, stopping for 50min every 10min, and circulating for 12 times.
4. The leather pickling-free salt-free high-absorption chrome tanning process method as claimed in claim 1, wherein in the step 4, water washing is carried out for 20-30min by adding 1.5-2 times of water into the raw leather.
5. The leather pickling-free, salt-free and high-absorption chrome tanning process method as claimed in claim 1, wherein in the step 5, the pre-deliming step is to add 0.8-1.2 times of water and 0.5 times of ammonium sulfide, rotate for 50-60min, and drain water.
6. The leather pickling-free, salt-free and high-absorption chrome tanning process as claimed in claim 1, wherein in the step 6, the softening compound enzyme comprises 40 parts by weight of acid protease, 30 parts by weight of saccharifying enzyme and 30 parts by weight of lipase.
7. The leather pickling-free, salt-free and high-absorption chrome tanning process as claimed in claim 1, wherein in the step 6, the auxiliary agent comprises 30 parts by weight of enzyme penetration assisting agent, 20 parts by weight of enzyme activating agent and 50 parts by weight of diluting agent.
8. The leather pickling-free, salt-free and high-absorption chrome tanning process as claimed in claim 1, wherein in the step 8, the tanning assistant is an aldehyde acid type high-molecular leather tanning agent.
9. The leather pickling-free, salt-free and high-absorption chrome tanning process as claimed in claim 1, wherein in the step 12, the semi-finished product after being out of the drum is shaved, neutralized, dyed, oiled and finished to form a final finished product.
10. The leather pickling-free, salt-free and high-absorption chrome tanning process as claimed in claim 1, wherein in the step 8, the chrome tanning agent is basic chrome salt.
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| CN115323081A (en) * | 2022-09-23 | 2022-11-11 | 四川大学 | Softening method for preventing damaged surface and loose surface of leather |
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