皮革技术

Bleaching methods

1.Pelts and leathers tanned with formaldehyde, aluminium and fish oila.Oxidation bleach:

1.Potassium permanganate/sodium bisulphite2.Hydrogen peroxide3.Sodium chloriteb.Reduction bleach:

2.Vegetable/synthetic tanned leathera.Bleaching with Basyntan D, DLE, DLX-N or WL.b.Bleaching with Tamol NNOL.

c.Bleaching with acid auxiliary tanning agents (Basyntan FC).3.Chrome leather

a.Treatment with pale-tanning Basyntan or Tamol types.

b.Sodium thiosulphate/acid treatment (deposition of colloidal sulphur).

c.Bleaching the leather by deposition of insoluble white salts. Pretreatment with barium

chloride or lead acetate and after-treatment with sulphuric acid or magnesium sulphateor by deposition of titanium dioxide.

Bleaching, fixationBASF bleach-tanning agents and bleaching auxiliariesBasyntan FC

Basyntan D, DLE, DLX-NBasyntan WLTamol NNOL

ü

ý cf. chapter“BASF synthetic tanning agents”þ

Anionic, light fast levelling agent with bleach effect.

Fixing agents for vegetable tannins and syntans

The object of fixing is to convert the unbound tannins and syntans in the leather into such aform that they cannot be removed by washing.Bastamol K

Fixing agent used to fix all types of anionic tanning agents.Reduces the water absorption of vegetable-tanned leatherand the loss by washing. Enhances the colour of theleather and its perspiration resistance. Chrome-tannedleathers are fuller and have a tighter grain.

Loading agentsProduct

Magnesium sulphate(Epsom salt)Barium sulphate(heavy spar)Lead sulphate

Chem. formulaMgSO4 · 7H2O BaSO4PbSO4

Properties

Precipitates tan solutions, increases weight,strongly increases ash.

Produced on leather by conversion of bariumchloride with sulphates or sulphuric acid.

Produced on leather by conversion of lead acetatewith sulphates or sulphuric acid.

Vegetable tanning materials and molasses are also used.

Tanner´s toolsTannery machinesFleshing machine – operating principle

Splitting machine – operating principle

Tannery machinesSamming machine – operating principle

Shaving machine – operating principle