DEVELOPMENT AND CHARACTERIZATION OF SELF-HEALING CAR PAINT USING CHITOSAN

DEVELOPMENT AND CHARACTERIZATION OF SELF-HEALING CAR PAINT USING CHITOSAN

Abstract:

Car surfaces are vulnerable to scratches from environmental conditions, thereby prompting car users to visit car workshop for re-spray. This process does not usually bring permanent solution to scratches on car surfaces since they are often re-spray with non-self-healing paint. The aim of this work was to develop self-healing car paint. In doing this, response surface methodology (RSM) was used to obtain an optimum paint formulation which was then improved into a self-healing car paint by incorporating chitosan into the formulation, sprayed on substrates, allowed to dry, scratched with a pin, exposed with UV light from the sun and then investigated for self-healing using scanning electron microscope (SEM). The model developed for drying time and coverage responses using (ANOVA) in the RSM study were significant as their respective “Prob > F” values were less than 0.0500 with R2 values 0.8693 and 0.9204 respectively. The “lack of fit” in both cases were not significant which is desirable in statistical analysis of this nature. Physico-chemical analysis (viscosity, density and pH) were done on the 20-runs of formulated paint where runs 1, 3, 7, 8 and 13 had the best density values of 0.956 g/cm3, 0.977g/cm3, 0.875 g/cm3, 0.896 g/cm3 and 0.944 g/cm3respectively as compared to other runs. Runs 1, 3, 7, 8 and 13 viscosity values fall within range of “30±5 cp”,(ASTM, 2009; PAN, 2013) standard specification for car paint. The pH values of the twenty runs were in the range of 6.6 to 6.9. The physico-chemical test performance of runs 1, 3, 7, 8 and 13 was a criteria for their selection to undergophysico-mechanical test, in which run 8 among the other runs selected had the optimum performance in terms of gloss, film thickness, cross-scratch, punch, chemical resistance, heat resistance and colour stability tests as its results agreed closely to ASTM/PAN car paint standard specifications.The SEM analysis done on the coated substrates showed that chitosan has self-healing effect.

TABLE OF CONTENTS

CONTENTS

PAGES

DECLARATION

CERTIFICATION

DEDICATION

ACKNOWLEDGEMENT

ABSTRACT

TABLE OF CONTENTS

LIST OF FIGURES

LIST OF TABLES

LIST OF PLATES

ABBREVIATIONS

CHAPTER ONE
1.0 INTRODUCTION 1
1.1 Problem Statements 4
1.2 Justifications 4
1.3 Aim and Objectives 4
1.4 Research Scopes 5

CHAPTER TWO
2.0 LITERATURE REVIEW 6
2.1 Classification of Paints 6
2.1.1 Emulsion paint 6
2.1.2 Gloss paint 7
2.2 Composition of Paints 7
2.2.1 Binders 8
2.2.1.1 Convertible binders 8
2.2.1.2 Non-Convertible binders 9
2.2.1.3 Alkyd resin 10
2.2.2 Pigments 11
2.2.2.1 Classification of pigments 12
2.2.3 Solvents 14
2.2.3.1 Hydrocarbon Solvents 15
2.2.3.2 Oxygenated solvents 15
2.2.3.3 Chlorinated solvents 16
2.2.4 Additives 16
2.3 Paint Formulation Process 16
2.4 Hazards Associated with Paint Formulations and it Preventive 17

Measures
2.4.1 Preventive measures 19
2.5Physico-Chemical Analysis of Paint 21
2.5.1 Viscosity measurement 21
2.5.2 Density test 21
2.5.3 pH test 21
2.5.4 Drying time 22
2.5.4.1 ASTM test method of drying time 22
2.6Physico-Mechanical Analysis 23
2.6.1 Film thickness 23
2.6.2 Gloss (Opacity) analysis 24
2.6.3 Chemical resistance 24
2.6.4 Punch test 25
2.6.5 Cross-scratch test 25
2.6.6 Colour stability 26
2.7 Modelling of Experimental Formulation 26
2.7.1 Response surface methodology (RSM) 27
2.7.1.1 Fitting of model analysis 27
2.8 Self-Healing Coating Polymers 29

2.8.1 Benefit of self-healing coatings 30
2.8.1.1 Intrinsic self-healing 31
2.8.1.1.1 Self-healing based on physical interactions 31
2.8.1.1.2 Self-healing based on chemical interactions 32
2.8.2 Extrinsic self-healing 34

CHAPTER THREE
3.0 MATERIALS AND METHOD 35
3.1 Materials and Equipment 35
3.2 Methodology 37
3.2.1 Source of raw materials 37
3.2.2 Experimental design 37
3.2.3 Paint formulation procedure 39
3.2.4 Paint viscosity measurement 39
3.2.5 Density test 40
3.2.6 pH measurement 40
3.2.7 Preparation of plates for spray 40
3.2.8 Drying time and coverage responses determination 41
3.2.9. Analysis of the applied paints on substrates 41

3.2.10 Spraying of the substrates 41
3.2.10.1 Gloss test 42
3.2.10.2 Film thickness test 42
3.2.10.3 Cross-scratch test 43
3.2.10.4 Punch test 43
3.2.10.5 Chemical resistance test 43
3.2.10.6 Heat resistance test 44
3.3 Self-Healing Car Paint Formulation 44
3.3.1 Investigation of self-healing property of the paint on coated substrates 45
3.3.2 Fourier transform infrared analysis 45

CHAPTER FOUR
4.0 RESULTS AND DISCUSSIONS 46
4.1 Effect of Component Proportioning on Viscosity of Formulated Paint 46
4.2 Effect of Component Proportioning on Density of Formulated Paint 48
4.3 Effect of Component Proportioning on pH of Formulated Paint 48
4.4 Physico-Mechanical Analysis 48
4.4.1 Gloss (opacity) test 49
4.4.2Film thickness test 50
4.4.3Cross-scratch test 51
4.4.4Punch test 52
4.4.5Chemical resistance test 53
4.4.6 Heat resistance/colour stability test 54
4.5 Drying Time and Coverage Responses 56
4.6 Drying Time and Coverage Mathematical Models 58
4.7 Statistical Analysis for Drying Time and Coverage 59
4.7.1Drying time response 59
4.7.2 Coverage response 61
4.8 Predicted and Actual Drying Time and Coverage Relationship 62
4.9 3D-Surface Plots of Variable Parameters and Responses Studied 64
(Drying Time and Coverage)
4.10 Optimized Solutions from the Simulated Responses 66
4.11 Self-Healing Property of Chitosan Investigation on the Formulated 67
Paint
4.12 Fourier Transform Infrared Spectroscopy (FTIR) 71

CHAPTER FIVE
5.0 CONCLUSIONS AND RECOMMENDATIONS 74
5.1 CONCLUSIONS 74
5.2RECOMMENDATIONS 75

REFERENCES 76
APPENDIX A 82
APPENDIX B 88

CHAPTER ONE

1.0         INTRODUCTION

The surfaces of any object is vulnerable as it often makes continual contact with the corroding (or oxidizing) air, most especiallywhen left in an open place, thereby bearthe brunt of the sun, rain,fug, dew and snow (Rodger, 2008). Thus, under these conditions, the surfaces tend to rust, disintegrate, corrode and crackresulting to wear of daily use.However, these effects can be prevented or managed with various surface coating medium such as wallpapers, plastic sheet, chrome, silver plating and paint which have being identified and applied to decorate and smooth out any surface roughness or irregularities (Jonathan, 2009). Paint is commonly used as compared to other surface coating due to its ease of application, maintenance and versatility (Jonathan, 2009).

Paint is defined as an engineered material made of several ingredients such as resin, solvent, pigments and additives that are mixed together to create a specific product with its own unique properties (Rodger, 2008). It is classified based on purposes and area of applications. A paint whose diluent of formulation and medium of cleanliness is solvent is refers to as „gloss paint. This type of paint can be formulated for car surface coating, refinery equipment coating, road marking purposes, varnishes and so on (Rodger, 2008; Alirezaet al., 2009). While a water base paint is term as an emulsion paint which can be applied for architectural building (Michael, 2005; Rodger, 2008). It can be formulated from four major components, be it solvent base or water base type(Michael, 2005). These components are resin (binder), pigments (sometimes in conjunction with extenders), solvent and additives (Rodger,2008).

Paint has been in existence for decades and there are standard formulation for its high quality, though there are no much published work on its detail experimental apart from the general knowledge of its product, this may be due to the products being mostly patented. However, it has been established that, mixing binder, solvent, pigments and additives in random proportion will result to paint product, but its certified quality depends on its ability to meet standard specification test, where its best performance after application tells and differentiate it from low quality product (Turner, 1999;DuPont, 2010;Shawn, 2011; PAN, 2013). Thus, having knowledge of the appropriate proportions of each component of the paint to be added during formulation will give rise to a desired quality product as may be proved from analysis of its physico-chemical/physico-mechanical test before and after application (Alirezaet al., 2009).

Oragwu (2013), used castor seed oil as plasticizer in 23.65wt% titanium dioxide, 70ml of white spirit and 90ml of alkyd resin in car paint formulation. But there was no justification to why these ranges or proportions of raw materials for the paint formulation were chosen and there was no physico-mechanical test done on substrate where such paint was applied to ascertain its quality.

However, design of experiment technique incorporated with response surface methodology (RSM) can be used to generate runs of experiment by inputting desirable variable conditions that will result to optimum paint formulation from expected responses. The technique (RSM), is a dynamic tool in which set of statistical design of experiment (DOE) are used, which aids the relationship between output variables with process input decision variables to accomplish the objective of maximization or minimization of the responses (Ali et al., 2011;Li et al, 2012; Ali, 2014).

Ali et al., (2013) use RSM to evaluate the compositional variations and interactions of glycerylbehenate and poloxamer 188 as lipid carrier and surfactant respectively in developing theophylline. Also, Ali (2014) optimized the process variables for fluorideion removal with the aid of maghenite nanoparticles using RSM. Keshaniet al., (2010) also applied RSM in the optimization of concentration process on pomelo fruit juice. Moreover, optimization of process conditions for tomato foam development was done by Balasubramanianet al., in 2012, using RSM. RSM was used by Yaminet al., (2013) for lead ion removal from aqueous solution with the aid of intercalated tartrate-Mg.Al layered double hydroxides. Xinyueet al., (2014) also applied RSM in the optimization of process parameters for litopenaceusvannmei seafood sauce. Bulent et al., (2007) determined the effects of drying air velocity and pepper size on drying time, drying product‟s ascorbic acid level and colour using RSM. Therefore, it can be assumed that RSM is suited for the optimization of car paint formulation.

Due to daily technology development most especially on polymer modification, satisfied quality car paint can as well be improved on as it has been done to other polymer materials that exhibit self-healing property. Self-healing car paint differs from ordinary car paint in that, it contains an autonomic healing materials capable of responding to harsh environmental effects which subsequently repair damages incurred on coating where it is been applied without external intervention (Chris et al., 2011).

Kousouraki and Mouritz (2010), worked on the effect of self-healing hollow fibres on the mechanical properties of polymer composites. Kessler et al., (2003), used microencapsulated healing agent on self-healing fibre reinforced polymer matrix composite material. Also, in (2011), Yan et al., used epoxy-mercaptan as self-healing agent in self-healing of low-velocity impact damage in glass fabric/epoxy composites study. A scandium (iii) triflate catalysed self-healing system in an epoxy based fibre reinforced polymer composite material was investigated in (2011) by Tim et al. Also, Biswajitet al., (2011), studied self-healing ability of oxetane-substituted chitosan in polyurethane resin coating. While, Hüsnügület al., (2013) investigated self-healing property of chitosan in an epoxy dye.

While RSM has been used extensively in studies of several processes, it use in paint formulation has not been investigated. More so, scanty literature source is available on the use of chitosan on self-healing application in car paint formulation.

The present investigation is on the production of self-healing car paint, where attempt was made to fill research gap that exist in previous works.

1.1          Problem Statements

The standard formulation of auto base paint is hidden as there is no published work that has stated clearly the right proportions of each component that make up the formulation with optimum properties.Also, lot of human hours/resources are wasted by car owners visiting auto shops frequently. Finally, researches on self-healing car paint and use of RSM in paint production are scanty.

1.2          Justifications

The research will establish optimum car paint formulation using Design of Experiment (DOE) incorporated with Response Surface Methodology (RSM). More so, improved quality special car paint will be formulated (self-healing car paint), thereby reducing constant visit of car owners to car spray workshop. More so, there is availability of raw materials for chitosan synthesis in Nigeria which will create employment and market value for the sources of chitosan.

1.3 Aim and Objectives

The aim of this work is to develop a self-healing car paint; with the objectives of:

• Developing empirical model for paint formulation using response surface methodology (RSM) technique

• Optimization for optimal formulation

• Incorporation of chitosan in the optimum formulation and analyze for self-healing property.

1.4 Research Scopes

The scope of this work involved

• The design of experiment(DOE) using RSM.
• Use of medium oil alkyd resin for the formulation of car paint with the help of experimental design.

• Physico-chemical/physico-mechanical characterization of the formulated paint

• Incorporation of chitosan in the formulation for self-healing verification of the paint.

DEVELOPMENT AND CHARACTERIZATION OF SELF-HEALING CAR PAINT USING CHITOSAN