Water-resistant Leather is suitable for making high-grade dress pants, shirts, ties, gloves, etc. It can also be used as wiping leather for precision instruments and equipment. In addition to the requirement of rich and soft, elastic, breathable, good water vapor permeability and stable physical and chemical properties like common soft leather, water resistant leather must also have two other important indexes, namely Leather Washing Colour Fastness and rub resistance color fastness.
How to improve Leather Washing Colour Fastness?
After washing or soaping, the area, skin shape and color will not change significantly, and the fullness, elasticity, softness, physical strength and shrinkage temperature will not deteriorate significantly.
In order to make the washable leather have the above performance characteristics, the processing must do "three solid combination".
(1) Tanning agent and leather fiber are firmly combined. Only when the tanning agent is firmly combined, the leather will not be tanned after washing or soaping, so that the area of the leather will not be obviously reduced and the shape of the leather will not be obviously changed, and the fullness, elasticity, softness, physical strength and shrinkage temperature will not be obviously reduced.
(2) The fatliquor is firmly combined with the leather fiber. Because only when the fatliquor is firmly bonded, the grease will not be washed off in water washing or soaping, so that the original softness, fullness and physical strength of leather can be maintained.
(3)Dyestuff and leather fiber are firmly combined. Because only if the dyestuff is firmly bonded, it can ensure that the dyestuff bonded with leather fiber will not be leached out and migrated after washing, so that the color of leather will not be changed obviously.
In order to improve the washing resistance of leather, we must take measures around the above "three binding firmly".
(1)Improve the uniformity of chrome tanning and enough amount of chrome salt to make sure the shrinkage temperature of leather is more than 100 ℃.
(2)The combination of chrome and aldehyde retanning can greatly improve the washing resistance of leather, because the aldehyde tanning agent can not only combine with the amino group on the collagen fiber, but also promote the penetration and combination of chrome salt, grease and dye.
(3)Use polymer materials which are both oiling, retanning and waterproof, such as SOF from TFL, FRT from Chengdu Organic Institute, etc.
(4) Use waterproof greasing agent and combined greasing agent, and use less or no synthetic greasing agent, mineral oil and animal raw oil which have high migration. When fixing grease, use aluminum, chromium and other metal salts to strengthen the fixing effect.
(5) Use high quality dyes with good color fastness and achieve good fixation in dyeing.
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