preparation of styrene acrylic copolymers
DESCRIPTION
Preparation of Styrene Acrylic CopolymersTRANSCRIPT
PREPARATION OF STYRENE ACRYLIC COPOLYMERS
AS TONER RESIN BY
SUSPENSION POLYMERIZATION
TANG BEE KIM
FACULTY OF SCIENCE
UNIVERSITI OF MALAYA
KUALA LUMPUR
2012
ABSTRACT
Toner resins are polymeric materials used in the manufacturing of toners to be used
in the photocopy machines and LaserJet printers. The popular commercial resins are the
styrene acrylic copolymers. A typical toner resin has a bimodal molecular weight
distribution, having one fraction of lower molecular weight and another of higher molecular
weight, so that it can impart good fixing and offset properties to provide the performance of
a good toner.
This research project describes the synthesis of toner resins by suspension
polymerization, using poly(vinyl alcohol) and benzoyl peroxide as a colloid stabilizer and
initiator respectively, in an aqueous medium to produce the copolymers in the form of tiny
beads. Three series of experiments were carried in the study: (i) synthesis of low molecular
weight styrene acrylic copolymers, (ii) synthesis of high molecular weight styrene acrylic
copolymers and (iii) blending the both high and low molecular weight copolymers at
different ratios to obtain the desired properties.
Gel permeation chromatography (GPC) was used to study molecular weight
distribution (MWD); melt flow index (MFI) reflected the flow ability of resin; Differential
Scanning Calorimetry (DSC) was used to study the thermal properties; and acid number
(AN) to quantify the amount of acidic groups in the resin.
The effects of monomer ratio, concentration of initiator and concentration of
crosslinking agent on the properties of high and low molecular weight resins had been
investigated. The desired glass transition temperature of toner resin was obtained by
varying the monomer ratio. By increasing the concentration of initiator, the number average
of molecular weight of resin tends to shift to lower molecular weight presumably due to the
excess free radicals that could lead to more chain termination and chain transfer reactions.
The addition of cross-linking agent leads to gel formation. The percentage of
tetrahydrofuran (THF) insoluble fraction has increased as the concentration of cross-linking
agent was increased. The properties of synthesized toner resins were compared to those of
selected commercial resins.
The synthesized resins after blend at different ratios have glass transition
temperature in the range of 56-69oC; MFI in the range of 13 – 55 g/10 min; AN in the range
of 2.5 - 3.4 mg KOH/g; Mw in the range of 7.00 x 103 – 3.20 x 10
3 Daltons (1 Daltons =
1.66 x 10-27
kg) with 9 - 14% of tetrahydrofuran (THF) insoluble fraction. Three of the
synthesized resins with desired properties had been tested in a lab scale production of toner.
Print test had been carried out to evaluate the print quality. Image density of the test images
are in the range of 1.33 - 1.58 which is comparable to commercial toner, while background
density is around 0.12-0.13 which is slightly higher than commercial toner.
ABSTRAK
Resin toner adalah polymer yang digunakan untuk membuat toner bagi mesin
fotokopi dan alat pencetak laserjet. Resin komersial yang paling popular adalah kopolimer
stirena akrilik. Resin toner biasanya mempunyai taburan berat molekul bimodal tinggi
dengan bahagian berat molekul rendah. Ini dapat memberi sifat penetapan dan
pengimbangan agar menjadi toner yang baik.
Projek ini melibatkan sintesis resin toner dengan kaedah pempolimeran ampaian.
Penstabil koloid yang digunakan dalam pempolimeran adalah poli(vinil alkohol), manakala
pemula adalah benzoil peroksida. Pelarut dalam proses pempolimeran ampaian adalah air
suling. Tiga siri eksperimen telah dijalankan sepanjang kajian: (i) sintesis kopolimer stirena
akrilik berberat molekul rendah, (ii) sintesis kopolimer stirena akrilik berberat molekul
tinggi, (iii) Pencampuran kedua-dua kopolimer stirena akrilik dengan berat molekul rendah
dan berat molekul tinggi. Nisbah antara kopolimer dengan berat molekul rendah dan tinggi
telah dicampur untuk mendapat sifat-sifat yang dikehendaki.
Kromatograf Penelapan Gel (GPC) telah digunakan untuk mengkaji taburan berat
molekul; Alat Indeks Aliran Leburan (MFI) menunjukkan keupayaan aliran resin;
Kalorimetri Pengimbasan Pembeza (DSC) telah digunakan untuk mengkaji sifat-sifat
terma resin; Nombor asid (AN) untuk jumlah kumpulan berasid dalam resin toner. Kesan-
kesan bagi nisbah monomer, kepekatan pemula dan kepekatan penyilangan ejen pada sifat-
sifat resin dengsan berat molekul rendah dan tinggi telah dikaji. Sifat-sifat resin toner yang
disintesis dan resin toner komersial telah dibandingkan.
Resin yang disintesis yang telah dicampur pada nisbah berbeza mempunyai suhu
peralihan kaca, Tg dalam lingkungan 56 - 69oC; MFI dalam lingkungan 13 – 55 g/10 min;
AN dalam lingkungan 2.5 - 3.4 mg KOH/g; Mw dalam lingkungan 7.00 x 103 – 3.20 x 10
3
Daltons (1 Daltons = 1.66 x 10-27
kg) dengan mengandungi 9 - 14 % yang tidak larut dalam
THF. Tiga resin yang disintesis yang mempunyai sifat-sifat yang dikehendaki telah diuji
untuk menghasilkan toner dalam skala makmal. Tiga siri ujian cetakan telah dijalankan
untuk menilai mutu cetakan dengan kaedah membandingkan mutu cetakan toner komersial.
Kepadatan imej yang diperolehi daripada imej yang diuji adalah dalam lingkungan 1.33 –
1.58, nilai ini adalah sebanding dengan toner komersial. Kepadatan latar belakang adalah
dalam lingkungan 0.12 – 0.13, nilai ini adalah lebih tinggi daripada toner komersial.
ACKNOWLEDGEMENTS
I wish to express my sincere gratitude and deepest appreciation to my supervisor
Professor Dr. Gan Seng Neon for his timely advice, guidance and constant encouragement
throughout the length of this work. I would also like to thank Professor Dr. Rosiyah Yahya
(co-supervisor) for her time and valuable assistance.
I would like to thank all the members of the Polymer group, both past and present
who have helped me directly or indirectly during this research. Financial and research
assistantship from the Jadi Imaging Technologies Sdn. Bhd. is also appreciated. Finally, I
am grateful to all the members of my family for their love, encouragement and support
throughout my education, without which this would not have been possible.
CONTENTS
ABSTRACT III
ABSTRAK V
ACKNOWLEDGEMENTS VII
CONTENTS VIII
LIST OF FIGURES XIV
LIST OF TABLES XIX
LIST OF ABBREVIATIONS XXII
CHAPTER ONE: INTRODUCTION
1.1 Toner 1
1.2 Electrophotography 3
1.3 Conventional toner Manufacturing Process 5
1.4 Components of a toner 6
1.4.1 Binder Resins 6
1.4.2 Colorant 7
1.4.3 Magnetic Additives 8
1.4.4 Charge Control Agent (CCA) 8
1.4.5 Other Additives 9
1.5 Required Properties of toner 9
1.5.1 Glass Transition Temperature, Tg 10
1.5.2 Molecular Weight Distribution 10
1.5.3 Melt Viscosity 11
1.5.4 Particle Size Distribution 11
1.6 Prints Defects in Laser Printers 11
1.6.1 Banding 12
1.6.2 Repetitive Marks 12
1.6.3 Ghosting 13
1.7 Suspension Polymerization 14
1.7.1 Monomer to water volume ratio 16
1.7.2 Agitation speed 17
1.7.3 Type and concentration of stabilizer 17
1.7.4 Concentration of initiator 18
1.7.5 Reaction temperature 18
1.8 Free Radical Polymerization 18
1.9 Gel Effect 20
1.10 Selection of Monomers 20
1.11 Scope of Study 21
CHAPTER TWO: EXPERIMENTAL
2.1 Synthesis of Styrene Acrylic Copolymers 22
2.1.1 Materials 22
2.1.2 Apparatus 22
2.1.3 Suspension polymerization 23
2.2 Formulations 24
2.2.1 Low Molecular Weight Styrene Acrylic Copolymer 24
2.2.2 High Molecular Weight Styrene Acrylic Copolymer 25
2.3 Mixing of High Molecular Weight and Low Molecular Weight Styrene
Acrylic Copolymer 26
2.4 Preparation of raw toner by using Pilot Plant 26
2.4.1 Materials 26
2.4.2 Procedures 27
2.4.3 Formulation 28
2.5 Preparation of toner 28
2.5.1 Materials 28
2.5.2 Procedures 29
2.5.3 Formulation 29
2.6 Evaluation of Print Quality 29
2.7 Characterization of toner resins and toners 31
2.7.1 Determination of Glass Transition Temperature, Tg 31
2.7.2 Determination of Molecular Weight Distribution 31
2.7.3 Infrared IR Spectrum 32
2.7.4 Percentage of Conversion 32
2.7.5 Percentage of Tetrahydrofuran (THF) Insoluble Fraction 33
2.7.6 Melt Flow Index 33
2.7.7 Determination of Acid Number 34
2.7.8 Tribo-charge 36
2.7.9 Apparent Density 37
2.7.10 Flowability 37
2.7.11 Particle Size Distribution 38
2.7.12 Magnetic Content 38
2.7.13 Image Density (ID) and background density (BD) 38
CHAPTER THREE: RESULTS AND DISCUSSION
3.1 Synthesis of Low Molecular Weight Styrene Acrylic Copolymer 39
3.1.1 Series 1: Different monomer ratios at constant initiator
concentration 39
3.1.2 Series 2: Different concentration of initiator at constant
monomer ratio 45
3.2 Synthesis of High Molecular Weight Styrene Acrylic Copolymer 48
3.2.1 Series 3: Different monomer ratio at constant AA, initiator and
cross-linking agent concentration 48
3.2.2 Series 4: Different Concentration of Cross-linking Agent at
constant monomer ratio and initiator concentration 54
3.3 Mixing High Molecular Weight and Low Molecular Weight Styrene Acrylic
Copolymers 59
3.4 Properties Results of toner 63
3.5 Comparison between the synthesized toner resin and commercial
toner resins 77
3.6 Comparison between the synthesized toner and commercial toner 78
CHAPTER FOUR: CONCLUSION
4.1 Summary 82
4.2 Presentations at Conferences/Seminars 83
4.3 Suggestions of Future Works 84
REFERENCES 85
APPENDIX
A Machines used to produce raw toner
B Instruments used for sample characterization
C DSC profiles of toner resins and toners
D TGA profiles of toners
E GPC profiles of toner resins and toners
F Particle Size Distribution Data Sheet
G Calculation of Acid Number of High Molecular Weight Styrene Acrylic
Copolymers and Blended Resins
H Calculation of Percentage of THF Insoluble Fraction of High Molecular Weight
Styrene Acrylic Copolymers and Blended Resins
I Estimation of Tg by using Fox equation and Gordon-Taylor equation
J Test Print Images of M09-FT
K Test Print Images of M10-FT
L Test Print Images of M11-FT
M Test Print Images of commercial toner A
LIST OF FIGURES
CHAPTER ONE: INTRODUCTION
Figure 1.1 SEM photograph of (a) chemically produced toner and (b) conventional
toner
Figure 1.2 Basic principle of electrophotography
Figure 1.3 Diagram of the manufacturing process for conventional toner
Figure 1.4 Image with banding defect
Figure 1.5 Image with repetitive marks
Figure 1.6 Image with positive ghosting defect
Figure 1.7 Schematic diagram of the stages of dispersion in suspension polymerization
Figure 1.8 Thermal decomposition of benzoyl peroxide
CHAPTER TWO: EXPERIMENTAL
Figure 2.1 Apparatus for synthesis Styrene Acrylic Copolymer (A: mechanical stirrer,
B: condenser, C: thermometer, D: reactor flask with detachable lid, E:
heater controller, F: water bath)
Figure 2.2 Process to produce raw toner
Figure 2.3 Test images
CHAPTER THREE: RESULTS AND DISCUSSION
Figure 3.1 DSC thermogram of L20-TR, L21-TR, L22-TR, L15-TR and L16-TR at the
heating rate of 10oC/min
Figure 3.2 Comparison of Tgs of Styrene Acrylic Copolymers obtained from
experimental and calculation by Fox equation and Gordon-Taylor equation
(k=0.3445)
Figure 3.3 FT-IR spectra of L20-TR, L22-TR and L16-TR
Figure 3.4 DSC thermogram of L23-TR, L24-TR, L25-TR, L18-TR and L16-TR at the
heating rate of 10oC/min
Figure 3.5 DSC thermogram of H22-TR, H15-TR, H16-TR, H17-TR and H23-TR at
the heating rate of 10oC/min
Figure 3.6 Comparison of Tgs of Styrene Acrylic Copolymers obtained from
experimental and calculation by Fox equation and Gordon-Taylor equation
(k=0.5461)
Figure 3.7 FT-IR spectra of H22-TR, H16-TR and H23-TR
Figure 3.8 Plausible cross-linking reaction to form cross-linked Styrene Acrylic
Copolymer
Figure 3.9 DSC thermogram of H17-TR, H18-TR and H19-TR at the heating rate of
10oC/min
Figure 3.10 GPC profiles of H18-TR, L18-TR and M10-TR
Figure 3.11 Comparison of GPC chromatogram of Blended Resins at different blending
ratios
Figure 3.12 DSC thermogram of M08-TR, M09-TR, M10-TR, M11-TR and M12-TR at
the heating rate of 10oC/min
Figure 3.13 M09-FT (A: under magnification 40X, B: under magnification 100X)
Figure 3.14 M10-FT (A: under magnification 40X, B: under magnification 100X)
Figure 3.15 M11-FT (A: under magnification 40X, B: under magnification 100X)
Figure 3.16 TGA curves of M09-FT, M10-FT and M11-FT at the heating rate of
30oC/min
Figure 3.17 Example of test images template (A: text target, B: black page uniformity,
C: image and background density target)
Figure 3.18 Example of test images template (A & B: tone reproduction, line edge
raggedness and resolution test target, C: gray page uniformity)
Figure 3.19 Example of test images template (A: thermal banding target, B & C:
monochrome toner yield)
Figure 3.20 DSC thermogram of of M10-TR, commercial resin A, commercial resin B,
commercial resin C and commercial resin D at the heating rate of
10oC/min
Figure 3.21 Microscope pictures of (a) M10-FT and (b) Commercial toner A
APPENDIX A: Machines used to produce raw toner
Figure A.1 Henschel Mixer (A: Sample container with cooling jacket, B: Power button)
Figure A.2 Extruder
Figure A.3 Crusher
Figure A.4 Jet mill and Classifier
Figure A.5 Blender (A: Sample container, B: timer, C: speed controller)
APPENDIX B: Instruments used for sample characterization
Figure B.1 Mettler Toledo Differential Scanning Calorimeter 822e
Figure B.2 Gel Permeation Chromatography (GPC)
Figure B.3 Ray-ran Melt Flow Indexer (A: specified weight load, B: Automatic Flow
Rate Timer, C: Temperature Controller, D: Heater and Insulation)
Figure B.4 (a) Instrument for tribocharge determination (A: tribometer, B: electrometer,
C: sample cell which held by tribometer)
Figure B.5 Apparatus for Apparent Density Test (A: funnel, B: density cup, C: flowmeter
funnel)
Figure B.6 The Flotest Tester (A: funnel, B: sample container, C: flow disc with holes of
various diameters)
Figure B.7 CILAS 1064 particle size analyzer
Figure B.8 Tectron Ag. 916 Fluxmeter
Figure B.9 QUIKDens 100 Densitometer
APPENDIX C: DSC profiles of toner resins and toners
Figure C.1 DSC profile of L20-TR
Figure C.2 DSC profile of L21-TR
Figure C.3 DSC profile of L22-TR
Figure C.4 DSC profile of L15-TR
Figure C.5 DSC profile of L16-TR
Figure C.6 DSC profile of L23-TR
Figure C.7 DSC profile of L24-TR
Figure C.8 DSC profile of L25-TR
Figure C.9 DSC profile of L18-TR
Figure C.10 DSC profile of H22-TR
Figure C.11 DSC profile of H15-TR
Figure C.12 DSC profile of H16-TR
Figure C.13 DSC profile of H17-TR
Figure C.14 DSC profile of H23-TR
Figure C.15 DSC profile of H18-TR
Figure C.16 DSC profile of H19-TR
Figure C.17 DSC profile of M08-TR
Figure C.18 DSC profile of M09-TR
Figure C.19 DSC profile of M10-TR
Figure C.20 DSC profile of M11-TR
Figure C.21 DSC profile of M12-TR
Figure C.22 DSC profile of Commercial Resin A
Figure C.23 DSC profile of Commercial Resin B
Figure C.24 DSC profile of Commercial Resin C
Figure C.25 DSC profile of Commercial Resin D
APPENDIX D: TGA profiles of toners
Figure D.1 TGA curve of M09-FT
Figure D.2 TGA curve of H10-FT
Figure D.3 TGA curve of M11-FT
Figure D.4 TGA curve of magnetite pigment
Figure D.5 TGA curve of charge control agent
APPENDIX E: GPC profiles of toner resins and toners
Figure E.1 GPC profile of L18-TR
Figure E.2 GPC profile of H18-TR
Figure E.3 GPC profile of high molecular weight fraction of M10-TR
Figure E.4 GPC profile of low molecular weight fraction of M10-TR
Figure E.5 GPC profile of high molecular weight fraction of M10-FT
Figure E.6 GPC profile of low molecular weight fraction of M10-FT
APPENDIX F: Particle Size Distribution Data Sheet
Figure F.1 Particle size distribution of M09-FT
Figure F.2 Particle size distribution of M10-FT
Figure F.3 Particle size distribution of M11-FT
LIST OF TABLES
CHAPTER ONE: INTRODUCTION
Table 1.1 Classification of print quality defects
CHAPTER TWO: EXPERIMENTAL
Table 2.1 Series 1 - Different monomer ratios at constant initiator concentration
Table 2.2 Series 2 - Different concentrations of initiator at constant monomer ratio
Table 2.3 Series 3 - Different monomer ratios at constant AA, initiator and CLA
concentration
Table 2.4 Series 4 - Different concentrations of cross-linking agent (CLA) at constant
monomer ratio and initiator concentration
Table 2.5 Formulation to produce raw toner
Table 2.6 Formulation to produce toner
CHAPTER THREE: RESULTS AND DISCUSSION
Table 3.1 FT-IR spectral peak area ratio of1601 cm-1
/1724 cm-1
bands in the
Styrene Acrylic Copolymers
Table 3.2 Effect of varying monomer ratios at constant initiator concentration
Table 3.3 Effect of varying initiator concentration at constant monomer ratio
Table 3.4 FT-IR spectral peak area ratio of1601 cm-1
/1724 cm-1
bands in the
Styrene Acrylic Copolymers
Table 3.5 Effect of varying monomer ratio at constant AA, initiator and cross-linking
agent concentration
Table 3.6 Effect of varying cross-linking agent concentration at constant monomer
ratio and initiator concentration
Table 3.7 Effect of blending High Molecular Weight and Low Molecular Weight
Copolymers at different ratios
Table 3.8 Properties Results for toners
Table 3.9 Percentage weight loss of toners at different temperature region obtained
from TGA at the heating rate of 30oC/min
Table 3.10 Thermal decomposition temperature of toners obtained from TGA at the
heating rate of 30oC/min
Table 3.11 Image density values of the three print test images
Table 3.12 Background density values of the three print test images
Table 3.13 Properties of the synthesized toner resin and commercial toner resins
Table 3.14 Properties of the synthesized toner and a commercial toner
Table 3.15 Image density values of M10-FT and Toner A
Table 3.16 Background density values of M10-FT and Toner A
APPENDIX G: Calculation of Acid Number of High Molecular Weight Styrene
Acrylic Copolymers and Blended Resins
Table G.1 Calculation of Acid Number of High Molecular Weight Styrene Acrylic
Copolymers
Table G.2 Calculation of Acid Number of Blended Resins
APPENDIX H: Calculation of Percentage of THF Insoluble Fraction of High
Molecular Weight Styrene Acrylic Copolymers and Blended Resins
Table H.1 Calculation of Percentage of THF Insoluble Fraction of High Molecular
Weight Styrene Acrylic Copolymers
Table H.2 Calculation of Percentage of THF Insoluble Fraction of Blended Resins
APPENDIX I: Estimation of Tg by using Fox equation and Gordon-Taylor equation
Table I.1 Estimation of Tg of Low Molecular Weight Styrene Acrylic Copolymers by
using Fox equation
Table I.2 Estimation of Tg of High Molecular Weight Styrene Acrylic Copolymers by
using Fox equation
Table I.3 Calculation of fitting factor, k of Low Molecular Weight Styrene Acrylic
Copolymers by using Gordon-Taylor equation
Table I.4 Calculation of fitting factor, k of High Molecular Weight Styrene Acrylic
Copolymers by using Gordon-Taylor equation
Table I.5 Estimation of Tg of Low Molecular Weight Styrene Acrylic Copolymers by
using Gordon-Taylor equation
Table I.6 Estimation of Tg of High Molecular Weight Styrene Acrylic Copolymers by
using Gordon-Taylor equation
LIST OF ABBREVIATIONS
AA Acrylic Acid
AN Acid Number
BA Butyl Acrylate
BD Background density
BPO Benzoyl Peroxide
CCA Charge Control Agent
CLA Cross-linking Agent
CPT Chemically Produced Toner
DSC Differential Scanning Calorimetry
GPC Gel Permeation Chromatography
ID Image Density
MFI Melt Flow Index
Mn Number Average Molecular Weight
Mw Weight Average Molecular Weight
Mp Peak Value for Molecular Weight Distribution
Mz Z-average Molecular Weight
Q Polydispersity Index
MWD Molecular Weight Distribution
Tg Glass Transition Temperature