For Further Information Please Contact

Head, Leather Chemicals,
Central Leather Research Institute,
Adyar, Chennai – 600 020
Tel : +91 44 2491 5238/2491 1386
Fax : +91 44 2491 5238/24911589
e-mail : bpd@clri.res.in , bpdclri@yahoo.com

 

Leather Chemicals

LEATHER CHEMICAL TECHNOLOGY

Aluminium based syntan (ALUTAN)
It is essentially a synthetinc tanning material based on complexed aluminium, naphthalein sulphonic acid formaldehyde condensed product as the base matrix.The preparation process of the product involves sulphonation of aromatic compound, followed by condensation with amino resin, aluminium salt complexation and subsequent drying. It is a potential partial replacement for chrome, exhibiting high exhaustability, thereby providing eco-friendly option for tanning. It produces soft, supple, full and white leather with little stretch.It is very much suitable for suede leather. It also ensures good brilliance with less amount of dye. The technology has been commercialized.

High performance syntan based on Aluminium and Chromium (ALCROTAN)
It is essentially a synthetinc mineral tanning agent containing chromium and aluminium complexed, naphthalein sulphonic acid being the base matrix.The preparation process of the product involves sulphonation of aromatic compound, followed by condensation, complexation and subsequent drying. It has potential use as a retanning agent. It can also be used as a self-tanning agent. The product exhibits about 96% exhaustability. It ensures rich and uniform dyeing and produces soft and full leather without loaded feel. The technology has been commercialized.

Formaldehyde free chrome syntan (Ecochrome 2000)
The product, which is a homogeneous chemical formulation with 16-18% Cr 2 O 3 , is essentially an organo-chromium complex wherein the polymeric backbone is built up without using formaldehyde. Aromatic polymeric matrix, prepared by treating sulfonated aromatic compound with polymeric network along with ligands, is complexes with chromium (III) to obtain formaldehyde free organo-chrome complex, that can be used as self-tanning as well as retanning agent in leather processing industry. The product withstands precipitation to pH 5.5-6.0. The unique advantage of this product is that it enables pickle-less tanning, thereby reducing a) TDS load by 50-60% and b) chlorides load by 98-99%. It exhibits above 90% chrome uptake with as low as 200ppm of Cr(III) in the effluent as against 3000 ppm in the conventional tanning. The technology is patent protected and has been commercialized.

Formaldehyde free polymeric syntan
The product is essentially a multi-functional organo-polymeric matrix, which is free from formaldehyde. This formaldehyde free polymeric syntan has potential application in chrome tanning of leather as an exhaust aid for chrome. Moreover, it is possible to avoid the pickling operation by using this syntan, which emerges as an effective solution for tackling the problem of TDS associated with the effluent of leather processing industry. Moreover, use of this syntan in tanning enhances the chromium uptake to more than 93%. The presence of this syntan enables a reduction in the offer of filling syntan in wet finishing by about 30-40%. Further, the syntan does not undergo photo-oxidation on ageing. The product provides a very economical as well as eco-friendly option of leather processing.
The technology is patent protected and has been commercialized.

Blended Vegetable Tanning Extract
The extract is manufactured from individual as well as blended vegetable tanning materials. The process involves size reduction of the tannin bearing materials, aqueous extraction, concentration and spray drying. The use of this product is an eco-friendly option for leather tanning.

Acrylic Syntan
The process involves copolymerisation of marine oil under controlled conditions to obtain product of desired chain length and functional properties. The product is used as retanning material for chrome tanned leather. Leathers treated with acrylic syntan have fullness, tightness of grain, good buffing characteristics and improved dye intensity. The technology is available at lab scale level.

Chromium-Silica Tanning agent
It is essentially a synthetic mineral tanning agent containing matrix of chromium and silica complexes with organic ligands. The preparation process of the product involves reacting hexavalent chromium salt with a silica salt in the presence of a reducing agent and subsequent complexation with organic ligands, followed by conventional drying of the resulting slurry formed thereby to get the tanning agent in the powder form. It has potential use as a self-tanning agent as well as retanning agent. The product exhibits about 85-95% exhaustion for both chromium and silica. The leather produced by this syntan exhibits excellent fullness with shrinkage temperature of more than 105 o C. The technology is available at lab scale level.

Chromium-Iron Tanning agent (SPECTRATAN FE)
It is essentially a synthetic mineral tanning agent containing matrix of chromium and iron complexes with organic ligands. The preparation process of the product involves reacting hexavalent chromium salt with iron salt in the presence of sulphuric acid and complexing the resulting matrix with organic ligands in the presence of reducing agent, followed by ageing and drying to get the tanning agent in the powder form. The product has potential use as a self-tanning agent to produce fuller leather without any drawn grain appearance. It withstands precipitation upto pH 6.5. The product may also be used as a natural aid for developing various shades based on black and brown, on leathers tanned with this tanning agent by adding non-dye external aids, thereby avoiding the use of carcinogenic benzidine based dyes. The product exhibits around 90-95% exhaustion of both chromium and iron. It is possible to produce leather exhibiting shrinkage temperature upto 115 o C.

Zirconium tanning agent (Organozir)
It is a synthetic tanning salt based on zirconium. In this tanning salt, zirconium is in the complexes form and is irreversibly bound to the substrate. The product can be used as self tanning agent as well as in combination with chromium. It is essentially based on a polymeric network carrying suitable liganding sites to increase chrome fixation when used in combination with BCS. It can withstand precipitation upto pH 5 to 6. The product finds application as a chrome saver and gives full white leathers with minimized drawn grain. The resulting leathers can be readily dyed to rich shades. This tanning salt can also be used for retanning of several types of leathers.
The technology is available at 2Kg/batch level.

Synthetic Aluminium tanning agent
It is essentially a formaldehyde free organic matrix irreversibly bonded with aluminium with the help of organic ligands in combination with critical additives having ligating sites. The preparation process involves sulfonation of an aromatic compound followed by complexation with aluminium, organic ligands and polyfunctional polymer and subsequent conventional drying to get the tanning agent in the powder form. The product has potential application self tanning agent for producing white and soft leather. Moreover, the white base of the leathers enhances dyeability and acts as dye saver. It may also be used as retanning agent and co-tanning agent with BCS, whereby it enhances chrome exhaustion. Another unique feature of the product is that the leathers tanned with this product do not show any discolouration on ageing. The technology is available at lab scale level.

Phosphated fatliquor
The preparation process involves interesterification of glycerides of low I.V. veg/ marine / animal oil, and subsequent phosphating of the ester under hot air current in the presence of catalyst at 80-90 o C. It has potential application in leather, textile and cosmetic industry.

Acrylic soft Binder
Acrylic soft binder has been in use in leather finishing formulation especially for soft upper leathers. The process for preparation of this binder involves co-polymerisation of acrylic esters and vinyl monomers in presence of catalysts in order to obtain the required chain length and degree of polymerisation.
The uniqueness of the binder is its improved functional properties. It forms a soft, firmly adhering and stretchy film on leather with good fastness properties and cold crack as well as scuff resistance. The film is resistant to swelling. The binder does not load the grain, thereby retaining the natural look and feel of leather.

Acrylic Medium Soft Binder
Acrylic medium soft binder has been in use in leather finishing formulation. The process for preparation of this binder involves co-polymerisation of acrylic esters and vinyl monomers in presence of catalysts in order to obtain a film of medium hardness and gloss on leather to be finished. The uniqueness of the binder is its improved functional properties. It forms a medium hard and stretchy film on leather with good fastness properties. The film is resistant to ageing and light.

For Further Information Please Contact

Head, Leather Chemicals,
Central Leather Research Institute,
Adyar, Chennai – 600 020
Tel : +91 44 2491 5238/2491 1386
Fax : +91 44 2491 5238/24911589
e-mail : bpd@clri.res.in , bpdclri@yahoo.com