| 摘要 |
PURPOSE: A method for preparing natural leather is provided which does not harm the worker as well as does no cause the secondary environmental contamination and is able to extend the life of leather and produce products having good quality by using a mixed aqueous resin of water and polyurethane for surface-treatment of the leather. CONSTITUTION: The method comprises steps of: (A) adhesive formation process comprising steps of: (i) a buffing step which smoothes the surface of leather by a mechanical device; (ii) a first coating step which permeates a mixed aqueous resin of 75-82% of water and 25-18% of polyurethane to the leather by spray coating and dries and ripens it at room temperature for 24 hours; (iii) a smoothing step which improves the smoothness of the leather surface by ironing with 10-20 Kg/square centimeter pressure and 80°C temperature; and (iv) a second coating step which sprays a mixed solution of 100 wt.% of aqueous resin and 15-30 wt.% of toner with the thickness of 0.03-0.05 millimeter on the leather surface and dries at the temperature of 90-110°C for 3-4 minutes; (B) base-coating process which sprays a mixed solution of 100 wt.% of aqueous resin, 15-30 wt.% of toner and a small amount of pigment on the leather surface with the thickness of 0.06-0.08 millimeter and dries for 5-6 minutes with gradually increasing the temperature up to 45-65°C; and (C) drying and hardening process comprising steps of: (i) a drying step which ripens the base coating by drying at the temperature of 80-120°C for about 3 minutes to maintain the water-content at 12-14%; and (ii) a hardening step which sprays a mixed solution of 100 wt.% of water, 30 wt.% of polyurethane, 100 wt.% of methanol and 2.3 wt.% of hardening agent on the leather surface and dries at the temperature of 85-120°C for about 3 minutes.
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