CN115323081A - Softening method for preventing damaged surface and loose surface of leather - Google Patents
Softening method for preventing damaged surface and loose surface of leather Download PDFInfo
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- CN115323081A CN115323081A CN202211167418.2A CN202211167418A CN115323081A CN 115323081 A CN115323081 A CN 115323081A CN 202211167418 A CN202211167418 A CN 202211167418A CN 115323081 A CN115323081 A CN 115323081A
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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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Abstract
The invention belongs to the technical field of leather processing and manufacturing, and discloses a softening method for preventing a damaged surface and a loose surface of leather, which is characterized in that a protease preparation is used firstly in a peltry softening or tanning softening process, after protease fully permeates leather, the protease activity of the peltry or the tanning surface layer is greatly reduced or even completely inhibited by an environment-friendly protein or peptide protease inhibitor, so that the acting time of the protease on collagen fibers on the leather surface layer is shortened, the uniformity of the enzyme softening peltry or the tanning inner and outer layers is improved, and the technical problem that the damaged surface or the loose surface is easy to occur in the existing tanning peltry or tanning softening technology is solved.
Description
Technical Field
The invention belongs to the technical field of leather processing and manufacturing, and particularly relates to a softening method for preventing a damaged surface and a loose surface of leather and the leather prepared by the method.
Background
Softening is a process in which non-collagen proteins such as albumin, globulin, and elastin are removed from the skin by protease-catalyzed hydrolysis, and collagen fibers are properly dispersed. Because the leather has the advantages of softness, flat and fine grain surface, good sanitary performance (air permeability) and the like, the softening becomes an indispensable working procedure in the modern leather making process. With the development of leather-making technology, softening can be used for treating delimed pelts and also increasingly used for treating tanned leathers such as wet blue leathers and the like so as to achieve the aims of further dispersing collagen fibers, improving leather yield and sensory properties and the like.
Softening presents several problems while having a number of advantages. For example, in the softening of pelts, the skin is subjected to the prior alkali swelling treatment, and then the skin is subjected to the action of protease, so that the collagen fibers are easily damaged excessively; in addition, protease is slowly transferred in complex skin tissues and reacts quickly, and compared with a skin middle layer, a skin grain surface layer (surface layer) is longer in time and higher in strength under the action of enzyme hydrolysis, so that the quality problems of leather such as damaged surfaces, loose surfaces and the like are easily caused, and the product value is reduced. When the leather is softened and tanned, protease also has the problems of slow penetration in the tanned leather, longer action time on a grain surface layer, and easy quality problems of damaged leather surface, loose leather surface and the like.
In order to solve the problem that leather is easy to be damaged or loosened in the leather making and softening process, chinese patent CN105132600B discloses a method for regulating and controlling the selective action of protease on collagen and elastin in the animal skin, which comprises the steps of pretreating the animal skin by using an anionic surfactant, and then treating the animal skin by using the protease, or pretreating the animal skin by using the anionic surfactant, and then treating the animal skin by using the pretreated protease, so that the hydrolytic activity of the protease on the collagen in the animal skin is inhibited, and the hydrolytic activity of the protease on the elastin is improved. However, softening inherently requires a moderate hydrolysis of the collagen fibers for the purpose of further dispersing the collagen fibers. Therefore, this method can alleviate the problem of the occurrence of a wound or loose surface due to softening, but can reduce the collagen fiber dispersion effect, i.e., the softening effect. Chinese patent CN110643754B discloses a method for regulating and controlling protease catalytic activity in a leather-making process by simultaneously using a protease reversible inhibitor and a protease preparation, which can reduce the catalytic activity of protease at the initial softening stage, start to hydrolyze hide protein after the protease permeates naked skins, reduce the action time and strength of the protease on collagen fibers on the surface layers of the skins, and improve the uniformity of the hydrolysis action of the protease on collagen fibers on each layer in the skins. However, although this method can solve the technical problem that softening easily damages collagen fibers on the surface layer of leather and reduces the quality of leather, the ratio of the reversible inhibitor to the protease needs to be strictly controlled, and the problem that the protease activity is not recovered in time or the recovery degree is low in the later stage of softening easily occurs by some carelessness in the actual production, so that the softening effect is weakened.
In view of this, the invention is particularly proposed.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a softening method capable of preventing the wounded surface and loose surface of leather.
The leather tissue thickness is large, the structure is complex, the relative molecular mass and the molecular size of the protease are large, so that the protease is slowly transferred in the naked leather or the tanned leather in the tanning softening process, the action time and the action strength on the collagen fiber on the surface layer of the leather are obviously longer than or higher than the action time and the action strength on the inner layer (inside) of the leather, and the quality defects of leather surface layer collagen fiber, leather wound surface or loose surface and the like are easily excessively hydrolyzed by the existing softening technology. The method reduces the action time and the action strength of the protease on the leather surface layer, improves the action uniformity of the protease on the surface layer and the inner layer when treating the leather, and is undoubtedly the key for solving the technical problems that the softening process is easy to damage the surface or loosen the surface and the like.
In carrying out the present invention, applicants have found that trypsin activity, an important component of a typical tannery softening enzyme preparation, can be completely inhibited by using a sufficient amount of soybean trypsin inhibitor (see fig. 1, calculating the relative enzyme activity of trypsin after addition of the inhibitor, with the protease activity of trypsin being 100% when no inhibitor is added). Therefore, the present invention employs environmentally friendly protein, peptide or amino acid protease inhibitors to inhibit the catalytic activity of softening late-mid proteases. At the moment, the protease fully permeates the hide, and the inhibitor is added late and needs a certain time to permeate the hide, so that the inhibitor adding mode has the effects of greatly reducing or completely inhibiting the activity of the protease on the surface layer of the hide or the tanned hide, shortens the action time of the protease on the collagen fibers on the surface layer of the hide, improves the enzyme softening uniformity of the inner layer and the outer layer of the hide or the tanned hide, and solves the technical problems that the defects of wound surface, loose surface and the like easily occur in the existing softening process.
The technical scheme adopted by the invention is as follows: a softening method for preventing damaged surface and loose surface of leather comprises using protease preparation during softening of pelts or tanning, and inhibiting protease activity on the surface layer of pelts or tanning with protease inhibitor after protease permeates skin;
wherein, the protease inhibitor is selected from any one or more of protein, polypeptide, short peptide and amino acid.
The key point of the invention is the time of addition of the protease inhibitor. In the process of softening the naked skin or the tanned leather, firstly, protease is fully permeated into the leather, even the protease acts for a period of time, then, an inhibitor which can greatly reduce or completely inhibit the protease activity is added, so that the aim of reducing the acting time and the acting strength of the protease on the collagen fiber on the surface layer of the naked skin or the tanned leather is achieved, the uniformity of the acting degree on the surface layer and the inner layer (inner layer and outer layer) when the leather is treated by the protease is improved, and the technical problem that the surface or the loose surface is easily damaged by the existing leather-making softening technology is solved while the treatment effect (namely the softening effect) of the protease preparation on the leather is not influenced. As some preferred embodiments, the time of rotation after the addition of the protease preparation is controlled to be 1/8 to 5/6 of the total time of softening so as to achieve sufficient penetration of the protease and the effect for a certain period of time before a sufficient amount of the protease inhibitor is added.
Preferably, the protease inhibitor is selected from any one or more of soybean trypsin inhibitor, pumpkin trypsin inhibitor, wheat bran pepsin inhibitor, potato pepsin inhibitor, pumpkin pepsin inhibitor, coriolus versicolor pepsin inhibitor, ascaris pepsin inhibitor, leupeptin, aprotinin, pepstatin a and protein hydrolysate.
Preferably, the protease preparation is a peltry softening protease preparation or a tanning softening protease preparation commonly used in the art, and the protease in the protease preparation is any one or more selected from microbial protease, animal protease and plant protease.
Preferably, the specific process for softening the pelts can adopt any one of A or B:
a: according to the mass percent of the liming pelts, the liming pelts are put into a rotary drum, 80 to 200 weight percent of water is added, the temperature is adjusted to be between 28 and 35 ℃, 1.0 to 4.0 weight percent of deliming agent and 0.1 to 0.5 weight percent of degreasing agent are added, and the rotary drum rotates for 30 to 120min for deliming; then changing the liquid, adding 100-200 wt% of water, adjusting the temperature to 28-35 ℃, adding 0.1-2.0 wt% of protease preparation, and rotating to soften for 1/8-5/6 of the total time; adding 0.3-6.0 wt% of protease inhibitor, and continuing to intermittently rotate or continuously rotate until the softening is finished; the total softening time is 30-480 min, and the softened pelts are obtained.
B: according to the mass percent of the liming bare skin, putting the liming bare skin into a rotary drum, adding 80-200 wt% of water, adjusting the temperature to 28-35 ℃, adding 1.0-4.0 wt% of deliming agent and 0.1-0.5 wt% of degreasing agent, and rotating for 30-120 min for deliming; then, continuously adding 0.1-2.0 wt% of protease preparation without changing the solution, and rotating and softening for 1/8-5/6 of the total time; adding 0.3-6.0 wt% of protease inhibitor, and continuously rotating intermittently or continuously until the softening is finished; the total softening time is 30-480 min, and the softened pelts are obtained.
Preferably, the specific process of tanning softening can adopt any one of C-F:
c: according to the mass percent of the shaved wet blue leather or wet white leather, putting the shaved wet blue leather or wet white leather into a rotary drum, adding 150-300 wt% of water, adjusting the temperature to 35-45 ℃, adding 0.1-0.5 wt% of formic acid and 0.1-0.5 wt% of degreasing agent, and rotating for 30-90 min for rewetting; then changing the liquid, adding 150-300 wt% of water, adjusting the temperature to 30-50 ℃, adding 0.2-3.0 wt% of protease preparation, and rotating to soften for 1/8-5/6 of the total time; adding 0.3-9.0 wt% of protease inhibitor, and continuing to intermittently rotate or continuously rotate until the softening is finished; the total softening time is 60-480 min, and the softened tanned leather is obtained.
D: according to the mass percentage of the shaved wet blue leather or wet white leather, putting the shaved wet blue leather or wet white leather into a rotary drum, adding 150-300 wt% of water, adjusting the temperature to 30-50 ℃, adding 0.1-0.5 wt% of formic acid and 0.1-0.5 wt% of degreasing agent, and rotating for 30-90 min for rewetting; then, continuously adding 0.2-3.0 wt% of protease preparation without changing the solution, and rotating and softening for 1/8-5/6 of the total time; adding 0.3-9.0 wt% of protease inhibitor, and continuously rotating intermittently or continuously until the softening is finished; the total softening time is 60-480 min, and the softened tanned leather is obtained.
E: according to the mass percent of the shaved wet blue leather or wet white leather, putting the tanned leather after rewetting into a rotary drum, adding 100-250 wt% of water, adjusting the temperature to 30-40 ℃, adding 0.2-2.0 wt% of neutralization tannin and 0.5-2.0 wt% of sodium formate, rotating for 10-30 min, adding 0.5-1.0 wt% of baking soda, and rotating for 10-30 min for neutralization; then changing the liquid, adding 100-250 wt% of water, adjusting the temperature to 30-45 ℃, adding 0.2-3.0 wt% of protease preparation, and rotating to soften for 1/8-5/6 of the total time; adding 0.3-9.0 wt% of protease inhibitor, and continuing to intermittently rotate or continuously rotate until the softening is finished; the total softening time is 60-240 min, and the softened tanned leather is obtained.
F: according to the mass percent of the even-shaved wet blue leather or wet white leather, putting the tanned leather after rewetting into a rotary drum, adding 100-250 wt% of water, adjusting the temperature to 30-45 ℃, adding 0.2-2.0 wt% of neutralization tannin and 0.5-2.0 wt% of sodium formate, rotating for 10-30 min, adding 0.5-1.0 wt% of baking soda, and rotating for 10-30 min for neutralization; then, continuously adding 0.2-3.0 wt% of protease preparation without changing the solution, and rotating and softening for 1/8-5/6 of the total time; adding 0.3-9.0 wt% of protease inhibitor, and continuing to intermittently rotate or continuously rotate until the softening is finished; the total softening time is 60-240 min, and the softened tanned leather is obtained.
The invention also discloses leather obtained by adopting any one of the softening methods for preventing the damaged surface and the loose surface of the leather.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the softening method for preventing the damaged surface and the loose surface of the leather, the inhibitor is added to inhibit the activity of the protease on the surface layer of the leather after the protease fully permeates the leather, so that the acting time of the protease on collagen fibers on the surface layer of the leather can be shortened, the effect of treating the leather by using the protease preparation cannot be influenced, and the softening effect cannot be influenced.
2. The softening method for preventing the damaged surface and loose surface of the leather provided by the invention is convenient to operate, can effectively reduce the risk that collagen fibers in the leather grain surface layer are damaged by protease, improves the enzyme softening uniformity of the inner layer and the outer layer of the naked leather or the tanned leather, and solves the technical problem that the quality defects of the damaged surface or the loose surface of the leather and the like are easily caused by the existing softening technology.
3. The protease inhibitor provided by the invention is selected from protein, polypeptide, short peptide or amino acid, and is an environment-friendly auxiliary agent.
Drawings
FIG. 1 shows the effect of a sufficient amount of a soybean trypsin inhibitor on the inhibition of trypsin activity;
FIG. 2 is a scanning electron micrograph of the softened bare grain surfaces obtained in example 1 and comparative example 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the accompanying drawings in combination with the embodiments. It should be understood that the description is intended to be exemplary only, and is not intended to limit the scope of the present invention. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present invention. The examples, in which specific conditions are not specified, were carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
Example 1
The following materials are all calculated according to the mass percent (wt%) of the liming bare skin.
Putting the liming pelts into a rotary drum, adding 150wt% of water, adjusting the temperature to 32 ℃, adding 2.5wt% of deliming agent and 0.2wt% of degreasing agent, and rotating for 60min for deliming; then changing the liquid, adding 200wt% of water, adjusting the temperature to 32 ℃, adding 2.0wt% of protease preparation (containing animal protease) for peltry softening, and rotating for 60min; adding soybean trypsin inhibitor 5.0wt%, rotating for 15min, and adjusting to intermittent rotation (rotating for 20min per hour) until softening is finished, wherein the total softening time is 480min, and thus obtaining softened pelts.
Comparative example 1
The following materials are all calculated according to the mass percent (wt%) of the liming bare skin.
Putting the liming pelts into a rotary drum, adding 150wt% of water, adjusting the temperature to 32 ℃, adding 3.0wt% of deliming agent and 0.2wt% of degreasing agent, and rotating for 60min for deliming; then changing the liquid, adding 200wt% of water, adjusting the temperature to 32 ℃, adding 2.0wt% of protease preparation (containing animal protease) for peltry softening, and rotating for 60min; rotating for 15min, and adjusting to intermittent rotation (rotating for 20min per hour) until softening is finished, wherein the total softening time is 480min, and thus obtaining softened pelts.
The softening effect test was performed for example 1 and comparative example 1, and the test results are shown in fig. 2 and table 1. According to the results shown in fig. 2, the method for greatly reducing or even completely inhibiting the activity of the protease on the surface layer of the pelts by using the protease inhibitor after the protease fully permeates the pelts in the pelts softening process can protect the grain surface of the pelts from being damaged by the protease, namely, the effect of preventing the damaged surface of the leather is achieved. In addition, as can be seen from the data in table 1, the hydroxyproline concentration of the softening waste liquor in example 1 is significantly lower than that of comparative example 1, which shows that the method for using the protease inhibitor in the softening process provided by the invention can effectively reduce the damage of the skin collagen fibers by shortening the acting time of the protease on the collagen fibers on the surface layer of the naked skin. As can be seen from the results shown in fig. 2 and table 1, the softening method for preventing the damaged and loose leather surfaces provided by the present invention can effectively solve the technical problem that the damaged leather surfaces are easy to be softened by the conventional softening technology.
TABLE 1 comparison of softening effect (softening 480 min)
Note: a. the higher the concentration of hydroxyproline (collagen characteristic amino acid) in the softening waste liquid, the more damaged the collagen fibers.
Example 2
The following materials are all calculated according to the mass percent (wt%) of the liming bare skin.
Putting the liming pelts into a rotary drum, adding 200wt% of water, adjusting the temperature to 35 ℃, adding 4.0wt% of deliming agent and 0.5wt% of degreasing agent, and rotating for 30min for deliming; then changing the liquid, adding 150wt% of water, adjusting the temperature to 35 ℃, adding 0.1wt% of protease preparation (containing microbial protease and animal protease) for peltry softening, and rotating for 120min; adding 0.3wt% pumpkin trypsin inhibitor, rotating for 15min, and adjusting to intermittent rotation (rotating for 15min per hour) until softening is finished, wherein the total softening time is 360min, and thus obtaining softened pelts.
Example 3
The following materials are all used in percentage by mass (wt%) of the liming pelts.
Putting the liming pelts into a rotary drum, adding 80wt% of water, adjusting the temperature to 28 ℃, adding 1.0wt% of deliming agent and 0.1wt% of degreasing agent, and rotating for 120min for deliming; then changing the liquid, adding 100wt% of water, adjusting the temperature to 28 deg.C, adding 1.0wt% of protease preparation (containing animal protease and plant protease) for softening peltry, and rotating for 50min; adding 6.0wt% leupeptin, and keeping rotating continuously until softening is finished, wherein the total softening time is 60min, to obtain softened pelts.
Example 4
The following materials are all used in percentage by mass (wt%) of the liming pelts.
Putting the liming pelts into a rotary drum, adding 120wt% of water, adjusting the temperature to 28 ℃, adding 2.5wt% of deliming agent and 0.3wt% of degreasing agent, and rotating for 120min for deliming; then, continuously adding 0.1wt% of protease preparation (containing animal protease) for peltry softening without changing the solution, and rotating for 100min; adding 0.3wt% of aprotinin, and keeping rotating continuously until softening is finished, wherein the total softening time is 120min, to obtain softened pelts.
Example 5
The following materials are all calculated according to the mass percent (wt%) of the liming bare skin.
Putting the liming pelts into a rotary drum, adding 200wt% of water, adjusting the temperature to 32 ℃, adding 4.0wt% of deliming agent and 0.5wt% of degreasing agent, and rotating for 60min for deliming; then, continuously adding 1.0wt% of protease preparation (containing microbial protease and animal protease) for peltry softening without changing the solution, and rotating for 40min; adding 2.0wt% soybean trypsin inhibitor, and rotating continuously until softening is finished, wherein the total softening time is 60min to obtain softened pelts.
Example 6
The following materials are all calculated according to the mass percent (wt%) of the liming bare skin.
Putting the liming pelts into a rotary drum, adding 80wt% of water, adjusting the temperature to 35 ℃, adding 1.0wt% of deliming agent and 0.1wt% of degreasing agent, and rotating for 30min for deliming; then, 2.0wt% of protease preparation (containing microbial protease, animal protease and plant protease) for softening the pelts is continuously added without changing the liquid, and the mixture is rotated for 60min; adding 6.0wt% protein hydrolysate, rotating for 15min, and adjusting to intermittent rotation (rotating for 15min per hour) until softening is finished, wherein the total softening time is 480min to obtain softened pelts.
Example 7
The following materials are all calculated according to the mass percent (wt%) of the shaved wet blue leather.
Putting the evenly shaved wet blue leather into a rotary drum, adding 200wt% of water, adjusting the temperature to 35 ℃, adding 0.1wt% of formic acid and 0.1wt% of degreasing agent, and rotating for 30min for rewetting; then changing the liquid, adding 150wt% of water, adjusting the temperature to 30 ℃, adding 0.2wt% of protease preparation for tanning softening, and rotating for 90min; adding 0.3wt% of pepstatin A, and keeping rotating continuously until the softening is finished, wherein the total softening time is 240min, so as to obtain the softened tanned leather.
Example 8
The following materials were used in the amounts indicated in mass percent (wt%) of shaved wet white leather.
Putting the even white wet leather into a rotary drum, adding 150wt% of water, adjusting the temperature to 40 ℃, adding 0.3wt% of formic acid and 0.3wt% of degreasing agent, and rotating for 60min for rewetting; then changing the liquid, adding 200wt% of water, adjusting the temperature to 40 ℃, adding 2.0wt% of protease preparation (containing microbial protease and animal protease) for tanning softening, and rotating for 50min; adding 4.0wt% of wheat bran pepsin inhibitor, and keeping rotating continuously until softening is finished, wherein the total softening time is 60min, so as to obtain softened tanned leather.
Example 9
The following materials are all calculated according to the mass percent (wt%) of the shaved wet blue leather.
Putting the evenly shaved wet blue leather into a rotary drum, adding 300wt% of water, adjusting the temperature to 45 ℃, adding 0.5wt% of formic acid and 0.5wt% of degreasing agent, and rotating for 90min for rewetting; then changing the liquid, adding 300wt% of water, adjusting the temperature to 50 ℃, adding 3.0wt% of protease preparation (containing microbial protease and animal protease) for tanning softening, and rotating for 60min; adding 9.0wt% potato pepsin inhibitor, and turning intermittently (20 min per hour) until softening is finished, wherein the total softening time is 480min, to obtain softened tanned leather.
Example 10
The following materials are used in percentage by mass (wt%) of shaved wet blue leather.
Putting the evenly shaved wet blue leather into a rotary drum, adding 150wt% of water, adjusting the temperature to 30 ℃, adding 0.1wt% of formic acid and 0.1wt% of degreasing agent, and rotating for 30min for rewetting; then adding 3.0wt% protease preparation (containing animal protease) for softening tanning without changing liquid, and rotating for 60min; adding 5.0wt% of pumpkin pepsin inhibitor and 1.0wt% of roundworm pepsin inhibitor, and turning intermittently (turning for 15min per hour) until softening is finished, wherein the total softening time is 480min, thereby obtaining softened tanned leather.
Example 11
The following materials are used in percentage by mass (wt%) of shaved wet blue leather.
Putting the shaved blue wet leather or white wet leather into a rotary drum, adding 200wt% of water, adjusting the temperature to 40 ℃, adding 0.3wt% of formic acid and 0.3wt% of degreasing agent, and rotating for 60min for rewetting; then adding 1.5wt% protease preparation (containing animal protease) for softening leather without changing liquid, and rotating for 80min; adding 9.0wt% Coriolus versicolor pepsin inhibitor, and rotating intermittently (for 15min per hour) until softening is finished, wherein the total softening time is 240min to obtain softened tanned leather.
Example 12
The following materials were used in the amounts indicated in mass percent (wt%) of shaved wet white leather.
Putting the evenly-shaved wet white leather into a rotary drum, adding 300wt% of water, adjusting the temperature to 50 ℃, adding 0.5wt% of formic acid and 0.5wt% of degreasing agent, and rotating for 90min for rewetting; then adding 0.2wt% protease preparation (containing microbial protease and animal protease) for softening tanning without changing liquid, and rotating for 50min; adding 0.3wt% ascaris pepsin inhibitor, and keeping rotating continuously until softening is finished, wherein the total softening time is 60min, to obtain softened tanned leather.
Example 13
The following materials are all calculated according to the mass percent (wt%) of the shaved wet blue leather.
Putting the remoistened tanned leather into a rotary drum, adding 100wt% of water, adjusting the temperature to 30 ℃, adding 0.2wt% of neutralizing tannin and 0.5wt% of sodium formate, rotating for 10min, adding 0.5wt% of baking soda, and rotating for 10min for neutralization; then changing the liquid, adding 100wt% of water, adjusting the temperature to 30 ℃, adding 0.2wt% of protease preparation (containing microbial protease and animal protease) for tanning softening, and rotating for 50min; adding 0.3wt% soybean trypsin inhibitor, and keeping rotating continuously until softening is finished, wherein the total softening time is 60min, to obtain softened tanned leather.
Example 14
The following materials are used in percentage by mass (wt%) of the shaved wet and white leather.
Putting the remoistened tanned leather into a rotary drum, adding 150wt% of water, adjusting the temperature to 35 ℃, adding 1.0wt% of neutralizing tannin and 1.0wt% of sodium formate, rotating for 20min, adding 0.8wt% of baking soda, and rotating for 20min for neutralization; then changing the liquid, adding 150wt% of water, adjusting the temperature to 40 ℃, adding 1.5wt% of protease preparation (containing microbial protease and animal protease) for tanning softening, and rotating for 60min; adding 4.0wt% of pumpkin trypsin inhibitor and 0.5wt% of aprotinin, and keeping rotating continuously until softening is finished, wherein the total softening time is 120min, to obtain softened tanned leather.
Example 15
The following materials are used in percentage by mass (wt%) of the shaved wet and white leather.
Putting the remoistened tanned leather into a rotary drum, adding 250wt% of water, adjusting the temperature to 40 ℃, adding 2.0wt% of neutralizing tannin and 2.0wt% of sodium formate, rotating for 30min, adding 1.0wt% of baking soda, and rotating for 30min for neutralization; then changing the liquid, adding 250wt% of water, adjusting the temperature to 45 ℃, adding 3.0wt% of protease preparation (containing microbial protease and plant protease) for tanning softening, and rotating for 30min; adding 9.0wt% protein hydrolysate, and turning intermittently (15 min per hour) until softening is finished, wherein the total softening time is 240min, to obtain softened tanned leather.
Example 16
The following materials are all calculated according to the mass percent (wt%) of the shaved wet blue leather.
Putting the remoistened tanned leather into a rotary drum, adding 100wt% of water, adjusting the temperature to 30 ℃, adding 0.2wt% of neutralizing tannin and 0.5wt% of sodium formate, rotating for 10min, adding 0.5wt% of baking soda, and rotating for 10min for neutralization; then continuously adding 0.2wt% protease preparation (containing animal protease) for softening tanning without changing liquid, and rotating for 50min; adding 0.3wt% of aprotinin, and adjusting to intermittently rotate (rotating for 15min per hour) until softening is finished, wherein the total softening time is 60min, to obtain softened tanned leather.
Example 17
The following materials are all calculated according to the mass percent (wt%) of the shaved wet blue leather.
Putting the remoistened tanned leather into a rotary drum, adding 200wt% of water, adjusting the temperature to 40 ℃, adding 0.8wt% of neutralizing tannin and 1.0wt% of sodium formate, rotating for 15min, adding 0.7wt% of baking soda, and rotating for 15min for neutralization; then continuously adding 1.5wt% protease preparation (containing animal protease and plant protease) for softening tanning without changing the solution, and rotating for 70min; adding 3.0wt% leupeptin and 1.0wt% soybean trypsin inhibitor, and turning to intermittent rotation (15 min per hour) until softening is finished, wherein the total softening time is 180min, to obtain softened tanned leather.
Example 18
The following materials were used in the amounts indicated in mass percent (wt%) of shaved wet white leather.
Putting the remoistened tanned leather into a rotary drum, adding 250wt% of water, adjusting the temperature to 45 ℃, adding 2.0wt% of neutralizing tannin and 2.0wt% of sodium formate, rotating for 30min, adding 1.0wt% of baking soda, and rotating for 30min for neutralization; then continuously adding 3.0wt% of protease preparation (containing microbial protease, animal protease and plant protease) for tanning softening without changing the solution, and rotating for 30min; adding 9.0wt% protein hydrolysate, and keeping rotating until softening is finished, wherein the total softening time is 240min, to obtain softened tanned leather.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (7)
1. A softening method for preventing damaged surface and loose surface of leather is characterized in that in the softening process of naked skin or tanned leather, protease preparation is firstly used for fully penetrating leather, and then protease inhibitor is used for inhibiting the protease activity of the surface layer of the naked skin or the tanned leather; the protease inhibitor is selected from any one or more of protein, polypeptide, short peptide and amino acid.
2. The method of claim 1, wherein the protease inhibitor is selected from one or more of soybean trypsin inhibitor, pumpkin trypsin inhibitor, bran pepsin inhibitor, potato pepsin inhibitor, pumpkin pepsin inhibitor, coriolus versicolor pepsin inhibitor, ascaris pepsin inhibitor, leupeptin, aprotinin, pepstatin a, and protein hydrolysate.
3. The softening method for preventing leather from being wounded and loosened according to claim 1, wherein said protease in said protease preparation is any one or more selected from the group consisting of microbial protease, animal protease and plant protease.
4. A softening method for preventing the wounded surface and the loose surface of leather according to claim 1, wherein the specific process for softening the bare leather is selected from any one of the following processes:
according to the mass percent of the liming bare leather, putting the liming bare leather into a rotary drum, adding 80-200% of water, adjusting the temperature to 28-35 ℃, adding 1.0-4.0% of deliming agent and 0.1-0.5% of degreasing agent, and rotating for 30-120 min for deliming; then changing the liquid, adding 100-200% of water, adjusting the temperature to 28-35 ℃, adding 0.1-2.0 wt% of protease preparation, and rotating to soften for 1/8-5/6 of the total time; adding 0.3-6.0% protease inhibitor, and continuing to intermittently rotate or continuously rotate until the softening is finished; softening for 30-480 min to obtain softened pelts; or
According to the mass percent of the liming bare leather, putting the liming bare leather into a rotary drum, adding 80-200% of water, adjusting the temperature to 28-35 ℃, adding 1.0-4.0% of deliming agent and 0.1-0.5% of degreasing agent, and rotating for 30-120 min for deliming; then, continuously adding 0.1-2.0% of protease preparation without changing the liquid, and rotating and softening for 1/8-5/6 of the total time; adding 0.3-6.0% protease inhibitor, and continuing to intermittently rotate or continuously rotate until the softening is finished; the total softening time is 30-480 min, and the softened pelts are obtained.
5. A method of softening leather from bruising and raveling according to claim 1, wherein the tanning softening process is selected from any of:
according to the mass percentage of the shaved wet blue leather or wet white leather, putting the shaved wet blue leather or wet white leather into a rotary drum, adding 150-300% of water, adjusting the temperature to 35-45 ℃, adding 0.1-0.5% of formic acid and 0.1-0.5% of degreasing agent, and rotating for 30-90 min for rewetting; then changing the liquid, adding 150-300% of water, adjusting the temperature to 30-50 ℃, adding 0.2-3.0% of protease preparation, and rotating to soften for 1/8-5/6 of the total time; adding 0.3-9.0% protease inhibitor, and continuing to intermittently rotate or continuously rotate until the softening is finished; the total softening time is 60-480 min, and softened tanned leather is obtained; or
According to the mass percentage of the shaved wet blue leather or wet white leather, putting the shaved wet blue leather or wet white leather into a rotary drum, adding 150-300% of water, adjusting the temperature to 30-50 ℃, adding 0.1-0.5% of formic acid and 0.1-0.5% of degreasing agent, and rotating for 30-90 min for rewetting; then, continuously adding 0.2-3.0% of protease preparation without changing the liquid, and rotating and softening for 1/8-5/6 of the total time; adding 0.3-9.0% protease inhibitor, and continuing to intermittently rotate or continuously rotate until the softening is finished; the total softening time is 60-480 min, and the softened tanned leather is obtained.
6. A method of softening leather from wounds and loose surfaces according to claim 1, wherein the tanning softening process is selected from any one of:
according to the mass percent of the even-shaved wet blue leather or wet white leather, putting the tanned leather after rewetting into a rotary drum, adding 100-250% of water, adjusting the temperature to 30-40 ℃, adding 0.2-2.0% of neutralization tannin and 0.5-2.0% of sodium formate, rotating for 10-30 min, adding 0.5-1.0% of baking soda, and rotating for 10-30 min for neutralization; then changing the liquid, adding 100-250% of water, adjusting the temperature to 30-45 ℃, adding 0.2-3.0% of protease preparation, and rotating to soften for 1/8-5/6 of the total time; adding 0.3-9.0% protease inhibitor, and continuing to intermittently rotate or continuously rotate until the softening is finished; the total softening time is 60-240 min, and softened tanned leather is obtained; or
According to the mass percent of the even-shaved wet blue leather or wet white leather, putting the tanned leather after rewetting into a rotary drum, adding 100-250% of water, adjusting the temperature to 30-45 ℃, adding 0.2-2.0% of neutralization tannin and 0.5-2.0% of sodium formate, rotating for 10-30 min, adding 0.5-1.0% of baking soda, and rotating for 10-30 min for neutralization; then, continuously adding 0.2-3.0% of protease preparation without changing the liquid, and rotating and softening for 1/8-5/6 of the total time; adding 0.3-9.0% protease inhibitor, and continuing to intermittently rotate or continuously rotate until the softening is finished; the total softening time is 60-240 min, and the softened tanned leather is obtained.
7. Leather obtained by the softening method for preventing the wounded surface and the loose surface of leather according to any one of claims 1 to 6.
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