CN114085932B - Production method of soft vegetable tanned leather - Google Patents

Abstract

The invention discloses a production method of soft vegetable tanned leather, which comprises the following steps: s1 rinsing; s2 surface dyeing; s3 retanning neutralization: adding sodium formate and neutralizing tannin, rotating for 28-32 min, adding sodium bicarbonate, rotating for 18-22 min, adding displaced tannin and sulfited neat's foot oil, rotating for 75-85 min, stopping the drum overnight, controlling pH4-5, and completely neutralizing; s4 filling: adding a dicyandiamide resin tanning agent, a melamine resin quebracho tannin extract and a composite tanning agent, adding acrylic resin, a white tannin extract and an electrolyte-resistant fatting agent after rotation, rotating, adding bark gum, dispersing tannin, continuously rotating for 110 plus 130 minutes, and adding a composite dye and rotating for 50-70 minutes; s5, fat liquoring; s6, color fixing; s7 finishing and drying. Compared with the prior art, the invention has the following advantages: 1. the requirement on wet blue skin is low; 2. the usage amount of the plant tanning agent is reduced; 3. the skin is lifted.

Description

Production method of soft vegetable tanned leather

Technical Field

The invention relates to a production method of leather, in particular to a production method of soft vegetable tanned leather.

Background

The conventional vegetable tanning process is a traditional and ancient leather-making technology, which has been continuously evolved and improved for decades. The leather-making equipment, the chemical materials, the production method and the like. The quality and the variety of the product are greatly improved, but the application range of the product is narrow due to the remarkable characteristic of the leather property of the vegetable tanning leather, namely the button feeling (namely the vegetable tanning feeling) which is commonly called as the characteristic of stiff hand feeling and low physical property (tearing strength). Few technical solutions exist in the prior art to solve this problem. In view of the above, the inventors of the present application have conducted extensive studies to obtain a method for producing soft vegetable tanned leather.

Disclosure of Invention

The invention aims to provide a production method of soft vegetable-tanned leather, which overcomes the defects of stiff and low physical property of the original vegetable-tanned leather on the basis of keeping the vegetable-tanned feeling.

The technical purpose of the invention is realized by the following technical scheme:

a production method of soft vegetable tanned leather comprises the following steps:

a production method of soft vegetable tanned leather comprises the following steps: s1 rinsing; s2 surface dyeing; s3 retanning neutralization: 160 percent of liquid ratio, 36-38 ℃, 1-3 percent of sodium formate and 1-3 percent of neutralized tannin by weight are added, the mixture rotates for 28-32 minutes under the condition of 10-14 revolutions/min, 0.4-0.6 percent of baking soda is added, the mixture rotates for 18-22 minutes, 1-3 percent of displaced tannin and 0.8-1.2 percent of sulfited neat foot oil are added, the mixture rotates for 75-85 minutes, the drum is stopped overnight, the pH is controlled to 4-5, and the mixture is completely neutralized; s4 filling: the liquid ratio is 48-52%, the temperature is 38-42 ℃, 3-5 wt% of dicyandiamide resin tanning agent, 3-5 wt% of melamine resin, 8-12 wt% of quebracho extract and 1-4 wt% of compound tanning agent are added, after rotating for 35-45 minutes, 6-10 wt% of acrylic resin, 6-8 wt% of white tannin extract and 0.8-1.2 wt% of electrolyte-resistant fatting agent are added, the rotation is 50-70 minutes, 5-7 wt% of bark extract and 1-3 wt% of dispersed tannin are added, the continuous rotation is 110-one-time for 130 minutes, and 1-3 wt% of compound dye is added, and the rotation is 50-70 minutes; s5, fat liquoring; s6, color fixing; s7 finishing and drying.

In a preferred embodiment, the S1 rinsing specifically includes: taking the blue wet skin after standing for wringing, evenly shaving and weighing, wherein the liquid ratio is 190 percent, the temperature is 40-50 ℃, the rotating drum rotating speed is 10-14 r/min, after evenly blending, adding 0.5-0.7wt percent of moisture returning agent, 0.1-0.3wt percent of degreasing agent, 0.3-0.5wt percent of formic acid and 0.7-0.9wt percent of oxalic acid, and carrying out rotary rinsing for 50-70 minutes under the condition.

In a preferred embodiment, the step of S5 fatliquoring specifically includes: adding water, heating to 52-54 ℃, the liquid ratio is 140-160%, adding 2-3 wt% of sulfated neat's foot oil, 1-2 wt% of soft fat-liquoring agent, 1-3 wt% of protein filler, rotating for 35-45 minutes, adding 0.9-1.1 wt% of lecithin, and rotating for 25-35 minutes.

In a preferred embodiment, the S6 color fixation specifically includes: adding 1-3 wt% of formic acid with the content of 80-90 wt% into one bath, adding the formic acid for three times at intervals of 18-22 minutes, carrying out closed washing on the leather blank after color fixation by using normal-temperature water once, cooling, taking out the leather blank, stacking and standing.

In a preferred embodiment, the S7 finishing and drying specifically includes: standing the leather blank overnight, then performing splitting treatment, performing water squeezing and stretching by using a front three-knife method at the vacuum temperature of 40-50 ℃ for 110-130 seconds, hanging and drying for 47-49 hours, and then drying for 1.8-2.2 hours.

In a preferred embodiment, the step S2 specifically includes: the liquid ratio is 110%, the temperature is 34-36 ℃, the dye is added in 0.4-0.6 wt%, and the rotation is carried out for 18-22 minutes.

In a preferred embodiment, the method further comprises the following steps: s8 rewetting: spraying a small amount of water on the back surface for rewetting until the water content is 13-17%, and standing overnight; s9 softening: softening once by using an oscillation softening machine, and alternately coating and finishing; s10 softening: coating, connecting to a leather blank, and rolling the leather blank to a required softness through a rolling drum; s11 toggling: the fallen skin blank is subjected to toggling to enable the skin to be flat and stretched; s12 wax spraying: spraying a layer of polishing oil wax on the stretched leather blank, and standing for 3-5 hours; s13 polishing: polishing the semi-finished product standing for a certain time by using an imported polishing machine to enable the skin to be flat and thin and have a bottom polished, and then carrying out the next working procedure; s14, primary ironing: the polished semi-finished product is polished and then coated by an ironing machine; s15 spraying: spraying and coating the middle layer and the top layer on the ironed semi-finished product again, and standing for 3-5 hours; s16 secondary ironing: and finally ironing the sprayed skins to achieve the luster required by the finished product.

Compared with the prior art, the invention has the following advantages: 1. the quality requirement on wet blue peels is not high, the wet blue peels can be produced in a large scale to meet the market demand, the economic benefit is effectively improved, the time consumed by selecting and treating the blue peels is reduced, and the working hours are effectively shortened; 2. the use amount of the plant tanning agent is too large, so that the softness, extensibility, light resistance and tear resistance of leather are reduced, the fullness of the leather, particularly loose parts, can be increased by using the anionic amino resin to be matched with the plant tanning agent, the tannin extract can be helped to permeate into the leather, negative charges of grain surface tannin are reduced, the grain surface is compact, smooth, drop-resistant and soft to be enhanced, and the use amount of the plant tanning agent is reduced by 50%; 3. the synthetic fat liquor based on animal fat is used, and the animal fat can make the finished leather soft, full and good in greasiness, but easily loosens the tissue structure of the leather to cause loose surface; the affinity of the mineral oil to the leather is small, but the mineral oil has good lubrication, the flexibility can be improved, the body and the bone of the leather are poor due to excessive consumption, the strength is reduced, the characteristics of light resistance, heat resistance, electrolyte resistance and the like of common animal oil and natural grease can be compensated by adding a proper amount of synthetic fatting agent in the main fatting, the tensile strength and the Gaussian strength of the vegetable tanning are improved, the proper softness can be achieved, and the skin and the body can be improved; 4. the two substitute materials not only well maintain the 'vegetable tanning' effect of the product, but also well solve the problem of narrow application range caused by the stiffness of the traditional vegetable tanning leather, and are popularized to the high-grade leather shoe industry from the previous simple case.

Detailed Description

The present invention will be described in further detail below.

The present embodiment is only for explaining the present invention, and it is not limited to the present invention, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present invention.

The first embodiment is as follows:

a production method of soft vegetable tanned leather comprises the following steps: s1 rinsing; s2 surface dyeing; s3 retanning neutralization: the liquid ratio is 140 percent, the temperature is 36 ℃, 1 weight percent of sodium formate and 1 weight percent of tannin are added, the mixture is rotated for 28 minutes under the condition of 10 revolutions per minute, 0.4 weight percent of baking soda is added, the mixture is rotated for 18 minutes, 1 weight percent of displaced tannin and 0.8 weight percent of sulfited neat foot oil are added, the mixture is rotated for 75 minutes, the drum is stopped overnight, the pH value is controlled at 4, and the mixture is completely neutralized; s4 filling: the liquid ratio is 48%, the temperature is 38 ℃, 3 wt% of dicyandiamide resin tanning agent, 3 wt% of melamine resin, 8 wt% of quebracho tannin extract and 1 wt% of composite tanning agent are added, after 35 minutes of rotation, 6 wt% of acrylic resin, 6 wt% of quebracho tannin extract and 0.8 wt% of electrolyte-resistant fatliquor are added, 50 minutes of rotation are carried out, 5 wt% of bark gum and 1 wt% of dispersed tannin are added, continuous rotation is carried out for 110 minutes, and 1 wt% of composite dye is added, and 50 minutes of rotation are carried out; s5, fat liquoring; s6, color fixing; s7 finishing and drying.

The rinsing of S1 specifically comprises: squeezing, shaving and weighing the standing wet blue leather, wherein the liquid ratio is 170%, the temperature is 40 ℃, the rotating speed of the rotating drum is 10 r/min, after uniform rotation, 0.5 wt% of moisture returning agent, 0.1 wt% of degreasing agent, 0.3 wt% of formic acid and 0.7 wt% of oxalic acid are added, and the wet blue leather is rotated and rinsed for 50 minutes under the condition.

The S5 greasing specifically comprises the following steps: adding water, heating to 52 ℃, adding 140% of liquid ratio, adding 2 wt% of sulfated neat's foot oil, 1 wt% of soft fat-liquoring agent, 1 wt% of protein filler, rotating for 35 minutes, adding 0.9 wt% of lecithin, and rotating for 25 minutes.

The S6 fixation specifically comprises the following steps: adding 1 wt% of formic acid with the content of 80 wt% into the same bath, adding the formic acid into the bath in three times at intervals of 18 minutes, carrying out closed washing on the leather blank after color fixation by using normal-temperature water once, and carrying out stacking and standing after cooling.

The S7 finishing and drying specifically comprises the following steps: standing the leather blank overnight, then performing splitting treatment, performing water squeezing and stretching by using a front three-knife method, performing vacuum temperature of 40 ℃ for 110 seconds, hanging and airing for 47 hours, and then drying for 1.8 hours.

The step S2 specifically includes: the liquid ratio is 100 percent, the temperature is 34 ℃, 0.4 weight percent of dye is added, and the rotation is carried out for 18 minutes.

The production method of the soft vegetable tanned leather further comprises the following steps: s8 rewetting: spraying a small amount of water on the back surface for rewetting until the water content is 13%, and standing overnight; s9 softening: softening once by using an oscillation softening machine, and alternately coating and finishing; s10 softening: coating, connecting to a leather blank, and rolling the leather blank to a required softness through a rolling drum; s11 toggling: the fallen skin blank is subjected to toggling to enable the skin to be flat and stretched; s12 wax spraying: spraying a layer of polishing oil wax on the stretched skin blank, and standing for 3-5 hours; s13 polishing: polishing the semi-finished product standing for a certain time by using an imported polishing machine to enable the skin to be flat and thin and have a bottom polished, and then carrying out the next working procedure; s14 primary ironing: the polished semi-finished product is polished and then coated by an ironing machine; s15 spraying: spraying and coating the middle layer and the top layer on the ironed semi-finished product again, and standing for 3 hours; s16 secondary ironing: and finally ironing the sprayed skins to achieve the luster required by the finished product.

Example two:

a production method of soft vegetable tanned leather comprises the following steps: s1 rinsing; s2 surface dyeing; s3 retanning neutralization: the liquid ratio is 160 percent, the temperature is 38 ℃, 3 weight percent of sodium formate and 3 weight percent of neutralized tannin are added, the mixture is rotated for 32 minutes under the condition of 14 revolutions per minute, 0.6 weight percent of baking soda is added, the mixture is rotated for 22 minutes, 3 weight percent of displaced tannin and 1.2 weight percent of sulfited neat foot oil are added, the mixture is rotated for 85 minutes, the drum is stopped overnight, the pH value is controlled at 5, and the mixture is completely neutralized; s4 filling: the liquid ratio is 52%, the temperature is 42 ℃, 5 wt% of dicyandiamide resin tanning agent, 5 wt% of melamine resin, 12 wt% of quebracho tannin extract and 4 wt% of composite tanning agent are added, 10 wt% of acrylic resin, 8 wt% of white tannin extract and 1.2 wt% of electrolyte-resistant fatliquor are added after rotating for 45 minutes, rotating for 70 minutes, 7 wt% of bark gum and 3 wt% of disperse tannin are added, rotating for 130 minutes continuously, and 3 wt% of composite dye is added and rotating for 70 minutes; s5, fat liquoring; s6, color fixing; s7 finishing and drying.

The rinsing of S1 specifically comprises: and (3) squeezing, uniformly shaving and weighing the standing wet blue leather, wherein the liquid ratio is 190%, the temperature is 50 ℃, the rotating speed of a rotating drum is 14 r/min, after uniform rotation, 0.7 wt% of a moisture returning agent, 0.3 wt% of a degreasing agent, 0.5 wt% of formic acid and 0.9 wt% of oxalic acid are added, and the blue wet leather is rotated and rinsed for 70 minutes under the condition.

The S5 greasing specifically comprises the following steps: adding water, heating to 54 ℃, keeping the liquid ratio at 160%, adding 3 wt% of sulfated neat's foot oil, 2 wt% of soft fat-liquoring agent, 3 wt% of protein filler, rotating for 45 minutes, adding 1.1 wt% of lecithin, and rotating for 35 minutes.

The S6 fixation specifically comprises the following steps: 3 percent of formic acid with the content of 90 percent by weight is added into the same bath, the formic acid is added into the bath for three times at intervals of 22 minutes, the leather embryo after color fixation is stuffy washed once by normal temperature water, and is taken out, stacked and kept stand after being cooled.

The S7 finishing and drying specifically comprises the following steps: standing the leather blank overnight, then performing splitting treatment, performing water squeezing and stretching by using a front three-knife method, performing vacuum temperature of 50 ℃ for 130 seconds, hanging and airing for 49 hours, and drying for 2.2 hours.

The step S2 specifically includes: the liquid ratio is 110%, the temperature is 36 ℃, 0.6 wt% of dye is added, and the rotation is carried out for 22 minutes.

The production method of the soft vegetable tanned leather further comprises the following steps: s8 rewetting: spraying a small amount of water on the back surface for rewetting until the water content is 17%, and standing overnight; s9 softening: softening once by using an oscillation softening machine, and alternately coating and finishing; s10 softening: coating, connecting to a leather blank, and rolling the leather blank to a required softness through a rolling drum; s11 toggling: the fallen skin blank is subjected to toggling to enable the skin to be flat and stretched; s12 wax spraying: spraying a layer of polishing oil wax on the stretched leather blank, and standing for 5 hours; s13 polishing: polishing the semi-finished product standing for a certain time by using an imported polishing machine to enable the skin to be flat and thin and have a bottom polished, and then carrying out the next working procedure; s14 primary ironing: the polished semi-finished product is polished and then coated by an ironing machine; s15 spraying: spraying and coating the middle layer and the top layer on the ironed semi-finished product again, and standing for 5 hours; s16 secondary ironing: and finally ironing the sprayed skins to achieve the luster required by the finished product.

Example three:

a production method of soft vegetable tanned leather comprises the following steps: s1 rinsing; s2 surface dyeing; s3 retanning neutralization: the liquid ratio is 150%, the temperature is 37 ℃, 2 wt% of sodium formate and 2 wt% of neutralized tannin are added, the mixture is rotated for 30 minutes under the condition of 13 revolutions per minute, 0.5 wt% of baking soda is added, the mixture is rotated for 20 minutes, 2 wt% of displaced tannin and 1 wt% of sulfited neat foot oil are added, the mixture is rotated for 80 minutes, the drum is stopped and the mixture is overnight, the pH value is controlled at 4, and the neutralization is completely performed; s4 filling: the liquid ratio is 50%, the temperature is 40 ℃, 4 wt% of dicyandiamide resin tanning agent, 4 wt% of melamine resin and 10 wt% of quebracho tannin extract and 3 wt% of composite tanning agent are added, 8 wt% of acrylic resin, 7 wt% of quebracho tannin extract and 1 wt% of electrolyte-resistant fatliquor are added after the mixture rotates for 40 minutes, the mixture rotates for 60 minutes, 6 wt% of bark tannin and 2 wt% of disperse tannin are added, the mixture rotates for 120 minutes continuously, and 2 wt% of composite dye is added and rotates for 60 minutes; s5, greasing; s6, color fixing; s7 finishing and drying.

The rinsing of S1 specifically comprises: squeezing, shaving and weighing the standing wet blue leather, wherein the liquid ratio is 180%, the temperature is 45 ℃, the rotating speed of the rotating drum is 12 r/min, after uniform rotation, 0.6 wt% of moisture returning agent, 0.2 wt% of degreasing agent, 0.4 wt% of formic acid and 0.8 wt% of oxalic acid are added, and the wet blue leather rotates and rinses for 60 minutes under the condition.

The S5 greasing specifically comprises the following steps: adding water, heating to 53 ℃, keeping the liquid ratio at 150%, adding 2.5 wt% of sulfated neat's foot oil, 1.5 wt% of soft fat-liquoring agent, 2 wt% of protein filler, rotating for 40 minutes, adding 1 wt% of lecithin, and rotating for 30 minutes.

The S6 fixation specifically comprises the following steps: 2 wt% of formic acid with the content of 85 wt% is added in one bath, the formic acid is added in three times at intervals of 20 minutes, the leather blank after color fixation is subjected to closed washing once by normal-temperature water, and is taken out of a drum after temperature reduction and stands.

The S7 finishing and drying specifically comprises the following steps: standing the leather blank overnight, then performing splitting treatment, performing water squeezing and stretching by using a front three-knife method, performing vacuum temperature of 45 ℃ for 120 seconds, hanging and airing for 48 hours, and then drying for 2 hours.

The step S2 specifically includes: the liquid ratio is 105 percent, the temperature is 35 ℃, 0.5 weight percent of dye is added, and the rotation is carried out for 20 minutes.

The production method of the soft vegetable tanned leather further comprises the following steps: s8 rewetting: spraying a small amount of water on the back surface for rewetting until the water content is 15%, and standing overnight; s9 softening: softening once by using an oscillation softening machine, and alternately coating and finishing; s10 softening: coating, connecting to a leather blank, and rolling the leather blank to a required softness through a rolling drum; s11 toggling: the fallen skin blank is subjected to toggling to enable the skin to be flat and stretched; s12 wax spraying: spraying a layer of polishing oil wax on the stretched leather blank, and standing for 4 hours; s13 polishing: polishing the semi-finished product standing for a certain time by using an imported polishing machine to enable the skin to be flat and thin and have a bottom polished, and then carrying out the next working procedure; s14 primary ironing: the polished semi-finished product is polished and then coated by an ironing machine; s15 spraying: spraying and coating the middle layer and the top layer on the ironed semi-finished product again, and standing for 4 hours; s16 secondary ironing: and finally ironing the sprayed skins to achieve the luster required by the finished product.

The method in the embodiment has the following advantages: 1. the quality requirement on the wet blue skin is not high, the wet blue skin can be produced in large scale to meet the market demand, the economic benefit is effectively improved, the time consumed by skin selection and treatment is reduced, and the working hours are effectively shortened; 2. the use amount of the plant tanning agent is too large, so that the softness, extensibility, light resistance and tear resistance of leather are reduced, the fullness of the leather, particularly loose parts, can be increased by using the anionic amino resin to be matched with the plant tanning agent, the tannin extract can be helped to permeate into the leather, negative charges of grain surface tannin are reduced, the grain surface is compact, smooth, drop-resistant and soft to be enhanced, and the use amount of the plant tanning agent is reduced by 50%; 3. the synthetic fat liquor based on animal fat is used, and the animal fat can make the finished leather soft, full and good in greasiness, but easily loosens the tissue structure of the leather to cause loose surface; the affinity of the mineral oil to the leather is small, but the mineral oil has good lubrication, the flexibility can be improved, the body and the bone of the leather are poor due to excessive consumption, the strength is reduced, the characteristics of light resistance, heat resistance, electrolyte resistance and the like of common animal oil and natural grease can be compensated by adding a proper amount of synthetic fatting agent in the main fatting, the tensile strength and the Gaussian strength of the vegetable tanning are improved, the proper softness can be achieved, and the skin and the body can be improved; 4. the two substitute materials not only well maintain the 'vegetable tanning' effect of the product, but also well solve the problem of narrow application range caused by the stiffness of the traditional vegetable tanning leather, and are popularized to the high-grade leather shoe industry from the previous simple case.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the phrases "comprising … …" or "comprising … …" does not exclude the presence of additional elements in a process, method, article, or terminal that comprises the element. Further, herein, "greater than," "less than," "more than," and the like are understood to exclude the present numbers; the terms "above", "below", "within" and the like are to be understood as including the number.

The foregoing description of the embodiments is provided to facilitate an understanding and use of the invention and it will be apparent to those skilled in the art that various modifications to the embodiments and the generic principles defined herein may be applied to other embodiments without the use of inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.

Claims (5)

1. The production method of the soft vegetable tanned leather is characterized by comprising the following steps: s1 rinsing; s2 surface dyeing; s3 retanning neutralization: 160 percent of liquid ratio, 36-38 ℃, 1-3 percent of sodium formate and 1-3 percent of neutralized tannin by weight are added, the mixture rotates for 28-32 minutes under the condition of 10-14 revolutions/min, 0.4-0.6 percent of baking soda is added, the mixture rotates for 18-22 minutes, 1-3 percent of displaced tannin and 0.8-1.2 percent of sulfited neat foot oil are added, the mixture rotates for 75-85 minutes, the drum is stopped overnight, the pH is controlled to 4-5, and the mixture is completely neutralized; s4 filling: 48-52% of liquid ratio, 38-42 ℃, adding 3-5 wt% of dicyandiamide resin tanning agent, 3-5 wt% of melamine resin, 8-12 wt% of quebracho tannin extract and 1-4 wt% of composite tanning agent, rotating for 35-45 minutes, adding 6-10 wt% of acrylic resin, 6-8 wt% of white tannin extract, 0.8-1.2 wt% of electrolyte-resistant fatliquor, rotating for 50-70 minutes, then adding 5-7 wt% of bark gum, 1-3 wt% of dispersed tannin, continuously rotating for 110-130 minutes, adding 1-3 wt% of composite dye, and rotating for 50-70 minutes; s5, fat liquoring; s6, color fixing; s7 finishing and drying; the S5 greasing specifically comprises the following steps: adding water, heating to 52-54 ℃, the liquid ratio is 140-160%, adding 2-3 wt% of sulfated neat's foot oil, 1-2 wt% of soft fat-liquoring agent, 1-3 wt% of protein filler, rotating for 35-45 minutes, adding 0.9-1.1 wt% of lecithin, and rotating for 25-35 minutes.

2. The method for producing soft vegetable tanned leather according to claim 1, wherein the rinsing step S1 specifically comprises: taking the blue wet skin after standing for wringing, evenly shaving and weighing, wherein the liquid ratio is 190 percent, the temperature is 40-50 ℃, the rotating drum rotating speed is 10-14 r/min, after evenly blending, adding 0.5-0.7wt percent of moisture returning agent, 0.1-0.3wt percent of degreasing agent, 0.3-0.5wt percent of formic acid and 0.7-0.9wt percent of oxalic acid, and carrying out rotary rinsing for 50-70 minutes under the condition.

3. The method for producing soft vegetable tanned leather according to claim 1, wherein the S7 finish drying specifically comprises: standing the leather blank overnight, then performing splitting treatment, performing water squeezing and stretching by using a front three-knife method at the vacuum temperature of 40-50 ℃ for 110-130 seconds, hanging and drying for 47-49 hours, and then drying for 1.8-2.2 hours.

4. The method for producing soft vegetable tanned leather according to claim 1, wherein the step S2 specifically comprises: the liquid ratio is 110%, the temperature is 34-36 ℃, the dye is added in 0.4-0.6 wt%, and the rotation is carried out for 18-22 minutes.

5. The method for producing soft vegetable tanned leather according to claim 1, further comprising the steps of: s8 rewetting: spraying a small amount of water on the back surface for rewetting until the water content is 13-17%, and standing overnight; s9 softening: softening once by using an oscillation softening machine, and alternately coating and finishing; s10 softening: coating, connecting to a leather blank, and rolling the leather blank to a required softness through a rolling drum; s11 toggling: the fallen skin blank is subjected to toggling to enable the skin to be flat and stretched; s12 wax spraying: spraying a layer of polishing oil wax on the stretched skin blank, and standing for 3-5 hours; s13 polishing: polishing the semi-finished product standing for a certain time by using an imported polishing machine to enable the skin to be flat and thin and have a bottom polished, and then carrying out the next working procedure; s14, primary ironing: the polished semi-finished product is polished and then coated by an ironing machine; s15 spraying: spraying and coating the middle layer and the top layer on the ironed semi-finished product again, and standing for 3-5 hours; s16 secondary ironing: and finally ironing the sprayed skins to achieve the luster required by the finished product.