Water- repellent treatment of le

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					                                                   Water-repellent treatment



Water-repellent treatment of leather
Purpose

Increasing the interfacial tension between leather fibres and water and
thus reducing or almost completely eliminating the wettability with water
by depositing water-repellents in the leather substance.

Hydrophobic = water-repellent
Oleophobic = oil- and dirt-repellent

The main water-repellents (general)

Chemical substances                       Mode of action
Water-insoluble fats, resins,             Deposition, clogging the interfibrillar
waxes, polymers, etc.                     spaces. Mainly statical action.
Chrome fatty acid complexes,              Fixation of the water-repellent
perfluorinated chrome fatty acid          complex to the fibre.
complexes, chrome and aluminium           Increasing the surface tension
alkylphosphates, etc.                     against water.
Compounds with free carboxylic            Formation of a water-repellent
groups and complexing emulsi-             complex on the fibre.
fiers, e. g. fatty acids and esters,      Increasing the surface tension
soaps, dicarboxylic acids, esters         against water.
of phosphoric acid, polymeric fatty
acids, imido acetic acid derivatives.
Polysiloxanes, carbon fluoride            Surrounding the fibre with a
resins, etc.                              water-repellent film. Increasing the
                                          surface tension against water.
Hydrophilic emulsifiers of the            Clogging the interfibrillar spaces
water-in-oil type, e. g., alkylated       by water absorption and
and alkylized derivatives of              formation of emulsion and
succinic acid, derivates of citric        swelling.
acid, esters of fatty acids of
polyvalent alcohols, hydroxy-
ethylated fatty acids or alcohols.
Nitrogen-containing compounds,              Blocking the phenolic groups
e. g., pyridinium chloride derivatives,     of tanning agents. Increasing the
alkylene derivatives, isocyanates.          surface tension against water.


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Water-repellent treatment


BASF water-repellents

All BASF water-repellents mentioned below are light fast and heat resis-
tant. They do not contain organic solvents or organic halogen com-
pounds, and so do not make any contribution to the AOX content of the
waste water.

The water-repellent effect can be generally improved by fixation with
metal salts.

Densodrin CD             Anionic water repellent for leathers that are
                         expected to fulfil the highest standards of water
                         resistance. Appropriate for leathers tested by
                         the Maeser method. Contains silicone.

Densodrin EN             Anionic water repellent with high fastness for
                         leathers with a medium degree of water
                         resistance. Appropriate for leathers tested
                         by the Bally Penetrometer method.

Densodrin ENS            Anionic water repellent with high fastness for
                         leathers with a moderate to high degree of
                         water resistance. Appropriate for leathers
                         tested by the Bally Penetrometer method.
                         Contains silicone.

Densodrin OF             Anionic, silicone-based water-repellent additive.
                         Applied in aqueous float with Densodrin CD,
                         Densodrin EN or Densodrin ENS. Enhances the
                         water resistance and softness of the leather
                         and gives a smooth, silky handle. Can also be
                         applied as a handle modifier in finishing.




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                                   Water-repellent treatment


Densodrin PS   Silicone containing polymer emulsion. It forms
               the basis of a new water-repellent system which
               has been specially developed to make it easier
               to produce stiff, water-resistant leather. Used in
               combination with other water-repellents e. g.
               Densodrin CD, Densodrin EN or Densodrin
               ENS. Appropriate for leathers tested by the
               Maeser method.

Densodrin S    Anionic, silicone-based water-repellent additive.
               Applied in an aqueous float with Densodrin CD,
               Densodrin EN or Densodrin ENS as the main
               water repellent.

Densodrin SI   Additive which contains silicone. Used to
               enhance the water resistance of leather,
               especially in combination with other products
               from the Densodrin range. Densodrin SI can
               also be applied to crust or finished leather in
               order to obtain a silky handle and to improve
               softness.

Densotan A     Novel type of polymer with a neutralizing and
               retanning action. Very effective for producing
               water-resistant leather. Boosts the penetration
               of water-repellents, speeds up the process,
               prevents drawn grain and enhances the
               levelling and penetration of dyes. Stabilizer
               for water-repellents and fatliquors. Used in
               neutralization and/or in small amounts together
               with the water-repellent.




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