REPORTS OF CHEMİCAL LEVANT AND MİXED TANNAGES PRACTİCES BY;EGEMEN

Aims:

Aim of  chemical levant: Skin from a worn out, see how different influence basified, and tannagespretannage to achieve different results in the twitching.

Aim of mixed tannages: from pickled skin, tanned and oiled, to see how different influenceretanning with aluminum salts, zirconium salts, iron salts and zinc salts.

CHEMİCAL LEVANT

•          Chemical levant refer leathers whose grain has been purposely shrunk. Often, the opposite has to be effected on other typed of leathers as they follow certain norms.This type of leather is used for footwear and fancy leather.The chemical levant process is a strong and astringent shrinking of the outer part of the leather (flesh and grain) caused by the superficial precipitation on the surface of astringent products of large molecule. These products become irreversibly fixed to the surface since levant conditions are extreme in terms of pH, temperature and concentration, both applying to the leather and to the product with levant chemical base.

•          We used pickle conservations leathers.We started  processes without water.we give chemical levants directly.These leathers has special effects.Their grain has been purposely shrunk and regional effects. We use these leathers  for footweat and fancy leather. They seems different from classic leathers. Shrunk effect related with  sudden changeable conditions such as these products become irreversibly fixed to the surface since levant conditions are extreme in terms of pH , temperature and concentration, both applying to the leather and to the product with levant chemical base. The leather is more sensitive to chemical sudden reactions, it has more reactive points, it is more collagenically pure, and more sensitive to changes in pH, temperature and concentration after bating. After this process, the pH is between 7.5 and 8.5, having washed at 20ºC, and the leather is collagenically clean.We can say some factors in chemical levants: type and amount of basifying product,type of product ,syntans , vegetable tannins,glutaraldehid ,amount of float,mechanical effect. These factors caused degree of special effects  an process time. Some factors like as mechanical effect and amount of float  related with physical effect.

•          Factors:

Type and amount of basifying product:before rettanning we have basification.more amount more basifying and slow basifying products are better for the result.

              

               Syntans:  they are special tanning material for the production of shrunken grain leather. Ensures   particularly uniform shrinkage of the grain.

            Vegetable tannins:gives more firm leathers for shrunken effect.

            Glutaraldehid:it gives white colour so that dyeing could be easier and better.

           Amount of float:must be right volume otherwise could be not enough penetration and fixation

          Mechanical effect:it develops penetrating

          Aldehydes:these are good levant agents although with a more empty appearance.glutaraldehyde is the more commonly employed one.

                  C5H8O2      O=CH-CH2-CH2-CH2-CH=O

Its in 50% solution,with pH between 3 and 4,the working scale of Ph ranges between 2 and9;maximum fixation is obtained at neutral pH,and prepication at pH higher than 7.This is the base of levants with aldehyde,where glutaric aldehyde forms covalent bonds with collagen fibres when using two extreme functional groups,giving irreversible and strong bonds.

With amino groups it my react in 3 ways:

MİXED TANNAGE

•          Chromium is not so ecofriendly  so that  people research new tanning metarials. These are more ecofriendly than  chromium. zirconium,iron,copper,aluminium salts as tanning  retanning agents is well known.

ALUMINIUM SALTS : Aluminium gives white colour to the leather so that we  call the leather wet white.Reactions of aluminium with carboxyl groups isless strong than chromium reactions.So that aluminium does not have strong bonds with collagen than it can easily remove  with washing so their washing fastness is not good.Tanned leathers with aluminium are more hard,firm and not washing prof.Shrinkage temperature is about 70 C.When comparing with chromium its cheaper and more ecofriendly and gives white leathers it has advantages in dyeing process.Aluminium uses in tanning as Kal(SO4)2.12H2O or as Al(SO4) or AlCl3 form.Because of some dissadvantages of tanning leathers only with aluminium its more useful to make combinations with other tanning materials like chromium,vegetable,aldahydes or zirconium.We can prepeare basic aluminium sulphate  (%33 basicty)  like as chromium sulphate .For example 10 kg  Al2(SO4)3  and 10 kg water mix . One night waiting gives better results. The next day 700 gr sodium cytrate adding  and mixing. In addition another solution prepared (20 kg water  and 1.750 gr sodiumcharbonate)  and adding into the  first solution. SO we have Al2O3. Another Aluminium salt is AlCl3 .AlCl3 has less tanning power than Al2(SO4)3.

Aluminium  can’t occur stabile acid complex with carboxyl groups of collagen so that washing and shrinkage temperature less than wet white tanned leathers.

ZIRCONIUM SALTS :  Basic Zirconium salts have definite tanning action with a shrinkage temperature of 90-95 ⁰C. Such leather is of firm, full substance and has excellent white apparence. As with chromium, the sulphate, rather than the chloride, is the prefered starting material for making the tanning salt. It would find wide application provided high cost of tannin salts could be diminished. Large amounts of zirconium salts are needed (more than double the amount required for chromium tannage) to produce satisfactory leather, this is particularly with solutions of 33 % basicity and may be  due to large particle size involved. Zirconium tannage most probably is a salt formation involving anionic zirconium complexes and basic groups in collagen.
Zirconium is Zr⁺⁴ and has coordination number 8. Neither the zirconyl group, Zr=O, nor the Zr-Zr group is found in solution.

We can have bright colur tones with  anionic dyestuffs  in zirconium tanned leathers. The initial working pH will be lower than 3 in order to prevent a surface precipitation on the surface of the basic zirconium sulphate .An effective fatliquoring of the grain has to be carried out subsequently during the course of the dyeing and fatliquoring operations.

IRON SALTS :  Iron tanned leathers similar to aluminium or chrom tanned leathers . they seems same characteristics like as aluminium and chrom. Masking degree is important factor for iron tanning. Because it can be change between pH 2 – 5.5 . if we shouldn’t careful , may occur precipitating on grain .We can use hydroxide for masking but hydroxacids from high stable complex but they also decrease  iron tanning ability. Fixation speed is depend on  concentration of iron salts. Iron tanned leathers has  between 90 -95 C shrinkage temperature. We have  compact leathers, grain is dry  some region cracky with iron tanning.Their characteristic like  as vegetable tanned leathers.

ZINC SALTS : Zinc is not tanning material which that can be coordinated with phenolic groups  of the different molecules of  the vegetable tannins.They can increase crosslinks among of collagen fibres . Zinc  occur  big complexes with tannın molecules. So that increase shrinkage temperature 100-110 C .We use with quebracho or mimosa tannins commonly. If we use high concentration of zinc in tannery, tensile strength elongation and crack resistance decrease. However, if we use sulphate zinc with chestnut tannins  these properties increase.

    BIBLIOGRAPHY

·         http://www.leatherchemists.org

·        Prof. Dr. Özcan Sarı, Tabaklama Maddeleri Ders Notları, Ege Üniversitesi Deri Mühendisliği Bölümü

·        Yrd. Doç. Dr. Selime Çolak, Deri Teknolojisi-1 Ders Notları, Ege Üniversitesi Deri Mühendisliği Bölümü

·        JEFFRY JAMES GUTHRIE-STRACHAN-THE INVESTIGATION, DEVELOPMENT AND CHARACTERISATION OF NOVEL ZIRCONIUM-BASED TANNING AGENTS

4. Chemical levant



Tense chemical: name that is known to hides where there has been a tension in the flower. Often, you have to do the opposite of what for other kinds of leather are rules.This type of leather used for footwear and leather goods.

Objectives: Skin from a worn out, see how different influence basified, and tannages pretannage to achieve different results in the twitching.

Operating Method: a large piece of skin rendered cut 6 small pieces which are made in a different tanning pretannage and described below.






Practice 1:

Skins: rendered undrained


Basification 1.8% Basifying
Ride 30 minutes.
Pretannage: 2% aldehyde
Ride 30 minutes.
6% synthetic retanning
Acidification: 1.5% formic acid
Roll 2 hours. Look pH.
Drain bathroom.
Tanning: 50% Water at 35 ° C
6% 66% chromium salt basicity
Roll 6 hours. Watch the pH.















Practice 2:

Skins: rendered and drained


Basification: 2% sodium carbonate
Ride 30 minutes.
Pretannage: 2% aldehyde
Ride 30 minutes.
6% synthetic retanning
Acidification: 1.5% formic acid
Roll 2 hours. Look pH.
Drain bathroom.
Tanning: 50% Water at 35 ° C
6% 66% chromium salt basicity
Roll 6 hours. Watch the pH.















Practice 3:

Skins: rendered and drained


Pretannage: 10% synthetic retanning
2.5% formic acid
Shooting 3 hours. Look pH.
Drain bathroom.
Tanning: 50% Water at 35 ° C
6% 66% chromium salt basicity
Roll 6 hours. Watch the pH.

Practice 4:

Skins: rendered and drained


Pretannage: 10% synthetic retanning
2.5% formic acid
Roll 2 turns. Stop 30 minutes.
Roll 2 turns. Stop 30 minutes.
Roll 2 turns. Sleep night. Watch the pH.
Drain bathroom.
Tanning: 50% Water at 35 ° C
6% 66% chromium salt basicity
Roll 6 hours. Watch the pH.


Practice 5:

Skins: rendered and drained


Pretannage:chestnut 10%
6% synthetic retanning
2.5% formic acid
Roll 6 hours. Watch the pH.
Drain bathroom.
Tanning: 50% Water at 35 ° C
6% 66% chromium salt basicity
Roll 6 hours. Watch the pH.



Practice 6:

Skins: rendered and drained


Pretannage: 10% Quebracho
6% synthetic retanning
2% formic acid
Roll 6 hours. Watch the pH.
Drain bathroom.
Tanning: 50% Water at 35 ° C
6% 66% chromium salt basicity
Roll 6 hours. Watch the pH.

Results and conclusion;

We can see we have differences drained or undrained  drained leather 2th one levant grains obtained are smaller and highly embossed.1th is soft shrink and 2th one has more effective looking.3th one we made regular crispy we can see 3th one is more homogenius but 4th one is irregular type so we can see effects on surface.differencers between 2 and 3 is in 2 we used bazifying and aldehyde aldehyde gave more empty appearance and more effect on surface we can see.6th one is less shrinking than 5th one and more regular also and more effective looking.most shrinking one is chestnut (5th) one.than 6th than 2th than 3th and 4th than 1th one.first one has more blue appearance 2th one is effective appearance with Brown on blue and 3th has most white appearance and 4th one is irregular type of 3th one we can say with blue dark effects on surface.and 5th and 6 th ones we used vegetable tannins so we can see colours like Brown and 5th one is more irregular and effect on surface we can see.

5. Mixed tannages


Tannages mixed: The chrome tanning as well as being the most widely used is the one that has received in recent years more stringent environmental restrictions. In addition to cultural pressure toward advertising tanning methods or processes greener. This has prompted consideration of other combinations that could replace its use with more or less security.

Employment as a tanning-retanning of basic salts of aluminum, zirconium, titanium, iron, copper, etc.. is known and feasible for certain desired characteristics for chrome tanning.

Objectives: from pickled skin, tanned and oiled, to see how different influence retanning with aluminum salts, zirconium salts, iron salts and zinc salts.

Operating Method: a large piece of skin pickling, tanning and will be a certain grease then cut 4 pieces to make a retanning with different salts.



Practice 1: retannage with aluminum salts

Skins: pickled to pH 4.5 to 4.8
Weight% of pickling
Tanning: 50% Water at 20 ° C
4% synthetic dispersant
Mimosa 10%
Sulfitado fatliquoring stable 0.5%
Roll 2 hours.
Mimosa 15%
Roll to penetrate.
Flush.
Drain and cut to 1.7 to 1.75 mm.

Grease: 100% Water at 45 ° C
4% sulfonated fatliquoring ox leg
2% synthetic sulfitado fatliquoring
Fatliquoring 2% crude ox leg
Roll 90 minutes. Watch the pH.
Drain the bath.
Watch the temperature of contraction at 24 hours.

Retanning: 100% Water at 25 ° C
Ride 5 minutes.
Drain the bath
100% Water at 30 ° C
10% basic aluminum sulfate adjusted to pH = 2.5 HCOOH
Shooting 3 hours. (To cross). pH = 2.8 to 3. Bath exhausted.
Sodium bicarbonate 1.1% (1:20)
Roll 2 hours. pH = 5.0 to 5.5
Drain bathroom.
Grease: 100% Water at 45 ° C
4% of beef leg fatliquoring sulfonated
2% synthetic sulfitado fatliquoring
Fatliquoring 2% raw beef leg
20% Water at 50 ° C
Roll 90 minutes.
Look pH and bath exhaustion.
Drain bathroom.
Rest for 24 hours.
Watch the temperature of contraction.



Practice 2: retannage zirconium salts

Skins: pickled to pH 4.5 to 4.8
Weight% of pickling
Tanning: 50% Water at 20 ° C
4% synthetic dispersant
Mimosa 10%
Sulfitado fatliquoring stable 0.5%
Roll 2 hours.
Mimosa 15%
Roll to penetrate.
Flush.
Drain and cut to 1.7 to 1.75 mm.

Grease: 100% Water at 45 ° C
4% sulfonated fatliquoring ox leg
2% synthetic sulfitado fatliquoring
Fatliquoring 2% crude ox leg
Roll 90 minutes. Watch the pH.
Drain the bath.
Watch the temperature of contraction at 24 hours.

Retanning: 100% Water at 25 ° C
0.5% formic acid (1:5)
Roll 10 minutes.
Drain the bath
50% Water at 20 ° C
2% formic acid (1:5)
Roll 10 minutes. pH = 2.5
7% zirconium sulfate
Roll 4 hours. (To cross). pH = 2.5 to 2.8. Bath exhausted.
Sodium bicarbonate 2.2% (1:20)
Roll 2 hours. pH = 4.5 to 5.0
Drain bathroom.

Grease: 100% Water at 45 ° C
4% of beef leg fatliquoring sulfonated
2% synthetic sulfitado fatliquoring
Fatliquoring 2% raw beef leg
20% Water at 50 ° C
Roll 90 minutes.
Look pH and bath exhaustion.
Drain bathroom.
Rest for 24 hours.
Watch the temperature of contraction.



Practice 3: retannage with iron salts

Skins: pickled to pH 4.5 to 4.8
Weight% of pickling
Tanning: 50% Water at 20 ° C
4% synthetic dispersant
Mimosa 10%
Sulfitado fatliquoring stable 0.5%
Roll 2 hours.
Mimosa 15%
Roll to penetrate.
Flush.
Drain and cut to 1.7 to 1.75 mm.

Grease: 100% Water at 45 ° C
4% sulfonated fatliquoring ox leg
2% synthetic sulfitado fatliquoring
Fatliquoring 2% crude ox leg
Roll 90 minutes. Watch the pH.
Drain the bath.
Watch the temperature of contraction at 24 hours.

Retanning: 100% Water at 25 ° C
Ride 5 minutes.
Drain the bath
50% Water at 30 ° C
0.5% formic acid (1:5)
Roll 1 hour. pH = 3.2 to 3.4
4% iron oxide from hydrated iron sulphate
Roll 4-5 hours. (To cross).
pH = 3.8 to 4. Very dark brown.
Sodium bicarbonate 2.2% (1:20)
Roll 2 hours. pH = 6.8 to 7.0
Drain bathroom.

Grease: 100% Water at 45 ° C
4% of beef leg fatliquoring sulfonated
2% synthetic sulfitado fatliquoring
Fatliquoring 2% raw beef leg
20% Water at 50 ° C
Roll 90 minutes.
Look pH and bath exhaustion.
Drain bathroom.
Rest for 24 hours.
Watch the temperature of contraction.



Practice 4: retannage with zinc salts

Skins: pickled to pH 4.5 to 4.8
Weight% of pickling
Tanning: 50% Water at 20 ° C
4% synthetic dispersant
Mimosa 10%
Sulfitado fatliquoring stable 0.5%
Roll 2 hours.
Mimosa 15%
Roll to penetrate.
Flush.
Drain and cut to 1.7 to 1.75 mm.

Grease: 100% Water at 45 ° C
4% sulfonated fatliquoring ox leg
2% synthetic sulfitado fatliquoring
Fatliquoring 2% crude ox leg
Roll 90 minutes. Watch the pH.
Drain the bath.
Watch the temperature of contraction at 24 hours.
Retanning: 100% Water at 30 ° C
Ride 5 minutes.
Drain the bath
50% Water at 35 ° C
0.5% formic acid (1:5)
Roll 1 hour. pH = 3.2 to 3.4
10% zinc sulfate hydrate
Roll 4-5 hours. (To cross).
pH = 3.8 to 4. Brown color.
Sodium bicarbonate 2.5% (1:20)
Roll 2-3 hours. pH = 6.8 to 7.0
Drain bathroom.

Grease: 100% Water at 45 ° C
4% of beef leg fatliquoring sulfonated
2% synthetic sulfitado fatliquoring
Fatliquoring 2% raw beef leg
20% Water at 50 ° C
Roll 90 minutes.
Look pH and bath exhaustion.
Drain bathroom.
Rest for 24 hours.
Watch the temperature of contraction.

Results and conclusion;

First one is aluminium basic sulphate tanned so we can see frim and whiter tones of hue.2th one is zirconium tanned leather  it has quite same characteristics with aluminium but more intensity on the colour we can see.3th one is iron tanned leather its colour black its softer than others its like chromium leather but some region is cracy.4th one is zinc tanned its most firm one colour darker like between  brown and light red.if we compare leathers by firmness:4>1>2>3,we found shrinkage temperatures aluminium 75C,zirconium 92C,iron 90C,zinc 102C so if we compare shrinkage temperature 4>2>3>1.

REPORTS OF CHEMİCAL LEVANT AND MİXED TANNAGES PRACTİCES

BY;EGEMEN