Article

Balancing of properties of Veg Tan/Muf leathers by mixed chestnut/condensed tannins

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

A study was performed to balance two properties, namely, light/color fastness and shrinkage temperature. Hybrid chestnut/mimosa mixtures in combination with the MUF resin yield the wanted the balance properties.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Simon and Pizzi reports [2] that after tanning with several tannins shrinkage temperature of leather reaches only 61-65 o C. The results of our investigation show that tanning with CT tannins of non-bated hide allows reaching sufficiently high shrinkage temperature (73.6 o C). This value is only negligible lower than after tanning with Ormotan C or Blancotan W. The highest shrinkage temperature is reached when tanning wit quebracho tannins (Indusol ATO), which characterizes by good tanning properties. ...
Article
Full-text available
Presented research devoted for investigation of Common tormentil (Potentilla erecta) tannins properties and tanning peculiarities. It was established that tormentil tannins have high affinity to collagen. Leather tanned with tormentil tannins distinguished by brownish grain colour, grain was not shrunk, and it had high tensile strength but low relative elongation. Shrinkage temperature of leather tanned with tormentil tannins reaches 73.6oC, and it is almost same like after tannins with modified vegetable tannins or synthans.
Article
The research relates to use of Jatropha curcas seed oil as co-stabilizing agent for skins and hides in tanning process. Conventionally most of the skins and hides are stabilized through mineral tanning agents predominantly using chromium salts. However due to the ecological and safety concerns associated with chromium salts and other mineral tanning systems there arose a need for an alternative tanning system. Disposal of used leather products has also come under surveillance for their eco-compatibility posing challenges to choice and designing of novel tanning systems. Emerging criteria for such new tanning systems are environmental safety and easy biodegradability of leather products after use. Vegetable tanning agents based on poly phenols of plant materials which were in vogue prior to advent of mineral tanning are re-emerging as principal tanning materials to offset the perceived concerns of mineral tanning. This calls for overcoming the inherent shortcomings associated with the traditional vegetable tanning agents and processes. The major limitations of the vegetable tanned leathers are poor physical characteristics and their high susceptibility to fungal growth. In order to overcome short comings of vegetable tanning, use of multifunctional material(s) of plant origin has been attempted. J. curcas seed oil provides a possibility for its use in tanning as an adjunct along with poly phenols. This oil when used as a co-tanning agent along with vegetable tannins eliminates most of the drawbacks associated with conventional tanning. Detailed study has been made by varying the process parameters of tanning. The improvement in softness characteristics has been quantified using a softness tester. Fresh mature cultures of fungal species, Asp. Niger, Asp. flavus and Trichoderma viridae have been used as sources of inoculum for assessment of improvements in fungal resistance. The study indicates a novel tanning process using J. curcus seed oil along with vegetable tanning agents can emerge as a viable tanning system based on replenishable resources.
Article
A new sulphonated melamine-urea-formaldehyde (MUF) resin of relatively low melamine content, prepared according to a sequential procedure, has been shown to be highly effective when coupled with different natural vegetable tannins to produce leather with the same good characteristics of leather prepared with chrome salts. In particular the shrinkage temperature of the leather prepared according to the new approach is comparable to that obtained with chrome-tanned leathers. Leathers produced using tanning formulations based on the combination of this MUF resin with either flavonoid (condensed: mimosa or quebracho) tannins and hydrolysable ellagitannins (chestnut) have shown good colour stability. Leathers prepared with Chestnut or Mimosa combined with MUF tannage in 50/50 and in 75/25 weight ratios exhibited the most promising physical properties. Furthermore, there are a number of other formulations to choose from which are capable to overcome the major drawback of vegetable tanning in relation to chromium tanning.
Article
A new sulfonated melamine-urea-formaldehyde (MUF) resin of relatively low melamine content, prepared according to a sequential formulation, has been shown to be highly effective when coupled with different natural vegetable tannins to produce leather with the same good characteristics of leather prepared with chrome salts. In particular, the antishrinkage effectiveness of the leather prepared according to the new approach is comparable to that obtained with chrome tanned leathers. The comparison of the traditional leather shrinkage temperatures test method with a new thermomechanical analysis (TMA) test method in tension yields thermograms presenting three major modulus of elasticity (MOE) peaks. These are closely connected to molecular level phenomena determining the shrinkage temperature of leather. The three determining parameters appear to be as follows: (1) The average value of the temperatures at which the three MOE peaks occur: the higher the value of this average, the lower is the shrinkage of leather. (2) The average of maximum MOE values of the TMA peaks: the higher this average is, the better is theleather in regard to antishrinkage effectiveness. This means the leather maximum MOE at each peak is a measure of the resistance to the contraction force induced by heat. (3) The relative intensity of the first TMA peak in relation to the second: the higher the value of the MOE for the first TMA peak is in relation to the second peak, the lower the leather shrinkage appears to be. However, it has not been possible to better define or quantify this latter effect. This new TMA test method in tension has also yielded a mathematical relationship correlating the thermogram peak temperatures and MOE averages with the traditional shrinkage temperature to a high degree of confidence. A previous TMA test method, in compression, has proven to yield more problematic and finally not very reliable results when one needs to apply it to a wide variety of different cases.
European Commission contract project QLRT-99-00913
  • A Pizzi
  • C Simon
  • B George
  • A Trosa
Pizzi, A., Simon, C., George, B., and Trosa, A.; European Commission contract project QLRT-99-00913, 2000-2003.
  • C Simon
  • A Pizzi
Simon, C. and Pizzi, A.; J. Appl. Polymer Sci., in press 2002