Wet Blue Bated With Enzymes

Bating wet blue with enzyme is a new technology in leather manufacture process that can make leather softer and improve the quality of leather. A compound enzyme prepared by our laboratory was used to bate wet blue, and its characteristics were studied, and the optimal process conditions were established. Bating effect of the compound enzyme was studied from many aspects, and compared with several enzymes often used in leather making. A new method based on the relation of leather softness with its flexing strength and compressing properties for testing leather softness was established.When the bating effect was estimated by determining the concentration of hydro-proline in the bate-liquor, effects of many factors including pH, reaction temperature and time, dosage of compound enzyme, chrome content of wet blue and surfactants on bating effect were studied. The bating effect of compound enzyme and AS 1.398 protease, pancreatin, 166 protease and 537 protease were compared. In addition, the effect of pH on grain was also studied. The results show it is an effective method that bating effect is estimated by determining the concentration of hydro-proline in the bate-liquor. In respect of the effect of reaction conditions on bating effect and grain and the process conditions achieved easily, when the compound enzyme is used to bate wet blue, the optimal temperature, pH, dosage of enzyme respectively are 55℃, 5.5 and 300U/g. the bating effect decreases with the chrome content of wet blue increases, and the better bating effect can be obtained when the chrome content (Cr3+ %) of wet blue is less than 2.7 %. Anionic surfactants such as sodium lauryl benzene sulfonate make the bating effect decreased, but non-ionic surfactants such as TX-10, OP-10 benefit to improve bating effect.Compared the bating effect of compound enzyme with that of other enzymes, it was found that the compound enzyme have best bating effect, and the decrease sequence of the bating effect of other enzymes is 537 protease, pancreatin, AS 1.398 protease and 166 protease.Effects of bating wet blue with enzymes on the fibrous structure, chrome content, shrinkage temperature (Ts) of wet blue and appearance, hand, dimension and physical properties of finished leather were studied. The results show that bating wet blue with enzymes mentioned above have little effect on final chrome content and Ts. The fibrous structure of wet blue bated with compound and 537 protease is looser, and bating wet blue with other enzymes have no obvious effect on the fibrous structure of wet blue. Finished leathers made from the wet blue bated with compound and 537 protease have more uniform grain and better hand . Finished leathers made from wet blue bated with AS 1.3 98 protease, pancreatin and 166 protease have more coarse grain and its feel have no obvious difference with that of control. The tensile strength and tearing strength of finished leathers decreased when wet blue is bated with any kind of enzyme, but the elongation increased obviously when wet blue is bated with compound enzyme and 537 protease.There is close relation between softness of leather with its flexing strength and compressing strength, therefore a new method based on the relation for testing leather softness was established, and the bating effect of different enzymes were compared by testing softness of finished leathers with this new method. The results show that this method have several virtues such as simple apparatus , operating easily, reliable result, and leathers tested would not be damaged , so it is a better new method for testing leather softness. When wet blue is bated respectively with compound enzyme, AS1.398protease, pancreatin, 166 protease and 537 protease, the bating effect of compound enzyme is best.