阅读说明：本技术 一种纳帕型高档平面沙发革及其生产工艺 (Napa type high-grade plane sofa leather and production process thereof ) 是由 牛泽 杨义清 魏冠凯 位博宇 孙传基 于 2021-10-22 设计创作，主要内容包括：本发明公开了一种纳帕型高档平面沙发革及其生产工艺,依次包括如下工序:蓝湿革组批→挤水、片皮、削匀、称重→回软→中和I→复鞣填充I→铝复鞣→中和II→复鞣填充II、染色→加脂→干燥整理→涂饰；在所述中和I、中和II工序中加入强碱弱酸盐、中和剂、聚合物复鞣剂、合成酯复配加脂剂；在所述复鞣填充I工序中加入聚合物复鞣剂、合成鞣剂、复合树脂鞣剂；本申请通过所述纳帕型高档平面沙发革的生产工艺制得的纳帕型高档平面沙发革,不光具有手感舒适、整张革厚薄均匀一致、涂层耐光耐磨耐擦、物理机械强度好等一般特点,还同时具有粒面细致紧实不松面、身骨丰满绵泡柔软、表面触感丝滑滋润等性能优异,提升了生态环保性能。(The invention discloses a Napa type high-grade plane sofa leather and a production process thereof, which sequentially comprises the following procedures of blue wet leather batch → water squeezing, splitting, shaving, weighing → softening → neutralization I → retanning filling I → aluminum retanning → neutralization II → retanning filling II, dyeing → fatliquoring → dry finishing → coating; adding strong base weak acid salt, a neutralizing agent, a polymer retanning agent and a synthetic ester compound fatliquoring agent in the step I and the step II; adding a polymer retanning agent, a synthetic tanning agent and a composite resin tanning agent in the step I of retanning filling; the nappa-type high-grade plane sofa leather prepared by the production process of the nappa-type high-grade plane sofa leather has the general characteristics of comfortable hand feeling, uniform thickness of the whole piece of leather, light resistance, wear resistance, abrasion resistance, good physical and mechanical strength and the like, and also has the excellent performances of fine, compact and loose grain surface, full body and soft foam, silky and moist surface touch feeling and the like, and the ecological environmental protection performance is improved.)

1. A production process of Napa type high-grade plane sofa leather is characterized by comprising the following steps: the process sequentially comprises the following procedures of blue wet leather batch → wringing, splitting, shaving, weighing → softening → neutralizing I → retanning filling I → aluminum retanning → neutralizing II → retanning filling II, dyeing → fatliquoring → dry finishing → coating;

adding sodium formate, sodium bicarbonate, a neutralizing agent, a polymer retanning agent and a synthetic ester compound fatliquor in the step I and the step II;

adding a polymer retanning agent, a synthetic tanning agent and a composite resin tanning agent in the step I of retanning filling;

adding an aluminum-containing tanning agent, an amphoteric biopolymer and an electrolyte-resistant fatliquor in the aluminum retanning procedure;

and adding a polymer retanning agent, a synthetic tanning agent, a composite resin tanning agent, a plant tannin extract and a neat foot oil fatting agent in the retanning filling II and dyeing processes.

2. The production process of the napa type high-grade plane sofa leather according to claim 1, which is characterized in that:

oxalic acid, a multifunctional rewetting agent and an enzyme-containing degreasing agent are at least added in the softening procedure;

in the step of fatliquoring, at least a fatliquoring agent and a polymer retanning agent are added;

the drying and finishing process at least comprises squeezing and stretching, drying and finishing, wet toggling, moisture returning, vibrating and softening, breaking and drying toggling.

3. The production process of the napa type high-grade plane sofa leather according to claim 1, which is characterized in that:

the neutralization I process comprises the following steps: adding 50-150 parts of 25-35 ℃ water, 1-2 parts of strong base and weak acid salt and 1-2 parts of neutralizing agent into a rotary drum, rotating, and adjusting the pH value of bath liquid to 4.5-5.0;

the retanning filling procedure I comprises the following steps: adding 2-5 parts of polymer retanning agent into the bath solution of neutralization 1, and rotating; adding 2-5 parts of synthetic tanning agent and 3-6 parts of composite resin tanning agent, and rotating; adding 1-2 parts of formic acid, rotating, and adjusting the bath liquid ph to 3.4-3.6;

the aluminum retanning procedure comprises the following steps: adding 2-5 parts of aluminum-containing tanning agent, 1-3 parts of amphoteric biopolymer and 0.5-1.5 parts of electrolyte-resistant fatliquor into retanning filling 1 bath solution, and rotating; adding 1-2 parts of sodium formate, and rotating; adding 0.2-0.8 part of baking soda, rotating, adjusting pH of bath liquid to 3.8-4.2, and discharging liquid;

the step II of neutralization is as follows: adding 200 parts of water at 25-35 ℃, 2-4 parts of strong base and weak acid salt and 1-2 parts of neutralizing agent into the rotary drum, rotating, and adjusting the pH value of the bath liquid to 4.8-5.2; adding 1-3 parts of polymer retanning agent and 1-2 parts of synthetic ester compound fatliquoring agent, rotating and discharging liquid;

the retanning filling II and dyeing process comprises the following steps: adding 20-100 parts of water with the temperature of 25-35 ℃ and 3-8 parts of polymer retanning agent into the rotary drum, and rotating; adding 2-5 parts of plant tannin extract, 5-8 parts of composite resin tanning agent, 3-6 parts of synthetic tanning agent, 0.5-1.5 parts of neatsfoot oil fatting agent and dye, and rotating; adding 2-5 parts of polymer retanning agent, and rotating; adding water of 100-200 parts at 50-60 ℃ and formic acid of 0.5-1.5 parts, rotating, adjusting the pH value of the bath liquid to 4.0-4.2, and discharging the liquid.

4. The production process of the napa type high-grade plane sofa leather according to claim 1, which is characterized in that:

the step of greasing comprises the following steps: adding 200 parts of water at 50-60 ℃, 8-15 parts of fatting agent and 1-3 parts of polymer retanning agent into the rotary drum, and rotating; adding 1-2 parts of formic acid, rotating, adjusting the pH value of the bath liquid to 3.4-3.6, and discharging liquid;

the rewetting process comprises the following steps: adding water of 150-300 parts at 35-45 ℃, oxalic acid of 0.2-1.0 part, multifunctional rewetting agent of 0.3-1.0 part and enzyme-containing degreasing agent of 0.5-1.5 part into the rotary drum, rotating, controlling the pH value of the final bath liquid at 3.0-3.5, and discharging the liquid.

5. The production process of the napa type high-grade plane sofa leather according to claim 1, which is characterized in that:

the drying and finishing temperature is 30-40 ℃, the time is 2-5min, and the water content is controlled to be 40-50%;

the temperature of the wet toggling plate is 40-50 ℃, the toggling distance is 1-6cm, and the water content is controlled at 6-10%;

the rewetting is double-sided water spraying, standing for 8-12h, and controlling the water content at 13-16%;

the milling time is 10-30h, and the water content is controlled at 15-20%;

the temperature of the dry stretching plate is 40-50 ℃, the stretching distance is 6-12cm, and the water content is controlled at 10-15%.

6. The process for producing high-grade sofa leather in Napa type according to claim 1, wherein the polymer retanning agent is at least two selected from an acrylic polymer retanning agent, a polyurethane polymer retanning agent, a vinyl polymer retanning agent, a hyperbranched polymer retanning agent and an amphoteric polymer retanning agent.

7. The process for producing napa-type high-grade sofa leather according to claim 1, wherein the aluminum-containing tanning agent is at least one selected from an aluminum complex tanning agent, a zirconium-aluminum complex tanning agent and a zirconium-aluminum-titanium complex tanning agent.

8. The process for manufacturing a napa-type high-grade sofa leather according to claim 1, wherein the plant tannin extract is selected from at least one of a wattle tannin extract, a quebracho tannin extract, a tara tannin extract and a white tannin extract;

the synthetic tanning agent is at least two selected from phenolic synthetic tanning agent, naphthalene synthetic tanning agent, sulfone synthetic tanning agent and sulfonic acid synthetic tanning agent.

9. The process for producing napa-type high-grade sofa leather according to claim 1, wherein the fatliquoring agent is selected from at least four of lecithin fatliquoring agent, synthetic fatliquoring agent, phospholipid mixed fatliquoring agent, phosphorylation fatliquoring agent, neat's foot oil fatliquoring agent and lanolin fatliquoring agent.

10. A napa-type high-grade flat sofa leather, which is characterized by being prepared by the method of any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of leather-making chemistry and engineering, in particular to nano-handkerchief type high-grade plane sofa leather and a production process thereof.

Background

The traditional sofa leather is mainly made of falling patterns, and comprises natural falling pattern sofa leather, embossed falling pattern sofa leather and the like. The textured sofa leather has been popular for more than 20 years and has caused aesthetic fatigue to consumers, and in recent years the selling price has gone all the way down to 8-10 yuan per square foot and has been selling at a cost price with a profit of substantially zero. On the basis, the plane sofa leather is produced and develops towards the direction of 'softness, fullness and compactness', namely the nappa type leather.

Compared with the traditional textured sofa leather, the nappa-type plane sofa leather has the general characteristics of comfortable hand feeling, uniform and consistent thickness of the whole leather, light resistance, wear resistance, abrasion resistance, good physical and mechanical strength and the like, also has the nappa leather characteristics of flat, fine and compact grain surface, soft, full and elastic body and smooth and moist surface and the like, and conforms to the current fashion trend. However, in recent years, the growth cycle of beef cattle at home and abroad is short (basically less than 1.5 years), the cattle raw leather fiber is woven loosely, which causes great difficulty to the production of compact leather, so that the problems of poor compactness, high surface tension, falling resistance, stretching resistance and the like of the conventional plane sofa leather generally exist. In addition, the current production of the flat sofa leather mainly adopts a chromium retanning process, so that the pollution is serious.

Disclosure of Invention

The embodiment of the application provides the napa type high-grade plane sofa leather and the production process thereof, and solves the problems of poor compactness, high surface loosening rate, falling resistance and tension resistance in the production and processing process of the plane sofa leather in the prior art; the prepared nano-handkerchief type high-grade plane sofa leather has the general characteristics of comfortable hand feeling, uniform and consistent thickness of the whole leather, light resistance, wear resistance, abrasion resistance, good physical and mechanical strength and the like, and also has the excellent performances of fine, compact and loose grain surface, full and soft body and bones, silky and moist surface touch feeling and the like, and the process does not adopt chromium powder and chromium-containing materials in the implementation process, thereby effectively reducing the environmental pollution and improving the ecological environmental protection performance.

The embodiment of the application provides a production process of Napa-type high-grade plane sofa leather, which sequentially comprises the following procedures of blue wet leather batching → water squeezing, splitting, shaving, weighing → softening → neutralization I → retanning filling I → aluminum retanning → neutralization II → retanning filling II, dyeing → fatliquoring → dry finishing → coating;

adding sodium formate, sodium bicarbonate, a neutralizing agent, a polymer retanning agent and a synthetic ester compound fatliquor in the step I and the step II;

adding a polymer retanning agent, a synthetic tanning agent and a composite resin tanning agent in the step I of retanning filling;

adding an aluminum-containing tanning agent, an amphoteric biopolymer and an electrolyte-resistant fatliquor in the aluminum retanning procedure;

and adding a polymer retanning agent, a synthetic tanning agent, a composite resin tanning agent, a plant tannin extract and a neat foot oil fatting agent in the retanning filling II and dyeing processes.

Furthermore, oxalic acid, a multifunctional rewetting agent and an enzyme-containing degreasing agent are at least added in the softening procedure;

in the step of fatliquoring, at least a fatliquoring agent and a polymer retanning agent are added;

the drying and finishing process at least comprises squeezing and stretching, drying and finishing, wet toggling, moisture returning, vibrating and softening, breaking and drying toggling.

Further, the neutralization I process comprises the following steps: adding 50-150 parts of 25-35 ℃ water, 1-2 parts of strong base and weak acid salt and 1-2 parts of neutralizing agent into a rotary drum, rotating, and adjusting the pH value of bath liquid to 4.5-5.0;

the retanning filling procedure I comprises the following steps: adding 2-5 parts of polymer retanning agent into the bath solution of neutralization 1, and rotating; adding 2-5 parts of synthetic tanning agent and 3-6 parts of composite resin tanning agent, and rotating; adding 1-2 parts of formic acid, rotating, and adjusting the bath liquid ph to 3.4-3.6;

the aluminum retanning procedure comprises the following steps: adding 2-5 parts of aluminum-containing tanning agent, 1-3 parts of amphoteric biopolymer and 0.5-1.5 parts of electrolyte-resistant fatliquor into retanning filling 1 bath solution, and rotating; adding 1-2 parts of sodium formate, and rotating; adding 0.2-0.8 part of baking soda, rotating, adjusting pH of bath liquid to 3.8-4.2, and discharging liquid;

the step II of neutralization is as follows: adding 200 parts of water at 25-35 ℃, 2-4 parts of strong base and weak acid salt and 1-2 parts of neutralizing agent into the rotary drum, rotating, and adjusting the pH value of the bath liquid to 4.8-5.2; adding 1-3 parts of polymer retanning agent and 1-2 parts of synthetic ester compound fatliquoring agent, rotating and discharging liquid;

the retanning filling II and dyeing process comprises the following steps: adding 20-100 parts of water with the temperature of 25-35 ℃ and 3-8 parts of polymer retanning agent into the rotary drum, and rotating; adding 2-5 parts of plant tannin extract, 5-8 parts of composite resin tanning agent, 3-6 parts of synthetic tanning agent, 0.5-1.5 parts of neatsfoot oil fatting agent and dye, and rotating; adding 2-5 parts of polymer retanning agent, and rotating; adding water of 100-200 parts at 50-60 ℃ and formic acid of 0.5-1.5 parts, rotating, adjusting the pH value of the bath liquid to 4.0-4.2, and discharging the liquid.

Further, the step of greasing is as follows: adding 200 parts of water at 50-60 ℃, 8-15 parts of fatting agent and 1-3 parts of polymer retanning agent into the rotary drum, and rotating; adding 1-2 parts of formic acid, rotating, adjusting the pH value of the bath liquid to 3.4-3.6, and discharging liquid;

the rewetting process comprises the following steps: adding water of 150-300 parts at 35-45 ℃, oxalic acid of 0.2-1.0 part, multifunctional rewetting agent of 0.3-1.0 part and enzyme-containing degreasing agent of 0.5-1.5 part into the rotary drum, rotating, controlling the pH value of the final bath liquid at 3.0-3.5, and discharging the liquid.

Further, the drying and finishing temperature is 30-40 ℃, the time is 2-5min, and the water content is controlled to be 40-50%;

the temperature of the wet toggling plate is 40-50 ℃, the toggling distance is 1-6cm, and the water content is controlled at 6-10%;

the rewetting is double-sided water spraying, standing for 8-12h, and controlling the water content at 13-16%;

the milling time is 10-30h, and the water content is controlled at 15-20%;

the temperature of the dry stretching plate is 40-50 ℃, the stretching distance is 6-12cm, and the water content is controlled at 10-15%.

Further, the polymer retanning agent is selected from at least two of an acrylic polymer retanning agent, a polyurethane polymer retanning agent, a vinyl polymer retanning agent, a hyperbranched polymer retanning agent and an amphoteric polymer retanning agent.

Further, the aluminum-containing tanning agent is selected from at least one of an aluminum complex tanning agent, a zirconium-aluminum complex tanning agent and a zirconium-aluminum-titanium complex tanning agent.

Further, the plant tannin extract is selected from at least one of wattle tannin extract, quebracho tannin extract, tara tannin extract and white tannin extract;

the synthetic tanning agent is at least two selected from phenolic synthetic tanning agent, naphthalene synthetic tanning agent, sulfone synthetic tanning agent and sulfonic acid synthetic tanning agent.

Further, the fatliquor is selected from at least four of lecithin fatliquor, synthetic fatliquor, phospholipid mixed fatliquor, phosphorylation fatliquor, neat's foot oil fatliquor and lanolin fatliquor.

A Napa type high-grade plane sofa leather is prepared by the method described in the application.

One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

1. in the prior art, an operation method of 'chrome retanning → neutralization → filling' is generally adopted, wherein neutralization and retanning filling are carried out at one time after a chrome retanning process, and as a chrome tanning agent has strong cationic property, a subsequent anionic retanning filling material is often insufficient in penetration and uneven in distribution, the retanning filling effect is improved, the using amount of the retanning filling material is often increased, and the grain surface deposition phenomenon is also generated, so that the problems of stiff and thin leather body, rough grain surface, uneven filling, loose surface, falling resistance, stretching resistance and the like are finally caused. According to the operation method of 'neutralization I → retanning filling I → aluminum retanning → neutralization II → retanning filling II', before the cationic tanning agent is retanned to enhance the positive electrical property (aluminum retanning), firstly, a part of polymer retanning agent, synthetic tanning agent and composite resin tanning agent are matched to carry out first-step retanning filling (retanning filling I), so that the retanning filling material is favorable for deeply permeating and uniformly distributing in the leather, and firstly, neutralization (neutralization I) is carried out before the first-step retanning filling (retanning filling I), a chromium ion active group released by softening the retanning filling material is sealed by using a strong alkali weak acid salt and a neutralizing agent, so that a channel of the retanning filling material permeating to the center in the leather is further opened, and finally, a deeply permeating and uniformly distributed retanning filling effect is obtained in the leather, so that the leather body has good bone and meat feeling; then, carrying out aluminum retanning operation, replacing a chrome tanning agent with an aluminum-containing tanning agent and an amphoteric biopolymer for retanning, on one hand, strengthening the retanning filling effect by using the good tanning property of the aluminum-containing tanning agent and the amphoteric biopolymer, and improving the compactness and the flatness and fineness of the grain surface of the leather, on the other hand, fixing the first-step retanning filling material by using the cationic property of the aluminum-containing tanning agent and the amphoteric biopolymer, and further improving the retanning filling effect; after aluminum retanning is finished, the inside of crust leather is well filled and is uniform, then secondary neutralization (neutralization II) and retanning filling (retanning filling II) are carried out, the aluminum ion active group brought by chrome retanning is sealed by using strong base, weak acid salt and neutralizing agent in the secondary neutralization (neutralization II), the permeation channel of the retanning filling material is opened again, secondary retanning filling (retanning filling II) is carried out, the retanning filling effect is further enhanced by using polymer retanning agent, synthetic tanning agent, composite resin tanning agent and vegetable tanning extract, meanwhile, the added neat foot oil fatliquor can promote the uniform permeation of the retanning filling material, reduce grain surface deposition and endow leather with firm and soft hand feeling, and then the polymer retanning agent is continuously used for tightening grain surfaces, and improving the body fullness and grain surface compactness; finally, after secondary filling, a uniform, complex and stable multi-center multi-level net-shaped cross-linking structure (collagen fiber- "polymer retanning agent, synthetic tanning agent, composite resin tanning agent" - "aluminum-containing tanning agent, amphoteric biopolymer" - "polymer retanning agent, synthetic tanning agent, composite resin tanning agent, plant tannin extract" - "polymer retanning agent" - "collagen fiber) is formed in the leather from inside to outside, so that deep penetration and uniform retanning filling effects are obtained, the bone of the leather is soft, full and elastic, the whole body is uniform and rich in cotton bubble feeling, the grain surface is smooth, fine, compact and not loose, and mechanical operations such as falling, softening, toggling and the like are resisted.

2. The method adopts oxalic acid, a multifunctional rewetting agent and an enzyme-containing degreasing agent to carry out softening, wherein the oxalic acid mainly plays a role in rinsing the grain surface, washes away chromium ions which are not firmly combined in the leather and are unevenly combined on the leather surface, and releases active groups on collagen fibers; the multifunctional rewetting agent plays a role in deeply penetrating and uniformly rewetting, deeply permeates the leather core, lubricates collagen fibers and opens a permeation channel of a subsequent material; the enzyme-containing degreasing agent has mild performance and dual functions of rewetting and softening, emulsifies grease in leather, loosens fibers in the leather and opens grain surface lines, can effectively improve the leather yield, and simultaneously plays a certain role in protecting a fiber crosslinking structure in the leather, so that grain surface blistering and loose surface caused by damage can be avoided; the three components are combined to play a role in deeply penetrating, uniformly and softly rewetting and softening, and lay a foundation for obtaining flat, thin, compact, soft and plump body bones.

3. The nappa-type high-grade plane sofa leather prepared by the production process of the nappa-type high-grade plane sofa leather has the general characteristics of comfortable hand feeling, uniform thickness of the whole piece of leather, light resistance, wear resistance, abrasion resistance, good physical and mechanical strength and the like, and also has the excellent performances of fine, compact and loose grain surface, plump and soft body, silky and moist surface touch and the like, and effectively solves the problems of poor compactness, high loose surface rate, falling resistance and tension resistance existing in the production and processing processes of the current plane sofa leather, and the process does not adopt chromium powder and chromium-containing materials in the implementation process, thereby effectively reducing the environmental pollution and improving the ecological environmental protection performance; and the process flow is simple and easy to realize, convenient to operate, simple, direct and practical, and has high leather yield and strong practicability.

Detailed Description

In order to better understand the technical solutions, the technical solutions will be described in detail with reference to the description and the specific embodiments.

A production process of nappa-type high-grade plane sofa leather comprises the following process steps:

step (I), batching blue wet leather: classifying the wet blue leather according to the principle that the leather source is consistent in producing area, size, thickness and grade to form a production batch;

step two, water squeezing, peeling, shaving and weighing: sequentially carrying out water squeezing, splitting, shaving and weighing on the selected blue wet leather in the batch; the dosage of the reagent used in the subsequent procedures is calculated according to the weight percentage of the shaved wet blue leather obtained by weighing (namely the shaved wet blue leather is 100 percent, the dosage of the oxalic acid is 0.5 percent, namely the shaved wet blue leather is 100kg, and the oxalic acid is 0.5 kg);

softening in the third step: adding 250 parts of water with the temperature of 40 ℃, 0.5 part of oxalic acid (conventional industrial oxalic acid), 0.5 part of multifunctional rewetting agent (MPC of the West chemical company) and 1 part of enzyme-containing degreasing agent (80 PA of the Cromo chemical company) into a rotary drum, rotating for 120min, and discharging liquid when the pH value of the final-point bath liquid is 3.3;

step (IV) neutralization I, namely adding 100 parts of 30 ℃ water, 1.5 parts of strong base weak acid salt (1 part of conventional industrial sodium formate and 0.5 part of conventional industrial baking soda) and 1 part of neutralizer (PAK of Langshan chemical company) into a rotary drum, rotating for 90min, and controlling the pH value of the bath solution at the end point to be 5.0;

step (V), retanning and filling I: adding 3 parts of polymer retanning agent (vinyl polymer retanning agent Q-307 of EXCL chemical company) into neutralization 1 bath solution, and rotating for 60 min; adding 3 parts of synthetic tanning agent (sulfonic acid synthetic tanning agent BL of Baistum chemical company) and 4 parts of composite resin tanning agent (XHL of basf chemical company), and rotating for 60 min; adding 1.5 parts of formic acid (conventional industrial formic acid), rotating for 40min, and bath liquid ph is 3.5;

step (six), aluminum retanning: adding 4 parts of aluminum-containing tanning agent (aluminum tanning agent BN of basf chemical company), 2 parts of amphoteric biopolymer (X-R of Langshan chemical company) and 1 part of electrolyte-resistant fatliquor (B1 of Toeplier chemical company) into retanning filling 1 bath solution, and rotating for 90 min; adding 2 parts of sodium formate, and rotating for 30 min; adding 0.5 part of baking soda, rotating for 60min, discharging liquid when the pH value of the bath liquid is 4.0 at the end point;

step (seven) neutralization II: the step II of neutralization is as follows: adding water 150 parts at 30 deg.C, strong base weak acid salt 3 parts (sodium formate 2 parts, sodium bicarbonate 1 part), and neutralizer 1.5 parts (FBV of ATC chemical company), rotating for 60min to obtain bath solution with pH of 5.0; adding 2 parts of polymer retanning agent (acrylic acid polymer retanning agent B4 of TAGE chemical company) and 1 part of synthetic ester compound fatting agent (505 of KEY chemical company), rotating for 60min, and discharging liquid;

step (eight) retanning filling II and dyeing: adding 30 deg.C water 50 parts and 6 parts polymer retanning agent (EXCL vinyl polymer retanning agent Q-3073 parts, Apa chemical company acrylic acid polymer retanning agent TP3403 parts) into the rotary drum, and rotating for 80 min; adding 4 parts of plant tannin extract (VW 2 parts of white tannin extract of Steyr chemical company, TARA2 parts of Tara tannin extract of Demei chemical company), 6 parts of composite resin tanning agent (XHL 3 parts of Pasv chemical company, 608/C3 parts of Keka chemical company), 5 parts of synthetic tanning agent (RL 2 parts of sulfone synthetic tanning agent of Derui chemical company, 144683 parts of phenol synthetic tanning agent of Macrolin chemical company), 1 part of neatsfoot oil fatting agent (FL-75 parts of Daviga chemical company) and dye, and rotating for 90 min; adding 3 parts of polymer retanning agent (amphoteric polymer retanning agent R83 from Langshan chemical company), and rotating for 40 min; adding 150 parts of water with the temperature of 55 ℃ and 1 part of formic acid, rotating for 40min, discharging liquid when the pH value of the bath liquid at the end point is 4.0;

step (nine) fat liquoring: adding 150 parts of water with the temperature of 55 ℃, 13 parts of fatting agent (lecithin fatting agent LC-133 parts of Keka chemical company, synthetic fatting agent 94S 3 parts of Sima chemical company, phospholipid mixed fatting agent DB 2 parts of Thompler chemical company, neat' S foot oil fatting agent CK 3 parts of Taige chemical company, lanolin fatting agent ZBN 2 parts of Bai Europe chemical company) and 2 parts of polymer retanning agent (acrylic polymer retanning agent HF of Pasf chemical company) into a rotary drum, and rotating for 90 min; adding 1.5 parts of formic acid, rotating for 60min, discharging liquid when the pH value of the bath liquid is 3.5 at the end point;

step (ten) drying and finishing: squeezing and stretching the greased and out-rolled crust leather, drying and finishing, wetting the flat, rewetting, vibrating and softening, breaking soft and drying the flat in sequence, wherein the temperature for drying and finishing is 35 ℃, the time is 4min, the moisture content is controlled to be 40-50%, the temperature for wetting the flat is 45 ℃, the stretching distance is 3cm, the moisture content is controlled to be 6-10%, the rewetting is double-sided water spraying, standing is 10h, the moisture content is controlled to be 13-16%, the time for breaking soft is 20h, the moisture content is controlled to be 15-20%, the temperature for drying the flat is 45 ℃, the stretching distance is 12cm, and the moisture content is controlled to be 10-15%;

coating: sequentially performing repairing, leather grinding, bottom slurry spraying, roller burnishing, roller pore pattern rolling, softening, surface slurry spraying, roller burnishing, hand slurry spraying and roller burnishing on the dried and finished crust leather, wherein the repairing comprises scraping and roller repairing, the leather grinding comprises point grinding and surface grinding, the roller pore pattern comprises roller coarse pore patterns and roller fine pore patterns, the temperature of the roller pore patterns is 120-150 ℃ and the pressure is 50-100kg, the temperature of the roller pore patterns is 100-130 ℃ and the pressure is 20-50 kg.

The leather obtained by the production process of the nano-handkerchief type high-grade plane sofa leather has the general characteristics of comfortable hand feeling, uniform and consistent thickness of the whole leather, light resistance, wear resistance, abrasion resistance, good physical and mechanical strength and the like, and also has the excellent performances of fine, compact and loose grain surface, plump and soft body, silky and soft foam, silky and moist surface touch feeling and the like, and is resistant to falling and stretching, and high in leather yield.

The above description is only an embodiment utilizing the technical content of the present disclosure, and any modification and variation made by those skilled in the art can be covered by the claims of the present disclosure, and not limited to the embodiments disclosed.