TABLE OF CONTENTS
Title Page
Abstract
Table of Contents
List of Abbreviations/Symbols
CHAPTER ONE
1.0 INTRODUCTION
1.1 The Chemistry and Development of Finished Leathers
1.2 Statement of the Research Problem
1.3 Research Aim and Objectives
1.3.1 Objectives
1.4 Justification
CHAPTER TWO
2.0 LITERATURE REVIEW
CHAPTER THREE
3.0 MATERIALS AND METHODS
3.1 Materials
3.1.1 Experimental equipments
3.1.2 Finishing consumables
3.2 Methodology
3.2.1 Viscosity measurement of the resin binder
3.2.2 Melting point determination of the resin binder
3.2.3 Preparation of leather substrate
3.2.4 Preparation of the finish formulations
3.2.5 Application of the finish formulations on the prepared leather substrate
3.2.6 Water vapour permeability test
3.2.7 Lastometer test
3.2.8 Shore A (o) hardness test
3.2.9 Wet rub fastness test
CHAPTER FOUR
4.0 RESULTS
4.1. Examination of Resin Binder
4.1.1 Viscosity and molecular weight measurement of the resin
4.2 Physical Testing of the Finished Leather
4.2.1 Water vapour permeability of leather
4.2.2 Distension and bursting strength
4.2.3 Shore A (o) hardness of finished leather and melting point of binder
4.2.4 Wet rub fastness
CHAPTER FIVE
5.0 DISCUSSION
CHAPTER SIX
6.0 CONCLUSION AND RECOMMENDATIONS
6.1 Conclusion
6.2 Recommendations
REFERENCES
APPENDICES
Abstract
The effect of acrylic polymer dispersions on the water vapour permeability and some other properties of finished leathers have been studied. An acrylic based commercial binder AE 558 Nycil has been characterized and its effect when applied in a finish formulation on some of the physical properties of originally retanned leathers was investigated. The binder was found to have an intrinsic viscosity of 227 dL/g, and a viscosity molecular weight (Mv) of 4.03x105. This was obtained by conducting a solution viscosity measurement of the solid polymer in toluene at 25 oC. The melting temperature of the solid binder has been found to be in the range 361.7 oC - 370 oC. The results of these physical properties suggest that this is a very high molecular weight polymer with high thermal stability. Formulations for leather finishing was prepared containing the binder at varied proportions of 125 g, 150 g, 175 g, 200 g and 250 g and was applied on the leather substrates corresponding to samples A1, A2, A3, A4, and A5 respectively. Tests on some of the physical properties of these coated samples were conducted. The water vapour permeability of the originally retanned (uncoated) leathers was reduced significantly after the finish was applied. A1 has the lowest permeability at 125 g of the binder in the formulation, while A5 has the highest permeability at 250 g of the binder in the formulation. Generally, the water vapour permeability of the coated leathers increases as the factor varied in this experiment was increased. A3 had the highest Shore A value at 175 g of the binder in the formulation while A5 has the lowest Shore A value at 250 g of the binder in the formulation. Distension and Bursting strength of the uncoated leathers was improved after the leathers were coated. However, there was no particular trend in effect as the quantity of the binder in the finish formulation increased. The fastness of the coated samples generally increased as the quantity of the binder in the finish formulations was increased with sample A5 having the best resistance to wet rub action.
CHAPTER ONE
1.0 INTRODUCTION
Acrylics are esters of acrylic acids, which are the products formed by the reaction of an acrylic acid and alcohol. The esters of acrylic acid polymerise readily to form exceptionally clear plastics. These are widely used in applications requiring clear durable surfaces, e.g. in the aircraft and automobile industries. In more common use are surface coatings involving acrylics. The physical properties of acrylics (such as gloss, hardness, adhesion and flexibility) can be modified by altering the composition of the monomer mixture used in the polymerisation process. Acrylics are used in a wide range of industries, and the list below is simply a selection of some of the more common examples: Adhesives, textile industry (e.g. making sponge fill used in padded
jackets), paper coatings, paint industry particularly in paints used for road markings.
The polymerisation process proceeds readily in the presence of catalysts and may be carried out in any one of four different ways: emulsion, bulk, solution or in suspension.
Emulsion polymerisation occurs in a water/monomer emulsion using a water-soluble catalyst. Emulsion polymerisation is the main process used in the production of acrylic polymers.
Bulk polymerisation is carried out in the absence of any solvent. The catalyst is mixed in with the monomer and the polymerisation is then left to occur with time. This is the method commonly used to manufacture acrylic sheets.
Solution polymerisation is carried out in a solvent in which both the monomer and subsequent polymer are soluble. Only low molecular weight polymers can be manufactured by this process, as high molecular weight polymers cause very high viscosities.
Suspension polymerisation is carried out in the presence of a solvent usually water, in which the monomer is insoluble, and in which it is suspended by agitation. To prevent the droplets of.....
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