Chapter 4 - Shodhgangashodhganga.inflibnet.ac.in/bitstream/10603/34650/9/09_chapter 4.pdf · Chapter 4 Department of Chemistry, S. P. University Page 107 considering electricity bills,

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.

Chapter 4


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.

Chapter 4


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

Chapter 4


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].

Chapter 4


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-

Chapter 4


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

Chapter 4


(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

Chapter 4


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

Chapter 4


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).

Chapter 4


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

Chapter 4


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


PPUDI5 2600 P 3H P VG


PPUDI7 2250 P 3H F VG

PPUDI8 2700 P 4H F VG


PPUDI12 3450 P 5H p G



PPUDI17 2650 F 4H F G

PPUDI18 3000 F 5H F G




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


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


PPUDT5 2450 P 3H P G




PPUDT11 2890 F 3H P G

PPUDT12 3240 F 3H F G



PPUDT17 2450 F 3H P G

PPUDT18 2820 F 3H F G







Chapter 4



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


HPUDI4 1900 F 3H F Ex

HPUDI5 1800 P 3H P Ex


HPUDI7 1800 F 3H F Ex


HPUDI9 1550 P 1H P G






Chapter 4



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






HPUDT10 1630 F 1H P G





Chapter 4



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


CPUDI5 1550 P 1H P G


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





Chapter 4


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


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




Chapter 4


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




Chapter 4


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




Chapter 4


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




Chapter 4


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




Chapter 4


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

Chapter 4


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


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



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



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


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


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


Figure 4.1: IR SPECTRUM OF PUD BASED ON HYDROXYL

TERMINATED ALKYD RESIN AND IPDI CURED FILM

(HPUDI1).

Chapter 4


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)


R SPECTRUM OF PUD BASED ON PEG (600) AND IPDI


Chapter 4

Page 133

OF PUD BASED ON PEG (600) AND IPDI


Figure 4 .3: IR SPECTRUM

CURED FILM.


IR SPECTRUM OF PUD BASED ON PEG (600) AND IPDI


Chapter 4

Page 134

OF PUD BASED ON PEG (600) AND IPDI

Chapter 4


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


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


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


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Chapter 4


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Chapter 4 - Shodhgangashodhganga.inflibnet.ac.in/bitstream/10603/34650/9/09_chapter 4.pdf · Chapter 4 Department of Chemistry, S. P. University Page 107 considering electricity bills,

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