Ideas and control points of blue leather process of natural falling sofa leather

Natural drop sofa leather is popular with end customers by its soft feel, natural and full pattern in the market, the market sales is very good in recent years.  Here I make a note for my experience and idea that I accumulated during many years of blue skin production for everyone’s reference. 

Cow skin and female cow skin is preferred in the production of natural sofa blue leather, because the grain surface layer of these two types of raw skin is thinner, it is easy to make the grain soft in the process of processing, it is easy to fall off large and full pattern during the process of fall of the leather crust.  But these two kinds of raw skin have natural quality defects, such as parts of the difference, thin side abdomen, empty loose.  At the same time, in order to pursuit the high yield rate and soft feel of sofa leather, the fiber loose very open and make coxal and body feel well while the side abdomen appears loose face.  So the first is to consider the weak part of this kind of raw skin in the production.  While reducing the difference in the blue skin, the overall softness may be somewhat lost, because the softness of the skin can be further adjusted by the retanning oil.  If the uniformity of blue leather is not good, the position difference is too large, it will be difficult to balance the process focus while the process of retanning and oiling.  

Process ideas and control points:  

1. Pre-soaking: the temperature should not be too high, generally 24-27 degrees is very appropriate.  Mechanical action should not be too strong, in the early feeding can turn 60-90 minutes, and then to turn and stop combined.  Depending on the condition of the raw skin, the average time is between 5 and 8 hours.  Dried rind can be extended appropriately.  The pH of the whole process should be controlled in the range of 9-8, and avoid too low pH that can cause slipping hair.  At the same time, fungicide TJ-A2266 can be added to inhibit bacterial reproduction, so as to protect the grain.  After pre-soaking, when removing meat, pay attention to the preservation of the meat membrane of the side abdomen, which can properly protect the side abdomen to a certain extent.  Soaking agent selection such as TJ-A139 anionic wetting speed and uniform material, at the same time with DOE this kind of environmental protection non-ionic degreasing agent, degreasing and emulsifying effect balance degreasing agent, can achieve the ideal backwater and degreasing effect.  

2. Main soaking: temperature 24-27 degrees, in the initial feeding can continue to turn 60-120 minutes, so that the pH value of the skin is appropriate and uniform, for the subsequent addition of enzyme preparation to create a uniform environment, and then you can play automatic overnight.  The main soaking time is generally controlled in 15-19 hours or so, according to the condition of raw skin to adjust.  The pH of the whole main soaking process should not be lower than 8, otherwise there will be the risk of hair slipping, fungicide TJ-A2266 can be added to effectively inhibit bacterial reproduction.  The proper addition of TJ-A4620 can remove the fibrous interstitium and loose fibers.  In the late stage of immersion, we should pay special attention to the state of the abdomen of the fur side, and check the feel of the hip at the same time, so as to achieve the balanced immersion effect and avoid exacerbating the emptiness of the abdomen.  

3. Liming: choose the liming agent which have good expansion inhibition effect and can help the rapid infiltration of ash alkali liming agent, such as TJ-A3016, it can be very good inhibition of expansion, open the growth lines, help the rapid infiltration of ash alkali.  The total amount of sulfide is generally about 2.1%-2.4%, which needs to fully remove the hair root and skin scale.  The dosage of lime is generally 4%-4.5%, and the expansion agent TJ-A3603E can achieve a good expansion effect.  TJ-A323 can be added at the end of lime dipping and feeding. It has a good dispersing effect on lime, helps lime suspend better in the bath liquid, and makes the expansion of lime skin more uniform.  After soaking the ash overnight, the ash should be controlled to remove about half of the ash solution, and then fill the water by 2% of lime. 

4. Deashing and softening: deashing must be made through the incision. In the selection of deashing agent, try to avoid using boric acid deashing agent alone, because the use of this kind of deashing agent will affect the feel of deashing bare skin.  For example, TJ-A3608E does not contain boric acid and ammonium salt, which is environmentally friendly. After deashing, the naked skin is soft and plump, and deashing is uniform, which can effectively protect the side abdomen and fine grain surface.  If you need a soft feel, the deashing can be appropriate to add ammonium chloride deashing, the effect will be better.  The softening temperature is generally 30-31 degrees, and the dosage of softening enzyme activity 1000LVU is 0.8%-1.5%, depending on the thickness of grey skin and the state of skin.  Softening time 60m-120m, check softening state to meet the requirements can be used to extend the softening time, softening effect more uniform, open growth lines better and larger.  

5. Acid tanning: When acid leaching, TJ-F5195 synthetic fat-adding agent can be appropriately added to further improve the softness.  When soaking in acid, the baume should be controlled between 7-8. If the baume is too high, it will also affect the feel.  Special attention should be paid to pH should be 2.6-2.8 after leaching.  Adding compound TJ-A5210 before tanning can slow down the binding speed of chromium powder and skin fiber, make the grain surface more fine, and make the chromium powder more evenly distributed in the skin, improve the absorption rate of chromium powder, and reduce the chromium content in waste chromium liquid.  Later PH 3.6-3.8 is ok, too high pH will make the blue leather overall feel tight.