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Chapter 4
Department of Chemistry, S. P. University Page 104
Chapter 4 comprises of the fi lm formation of the
synthesized polyurethane dispersions and their characterization.
The dispersions were casted into fi lms and were characterized by
physical properties such as drying time, surface dry, Tack-free
dry, hard dry and mechanical study (Tensile strength).
Dispersions were finally used for coating application and
characterized for various tests. The detail about fi lm casting and
data interpretation is furnished in this chapter.
4.1 Application of Polyurethane coatings
The primary applications for polyurethanes include inks,
adhesives, foams, and coatings where coatings are by far the
largest segment. Some of the more important coating applications
are found in everyday products such as hardwood, flooring, metal
and wood furniture, electrical wire and cable, release papers,
beverage cans, magazine covers, packaging, leather finishes,
computer magnetic media and optical fiber [1,2].
INDUSTRY APPLICATION
AIM Coatings
(Architectural/Industrial
/ Maintenance Coatings
applied to protect from
corrosive environment)
Metal and Concrete Structures
Pipes and Tanks
Processing Equipment
Aircraft Primers
Color Coats and Topcoats
Automotive Parts
Underbody paints
Primers
Color Coats and Topcoats
Refinishing
Coil CoatingsApplied to coiled sheet metal that is used
in: P.T.O.
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Department of Chemistry, S. P. University Page 105
Conti…
Household appliance Industries
Transportation Industries
Construction Industries
Container Industries
Dental Fillings
Electronics
Microelectronics photo masks &
Solder masks
Notations on Circuit Board
Encapsulation of circuits
Optical fiber coatings
Compact (CDs)
Digital Video Disks (DVDs)
Flexible Plastics
Decorative Laminates
Shrink Film
Magnetic Recording Media
Abrasive Films & Release Films
Highway
Coatings used to mark lanes
Coatings used to provide directional
arrows on roadway
Leather Finishes
Topcoats
Machinery and
Equipment
Farm Equipment
Construction Equipment
Electrical Machinery
Heating, Ventilating and air -
conditioning systems (HVAC)
Marine
Ships
Offshore Platforms
P.T.O.
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Conti…..
Other Steel and Aluminum
Structures.
Metal Containers Beverages and Food Cans
Lids and Closures
Optics Eyeglass Lenses
Optical Fibers
Paper and Paperboard
Record Albums
Folding Cartons
Juice Cartons
Magazines and Paper Books
Business Forms
Banknotes and Money
Release and Abrasive Coated Paper
Rigid Plastics
Vinyl Floor Covering and Tiles
Bottles
Credit Cards
Sports and Medical Equipment
Textiles Sizing
Fill coats and Topcoats
Wood Furniture
Furniture
Kitchen Cabinets
Doors
Trim and Moldings
Even with the above mentioned advantages, waterborne
polyurethane dispersion cured coatings are having a difficult t ime
emerging from their early status as a niche product. This is
mainly due to the high material ’s cost, capital investment and its
storage stabil i ty. However, polyurethane dispersion cured
coatings are often justified on a "total" cost basis when
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Department of Chemistry, S. P. University Page 107
considering electricity bil ls, reduction in waste, labor cost,
production time, and factory space availabil i ty.
Future market penetration will not only rely on acceptance
of waterborne coatings and the displacement of conventional
systems, but wil l also be determined by the rate of development
and innovation and its value to the industry.[3-10]
4.2 Literature review
4.2.1Characterization of PUD coatings.
Shengwen Zhang et. al. [11] have examine the effect of
sil ica nanoparticles on structure and properties of waterborne UV-
curable polyurethane nanocomposites and the resulting
nanocomposite f i lms are possibly interesting for the generation of
waterborne UV- curable transparent coating with good scratch-
resistance. The effect of acrylic acid on the physical properties of
UV- cured poly(urethane acrylates-co-acrylic acid) fi lms for metal
coating on the thermal stabil i ty and mechanical hardness has
been reproted [12].
A nanoclay reinforced UV curable waterborne PU hybrid and
have found that multifunctional cross-link as well as reinforcing
fi l ler significantly augmented hardness, tensile strength, Tg and
thermal stabil i ty [13].
Cook and Kelley et. al. [14] developed radiation curable
silyl ether of cel lulose ester .The silyl ether pendant groups
contain thiol functionality that can function as cross l inking
agents. Thiol groups are radical init iation sites and aid in the
formation of fully cured network. The hardness of coatings and
the level of solvent resistance showed excellent results.
The waterborne epoxy acrylates/ si l ica sol hybrid material
and their study by UV curing behaviour are reproted [15].
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An acryl ic polyol and trimer of isophorone diisocyanate
based PU coating showed good gloss, scratch resistance and
excellent adhesion. Also found that better thermal stabi l ity and
excellent chemical and solvent resistance [16].
The fi lms derived from UV- curable acrylates-modified
waterborne polyurethane and monodispersed colloidal si l ica was
fabricated with much better thermal stabil i ty and mechanical
properties than pure WPU-AC [17].
A novel polyester urethane acrylate resin modified by
linseed oil fatty acid (LFA) and EB curing coating were formulated
and the coating cured by EB radiation on the timber, the cured
coating possessed of good performances such as gloss, hardness
and adhesion.[18]
Hieudu et. al. [19] synthesized UV-curable coating
composition for the protection of plastics. A 3 mm thick PMMA
sheet dipped in this coating composition was f irst dried in air for
~5 min and irradiated with UV (100 mJ/cm2) and the resulting 10
µm film of coating showed 7H pencil hardness, good adhesion,
abrasion and water resistance.
The synthesis, characterization and UV curing of
hyperbranched urethane-acrylate coating were investigated in the
study by Tasic et. al. [20]. The coating gives good compromise
between hardness and flexibil i ty which obtained by combining a
high crosslink density with f lexible segments between the cross
l inks and have potential to be used in different UV curing
applications.
Thin f i lms under UV radiation using UV lamp intensity 254-
313 nm from formulations developed with three different types of
oligomers: epoxy acrylate, polyester acrylate and urethane
acrylate in the presence of a mono- functional monomer N-
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vinylpyrrolidone. Film hardness, gel content and tensile
properties (strength and elongation) were studied. [21]
The structure-property relationship on Mechanical and
Thermal properties of UV curable Urethane and Urea acrylates
has been extensively studied. [22-23]
The relative efficiencies of several photo initiator in curing
of tr ifunctional acrylate monomer in both air and inert
atmosphere with or without amine synergist and curing efficiency
were judged by physical test of the coating fi lms produced [23-
24].
Sundar saimani, et al [25] have synthesized polyurethane
macroiniferter(PUMI) including tetraphenylethane was
synthesized and used to prepare polyurethane-polyacrylic acid
multiblock copolymers. The effect of varying (PUMI) content,
polymerization time, and precent ionization on the properties of
multiblock copolymerc dispersions were studied in detail.
Kevin, Larry et al [26] synthesized novel type of
crosslinkable waterborne polyurethane ionomer by the acetone
process. In which two types of sulfonated diols compatible with
this process were synthesized form the dimethyl 5- sodium sulfo
isophthalate using a one ot two stage method. Isocyante
terminted polyurethane oligomers were prepared form the
sulfonted diols with various combinations of diols and
diisocyanates and subsequently reacted with amino silane
derivates. Stable low-volati le organic chemical, waterborne
dispersions of the sulfo-urethane si lanol polymers spontaneously
crosslink upon drying without extra additives or processing steps.
A series of water-based polyurethane dispersions by
polyaddition of IPDI, Poly (oxytetramethylene) glycol, and DMPA,
which were end-capped and crosslinked with 3-aminoproply
trimethoxysilane to produce silylated polyurethane dispersions
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(SPUDs). The properties of these prepolymer dispersions were
investigated. [27-29]
Ching-Tezer et al [30] prepared single-pack, self-curable,
aqueous-based polyurethane dispersion containing a disperse dye
with a latent curing agent, polyaziridine as a single-component.
Guixi Zhang et al [31] have prepared radiation induced
dispersion polymerization of methyl methacrylate using
waterborne polyurethane as stabil izer.
The use of hydroxyl-functional hyperbranched polymers
(HBPs) were studied by Marco Sangermano et. al. [32] with
respect to a UV cured epoxy system. Their presence induced an
increase of the f inal epoxy conversion, which was interpreted on
the basis of a chain-transfer reaction. A decrease in Tg value and
increase in density in the photo cured fi lms were observed when
the amount of HBP additive in the photo curable formulation was
increased, indicating a decrease in the free volume and increase
in toughness due to the plasticization effect. The coating were
characterized by mechanical properties and found very brittle and
fragile.
4.3 Experimental
4.3.1Application of PUD curing coating composition:
Sample to be tested for Polyurethane dispersions was
coated onto MS steel test panels (15 cm x 5 cm) as fol lows. An
excess of the sample was placed at one end of the test panel and
using a rod applicator (K-Bar No.5) drawn across the substrate
pushing excess material off the edge. This method produced
coating with average wet fi lm thickness of 19-24 μm.
For the curing of above test panels, the coated panel was
dried at room temperature for 24 hours and further allowed to
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dry in oven at 50o C for 6 hours. This method produced coating
with average wet fi lm thickness of 20-30 µm.
The polyurethane dispersion films were prepared by pouring
the PUD sample in glass plate and dried at room temperature for
24 hours and further allowed to dry in oven at 50o C for 4 hours.
4.4 Coating Evaluation
The cured fi lm of all coating compositions was characterized
for various properties l ike adhesion, f lexibil i ty, impact resistance
and scratch resistance. The fi lms were also evaluated for their
chemical, corrosion and solvent resistance as per standard
methods of their characterization described in the li terature. [33]
The results of the fi lm characterization are reported in Tables:
4.1-4.12. These cured fi lms were also characterized for IR-
Spectra.
4.4.1 Adhesion and Flexibility: (ASTM D 3359 and ASTM D
522)
For the adhesion test [34], a number of parallel cuts are
made through the f i lm up to the substrate at 1 mm distance using
a sharp knife. These are crossed by a second series of cuts
making numbers of 1 mm x 1mm squares to make 100 squares. If
the adhesion is poor some of these squares will pul lout and result
is expressed as failure. If the severity of the test needs to be
increased, it can be performed by pressing a strip of adhesive
tape across the squares followed by a quick pull off. The results
for all cured fi lm are shown in respective tables.
For the flexibil ity [35] test, the coated panel is placed
under a mandrel of prescribed diameter embodied in a hinge
(coated side) the panel is then bent through 180O in 1 sec. After
removing the panel, the band is examined for cracks and loss of
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Department of Chemistry, S. P. University Page 112
adhesion. The results of cured fi lms are shown in respective
tables (Tables 4.1-4.6).
4.4.2Impact Resistance: ASTM D 2794
It is the resistance of organic coatings to the effects of
rapid deformation (impact). The impact resistance [36] of
different cured fi lms in the present study was evaluated as per
standard method using a heavy- duty tubular impact tester with 2
lbs mass and 25 inch height with round nose punch according to
IS- 101-1989 method. The impact area was observed for cracks in
the coating and accordingly reported as passed or failed. The
results for the impact resistance of al l cured fi lms were shown in
respective tables. (Tables 4.1-4.6).
4.4.3Scratch Hardness [37]
The coated panel is fixed in a horizontal position on the
apparatus having a needle in vertical position with hemispherical
hardened steel point with 1 mm diameter, attached to a counter
balance arms. This arm is lowered at the time of test so that the
needle comes in contact with the coated panel. The weight is
placed on arm and then it is lowered gently on coated panel. The
needle is pulled across the panel at constant rate by the machine
and the lightening of the red l ight is observed during this
process. If there is no lightening of red light, the needle is
shifted by about 10 mm and more weight is placed on the needle.
It is again pulled as earl ier and the lightening of red l ight is
checked. If red light gets ON, it indicates that needle has reached
the substrate indicating failure of coating. The result is recorded
as the maximum load, which needed to apply to the needle
before bare metal is visible through scratch. The results for al l
cured fi lms are reported in respective tables. (Tables 4.1-4.6).
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4.4.4Chemical Resistance ASTMD 1308 [38]
The chemical resistance of the cured fi lms is measured by
the immersion of the coated panel in 5 % of the acid as well as
alkali solution. After immersion the test, panels were observed
from time to time for any deterioration of the fi lm. The results
for all cured fi lms are given in respective tables (Tables 4.7-
4.12).
4.4.5 Solvent Resistance ASTM D 5402 [38]
The solvent resistance of the cured fi lm is measured by the
solvent rub test. The coated panels were rubbed with ethyl
methyl ketone (MEK) soaked cotton pad. Any changes in the
appearance or deterioration of the f i lm are observed. The results
are reported in respective tables. (Tables 4.7-4.12).
4.4.6IR – Spectroscopy
The IR-Spectra of PUD cured fi lms were scanned on ABB IR-
spectrophoto-meter in the range of 4000–400 cm-1. The sample
was taken on cell directly and run the instrument. The samples of
PEG based PUDs were carried out at GIRDA laboratories (Baroda).
The IR spectra of the oligomers are shown in
Figures 5.1 to 5.4.
4.4.7 Physical Properties
Drying time (Surface dry, tack free dry and hard dry) of al l
the PUD fi lms were examined as per the standards. Results are
shown in the Tables 4.13-4.18.
4.4.8 Mechanical properties
The mechanical properties are measured using Universal
Testing Machine (UTM, Instron Co. USA) at 100mm min -1
crosshead speed. Polyurethane f i lms were dried at 800 C for 3
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days. Dog-bone type specimen was made of these f i lms. The
results are reported in Table.4.19
Table 4.1: Mechanical properties of Polyurethane dispersion coatings based on (PEG) and IPDI
Sample
Code
Scratch
Hardness
(gms)
Impact
Hardness
Pencil
Hardness
Flexibility
1/8”
mandrel
Cross
Hatch
Adhesion
PPUDI1 1730 P 2H P Ex
PPUDI2 2250 P 3H P Ex
PPUDI5 2600 P 3H P VG
PPUDI6 2950 P 4H P VG
PPUDI7 2250 P 3H F VG
PPUDI8 2700 P 4H F VG
PPUDI11 3100 P 4H P VG
PPUDI12 3450 P 5H p G
PPUDI13 1800 P 3H P VG
PPUDI14 2400 P 4H P VG
PPUDI17 2650 F 4H F G
PPUDI18 3000 F 5H F G
PPUDI19 1760 P 2H P Ex
PPUDI20 1980 P 3H P Ex
PPUDI23 2400 P 3H P VG
PPUDI24 2830 P 3H P G
P-Pass F-Fail Ex-Excellent VG-Very Good G-Good
6H>5H>4H>3H>2H>1H>H>HB>1HB>2HB>3HB>4HB>5HB>6HB
Chapter 4
Department of Chemistry, S. P. University Page 115
Table 4.2: Mechanical Properties of Polyurethane
dispersion coatings based on (PEG) andTDI
Sample
Code
Scratch
Hardness
(gms)
Impact
Hardness
Pencil
Hardness
Flexibility
1/8”
mandrel
Cross
Hatch
Adhesion
PPUDT1 1560 P 2H P VG
PPUDT2 2060 P 2H P VG
PPUDT5 2450 P 3H P G
PPUDT6 2730 P 3H P G
PPUDT7 2090 P 2H P VG
PPUDT8 2540 P 3H P VG
PPUDT11 2890 F 3H P G
PPUDT12 3240 F 3H F G
PPUDT13 1670 P 2H P VG
PPUDT14 2260 P 3H P G
PPUDT17 2450 F 3H P G
PPUDT18 2820 F 3H F G
PPUDT19 1590 P 1H P VG
PPUDT20 1740 P 2H P VG
PPUDT23 2260 P 2H P VG
PPUDT24 2640 P 2H P G
P-Pass F-Fail Ex-Excellent VG-Very Good G-Good
6H>5H>4H>3H>2H>1H>H>HB>1HB>2HB>3HB>4HB>5HB>6HB
Chapter 4
Department of Chemistry, S. P. University Page 116
Table 4.3: Mechanical Properties of Polyurethane
dispersion coatings based on Hydroxyl
terminated Alkyd resin and (IPDI)
Sample
Code
Scratch
Hardness
(gms)
Impact
Hardness
Pencil
Hardness
Flexibility
1/8”
mandrel
Cross
Hatch
Adhesion
HPUDI1 1800 P 3H P Ex
HPUDI2 1600 P 2H P VG
HPUDI3 1550 P 2H P VG
HPUDI4 1900 F 3H F Ex
HPUDI5 1800 P 3H P Ex
HPUDI6 1820 P 2H P VG
HPUDI7 1800 F 3H F Ex
HPUDI8 1730 P 2H P VG
HPUDI9 1550 P 1H P G
HPUDI10 1750 P 2H P VG
HPUDI11 1650 P 1H P G
HPUDI12 1520 P 1H P G
P-Pass F-Fail Ex-Excellent VG-Very Good G-Good
6H>5H>4H>3H>2H>1H>H>HB>1HB>2HB>3HB>4HB>5HB>6HB
Chapter 4
Department of Chemistry, S. P. University Page 117
Table 4.4: Mechanical Properties of Polyurethane
dispersions coatings based on Hydroxyl
terminated Alkyd resin and (TDI)
Sample
Code
Scratch
Hardness
(gms)
Impact
Hardness
Pencil
Hardness
Flexibility
1/8”
mandrel
Cross
Hatch
Adhesion
HPUDT1 1600 P 2H P VG
HPUDT2 1400 P 1H P G
HPUDT3 1350 F 1H P G
HPUDT4 1820 F 2H P VG
HPUDT5 1700 F 2H P VG
HPUDT6 1640 P 2H P G
HPUDT7 1700 F 2H P VG
HPUDT8 1560 P 1H P G
HPUDT9 1420 P 1H P G
HPUDT10 1630 F 1H P G
HPUDI11 1480 P 1H P G
HPUDT12 1390 P 1H P G
P-Pass F-Fail Ex-Excellent VG-Very Good G-Good
6H>5H>4H>3H>2H>1H>H>HB>1HB>2HB>3HB>4HB>5HB>6HB
Chapter 4
Department of Chemistry, S. P. University Page 118
Table 4.5: Mechanical Properties of Polyurethane
dispersions coatings based on Castor oil
and (IPDI)
Sample
Code
Scratch
Hardness
(gms)
Impact
Hardness
Pencil
Hardness
Flexibility
1/8”
mandrel
Cross
Hatch
Adhesion
CPUDI1 1800 P 3H P Ex
CPUDI2 1820 P 2H P VG
CPUDI3 1800 F 3H F Ex
CPUDI4 1730 P 2H P VG
CPUDI5 1550 P 1H P G
CPUDI6 1750 P 2H P VG
Table 4.6: Mechanical Properties of Polyurethane dispersion
coatings based on Castor oil and (TDI)
Sample Code Scratch
Hardness
(gms)
Impact
Hardness
Pencil
Hardness
Flexibility
1/8”
mandrel
Cross
Hatch
Adhesion
CPUDT1 2260 P 3H P G
CPUDT2 2450 F 3H P G
CPUDT3 2820 F 3H F G
CPUDT4 1590 P 1H P VG
CPUDT5 1740 P 2H P VG
CPUDT6 2260 P 2H P VG
P-Pass F-Fail Ex-Excellent VG-Very Good G-Good
6H>5H>4H>3H>2H>1H>H>HB>1HB>2HB>3HB>4HB>5HB>6HB
Chapter 4
Department of Chemistry, S. P. University Page 119
Table 4.7: Chemical Properties of Polyurethane dispersion coatings based on (PEG) and IPDI
Sample
Code
Acid
Resistance
5%HCl
Alkali
Resistance
5%NaOH
Corrosion
Resistance
5%Nacl
MEK
Double rub
PPUDI1 4 3 3 73
PPUDI2 4 3 4 80
PPUDI5 4 4 4 86
PPUDI6 5 4 5 92
PPUDI7 4 4 4 82
PPUDI8 4 4 4 87
PPUDI11 5 4 5 91
PPUDI12 5 5 5 93
PPUDI13 4 3 4 79
PPUDI14 4 3 4 81
PPUDI17 4 4 4 87
PPUDI18 5 4 5 90
PPUDI19 3 3 3 72
PPUDI20 4 3 3 78
PPUDI23 4 3 4 83
PPUDI24 4 4 4 88
0 Film completely removed 3 Loss of gloss
1 Film cracked and partially removed 4 Slight loss of gloss
2 Film partially cracked 5 Film Practically unaffected
Chapter 4
Department of Chemistry, S. P. University Page 120
Table 4.8 Chemical Properties of Polyurethane dispersion
coatings based on (PEG) and TDI.
Sample
Code
Acid
Resistance
5%HCl
Alkali
Resistance
5%NaOH
Corrosion
Resistance
5%Nacl
MEK
Double rub
PPUDT1 3 3 3 67
PPUDT2 3 3 3 73
PPUDT5 3 3 3 77
PPUDT6 4 3 4 84
PPUDT7 3 3 3 74
PPUDT8 4 3 3 77
PPUDT11 4 4 4 85
PPUDT12 4 4 4 89
PPUDT13 3 3 3 67
PPUDT14 3 3 3 72
PPUDT17 4 3 4 77
PPUDT18 4 4 4 86
PPUDT19 2 2 2 65
PPUDT20 3 2 2 71
PPUDT23 3 3 3 76
PPUDT24 3 3 3 81
0 Film completely removed 3 Loss of gloss
1 Film cracked and partially removed 4 Slight loss of gloss
2 Film partially cracked 5 Film Practically unaffected
Chapter 4
Department of Chemistry, S. P. University Page 121
Table 4.9: Chemical Properties of Hydroxyl terminated Alkyd
resin and (IPDI).
Sample
Code
Acid
Resistance
5%HCl
Alkali
Resistance
5%NaOH
Corrosion
Resistance
5%Nacl
MEK
Double rub
HPUDI1 5 4 5 86
HPUDI2 4 4 4 79
HPUDI3 4 3 4 75
HPUDI4 5 4 5 92
HPUDI5 5 4 5 88
HPUDI6 4 4 5 84
HPUDI7 5 4 5 90
HPUDI8 5 4 4 86
HPUDI9 4 3 4 79
HPUDI10 4 4 4 80
HPUDI11 4 3 4 73
HPUDI12 3 3 3 68
0 Film completely removed 3 Loss of gloss
1 Film cracked and partially removed 4 Slight loss of gloss
2 Film partially cracked 5 Film Practically unaffected
Chapter 4
Department of Chemistry, S. P. University Page 122
Table 4.10: Chemical Properties of Hydroxyl terminated
Alkyd resin and (TDI).
Sample
Code
Acid
Resistance
5%HCl
Alkali
Resistance
5%NaOH
Corrosion
Resistance
5%Nacl
MEK
Double rub
HPUDT1 4 4 4 78
HPUDT2 3 3 3 71
HPUDT3 3 3 3 68
HPUDT4 5 3 4 84
HPUDT5 4 3 4 77
HPUDT6 3 3 4 73
HPUDT7 4 4 4 81
HPUDT8 4 3 4 73
HPUDT9 3 3 3 67
HPUDT10 3 3 3 71
HPUDI11 3 3 3 64
HPUDT12 3 3 3 61
0 Film completely removed 3 Loss of gloss
1 Film cracked and partially removed 4 Slight loss of gloss
2 Film partially cracked 5 Film Practically unaffected
Chapter 4
Department of Chemistry, S. P. University Page 123
Table 4.11: Chemical Properties of Polyurethane dispersion
coatings based on Castor oil and (IPDI)
Sample
Code
Acid
Resistance
5%HCl
Alkali
Resistance
5%NaOH
Corrosion
Resistance
5%Nacl
MEK
Double rub
CPUDI1 4 4 4 85
CPUDI2 5 4 5 83
CPUDI3 4 3 4 92
CPUDI4 4 4 5 90
CPUDI5 4 3 4 88
CPUDI6 5 4 5 85
0 Film completely removed 3 Loss of gloss
1 Film cracked and partially removed 4 Slight loss of gloss
2 Film partially cracked 5 Film Practically unaffected
Chapter 4
Department of Chemistry, S. P. University Page 124
Table 4.12: Chemical Properties of Chemical Properties of
Polyurethane dispersion coatings based on
Castor oil & (TDI)
Sample
Code
Acid
Resistance
5%HCl
Alkali
Resistance
5%NaOH
Corrosion
Resistance
5%Nacl
MEK
Double rub
CPUDT1 3 3 4 82
CPUDT2 4 3 4 79
CPUDT3 3 3 4 89
CPUDT4 3 3 4 85
CPUDT5 3 3 3 84
CPUDT6 4 3 4 81
0 Film completely removed 3 Loss of gloss
1 Film cracked and partially removed 4 Slight loss of gloss
2 Film partially cracked 5 Film Practically unaffected
Chapter 4
Department of Chemistry, S. P. University Page 125
Table 4.13: Physical Properties of Polyurethane dispersions films
based on (PEG) and IPDI.
Sr. No
Sample Code
Drying time
Surface dry(min)
Tackfree dry (min)
Harddry (hrs)
1 PPUDI1 15-30 2-5 O/N
2 PPUDI2 15-30 2-5 O/N
3 PPUDI3 15-30 2-5 O/N
4 PPUDI4 15-30 2-5 O/N
5 PPUDI5 15-30 2-5 O/N
6 PPUDI6 15-30 2-5 O/N
7 PPUDI7 15-30 2-5 O/N
8 PPUDI8 15-30 2-5 O/N
9 PPUDI9 15-30 2-5 O/N
10 PPUDI10 15-30 2-5 O/N
11 PPUDI11 15-30 2-5 O/N
12 PPUDI12 15-30 2-5 O/N
13 PPUDI13 15-30 2-5 O/N
14 PPUDI14 15-30 2-5 O/N
15 PPUDI15 15-30 2-5 O/N
16 PPUDI16 15-30 2-5 O/N
17 PPUDI17 15-30 2-5 O/N
18 PPUDI18 15-30 2-5 O/N
19 PPUDI19 20-30 2-5 O/N
20 PPUDI20 20-30 2-5 O/N
21 PPUDI21 20-30 2-5 O/N
22 PPUDI22 20-30 2-5 O/N
23 PPUDI23 20-30 2-5 O/N
24 PPUDI24 20-30 2-5 O/N
O/N – Overnight
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Department of Chemistry, S. P. University Page 126
Table 4.14: Physical Properties of Polyurethane dispersions films
based on (PEG) and TDI
Sr. No
Sample Code
Drying time
Surface dry(min)
Tackfree dry (min)
Harddry (hrs)
1 PPUDT1 15-25 2-5 O/N
2 PPUDT2 15-25 2-5 O/N
3 PPUDT3 15-25 2-5 O/N
4 PPUDT4 15-25 2-5 O/N
5 PPUDT5 15-25 2-5 O/N
6 PPUDT6 15-25 2-5 O/N
7 PPUDT7 15-25 2-5 O/N
8 PPUDT8 15-25 2-5 O/N
9 PPUDI9 15-25 2-5 O/N
10 PPUDT10 15-25 2-5 O/N
11 PPUDT11 15-25 2-5 O/N
12 PPUDT12 15-25 2-5 O/N
13 PPUDT13 15-25 2-5 O/N
14 PPUDT14 15-25 2-5 O/N
15 PPUDT15 15-25 2-5 O/N
16 PPUDT16 15-25 2-5 O/N
17 PPUDT17 15-25 2-5 O/N
18 PPUDT18 15-25 2-5 O/N
19 PPUDT19 20-30 2-5 O/N
20 PPUDT20 20-30 2-5 O/N
21 PPUDT21 20-30 2-5 O/N
22 PPUDT22 20-30 2-5 O/N
23 PPUDT23 20-30 2-5 O/N
24 PPUDT24 20-30 2-5 O/N
O/N – Overnight
Chapter 4
Department of Chemistry, S. P. University Page 127
Table 4.15 Physical Properties of Polyurethane dispersions films
based on Hydroxyl terminated Alkyd resin and IPDI
Sr. No
Sample Code
Drying time
Surface dry(min)
Tackfree dry (min)
Harddry (hrs)
1 HPUDI1 15-30 2-5 O/N
2 HPUDI2 15-30 2-5 O/N
3 HPUDI3 15-30 2-5 O/N
4 HPUDI4 15-30 2-5 O/N
5 HPUDI5 15-30 2-5 O/N
6 HPUDI6 15-30 2-5 O/N
7 HPUDI7 15-30 2-5 O/N
8 HPUDI8 15-30 2-5 O/N
9 HPUDI9 15-30 2-5 O/N
10 HPUDI10 15-30 2-5 O/N
11 HPUDI11 15-30 2-5 O/N
12 HPUDI12 15-30 2-5 O/N
Chapter 4
Department of Chemistry, S. P. University Page 128
Table 4.16 Physical Properties of Polyurethane dispersions films
based on Hydroxyl terminated Alkyd resin and TDI
Sr. No
Sample Code
Drying time
Surface dry(min)
Tackfree dry (min)
Harddry (hrs)
1 HPUDT1 15-30 2-5 O/N
2 HPUDT2 15-30 2-5 O/N
3 HPUDT3 15-30 2-5 O/N
4 HPUDT4 15-30 2-5 O/N
5 HPUDT5 15-30 2-5 O/N
6 HPUDT6 15-30 2-5 O/N
7 HPUDT7 15-30 2-5 O/N
8 HPUDT8 15-30 2-5 O/N
9 HPUDT9 15-30 2-5 O/N
10 HPUDT10 20-30 2-5 O/N
11 HPUDI11 20-30 2-5 O/N
12 HPUDT12 20-30 2-5 O/N
Chapter 4
Department of Chemistry, S. P. University Page 129
Table 4.17 Physical Properties of Polyurethane dispersions films
based on Castor oil and IPDI
Sr. No
Sample Code
Drying time
Surface dry(min)
Tackfree dry (min)
Harddry (hrs)
1 CPUDI1 20-30 5-10 O/N
2 CPUDI2 20-30 5-10 O/N
3 CPUDI3 20-30 5-10 O/N
4 CPUDI4 20-30 5-10 O/N
5 CPUDI5 20-30 5-10 O/N
6 CPUDI6 20-30 5-10 O/N
Table 4.18 Physical Properties of Polyurethane dispersions films
based on Castor oil and TDI.
Sr. No
Sample Code
Drying time
Surface dry(min)
Tackfree dry (min)
Harddry (hrs)
1 CPUDT1 15-25 5-10 O/N
2 CPUDT2 15-25 5-10 O/N
3 CPUDT3 15-25 5-10 O/N
4 CPUDT4 15-25 5-10 O/N
5 CPUDT5 15-25 5-10 O/N
6 CPUDT6 15-25 5-10 O/N
O/N – Overnight
Chapter 4
Department of Chemistry, S. P. University Page 130
Table.4.19 Tensile Properties of PUD films.
Sr.No
Sample Code Width mm
Max. Load (N)
Max.Tensile Strength (Mpa)
Max. (%) Elongation
1 PPUDI2 10 9.5 8.5 300.00
2 PPUDI14 10 9.0 9.0 280.40
3 PPUDI23 10 10.0 11.5 230.50
4 PPUDT2 10 8.5 10.0 260.10
5 PPUDT14 10 9.0 10.5 215.50
6 PPUDT24 10 11 12.0 270.30
7 HPUDI1 10 11.5 12.5 290.50
8 HPUDI10 10 11.7 12.5 285.35
9 HPUDT1 10 10.5 11.0 270.50
10 HPUDT12 10 10.0 9.5 260.50
11 CPUDI1 10 12.0 12.8 310.15
12 CPUDT5 10 11.5 11.5 300.50
Where
Max = Maximum
MPa = MegaPascal
N = Netwon
Chapter 4
Department of Chemistry, S. P. University Page 131
Figure 4.1: IR SPECTRUM OF PUD BASED ON HYDROXYL
TERMINATED ALKYD RESIN AND IPDI CURED FILM
(HPUDI1).
Chapter 4
Department of Chemistry, S. P. University Page 132
Figure 4.2: IR SPECTRAM OF PUD BASED ON HYDROXYL
TERMINATED ALKYD RESIN AND TDI CURED FILM
(HPUDT2).
Department of Chemistry, S. P. University
Figure 4 .3: IR SPECTRUM
CURED FILM. (PPUDI13)
Department of Chemistry, S. P. University
R SPECTRUM OF PUD BASED ON PEG (600) AND IPDI
CURED FILM. (PPUDI13)
Chapter 4
Page 133
OF PUD BASED ON PEG (600) AND IPDI
Department of Chemistry, S. P. University
Figure 4 .3: IR SPECTRUM
CURED FILM.
Department of Chemistry, S. P. University
IR SPECTRUM OF PUD BASED ON PEG (600) AND IPDI
CURED FILM. (PPUDI13)
Chapter 4
Page 134
OF PUD BASED ON PEG (600) AND IPDI
Chapter 4
Department of Chemistry, S. P. University Page 135
4.5 Results and Discussion:
4.5.1 Adhesion and Flexibility:
Adhesion and Flexibil i ty are the prime important
characteristics of all coatings. To function effectively and
satisfactorily, the surface coatings must adhere well and should
not be affected by any mechanical abuse.
The results of flexibil i ty and adhesion had shown in the
Tables 4.1 to 4.6 reveals the excellent performance of most of
the experimental batches. In the case of different polyols and
different NCO/OH mole ratios containing samples reveals that the
results of cross hatch adhesion test of all samples are
satisfactory. Where as in flexibil i ty test of some samples were
failed because of its high molecular weight and due to these the
material becomes harder. Almost al l the compositions shows good
adhesion on both the substrates compositions from hydroxyl
terminated alkyd resin and castor oil shows good adhesion. This
might be attributed as incorporation of fatty acid chain in the
polymer backbone which increased the wetting properties of the
polymer and thus improves adhesion.
4.5.2Impact Resistance:
The results of impact resistance showed the similar trend in
all above mentioned experimental. Impact resistance of most of
the composition was found to be excellent. There was marginal
sign of damage in aromatic (TDI) PUDs. The results of Impact
resistance are shown in Tables 4.1 to 4.6.
4.5.3Scratch Hardness:
The results of scratch resistance are shown in Tables 4.1
to 4.6. The scratch hardness of the cured fi lms was found
different for different compositions. It is found that ionic content
(DMPA) increases scratch hardness decreases, high level of ionic
Chapter 4
Department of Chemistry, S. P. University Page 136
content (DMPA) of the polymer backbone results ultimately in
lowering the molecular weight of the polymer and hence poor
toughness of the fi lm is resulted. As the NCO/OH ratios increases
the scratch hardness increases. This is because as the hard
segments increased in polymer chain which results in toughness.
4.5.4Chemical Resistance and Solvent resistance:
The results of chemical and solvent resistance as shown in
Tables 4.7 to 4.12 were quite encouraged in terms of cured
coating performance. The higher cross l inking density (XLD) in
respective experimental sets showed improved solvent and
chemical resistance of the cured fi lms. Also the acid and alkali
resistance of the fi lms based on high NCO/OH mole ratio and
more number of polyurethanes segments showed better chemical
resistance.
4.5.5IR – Spectroscopy:
IR spectra of different polyurethane dispersion are depicted
in Figures 4.1 to 4.4 respectively. The spectral analysis was
mainly used to check the completion of the polymerization
reaction in terms of the disappearance of the NCO band at 2265
cm-1 and the appearance of the N-H band at 3000-3400 cm-1,
which could be ascribed to the hydrogen bonding between N-H
and carbonyl groups.
4.5.6 Physical Properties:
The results of physical properties all the PUD films were examined.
Surface dry, tack free dry and hard dry was observed and is reported in
Tables 4.13-4.18. It shows that all the composition show nearby time for
complete cured.
Chapter 4
Department of Chemistry, S. P. University Page 137
4.5.7 Tensile Properties:
The tensile properties such as maximum load (N), maximum tensile
strength (MPa) and Maximum percentage elongation of few of the
polyurethane dispersion films is examined and its results is shown in Table
4.19. It shows that with increasing the DMPA content and NCO/OH ratio
there is increase tensile strength and at the same time elongation decreases.
Moreover as the NCO/OH ratio increase, the chain extension reaction
produces urea linkage that contribute to hard segments of polyurethane
backbone which results in increased in tensile strength. The elongation
decreased linearly as the soft segment content decreases.
4.6 Conclusion
The waterborne polyurethane dispersion coatings based on
various polyols such as polyethylene glycols (Mol wt 200, 400,
600, and 1000), coconut oi l based alkyd resin and Castor oil as a
polyols are prepared satisfactorily and show good curing
characteristics. Performance properties of the dried f i lms like
mechanical properties, chemical resistance, solvent resistance,
and physical properties are mainly governed by the NCO/OH
equivalent mole ratio, %ionic content. Higher the ionic content
showed poor chemical resistance as well as mechanical
properties. Increasing the NCO/OH equivalent ratio (1.4-1.8) the
mechanical properties as well as performance of dried fi lms is
better. The physico-chemical properties of synthesized
polyurethane dispersions fi lms as well as the final coating
compositions of were in quite agreement with the currently used
equivalent polyester and epoxy as well as solvent base
polyurethane coatings. As all these compositions do not contain
the volati le organic solvents, which contribute to Volati le Organic
Compounds (VOC’s), the resulting coatings are eco-friendly and
meeting the legislative requirements by the various regulatory
authorities in the field of Surface Coatings.
Chapter 4
Department of Chemistry, S. P. University Page 138
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