CN115323081B - Softening method for preventing leather from damaging and loosening - Google Patents
Softening method for preventing leather from damaging and loosening Download PDFInfo
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- CN115323081B CN115323081B CN202211167418.2A CN202211167418A CN115323081B CN 115323081 B CN115323081 B CN 115323081B CN 202211167418 A CN202211167418 A CN 202211167418A CN 115323081 B CN115323081 B CN 115323081B
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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
Abstract
The application belongs to the technical field of leather processing and manufacturing, and discloses a softening method for preventing leather from damaging and loosening, which is characterized in that a protease preparation is firstly used in the process of softening naked leather or tanning leather, and after protease fully permeates the leather, the protease activity of the naked leather or the tanned leather surface layer is greatly reduced or even completely inhibited by using an environment-friendly protein or peptide protease inhibitor, so that the acting time of the protease on collagen fibers of the leather surface layer is shortened, the uniformity of enzyme softening the naked leather or the tanned leather inner and outer layers is improved, and the technical problem that the surface is easily damaged or loosened in the conventional tanning naked leather or tanned leather softening technology is solved.
Description
Technical Field
The application belongs to the technical field of leather processing and manufacturing, and particularly relates to a softening method for preventing leather from damaging and loosening and leather prepared by the method.
Background
Softening is a process of removing non-collagen proteins such as albumin, globulin, elastin and the like in skin by catalytic hydrolysis with protease, and properly dispersing collagen fibers. Because the leather has the advantages of softness, flat grain surface, good hygienic property (air permeability) and the like, the softening becomes an indispensable procedure in the modern leather making process. With the development of leather making technology, softening not only can be used for treating de-ashed pelts, but also is increasingly used for treating tanned leather such as blue wet leather and the like, so as to achieve the purposes of further dispersing collagen fibers, improving leather yield, organoleptic properties and the like.
Softening has a number of problems while possessing a number of advantages. For example, when the pelt is softened, the collagen fibers are easily damaged excessively because the pelt is already subjected to the earlier alkali swelling treatment, at which time the pelt is subjected to the action of protease; in addition, protease is slowly transferred in complex skin tissues and reacts fast, and compared with a skin intermediate layer, the leather grain surface layer (surface layer) has longer time and higher strength under the action of enzyme hydrolysis, so that leather quality problems such as damaged surfaces, loose surfaces and the like are easy to occur, and the product value is reduced. In the process of softening and tanning, protease has the problem of slow permeation in the process of tanning, the action time on a grain layer is longer, and quality problems such as leather damage, loose surface and the like are easily caused.
In order to solve the problem that leather damage or loose surface is easily caused in the tanning softening process, chinese patent CN105132600B entitled "method for regulating the selective action of protease on collagen and elastin in animal skin" discloses a method for pretreating animal skin with anionic surfactant and then treating animal skin with protease, or treating animal skin with protease pretreated with anionic surfactant and then treating animal skin with pretreated protease, which inhibits the hydrolytic activity of protease on collagen in animal skin and improves the hydrolytic activity of protease on elastin. However, softening would otherwise require moderately hydrolyzing the collagen fibers for the purpose of further dispersing the collagen fibers. Therefore, although this method can alleviate the problems of the damaged and loose faces caused by softening, it can reduce the dispersion effect of the collagen fibers, i.e., reduce the softening effect. Chinese patent CN110643754B entitled "method for regulating protease catalytic activity" discloses a method for regulating protease catalytic activity by using reversible protease inhibitor and protease preparation simultaneously in leather-making process, which can reduce catalytic activity of protease at initial stage of softening, and can hydrolyze preserved protein after the protease permeates naked skin, so that it can reduce action time and strength of protease on collagen fiber of skin surface layer and can raise uniformity of hydrolysis of collagen fiber of every layer in skin. However, although the method can solve the technical problems that the collagen fibers on the surface layer of the leather are easily damaged by softening and the quality of the leather is reduced, the proportion of the reversible inhibitor to the protease is strictly controlled, and the problems that the protease activity is not recovered in time or the recovery degree is low in the later stage of softening easily occur in actual production by a little carelessness, so that the softening effect is weakened.
In view of this, the present application has been made.
Disclosure of Invention
The application aims to overcome the defects in the prior art and provide a softening method capable of preventing leather from damaging and loosening.
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 peltry or tanned leather in the leather making and softening process, the action time and the action strength of the protease on the collagen fiber on the leather surface layer are obviously longer or higher than those on the inner layer (inside) of the leather, and the quality defects of excessive hydrolysis of the collagen fiber on the leather surface layer, leather damage or loose surface and the like are easily caused by the existing softening technology. The key point of solving the technical problems that the surface layer and the inner layer are easy to be damaged or loose in the softening process is undoubtedly to reduce the action time and the action intensity of protease on the surface layer of leather and improve the action uniformity of protease on the surface layer and the inner layer when the leather is treated.
Applicants have found in practicing the present application that the use of a sufficient amount of soybean trypsin inhibitor results in complete inhibition of trypsin (an important component of typical tannage enzyme preparations) activity (see FIG. 1. Calculated as the protease activity of trypsin without inhibitor, taken as 100%, the relative enzyme activity of trypsin after inhibitor addition). Thus, the present application employs environmentally friendly protein, peptide or amino acid protease inhibitors to inhibit the catalytic activity of the middle and late softening proteases. At this time, the protease fully permeates the skin, and because the inhibitor is added later and the inhibitor needs a certain time to permeate the skin, the method of adding the inhibitor has the effect of greatly reducing or completely inhibiting the activity of the protease on the surface layer of the pelt or tanned leather, shortens the action time of the protease on the collagen fibers on the surface layer of the skin, improves the enzyme softening uniformity of the inner layer and the outer layer of the pelt or tanned leather, and solves the technical problems that the prior softening is easy to cause defects such as surface injury, surface looseness and the like.
The application adopts the technical scheme that: a softening method for preventing leather from damaging and loosening is characterized in that in the process of softening or tanning pelts, a protease preparation is firstly used, and after protease fully permeates the pelts, a protease inhibitor is used for inhibiting the protease activity of the pelts or tanned surface layers;
wherein the protease inhibitor is selected from any one or more of protein, polypeptide, short peptide and amino acid.
The key point of the application is the addition time of the protease inhibitor. In the process of softening pelts or tanning leather, protease is fully permeated into the leather at first, even the protease acts for a period of time, then an inhibitor capable of greatly reducing or completely inhibiting the activity of the protease is added, so that the purposes of reducing the acting time and acting strength of the protease on collagen fibers on the pelts or tanned leather surface layers are achieved, the uniformity of acting degree on the surface layers and inner layers (inner and outer layers) when the leather is treated by the protease is improved, and finally the technical problem that the leather is easy to damage or loose when the leather is treated by the protease preparation (namely, the softening effect) is not influenced is solved. As some preferred embodiments, the application controls the time of rotation after adding the protease preparation to 1/8-5/6 of the total softening time so as to achieve adequate penetration of the protease and a period of time, and then adds a sufficient amount of protease inhibitor.
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, roundworm pepsin inhibitor, leupeptin, pepstatin A, protein hydrolysate.
Preferably, the protease preparation is a protease preparation for pelt softening or a protease preparation for tanning softening, which is commonly used in the art, and the protease in the protease preparation is selected from any one or more of microbial protease, animal protease and plant protease.
Preferably, the specific process of softening the pelts can be either A or B:
a: the method comprises the steps of (1) loading the limed pelts into a rotary drum according to the mass percentage of the limed pelts, adding 80-200 wt% of water, adjusting the temperature to 28-35 ℃, adding 1.0-4.0 wt% of a deliming agent and 0.1-0.5 wt% of a degreasing agent, and rotating for 30-120 min to carry out deliming; then changing liquid, adding 100-200wt% of water, adjusting the temperature to 28-35 ℃, adding 0.1-2.0wt% of protease preparation, and rotating for 1/8-5/6 of the total softening time; adding 0.3-6.0wt% protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 30-480 min, and the softened pelts are obtained.
B: the method comprises the steps of (1) loading the limed pelts into a rotary drum according to the mass percentage of the limed pelts, adding 80-200 wt% of water, adjusting the temperature to 28-35 ℃, adding 1.0-4.0 wt% of a deliming agent and 0.1-0.5 wt% of a degreasing agent, and rotating for 30-120 min to carry out deliming; then, without changing the liquid, continuously adding 0.1 to 2.0 weight percent of protease preparation, and rotating and softening for 1/8 to 5/6 of the total time; adding 0.3-6.0wt% protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 30-480 min, and the softened pelts are obtained.
Preferably, the specific process of tanning softening may take any of the following:
c: filling the evenly-cut blue wet leather or white wet 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 and softening for 1/8-5/6 of the total time; adding 0.3-9.0 wt% protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 60-480 min, and the softened tanning is obtained.
D: filling the evenly-cut blue wet leather or white wet 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, without changing the liquid, continuously adding 0.2 to 3.0 weight percent of protease preparation, and rotating and softening for 1/8 to 5/6 of the total time; adding 0.3-9.0 wt% protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 60-480 min, and the softened tanning is obtained.
E: according to the mass percentage of the shaved blue wet leather or white wet leather, the re-wet tanning leather is put into a rotary drum, 100 to 250 weight percent of water is added, the temperature is adjusted to 30 to 40 ℃, 0.2 to 2.0 weight percent of neutralized tannin and 0.5 to 2.0 weight percent of sodium formate are added, the rotary drum is rotated for 10 to 30 minutes, 0.5 to 1.0 weight percent of baking soda is added, and the rotary drum is rotated for 10 to 30 minutes for neutralization; then changing liquid, adding 100-250 wt% of water, adjusting the temperature to 30-45 ℃, adding 0.2-3.0 wt% of protease preparation, and rotating and softening for 1/8-5/6 of the total time; adding 0.3-9.0 wt% protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 60-240 min, and the softened tanning is obtained.
F: according to the mass percentage of the shaved blue wet leather or white wet leather, the re-wet tanning leather is put into a rotary drum, 100 to 250 weight percent of water is added, the temperature is adjusted to 30 to 45 ℃, 0.2 to 2.0 weight percent of neutralized tannin and 0.5 to 2.0 weight percent of sodium formate are added, the rotary drum is rotated for 10 to 30 minutes, 0.5 to 1.0 weight percent of baking soda is added, and the rotary drum is rotated for 10 to 30 minutes for neutralization; then, without changing the liquid, continuously adding 0.2 to 3.0 weight percent of protease preparation, and rotating and softening for 1/8 to 5/6 of the total time; adding 0.3-9.0 wt% protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 60-240 min, and the softened tanning is obtained.
The application also discloses leather obtained by adopting any softening method for preventing the leather from damaging and loosening.
Compared with the prior art, the application has the following beneficial effects:
1. according to the softening method for preventing the leather from damaging the surface and loosening the surface, after the protease fully permeates the leather, the inhibitor is added to inhibit the protease activity of the surface layer of the leather, so that the acting time of the protease on the collagen fibers of the surface layer of the leather can be shortened, the effect of treating the leather by the protease preparation can not be influenced, and the softening effect can not be influenced.
2. The softening method for preventing the damaged surface and the loose surface of the leather, which is provided by the application, is convenient to operate, can effectively reduce the risk of damaging collagen fibers in the grain surface layer of the leather 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 such as 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 application is selected from protein, polypeptide, short peptide or amino acid, and is an environment-friendly auxiliary agent.
Drawings
FIG. 1 shows the effect of soybean trypsin inhibitor on trypsin activity in sufficient amounts;
fig. 2 is a scanning electron micrograph of the softened pelt obtained in example 1 and comparative example 1.
Detailed Description
The objects, technical solutions and advantages of the present application will become more apparent by the following detailed description of the present application with reference to the accompanying drawings. It should be understood that the description is only illustrative and is not intended to limit the scope of the application. In addition, in the following description, descriptions of well-known structures and techniques are omitted so as not to unnecessarily obscure the present application. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Example 1
The following materials were used in the following amounts in mass percent (wt%) of the limed pelts.
Charging the limed pelts into a rotary drum, adding 150wt% of water, adjusting the temperature to 32 ℃, adding 2.5wt% of a deliming agent and 0.2wt% of a degreasing agent, and rotating for 60min to carry out deliming; then changing liquid, adding 200wt% of water, adjusting the temperature to 32 ℃, adding 2.0wt% of protease preparation (containing animal protease) for softening pelt, and rotating for 60min; adding 5.0wt% soybean trypsin inhibitor, rotating for 15min, and turning intermittently (20 min per hour) until softening is completed, wherein total softening time is 480min, to obtain softened pelt.
Comparative example 1
The following materials were used in the following amounts in mass percent (wt%) of the limed pelts.
Charging the limed pelts into a rotary drum, adding 150wt% of water, adjusting the temperature to 32 ℃, adding 3.0wt% of a deliming agent and 0.2wt% of a degreasing agent, and rotating for 60min to carry out deliming; then changing liquid, adding 200wt% of water, adjusting the temperature to 32 ℃, adding 2.0wt% of protease preparation (containing animal protease) for softening pelt, and rotating for 60min; rotating for 15min, and turning intermittently (rotating for 20min per hour) until softening is completed, wherein the total softening time is 480min, to obtain softened pelt.
Corresponding softening effect tests were performed on 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 protease activity of the surface layer of the pelt by using the protease inhibitor can protect the grain surface of the pelt from being damaged by the protease, namely, the effect of preventing the leather from damaging the surface is achieved after the protease fully permeates the pelt in the pelt softening process. In addition, as can be seen from the data in table 1, the hydroxyproline concentration of the softening waste liquid in example 1 is significantly lower than that in comparative example 1, which demonstrates that the method for using protease inhibitor in the softening process provided by the application can effectively reduce the damage of skin collagen fibers by shortening the action time of protease on the collagen fibers on the surface layer of pelt. As can be seen from a combination of the results of fig. 2 and table 1, the softening method for preventing the damage to the leather and the loose surface provided by the application can effectively solve the technical problem that the conventional softening technology is easy to damage the surface.
Table 1 softening effect comparison table (softening 480 min)
。
Note that: a. the higher the concentration of hydroxyproline (collagen characteristic amino acid) in the softening waste liquid, the greater the degree of damage to the collagen fibrils of the skin.
Example 2
The following materials were used in the following amounts in mass percent (wt%) of the limed pelts.
Charging the limed pelts into a rotary drum, adding 200wt% of water, adjusting the temperature to 35 ℃, adding 4.0wt% of a deliming agent and 0.5wt% of a degreasing agent, and rotating for 30min to carry out deliming; then changing liquid, adding 150wt% of water, adjusting the temperature to 35 ℃, adding 0.1wt% of protease preparation (containing microbial protease and animal protease) for softening pelts, and rotating for 120min; adding 0.3wt% of pumpkin trypsin inhibitor, rotating for 15min, and adjusting to intermittent rotation (15 min per hour) until softening is completed, wherein the total softening time is 360min, to obtain softened pelt.
Example 3
The following materials were used in the following amounts in mass percent (wt%) of the limed pelts.
Charging the limed pelts into a rotary drum, adding 80wt% of water, adjusting the temperature to 28 ℃, adding 1.0wt% of a deliming agent and 0.1wt% of a degreasing agent, and rotating for 120min to carry out deliming; then changing liquid, adding 100wt% of water, adjusting the temperature to 28 ℃, adding 1.0wt% of protease preparation (containing animal protease and plant protease) for softening pelts, and rotating for 50min; adding 6.0wt% leupeptin, and keeping rotating until softening is completed, wherein the total softening time is 60min, to obtain softened pelt.
Example 4
The following materials were used in the following amounts in mass percent (wt%) of the limed pelts.
Charging the limed pelts into a rotary drum, adding 120wt% of water, adjusting the temperature to 28 ℃, adding 2.5wt% of a deliming agent and 0.3wt% of a degreasing agent, and rotating for 120min to carry out deliming; then, the liquid is not changed, and a protease preparation (containing animal protease) for softening pelts with the weight percent of 0.1 percent is continuously added and rotated for 100 minutes; adding 0.3wt% aprotinin, and keeping rotating until softening is finished, wherein the total softening time is 120min, thus obtaining the softened pelt.
Example 5
The following materials were used in the following amounts in mass percent (wt%) of the limed pelts.
Charging the limed pelts into a rotary drum, adding 200wt% of water, adjusting the temperature to 32 ℃, adding 4.0wt% of a deliming agent and 0.5wt% of a degreasing agent, and rotating for 60min to carry out deliming; then, without changing the liquid, adding 1.0wt% protease preparation (containing microorganism protease and animal protease) for softening pelt, and rotating for 40min; adding 2.0wt% soybean trypsin inhibitor, and keeping rotating until softening is completed, wherein the total softening time is 60min, to obtain softened pelt.
Example 6
The following materials were used in the following amounts in mass percent (wt%) of the limed pelts.
Charging the limed pelts into a rotary drum, adding 80wt% of water, adjusting the temperature to 35 ℃, adding 1.0wt% of a deliming agent and 0.1wt% of a degreasing agent, and rotating for 30min to carry out deliming; then, without changing the liquid, adding 2.0wt% protease preparation (containing microorganism protease, animal protease and plant protease) for softening pelt, and rotating for 60min; adding 6.0wt% protein hydrolysate, rotating for 15min, and turning to intermittent rotation (15 min per hour) until softening is completed, wherein total softening time is 480min, to obtain softened pelt.
Example 7
The following materials are used in percentage by mass (wt%) of the shaved blue wet leather.
Loading the shaved blue wet 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 and softening, and rotating for 90min; adding 0.3wt% of pepstatin A, and keeping rotating until softening is finished, wherein the total softening time is 240min, thus obtaining softened tanned leather.
Example 8
The following materials are used in percentage by mass (wt%) of the shaved wet leather.
Placing the shaved 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 liquid, adding 200wt% of water, adjusting the temperature to 40 ℃, adding 2.0wt% of protease preparation (containing microbial protease and animal protease) for tanning and softening, and rotating for 50min; adding 4.0wt% wheat bran pepsin inhibitor, and keeping rotating until softening is completed, wherein the total softening time is 60min, to obtain softened tanned leather.
Example 9
The following materials are used in percentage by mass (wt%) of the shaved blue wet leather.
Loading the shaved blue wet 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 liquid, adding 300wt% of water, regulating the temperature to 50 ℃, adding 3.0wt% of protease preparation (containing microbial protease and animal protease) for tanning and softening, and rotating for 60min; adding 9.0wt% of potato pepsin inhibitor, and turning intermittently (turning for 20min per hour) until softening is completed, wherein total softening time is 480min, to obtain softened tannage.
Example 10
The following materials are used in percentage by mass (wt%) of the shaved blue wet leather.
Loading the shaved blue wet 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 (15 min per hour) until softening is completed, wherein the total softening time is 480min, to obtain softened tanning.
Example 11
The following materials are used in percentage by mass (wt%) of the shaved blue wet leather.
Loading 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 tanning without changing liquid, and rotating for 80min; adding 9.0wt% Coriolus versicolor pepsin inhibitor, and turning intermittently (15 min per hour) until softening is completed, wherein total softening time is 240min, to obtain softened tanning.
Example 12
The following materials are used in percentage by mass (wt%) of the shaved wet leather.
Placing the shaved white wet 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 microorganism protease and animal protease) for softening tanning without changing liquid, and rotating for 50min; adding 0.3wt% of roundworm pepsin inhibitor, and keeping rotating until softening is finished, wherein the total softening time is 60min, thus obtaining softened tannage.
Example 13
The following materials are used in percentage by mass (wt%) of the shaved blue wet leather.
Placing the rewetted tanning into a rotary drum, adding 100wt% of water, adjusting the temperature to 30 ℃, adding 0.2wt% of neutralized tannin and 0.5wt% of sodium formate, rotating for 10min, adding 0.5wt% of baking soda, and rotating for 10min for neutralization; then changing liquid, adding 100wt% of water, regulating the temperature to 30 ℃, adding 0.2wt% of protease preparation (containing microbial protease and animal protease) for tanning and softening, and rotating for 50min; adding 0.3wt% soybean trypsin inhibitor, and keeping rotating until softening is finished, wherein the total softening time is 60min, thus obtaining softened tannage.
Example 14
The following materials are used in percentage by mass (wt%) of the shaved wet leather.
Placing the rewetted tanning into a rotary drum, adding 150wt% of water, adjusting the temperature to 35 ℃, adding 1.0wt% of neutralized tannin and 1.0wt% of sodium formate, rotating for 20min, adding 0.8wt% of baking soda, and rotating for 20min for neutralization; then changing liquid, adding 150wt% of water, regulating the temperature to 40 ℃, adding 1.5wt% of protease preparation (containing microbial protease and animal protease) for tanning and softening, and rotating for 60min; adding 4.0wt% of pumpkin trypsin inhibitor and 0.5wt% of aprotinin, and keeping rotating until softening is finished, wherein the total softening time is 120min, so as to obtain softened tannage.
Example 15
The following materials are used in percentage by mass (wt%) of the shaved wet leather.
Placing the rewetted tanning into a rotary drum, adding 250wt% of water, adjusting the temperature to 40 ℃, adding 2.0wt% of neutralized 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 and softening, and rotating for 30min; 9.0wt% protein hydrolysate was added and batch rotation (15 min per hour) was adjusted until the softening was completed, and the total softening time was 240min, to give a softened tanned leather.
Example 16
The following materials are used in percentage by mass (wt%) of the shaved blue wet leather.
Placing the rewetted tanning into a rotary drum, adding 100wt% of water, adjusting the temperature to 30 ℃, adding 0.2wt% of neutralized tannin and 0.5wt% of sodium formate, rotating for 10min, adding 0.5wt% of baking soda, and rotating for 10min for neutralization; then, the solution is not changed, and a protease preparation (containing animal protease) for tanning softening with the weight percent of 0.2 percent is continuously added and rotated for 50 minutes; adding 0.3wt% aprotinin, turning intermittently (15 min per hour) until softening is completed, and softening for 60min to obtain softened tannage.
Example 17
The following materials are used in percentage by mass (wt%) of the shaved blue wet leather.
Placing the rewetted tanning into a rotary drum, adding 200wt% of water, adjusting the temperature to 40 ℃, adding 0.8wt% of neutralized tannin and 1.0wt% of sodium formate, rotating for 15min, adding 0.7wt% of baking soda, and rotating for 15min for neutralization; then, without changing the liquor, adding 1.5wt% of protease preparation (containing animal protease and plant protease) for softening tanning continuously, and rotating for 70min; adding 3.0wt% of leupeptin and 1.0wt% of soybean trypsin inhibitor, and turning intermittently (15 min per hour) until softening is completed, wherein the total softening time is 180min, thus obtaining softened tanning.
Example 18
The following materials are used in percentage by mass (wt%) of the shaved wet leather.
Placing the rewetted tanning into a rotary drum, adding 250wt% of water, adjusting the temperature to 45 ℃, adding 2.0wt% of neutralized tannin and 2.0wt% of sodium formate, rotating for 30min, adding 1.0wt% of baking soda, and rotating for 30min for neutralization; then, without changing the liquor, adding 3.0wt% protease preparation (containing microorganism protease, animal protease and plant protease) for softening tannage, and rotating for 30min; 9.0wt% of protein hydrolysate is added, and the continuous rotation is kept until the softening is finished, and the total softening time is 240min, so that the softened tanned leather is obtained.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application.
Claims (7)
1. A softening method for preventing the damage and loose of leather is characterized in that in the process of softening or tanning and softening naked leather, a protease preparation is firstly used for fully penetrating the leather, and then a protease inhibitor is used for inhibiting the protease activity of the naked leather or the tanned leather surface layer; the protease inhibitor is selected from any one or more of protein, polypeptide, short peptide and amino acid;
wherein, the adequate penetration of the protease preparation into the skin is controlled to be 1/8 to 5/6 of the total time of rotational softening after the protease preparation is added.
2. The softening process for preventing leather damage and pine noodles of claim 1, wherein the protease inhibitor is selected from any one or more of soybean trypsin inhibitor, pumpkin trypsin inhibitor, wheat bran pepstatin, potato pepstatin, pumpkin pepstatin, coriolus versicolor pepstatin, roundworm pepstatin, leupeptin, aprotinin a, protein hydrolysate.
3. A softening process for preventing leather damage and pine surfaces in accordance with claim 1, wherein the protease in the protease preparation is selected from any one or more of microbial proteases, animal proteases and plant proteases.
4. The softening method for preventing the damage to the leather and the loose-skin of claim 1, wherein the specific process for softening the pelt is selected from any one of the following:
the method comprises the steps of (1) loading the limed pelts into a rotary drum according to the mass percentage of the limed pelts, adding 80-200% of water, adjusting the temperature to 28-35 ℃, adding 1.0-4.0% of a deliming agent and 0.1-0.5% of a degreasing agent, and rotating for 30-120 min to carry out deliming; then changing liquid, adding 100-200% of water, adjusting the temperature to 28-35 ℃, adding 0.1-2.0 wt% of protease preparation, and rotating for softening 1/8-5/6 of the total time; adding 0.3-6.0% of protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 30-480 min, and the softened pelts are obtained; or (b)
The method comprises the steps of (1) loading the limed pelts into a rotary drum according to the mass percentage of the limed pelts, adding 80-200% of water, adjusting the temperature to 28-35 ℃, adding 1.0-4.0% of a deliming agent and 0.1-0.5% of a degreasing agent, and rotating for 30-120 min to carry out deliming; then, without changing the liquid, continuously adding a protease preparation accounting for 0.1 to 2.0 percent, and rotating and softening for 1/8 to 5/6 of the total time; adding 0.3-6.0% of protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 30-480 min, and the softened pelts are obtained.
5. A softening process for preventing leather damage and sagging of claim 1, wherein the tanning softening process is selected from any one of the following:
filling the evenly-cut blue wet leather or white wet 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 liquid, adding 150-300% of water, adjusting the temperature to 30-50 ℃, adding 0.2-3.0% of protease preparation, and rotating and softening for 1/8-5/6 of the total time; adding 0.3-9.0% of protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 60-480 min, and the softened tannage is obtained; or (b)
Filling the evenly-cut blue wet leather or white wet 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, without changing the liquid, continuously adding a protease preparation accounting for 0.2 to 3.0 percent, and rotating and softening for 1/8 to 5/6 of the total time; adding 0.3-9.0% of protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 60-480 min, and the softened tanning is obtained.
6. A softening process for preventing leather damage and sagging of claim 1, wherein the tanning softening process is selected from any one of the following:
according to the mass percentage of the evenly-cut blue wet leather or white wet leather, the retumped tanning leather is put into a rotary drum, 100 to 250 percent of water is added, the temperature is adjusted to 30 to 40 ℃, 0.2 to 2.0 percent of neutralized tannin and 0.5 to 2.0 percent of sodium formate are added, the rotary drum is rotated for 10 to 30 minutes, 0.5 to 1.0 percent of baking soda is added, and the rotary drum is rotated for 10 to 30 minutes for neutralization; then changing liquid, adding 100-250% of water, adjusting the temperature to 30-45 ℃, adding 0.2-3.0% of protease preparation, and rotating and softening for 1/8-5/6 of the total time; adding 0.3-9.0% of protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 60-240 min, and the softened tannage is obtained; or (b)
According to the mass percentage of the evenly-cut blue wet leather or white wet leather, the retumped tanning leather is put into a rotary drum, 100 to 250 percent of water is added, the temperature is adjusted to 30 to 45 ℃, 0.2 to 2.0 percent of neutralized tannin and 0.5 to 2.0 percent of sodium formate are added, the rotary drum is rotated for 10 to 30 minutes, 0.5 to 1.0 percent of baking soda is added, and the rotary drum is rotated for 10 to 30 minutes for neutralization; then, without changing the liquid, continuously adding a protease preparation accounting for 0.2 to 3.0 percent, and rotating and softening for 1/8 to 5/6 of the total time; adding 0.3-9.0% of protease inhibitor, and continuing intermittent rotation or continuous rotation until softening is finished; the total softening time is 60-240 min, and the softened tanning is obtained.
7. Leather obtainable by a softening process according to any one of claims 1 to 6 which prevents the damage and slackening of the leather.
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