development of novel polymer based...
TRANSCRIPT
Chapter 4
LEATHER BONDING
Chapter 4
Partl Studies on Polymeric Solution Adhesives for Bonding Leather
The footwear manufacture involves joining of many intricate parts using adhesives‘. The
forces of attraction may be strong chemical bonds or the weaker forces known as Van der Waal’s
attraction 1-‘. Bonding may also results from mechanical interlocking or by penetration ofadhesive
molecules into the substrates by dilfiision‘.
Neoprene rubber, nitrile rubber, polyurethane rubber 5'“ and natural rubber based adhesives
are common in shoe industry 7. Disadvantage ofnitrile based adhesives is that , it is necessary
to activate the substrates at higher temperature (70-80 "C) to get better bonding strength.
In this work we developed three diflerent types of novel solution adhesives are proposed
to be tried for leather to leather bonding . The peel and shear strength of the adhesive joints are
proposed to be compared with joints made with commercial adhesives.
Experimental:
Materials used:
Commercial N01: Poly urethane based commercial adhesive supplied by CLRI Madras.
Commercial N02: Dentrite adhesive supplied by Superchem
Adhesive preparation:
I- PVC based: Suspension grade PVC was dissolved in either cyclohexanone or
tetrahydro furan. The solid content of the solution was l0 percentage.
2. CR based: Chloroprene rubber was compounded as per the formulation in Table
4. l. I. This compound was then put in a solvent (usually toluene) and kept for two
days. After that a mechanical stirring was given to make the solution uniform, the
total solid content was about 20 percentage.
3. NR based: Natural mbber was compounded as per the formulations in Table 4.1.1.
This was then dissolved in solvent and the adhesive was prepared explained above.
93
Table 4.1.1 Formulations ofleather adhesives. pi-.1
i
1
r
I
I
V
l5. _
I
I
I
I
I
|
A Ingredients JNR adhesive SBR sole l
1
f"'":"" Z ‘it J" J “"—*"._‘:T“""'f:""'* " ' ‘_”*:""”1;T" o ' “|‘:"-" o of(:R adhesive i NR sole 1" MC sole
NRCR
ii sen1; NBR
PVC
ZnO
MgO
Stearic acid
Accinox 'l'Q
Clay
Silica
HAF
Aromatic oil
MBTS
TiO2
DNPT
PF resin
Wood rosin
DEG
DOP
Vulcafor F
SulphurTMTD
1
I
I ()0
2.0
1.5
20
20
——'777-—---v- _ '_,~-_ . ..l .5100 iI00 0ii i 1 00I
1
5 Z 4 44 ~ i2 21.01.0 1.0is
i45 40
‘ 2 ; 2. 1.5 1.5
20
l0
J 1'5 J 2.0
1.0i 1.0
>
1
' r
50
50
5
2
2
80
20
2
I0
2
1-5
5
1.5
1.5
0.5
I.‘Il
l
Commercial adhesive I: The polyurethane based adhesive chips supplied by CLRI
was dissolved in THF to get a 20 percentage solution. This was used as the commercial
adhesive in this study.
94
L
I. Upper Leather to Upper Leather bonding:
leather pieces ( hereafter menrmrmrg Q/'1<.'u!/zer means upper {cut/2t.'r) were cut into llilx Z5
mm size. lihese pieces were roughened using sand paper no.50 and wiped with MEK and dried.
These specimens were treated with the adhesives so that the pores, completely tilled and there
was a uniform layer of the adhesive formed. When the adhesive surface is dried another layer oi
adhesive was applied in the same manner. When the second adhesive film is dry to a point there
is still an aggressive tackiness but no tendency for the film to Iitt when tested with a finger. The
coated surface ofthe two strips were aligned face to face carefully, without entrapping air, in
such a way that the free ends of the strips lie in opposite direction for shear strength and lie in
the same direction for peel strength testing. The pieces were pressed together by applying a
pressure of around 10- I 2 kg/cm? The test specimens were conditioned for 48 hours. For peel
strength testing adhesive was applied over an area 2.5x2cm at one of the buffed surface of the
strips- For shear strength testing adhesive was applied over an area of 2.5x 4cm at one of the
bufled surface of each strip.
All the three types of adhesives prepared with two commercial adhesives were used for
bonding the adherends to determine the peel and lap shear strength. Adhesion strengths were
tested on a Zwick UTM model 1445 with a cross head speed of 50 mm/min. at room temperature
as per ASTM l876(89) ~ adhesive strength for two flexible adherends. For each result six
specimens were tested and the mean was taken.
The leather to leather joints made were kept immersed in water at room temperature for
24 hours. After that the specimens were taken out, dried and thier strengths were determined as
per ASTM D 1137 (90). Leather joints were kept in an air oven at 50°C for 24 hours. The
specimens were then taken outside, conditioned and strength were determined. The leather
pieces were tested after 30 minutes of joining in peel or lap shear form so that the quick stick ot
the adhesives were obtained. Flcxing was given to the leather joints on Ross flex instrument.
Number ofcycles to failure were noted. Leather in both peel and shear joints were tested for the
flex resistance.
95
\
Q
2. Bonding of different leather foot wear components:
Types ol'_joints tested;
I. Upper leather to sole leather
2. Upper leather to vulcanised natural rubber sole
3. Upper leather to vulcaniscd synthetic rubber(SBR) sole
4. Upper leather to microcellular (MC )sole
5 MC to vulcanised natural rubber sole
6, MC to vulcanised synthetic rubber sole.
7. Upper leather to plastic sole
8. Sole leather to plastic sole
Natural rubber (NR) sole, synthetic rubber (SBR) sole and micro cellular (MC) sole were
prepared in the laboratory as per the formulations in Table4. I .l. The compounds were prepared
on a two roll mill ( l 5.x 30 cm). The optimum cure time was determined on Goefertt elastograph
and they were vulcanised on a hydraulic press at l60"C for their optimum cure times. Vulcanised
soles were then conditioned for 24 hours and hardness ofthe soles were measured on a Zwick
durometer.
Leather pieces were cut into 150x25 mm size and vulcanised rubber soles were cut into
25x 25 mm size. The leather and rubber pieces were bonded as per IS 4663(68). Rubber and
leather pieces were abraded with sand paper no. 50 and wiped with MEK solvent and dried. Two
leather pieces were taken and in between these pieces the rubber piece was kept and bonded in
a sandwich model- The rubber piece was coated with the adhesive on both sides and jointed
with the leather pieces. Both peel and lap joints were prepared for strength measurement. For
joining MC and leather both the adherends were cut into l50x25mm size- Rubber and MC joints
and upper leather to plastic sole were also prepared as above. In all the ditferent types of joints
the adhesives prepared were used and strength were determined as above.
Optical mr'cr0sc0p:'c studies
Optical microscopic examination of the roughened and peeled off surfaces of upper leather,
sole leather, rubber sole and microcellular sole etc. with CR adhesive was examined. The
96
peeled otlsurfaces with commercial adhesive Dentrite were also studied by optical photographs.
Results and l)iscussion:
Figure 4. l. I shows ettect oftotal solid content on peel and lap shear strength ofleather to
leather joints. As the solid content increases peel strength increases, reaches a maximum and
then decreases. Lap shear strength also shows same trend in this figure. This may be due to
lower penetration of adhesives when solid content is very high.
-F.-......__ .,_____-_.___-_¢----—— i_a.-Q.’-..— .-- —-—-----_-o.a----——--he----I - - -->~—- -ii—--—-nu-r —---—--ii-------\--——— —sot‘ 1. —I— Shear N/cm2
Adhes on streng h
5 8 8 8 8 8 Es‘
0 *** " ’T’ * "i H it” 7; * 1-’ “Ti *' "*7 *'* " i I10 15 20 25 30 35 40 45Solid eontent.%
FIg.4.1.1 Effect of solid content on adhesion strength
Figure 4.1.2 shows the etlect of viscosity of adhesive to the peel and shear strength of
leather to leather joints. When the v iscosity increases joint strength both in peel and shear
increases to some extent and then decreases. However,when the viscosity is higher the penetration
of the adhesive solution is restricted, resulting in lower peel (series l)and shear strength (series 2).
97
Figure 4. i.3 shows the pecl strength ofditferenl adhesives used for bonding upper leatner
lo upper leather before and after soaking in water. Commercial adhesives show inferior properties
compared lo the adhesives prepared in laboratory.
-Q—"
eson s reng h
{-1
. i
AdhPeel strength,N/om
90
80
70
8
50
88
20
10
O
35
30
IOO’!B
.1U!
-AO
5
|
I
|.‘\U
|
I
4!I
if
T-.
-q}.\
I\
-0-— Peel Nlcm
-a— shear N/cm2
i
I
I
i
!
.1
-4
O
i— —7———.--_—— _ ' ______ ___ ._.__ _ _ 1? ' ——7 F------'7?-—---~. »1000 2000 3000 4000 H100 6000
Viscosity,cp
Fig.4.1.2 Effect of viscosity on adhesion strength
I
-'.
-n_|
--4
mbefore
.8119!‘
...7_.1 2 3 comm. 1 comm.2Adhesives used
Fig.4.1.3 Effect of water soaking on peel strength ofleatherjoints
98
-_-_.- -1-u-w-1. i__
Figure 4 1.4 shows the shear strength of lcathcrjoints before and after soaking in water.
Shear strength of commercial adhesives are found to he much lower than adhesives prepared in
laboratory. In hoth peel and shear strength NR based adhesives show tower strength compared
to PVC and CR adhesives. This may be due to the higher polarity of PVC and CR than NR
which gives more adhesion strength.
S cm2QU=aa8'a%88%85=8
m before ;' .3 . anef0-P :|
reng h NI
‘I ,-bvl
8fST18
1 2 3 com.1 com. 2Adhesives used
Fig.-1.1.4 Effect of hot water on shear strength of leatherjoints.
25 " i — ' _' ‘mi,’ 1- i f20 tIbetore :_ 15 II-MUH
strength N/crn2
E5
P88
01
qi ‘0% t1 2 3 eomfl com.2Achesixes used
Flg.4.1.6 Effect of ageing on peel strength of leather joints
99
wlnlncrmal adhesives.
strength N/0m2
0
ShearPee -strength N/cm2
Figure 4.I.5 shows the pccl etmngjth of dnflcrcnt adhunvus before and after abcmg
AdhLSl\/CS prcparcd in laboratory (an, iound '0 ba. bctlu IT} agung r,s|stanu. wmpurcd 10
Figure 4.1.6 shows the shear strpnglh OfdlflLl'LI1Iddht,blVCb bufon. and aitu" dgung Nauml
mbbcr solution based adhesive show lower fU§lSIdflCC COmp.1rCd chloroprcnc and PVC baud
58B-sQ
w _,______._______,_ ____h__ _ _ _ _,_ l_________ _ _____ _i ._______
2 3Acheswes used
Fig.4.1.6 Effect of agemg on shear strength of leather
1.?‘-;'.f_. _.' .t
-1»U1
_aQ
25 1% ‘Ah "T ‘ ‘ ” “.,_..{
1' ,..
!) '1" T'..|.~ \1-#:~5l'>
\ \‘,..J"p11,I .'.~‘|. ._]].-,
;_v.|.'s"":'Jl-‘ii
|i;.>'l L .
1 2 3Adheswes used
Flg.4.1.7 Quick peel strength of leather ;omts
__._._._l._-L-f,
com oom2
I quick suck
com1 com2
adhesives. This may be due to the better ageing resistance of CR and PVC than NR solution
Commercial adhesives show lower ageing resistance compared to adhesive prepared in laboratory
so so » g __ _45 in
4° "ii H original
Shear s rang h N/cm2-~ to re to ozU1 O U1 O U't-l _{ - it; 4-14
s‘ I quick shear ii l4-I
|
Q-I
l
l
l
|
10¢‘
5“J
1 2 3 com.1 com2Adhesives used
Fig.4.1.8 Quick shear strength of leather joints
Figure 4.1.7 and 4.1.8 show the quick stick values of the difi'erent adhesives in peel and
shear joints respectively. The quick stick strength in both peel and shear test shows that the
adhesives prepared in laboratory are superior to commercial adhesive. The adhesives prepared
in laboratory gained the adhesive strength within 30 minutes of time.
Table 4. I .2 shows number of cycles to failure of adhesive joints were failed. The adhesive
prepared in laboratory are found to be more resistance to flexing - Flex resistance ofeommereial
adhesives are found to be poor compared to adhesives prepared in laboratory.
101
O
Table 4.1.2 Flex test results:
J Adhesives No. of cycles to failure
i
6» wee
l. l 1I . peel p 2856 ’; 1 shear Above l lakh 12 peel l508lI 1 shear l Above I lakh E.1 5 1%1 3 11 peel 1 16446 Z
H shear Above l lakh it1 Commercial I 1; peel 50 1. 6 shear A 200 \1 ll1 Commercial 2 5 peel 1 15046A ' shear Above 1 lakh
Table 4- l .3 shows the strength of different foot wear components which were jointed with
the adhesives prepared in the laboratory. lt may be observed that the adhesive prepared in
laboratory shows much superior bonding compared to commercial ones.»
Table 4.1.3 Strength of the joints of different leather foot wear componentsI. --i-~-~v-~ ~ ———-~~~.---~e--~ ~ V —-ii ~ Y V -e -~ , ———~—i- ~~ ~— — ————————~———-—— - -vIp . 101.461 1 1 2 3 A Comm.l C0mm.2'5 T '_i _‘ *il>'"" 5"‘ 5’ ”””*_?* ‘r "r"? 5 '5 1" '5‘ ‘*7 5"“ _; __—“' " " ‘11 ' i 1 " ! 5 1 li A1, csrve 1' peel shear peel shear “ peel shear . peell shearL peel lshear Aj .. .__._ . ....__ __ ___l . ___ _ . . _" I
Q I_J'\OIO
ll " 7”_ "V _' irl __"——"'i'__ _‘ 1 1' Vii ‘— " '7 ' V-WT‘ ' _ ‘ —— if? 7*l l. 1 ll.5 5. 59.5 Z 15.7 1 43.] 11.44 4.9 1 l.2 9 8.6 Q 9-8 ..- I
2. T1 5.8 24.l 12.7 7 47.0 3.0 A 8.4 2 A 8.8 A 6.8 E“ 29.4 in‘i A i Ii . 3F 3. 4.6 1 31.7 ll 8.6 A 22.9 1 3.5 ll 6.4 1 0.2 04 1 6.2 1' 24.6 E1 l ‘ 4 | ‘ :1 . 1 ' I , ' | Iii 1 ‘ " ' E; ' 1 ‘ I‘ 1 '1. I p ‘ . 1' ' l. 4, a 16.412-4.9 13.3 l9_9 l.3 . 5.4 61 1.5 T 6.3 ll l().3 1; l9.5 1
5. 1 10.21 28.0 1 9.5 A 22-5 1 5.2 1 0.1 1 0.6 29 11 16-4 1I l 1 1 . 5 1 1 I A 1I. 1. =1 l Ii It 1 ‘1 '1 6 1 12-6 29.4 8.3 1 27.8 §10.6 . 13.7 1 0.5 1 6.1 1 11.71 114.2 1
A 7, 12.61 29.4 1 3.3 27.8 ? 10.6 § 18.7 0.5 6.1 . 11.7 1.-———~l-—— .. .. 1~ A e-- ~———.:~~~_:_——— . _,__-_-.a-L“; _- .-L-K __-__-_1+___._ _-_e_J _-~. ----444...;-_-_-T_ee___._—_— _
9°to
‘P’
.' -' “@
4. .,,
Photograph 4. l .l Roughed upper leather surface before adhesive application.
l
l
l$7‘ - -.- - — -1' —- - ~—
Photograph 4.1.2 Peeled ofl‘ upper leather surface with laboratory adhesive
.. lPhotograph 4. l .3 Peeled off upper leather surface with commercialadhesive.
5')Q
1--_“:m_ \_. _ _ ._ . . ‘_.-6‘ I‘ ~4- _,.' . ""7-; - _1' ' .,‘- - '- .-"_-5-_. §_q=:._ _»::.|..__.,';-_v _ _.-_. - , 3 ," "' —' .a'?"'-‘-.*"- .‘ u- “.+_--~"'\
» ,..*_'I“- --..?
.-1"? ~ {U;I 5*‘I-I '.
I .Q I-Q \'_ ' _:_ ,27*:‘
""1§r';wt’
JP kl"
__ _ ' ' I ..=-P." = -K"?-'1C . )~-b-'. f ~- I ;
V‘q * 0:?“_ ‘ri" .‘"" 1'.‘ .. - '_
. _‘Y \ = . "Ig-"‘¥.—‘»'. fkw’ 3
. -‘_ i ' __ ‘\ _\-'; __ -.-- ‘I .) '- IQ. \_'-‘* \ .1. - '- . |. T‘ ' :‘ 0.; Q
I
5-. ; Pi/.,' .. ' ' \_-'‘I .._< ‘J Q ‘T.5 . '- ' , In .-. ' "‘n -\ V‘.~r - .. ‘S':%‘~.9'|’ ‘ 1~‘ -*‘!o';‘.z "-_-I.‘ -.-.. .‘inf? _..
-'~ v
,.
_.- ~_'_ . ,- , _ J, » V1- w - . 0-» _-¢_ >' . ' " ‘c' 2' ‘.. _ ' . -9'$1 ,_I‘ -Q 'f . ‘ R ‘i 1' '1-1 ' ' .“-I ‘"- __ ,-<_....,q:. . I‘:If r. -|._J>_ q;'*>‘g:.;: "1 __~ ‘ " ‘.44 .
Fiim.
; |1%(,;[,<%_,-W1] ,¢1_1_4 Rougzhcd _§'()/Q lc2{1Tl1¢;?I' _<1|:'f’:1<r<;: hclmc :1(_H"|(2Si\/Q.‘ appli<:m.in
]')hQ{Ogr3ph 4 1 5' l7‘c;:<.:lc(i nl"l‘ -W/<L’L l0nll1<}"1" .~41,%|r'i‘:.":<.;%c with l;;1lm|'atm'f.? :1rih<:s' IV"
-\_w
“\
Photograph 4.1.6 Peelcd of!” $,,;@ leather sllrfacer with commercialadhesive.
i
|
I
4
I
I
I
Photograph 4.1.1 Roughed rubber surface before adhesive application
Photograph 4.1.8 Peeled off rubber surface with laboratory adhesive
Photograph 4.1.9 Peeled off rubber surface with commercial adhesive.
'32‘.--‘- - - _ , ‘I '- 4 .‘*>".\-»- - -T .. I1.:_-|.~,‘I|_‘l. -"‘:~'L,).\' U‘ , .‘ "~ 2" '. '
Photograph 4.1 .10Roughed M C surface before adhesive application.
Photograph 4.1.11Pee|ecl off M C surface with laboratory adhesive.
I-i1~‘§flE3*I'?5¥¥\ <7» “
Photograph 4.1.12. Peeled off M C surface with commercial adhesive
‘Y ‘ W ' 7* it‘ *' ' ' '_ T’ i C i’ ‘ ii‘ f ' ' i ' ' ‘ ‘ ‘ '* ""'iI .gt l. Upper leather to sole leather 1 5. MC to NR sole
2. Upper leather to NR sole Y” 6. MC to SBR sole *7
1* 3. Upper leather to SBR sole ;r 7. Upper leather to plastic sole i:
q 4. Upper leather to MC sole ~'iIL 717' 7 7'. _ __ _
Photograph 4. l .l shows the roughed upper leather surface and photographs 4- l .2and 4. 1.3
show the peeled ofi' surfaces with CR adhesive(laboratory) and commercial (Dentrite) adhesive
respectively.
Photograph 4.1.4 shows roughed sole leather surface. Photograph 4. l -5 and 4. l .6 show
peeled ofi" surfaces of sole leather with CR adhesive and commercial adhesive respectively.
Photo graph 4. 1.7 shows roughed rubber surface. Photograph 4- l .8 and 4- l .9 show peeled
off surfaces with CR adhesive and commercial adhesives respectively.
Photograph 4. l . l0 shows roughed surface of MC sole. Photograph 4. l . l l and 4. l . l 2 show
peeled off surfaces with CR adhesive and commercial adhesives respectively.
ln all the photographs the surfaces of CR adhesives and commercial adhesive are found to
be comparable.
Conclusions:
l. Natural rubber, chloroprene rubber and polyvinyl chloride based solution adhesives superior
to costly polyurethane based adhesives for bonding leather substrates.
2. The water resistance and ageing resistance of such adhesives are found to be superior compared
to the commercial adhesives.
3. Quick stick strength and flex resistance of these adhesives are also superior to commercial
adhesives.
l 03
References:
I. I-. Skeist. Hand bg0k_Qf Adhesives, second Edn, p 29, Van Nostrand Reinhold, New York
(1977).
2. R- K. Goel , R- K. Gupta, Industrial Adhesives and Gems First Edn. Small Business Pub
New Delhi,( I980).
3. Teppema, J. Manning, J-F, U.S. Patent 2379552 July 3, (1945).
4. D.D. Gerst, Adhesive age, 36, 13, p12 (I993).
5. R. Panda and H. Panda, Chem. weekly, 38, I7, p 137-144( I992).
6. T. Drozd and P. Penczek, Adhesion, 35, 4, p 30 (I991).
7. P. Cranley and O. G. Lay, Adhesive age, 37,6, p6 ( I994).
I 04
Part 2 Aqueous adhesives for bonding leather components
ln recent years concem for the environmental etlects of solvents is growing. The increasing
awareness ofthe impact of solvent emissions is leading to greater restrictions on solvent usagé.
Volatile organic solvent containing preparations such as adhesives and finishes are being
restricted nowadays Chlorinated solvents used as cleaners and propellants lead in depletion of
the ozone layer in the upper atmosphere which protect us from harmful UV radiations’ . Solvents
participate in photochemical reactions involving nitrogen oxides and sunlight to produce ozone
in the lower atmosphere which is harmful to biological processes and a major contribution to
smog. Two methods which may be used to avoid such pollution are to use solvent free adhesives
and to contain or destroy solvent vapours. Non solvent adhesives such as latex and hot melts are
used in footwear industry "‘.
l n this study, latex based adhesives for bonding leather components are proposed to be
developed . The peel and shear strength of the adhesive joints are proposed to be tested and the
resistance of the joints under different environments and shelf life of the adhesives are also to
be determined.
Experimental
NR ,VP and XNBR latices were compounded according to the formulations in Table
4.2.1. Leather pieces were bonded using these compounds and their peel and shear strengths
were determined as explained in part l of chapter 4.
Table 4.2.1 Formulations for latex adhesives , Pi-i1I. i_ _. — ____._ _ _1F;f*—-' __-._;--if, _._. - -'- 7 _;‘f_ fi;;:_;.* -- _.‘—"‘ __J_‘
It
j Ingredients ”NRlatex up VP latex j XNBR latex H
7 NR latex it 100 f ’M VP latex l00 lj XNBR latex 5; 100= KO}-l 7 0.l 0,1 0.l4E Ammo- caseinatey 5 5 5Starch i 2.5 2.5 2.5RF resin 7.5 , 7.5 I 7.5 j5 CMC 7 10 10 7 10, l. || |I ' 1l_.._ _t s fig _e_,_ _ :1 l._s__ H E4
ln order to compare the adhesion strength with a commercial latex based adhesive, joints
made with Fevicol were tested for peel and shear strength.
Results and Discussion
Figures 4.2.1 and 4.2-2 show the effect of ammonium caseinate in NR,VP and XNBR
latices for peel and shear strength of leather joints respectively. Ammonium caseinate acts as a
thickener in latices and increases the adhesion strength of the bonds initially, but after an optimum
amount there is a reduction in adhesion strength. When the amount of thickener increases
above the optimum level the inherent tackiness of latex molecules may get affected reducing
the bond strength .zse s » ~ll -0--N? l1 -l—VP ll- it VPBR \I ‘( I‘
strength N/cmE5 E5 8
l5 i l
Pee
0’~— » 10 2 4 e e 10 12Ammo.Caseinate,phr
Fig.4.2.1 Effect of ammo.caseinate on peel strength
*_i__.__ ___7 --____ _--—_ .-¢__ — ...-_ —-qqii..-_,i_.__.-.i_i_~_a-..,-..i__-ii.‘-m
100:1 ___,..£_-.._ -~'.-'so l1 5 " VP' 1 / I -“:H~XN8R s
s rength N/cm2
O)O
1
it r s " ""*"*r “"‘""i"‘-e ~~--%_. i40 1 Q
Shear
» l20!rO
O ,_______.
l\!
A
Oi
OD
-5O
.4M
I
-- __ . _”---i_ --%i-___~---_-i__-\—_?~.~1--i~--—ii- ----v-_ __. .-..i...._--- .-._.. ..---.___-_.-vt wu--- ---—- -- -1 — -- -- -- ‘
Arnm0.caseinate_phrfig.4.2.2 EffectofAmm.caseInate on shear strength
Figures 4.2.3 and 4.2.4 show the effect ofcarboxy methyl cellulose in NR,VP and XNBR
latices on peel and shear strength respectively. CMC is found to increase the taekiness of latex
particles thereby enhancing the adhesion strength . As the amount OTCMC inereasee aboxe It)
phr there is an increase in the viscosity ofthe adhesive and lacks its spreadability
N/cm2
.
10-0
rang h
IO-I
Shears
I
I6* /I#- ’§ L” 4~" ;- 4 il JA*__e__,_
~ _ —— ~ —___.-—_-& ~~— ——-_ ———~_\~ ——_7——— i _ i'______ _ _ __
N/cmU1
nghM (.0
F9
+; ' , if ~o' *““##f§#‘r —+—NR —a—VP iI
5
-0-Ii
Pee s
1 L _.»_ men ;0 "Ni iiifii ‘Q —'—T—— M ‘ii K-7 i — — ' hi i — — M i—i——i_f* i ' "_— _"—'__'_i
O *r—‘
N
-ts
O’)
CD
6
F3
CMC content, phr
Fig.4.2.3 Effect og CMC on peel strength of leatherjoints
25 ~1 -~=~——i»~ e ~~ —— ~— “M ~ » h|i -0- NR ir —I— VP * t-A---XNBR
6‘. 8
\
/" 1'-/ 5'
. I“ ‘i-'..-H-F
..-I»
Q
4 __ H __1._.e j'_ 7; ~I=_5 ‘$1 iI,
i0 -1 t i *7?’ t "*****—w " —%O 2 4 6 8 10 12CMC conter|t,phr
F ig.4.2.4 Effect of CIVIC on shear strength
I07
Figures 4.2.5 and 4.2.6 show the peel and strengths of leather joints with the variation oi
resoreinol formaldehyde (RF l)resin content in the latices. When the RF resin content increases
peel and shear strength ofleatherjoints increase, reach a maximum and then decrease. Resin
increases adhesion strength up to an optimum level , but further increase of resin may increases
the modulus of the adhesive films resulting in stiflening of the adhesive joints thus reducing the
adhesion strength 4 . The same pattem is observed for all the three cases , NR latex based shows
highest adhesion strength followed by VP and XNBR.
40 _ s _ .____s__ s e.______ _ __.._s e -.._____---l135 1!: \. 5
om
55
i .l l‘H __ .- ‘ii " ' ' tH ,.,.= -es" no e it
Peesengh,N/E5 Z; 8 8
| i, .__
F
//I _,/ —-0--— NRU‘r #-- —-I-—\/P5 A t XNBR
0 ‘*—’ _f—‘_——" '_';_l"" ' "“—'_"l ' i i‘ l'_*_’ “iii " F ‘i "" "'_ 7*’O 2 4 6 8 10 12RF1 resin, phr
Fig.4.2.5 Effect of RF1 resin on peel strength of leatherjoints
1
I
I
- l: /‘ "'———i0 I
-1}’ - . _. _____i__..--...----_ii..._--~ -_-.___i._._ - .--i--__._.. -- -Q -----___~-.----- —- —- — —— —|
Shear strength Nlcm2
Q e a so ~> - -~=
N, b
b
O5
Q
6
5 ._._______
"" A---—""'_'.so ts: as 4
i is ”"'“ ’ T’ " in’ '—" Tim‘ '— ii ii 1'7‘ ""“‘ _'—‘”+—"_ _"” " '
RF resinphr
-0-l\R -n—VP -4- XNBR
Fig-4.2.6VItdlonofshea|'st|'engtl1vdthRF1 neslnoontent
108
The variation of cooked starch content in NR, VP, XNBR latices on peel and shear strength
is shown in figures 4.2.7 and 4.2.8 respectively. There is a slight reduction in bond strength as
the amount of starch is increased from 2.5 to l0phr as expected. ln leather joints starch causes
slight reduction in bond strength and water resistance 5
N/cm
0
reng h
Q-ll
§-9
-1
Pee sShear strength N/cm2
10
9
8
7
6
5
4
3
CD-\l\)
27
BlE3PO-I
19
....s\l
ii"
-»
13
fl
J
"lfl
_I
lli
J¢_
/.____~__H“ k ‘
—o—NR
—§—-VP
a XNBR
“__l
--.‘_'--
W--\"x.
__,£
l
i
|
l
1
0 2 4 6 8 10 12Fig.4.2.7 Effect of starch on peel strength of leather joints
I .
|
2
l
.|
|
ll t—0—l\R
—I~—\/P
1 )Q\BR
15 L-_.____..___. ‘Mr...
7 — U‘-W **' l ' ——l_—‘_' l "ii 'T" _ "' f— "' l ll?!“ l *""
Starch, phr
——_.---- 7 TH - —._.i____ i _--.~-H?-_i@i_.-Qq------___~,,.__,.-_.__ii._-k-Q» Q --- .__,_
£
__-__ .
O 2 4 6 8 10 12Siarrhphr
F-19.428 Effed ofstamh on shear strength
109
l
l
\_._.-t. .-.-5. - -__
I
Figures 4.2.9 and 4.2.10 show the peel and shear strength of leather joints before and after
soaking in water. lfrom this it is clear that NR latex based adhesive shows highest strength
compared to otherilatices. This may be due to the higher solid content of NR latex. XNBR latex
based adhesive shows better bonding strength compared to VP latex. However, there is some
reduction in adhesive strength for all the adhesives due to the presence of water
40 i is c- » s- r M? r
_-J
renghN/emor 6 E3 8 El 8 8
s EtbeioreI >Ii’ ‘
---_
letterI-0-I ‘
Pee s
__fi_.._ _...__,i .._tBR VP )¢~BRLatices used
Fig.4.?_9 Effect of water soaking on peel strength
250 — ~ —
N/cm2
§
t mbetorelatter
>
5%
ngh
*"' 1 I|
{i
shear s re
§
504 in@t_ _T*.~ _,__ »A
XNBRNR Laticdspused
FIg.4.2.10 Effect of water soaking on shear strength ofleather joints
110
Figures 4.2.1 I and 4.2.12 show the peel and shear strength ofjoints before and alter soaking
in hot water at 80"C. ln the cases of VP and XN BR latices slight crosslinking may occur which
may be the reason for increase in adhesion strength. But in NR latex slight decrease in strength
is observed which may be due to naturally occurring easily decomposable materials present in
NR latex.
40 sag» - E »~ ssss -~
Peesrenghhl/cmas at 8 8
_“ "_aM"_"_aM-m__J
W zabefona__‘ 25 pi Iafler at4-0 ‘Q51 |'
_._—_ —
5 IO s——— — —- -%—-~ s -—1NR VP XNBR
Latices used
F ig.4.2.1 1 Effect of hot water on peel strength
250,,“ J» -~s ~ --
gth N/cm2
1% §
l ll, u before ILy I after ;
Shear stren
é‘
___ _,_ i.‘ii.50 ‘ ;i
4l r ,BR VP XNBR
Laioes used
Flg.4.2.12 Effect of hot water on shear strength
ll]
Figures 4.2. l3 and 4.2.14 show the peel and shear strength of leather joints before and
alter ageing in air oven at 50 "C. Leather pieces joined with NR latex based adhesive show
more decrease in strength compared to other two latices. This may be due to the higher degradation
of NR latex
4o»~~~ - ~ -—- — 135 II III
Peel strength N/cm
0» 6 a 8 2% 8
latter » e — I.>
I0 —.-— P-—iNR VP XNBRLatices used
Fig.4.2.13 Effect of ageing on peel strength
250 e - » » ---- W» as --e see»-I
?N/cm2
flD6lOf8Q Iafter
eng h
8
I
\—-0-0 I
Shear s
8 8
-iw i- —i—@ __ --_---..-.NR VP XNBRLatices used
F ig.4.2.14 Effect of ageing on shear strength
I12
The quick peel and shear strength of latex based adhesives are shown in figures 4.2. l5 and
4.2.16. All the three latices attain almost full joint strength within 30 minutes.
49 _ " at ewe em; '7i‘ _35 originall‘I -quick peel
Pee st N/cme at 8 8 8
4.4 - l
rang h
?- ‘Q
51 L .__.-_..r-___~i_ _i--1.__-__ .___NR VP XNBRLatices used
Fig.4.2.15 Quick peel strength of leatherjoints
250 sci has-as-so ~s— s
N/cm2
§
.__._..- .___._l
l 5: original" I quick peelQi
streng h
8 8
1‘I I4I l
l
t ,l
1
She
8
*6 INR VP XNBR
Latices used
Fig.4.2.16 Quick shear strength of leatherjoints
The peel and shear strength of latices stored for one to four weeks are shown in figure
4.2.17 and 4.2, I 8. NR latex shows slightly more reduction in peel and shear strength compared
H3
to VP and XNBR latices. This may be due to the comparatively low storage stability of NR
latex. So for better storage stability synthetic latices may be preferred to natural latex
35 ____30+ l
8 8+_i$~_4_l.__
g h,N/cm
Q-'4
en-LU1
OI‘
our _
QGST
3
_L5fi._¥_*
-+-—NR
-—I—\/P
-to ems._____“ atC
|
P
sal
0 '1'_~— —_ ill - I k -1’ " H 1"’ ‘W “Til ’: F" ' _"
' it '1 = e ' V“”“I
‘l
R Y
atO 1 2 3 4 5 6Storage time meek
Fig.4.2.17 Effect of storage of latices on peel strength
250 .];t__,_ _ _
n, N/cm2
“8’
eng-A -58 8
¢—?;'~;— ; _'T
44'
C-I
GSFST
¢ .-‘_ ‘_
-0-—NR
-l—VP-:- XNBR
Sh
w I e ' * ’-i'*"—' ~ __.___ _ __
0 U _ as s s 1
1
l4 _._ Il
W. I0 1 2F ig.4.2.18 Efiect of storage of latices on shear strength
Table 4.2.2 shows the peel and shear strength of different leather components jointed
using the latex based adhesives. The strength ofjoints made of NR latex based adhesives are
found to be superior compared to other two latices- This may be due to the highest solid
content of centrifuged latex.
_, ___.. |Storage time, weeks
1 14
3 4 5 6
Table 4.2.2 adhesion strength of different components by latex adhesives
Adhesives K Nlllatex it VP latex 1 XNBR latex 11 1 peel shear 2 peel T shear 1 peel 6 shear 1
_ _ _,_,_,_ __ ____]_i
N/cm 1 N/cm: N/cm N/cm: . N/cm N/em: .
1|
| 1Upper leather to
sole leather
Upper leather to
NR sole
Upper leather to
SBR sole
Upper leather to
Me sole
Me to NR sole
Me to SBR sole
Upper leather to
plastic sole
Table 4.2.3 shows the results in comparison with the commercial latex based adhesive
1
l.
1
3.4
3.5
9.4
4.3
6.4
10.2 1
3.5 11
1 J 1
. _fi_I
I
|
03.2 Ei
28.41K
28.5
24.3 1
16.9 p10.9 1
25.6
1 44.4
. 20.3
23-0
1 13.8. 12.2
11.1
Z 23.2
1
i
Table 4.2.3 Comparison of latex adhesives
10.9
1* 8.91
9.0
10.12 8.3
8.1
8.3
-- ---_--2 __‘
70.7 .
. 25
17.7 J
1 10.9 ‘1 10.9 1
11.9
A 20.3
Pevicol. The peel and shear strength of upper leather to upper leather is shown here
|_LV_ ._...__
—~* —————- — - —- -- - -- ‘ &— - - -— ~-- - — 7 — -V 2 7 ' —“i‘7:lYI ~
1
Latex adhesives i Peel strength, N/cm p Shcarstrength,N/em: 1
_ .‘_
NR
VP
1 XNBR4 Fevicol
— —~*--L2 ----~ as 1 as A -9 — 9-—~-—** is--1 -—- 9- *~-~- 4I
|
1
1
1
30.5
12.2
20
12.1
193.5
61.5
90.8
120.3 ‘
115
Conclusions
l. latices of NR, VP and XNBR can be used to prepare adhesives for bonding leather
components
2. Ammonium cascinate and CMC can be used as modifiers to increase the adhesion strength.
3. Starch can be used as a filler in latex based adhesives without much deterioration in
properties.
4- An optimum level of resorcinol formaldehyde resin can increase bond strength.
5. Compared to synthetic latices natural rubber latex shows marginally lower ageing resistance.
6. NR latex based adhesive for leather shows superior bond strength compared to commercial
latex based adhesive-Fevicol.
References
l. L.H. Lee (ed), Adhesive Chemistry Development and Trends, p 693, Plenum Press, New
York (I984).
2. J. Carol, Rubber World, p I8, Sept I993.
3. K. Palanivelu, Leathers, 46, July (1997)
4. M. Mitoh, lnt. Polymn. Sci. Techno], l4 (6), T/89 (I987).
5. D. C. Blackley, Polymer Latices, 2 nd cdn, Vol.1, p392, (I997).
I16
Part 3 Studies on novel low cost adhesive system for bonding different components in
leather products.
ln leather product industry many dissimilar adhcrcnds are jointed using ditierent types
of adhesives. The joining mechanisms relate to include the complex chemistry of the adherend
surfaces‘
Polyurethane based adhesives are widely used in the leather industry. These adhesives
have disadvantages like low tack, shorter pot life and limited durability’ ln foot wear
manufacture different adherends like upper leather, sole leather, rubber sole, plastic sole,
micro cellular sole s etc- are bonded using adhesives’ . The adhesive used should be compatible
with all the adherends used and must comprise of low cost and easily available components‘
ln this part of the study, adhesives from blends of thermoplastic elastomer solutions
are proposed to be developed and evaluated for bonding leather.
Experimental
Two types of adhesives based on thermoplastic elastomers from rubber/plastic blends
were prepared and i-vestigated for leather to leather bonding- The ellieiency ofsueh adhesives
was compared with those of commercial adhesives. Polyureathane based (Commercial l)
and dentrite (Commercial 2).
This part of the study also being patented The auther requests to be excused for not
giving the details ofthe materials and formulations.
Leather components were jointed with the adhesives prepared and also with the
commercial adhesive(l)entrite). The peel and shear strengths ofthe joints were detennmed
as per procedures explained in part l ofthis chapter.
H7
Results and discussion
Figure 4.3.! shows the variation of peel and shear strength of leather joints when the
viscosity of the adhesive blend type l changes. This shows that on decreasing the viscosity the
adhesion strength decreases. On reducing the viscosity the solvent content increases and solid
content decreases thus adhesion strength reduces. Similar behaviour is observed for blend 2
200 u- --1»--__--» ----i- - -~ - ----------q‘.
I1 V-0- peel Nlcm
éé
4- shear Nlcm2 ;140 E lto-I 1 _ ——I'e ' e—.-» ..; l
s reng h.-LMo
F
80 1 1
Jo'nt
so 0
see
O
9
‘F
L
_' —;__'i -— — i'*' f’ ‘ "*Y'"’ ' — "'—_' ' * ' '—0 500 1000 1 500 2000
Viseosity,cpFig.4.3.1 Effect of viscosity on joint strength of ble nd1
adhesive
w __.--.._.__._..-.....__i.-.- ..._. _ __.__. ___ __ _ ______,__,._,___________________ \___________ ,____jl80 I’ ____.s..._..___.--—-———"* 0 i ' A A ha. '
1,‘, _;
70 ; t
strength
8 8
__, 40 .i ——o—peel NIGHT!. -1-» shear N/cm2 f
Jon
8
20 ~j 101 -sassy ~~~ 1» ~~~ ea» EQ a ee___________ _ _____,__________________10 1000 2000 3000 4000 5-000 6000
v|scosity_cp
Fig.4.3.2 Viscosity of blend2 adhesive onjointstrength
I18
(figure 4.3.2) also. Higher viscosity if preferred for better strength but when viscosity increases
more than an optimum level the spreadability of the adhesive over the adherend decreases. So
we maintain a viscosity of around l000cp.
Figure 4.3.3 shows the effect of peel strength of leather joints when the amount of
thermoplastic content varied. When thermoplastic content is zero strength were very low in
39 ~_-___. ___-_-_. __ _ » .25 ‘J —o—blend1 L_l -——I— blend2 5a i;
ngnN/cma 8
~ l1 if0-I lli
1
I
'1l
-0-I3 ‘
Pee sre-5O
5-! _jr#-=4* I 'on —+—J l0 ‘1__: 1 * t*’* *"" ""'“"T’ “ _' A 7 —_’ *’ i”“_’ i lO 20 40 60 80 100
"thermoplastic c0ntent,phr
Fig.4.3.3 Effect of thermoplastic content on peelstrength of leatherjoints
both types blends. But when TP content increases peel strength increases as modulus of the
adhesive film increases 5 Thermoplastic alone is used then also peel strength is lower. This
may be due to the unique property ofthemoplastic elastomers. ln blend 2 the strength of adhesive
film is low so that adhesion strength also found to be lower. Similar behaviour was obtained as
in the case ofshear strength also in figure 4.3-4.
119
Figures 4.3.6 and 4.3.5 show the effect of tackificr resin in peel and shear strength of
leather adhesives based on thermoplastic elastomer solutions respectively. Peel strength of the
joints decreases as resin content increases but as resin content increases shear strength (fig.4.3.'5i)
r strength N/cm2
Q
SheaShear strength N/cm2
4~
200T180 -1
160 --0-blend1——I—b|8fld2
é
120 T,
§
Q)‘;60¢
waif
0 —-- "1 "-'* *-1* ~"— 1” r’ i0 20 40 60 80 100 120Thermoplastic content,phr
Fig.4.3.4 Effect of thermoplastic content on shearstrength
2 T-——'~-ii__-»<-ii--ea---,i__h.__-—-%i_i.... d Q--»i__~-H —- -ii—--u——i--vi-H ———i--\-w-ii —--
§2'§
5U:
0
/ -4--blend1a ——-I— blend2'11.»//as0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9
PF resin ,phrFig.4.3.5 Effect of PF resin on shear strength of leather
joints
I20
~-~u
___._-.__,--_ _._. _.
It\
E
(
!|
I
!
I
1
%" ’—’ K ‘ %—— *""*~~—r~~ ' -;-—'-1 ~ :‘ —- -L, e - ‘ ‘*7*'" :— -- *
increases reaches a maximum and then decreases in both types of adhesives.Thi shows that
resin present cannot increase the inherent strength of thermoplastic elastomers. As solid content
increases peel strength does not increases as in the case of shear strength‘ . So shear strength
initially increases when the resin is added to the adhesive.
Figures 4.3.7 and 4.3.8 show the efi°ect of a plastisicer in the thennoplastic elastomer
based adhesives on peel and shear strength of leather joints respectively. As the amount of
20 ~ e e ~-~ _18%;15% -#r~bbnd1 r
--I--UGIQ
Pmas hmvur-5 -L -5O N -In O5 Q O N -L
-5 -T44¥4_T4 \-’—- L 4
r
|
,.
1 ee ‘
rengt
“Lr —~_sQ‘. ‘ r1 "efi__ ,_T ____‘.+’
I -7 _—'7:—'1"“‘ 7 *_'__——lW ‘ " "f"'_'_ — '_ i ”"" 1|12 1.4 1.6 1.8 2PFres‘rtphr
Frg.4.3.6 Effect of PF resin on peel strength
3 s__.___-_._s___e_m _“_ we aa_-;i__t,,tt i_ it itII l
Pee nghNlcmM 0-! A U1 O‘)
8T8
{Ii
Q-Q . -4- b|end1 7r -u— b|end2 "i1-t“ A0 -»~----~---~-~-.--r--M»H ~-as as-as h-__.__,.___.._____~_-_;0 0.5 1 DOP‘ phr‘l.5 2 2.5Fig_4.3.7 Effect of DOP on peel strength of Ieatherjoints
plastisicer increases peel and shear strength of both the blends decreases. Plastisicers are used to
flexibilise the adhesive bonds but it reduces the adhesion strength of the joints ". This may be
due the more cohesive nature of the adhesive while plastisicer content increases.
35
30%
Ow‘O 05
Shear strength N/cm26 6 8 E3
51
v
44L}___A_|___.—L~
it
\
200
HSFBI1
IQ!‘
II!!!
0-Q
JO
20
0
I I ‘ 1I .._.-\¢ t ' t- : _ ':'~"=Z""~£@‘-*&" M'-.-I -' " . V - "'?"' . . = " P‘ ___ _ ll? . _~~- ;_;__w __ H I- “ ' 1 ""‘ |
—+—Uend1
—n—Uerd2
l .LI
‘i
"* "a 1 “ 1- ”~ r—*:‘ ~ a‘ *a 1 *—— :- i_"—*" ‘Mr
- 1 Mm 1.5H943-.8ElfectofDCPonsheastmngth
18° 1160$
K 14015 120 i
100 l,
ao60+ |f , , 149 J
:-'"'-"1-~+n I‘ %i 3E J P96*b8‘f0I'8'i Ipeel after
5* gshearbefore I. ; r I gsnear afterW .|\ ‘I 1r ~ 1V I!‘I 1 ‘ 'I I‘
2 2.5
btencfl bIend2 commAdhesives used
F ig.4.3.9 joint strength variation after soaking in water
122
Figure 4.3.9 shows the peel and shear strength of leather joints before and after soaking in
water. Strength of commercial adhesive(2) is also shown in the figure for comparison. Adhesives
based on lh6fl‘l’l0pl2lSiiC elastomers are found to display much improved water resistance.
Figure 4.3. l0 shows the effect of peel and shear strength of leather joints before and afler
soaking in hot water. This figure also shows the superior water resistance of the thermoplastic
elastomer based ashesives to commercial adhesive(2) ones.
Figure 4.3. ll shows the ageing behaviour of the adhesives. Both types of thermoplastic
elastomer based adhesives show better ageing resistance than commercial adhesive(2). Here1eo ii140 , ; IP9?] alter inT 4 i Qsheabeiore 5J ' I it [Jshear atter l0-I , ‘ '80-; 1! T
Joln strength
é E:
60* - 1 E40"?» 5 1 1 5l20 ._ . l l
O _ H, V _ _ _ t . J.-. .4 W; , __ A _ I l l‘btend1 btend2 Comm.Adhesives used
Fig.4.3.10 Effect of hot water on joint strength of leatherbonds
200 s - ~ .._j180 ii 1160 upeel before ll ll ' 1* Ll5. ‘ i; E1 shear before 1T, . gshear aft ,~ 100 in i l F" 6' l1
ngth
F3O
soil . A a 1
Join ere
so a ' I40 11 I A iE I l20 -l t 11 J-0 -- _ lblenolend1 d2 C0mm_
Adhesives used
Fig.4.3.11 Effect of ageing on joint strength123
also the thermal and ageing resistance of the thermoplastic adhesives are evident.
Figure 4.3.12 shows the quick stick resistance of the adhesives. In this case we can see
that thermoplastic elastomer based adhesives attain 80 % of their original strength within 30
minutes of bonding. Commercial adhesive(2) have only lower strength compared to the
thermoplastic elastomer based adhesives. Thermoplastic elastomer based adhesives are found
to be quick drying and attain the ultimate strength quicldy. So the production rate with this type
adhesives can be higher.
1 I
180+‘160% r‘ ' ~ ii140 L 5 it "°'i9i"°' ii g \ ‘Z Iqlickped ‘E
ii Ii Umgina ;i,, , l “ ljquick shear 1!__ ‘i \ ‘I
trength
QssssééiJon
\ t l‘ r‘I ‘ l!: i‘ 1 ll ' I~ it\ v- ! ..
lI I '' I1 rl 1 ‘ ‘blend1 blend2 Comm.
Adhesives used
Fig. 4.3. 12 Quick stick strength of leatherjointx
Figure 4.3.13 shows the effect of storage on peel strength of leather joint with
thermoplastic elastomer based adhesives. When these adhesive are stored adhesion strength is
found to be increasing. This may be due the slight increase in solid content due the evaporation
of solvents. From this figure it is evident that on storage the strength of the adhesives does not
get dreduced as so they have enough storage stability. Figure 4.3.14 shows the effect of shear
strength on storage of the adhesives.
124
rang h,N/cm2
Q‘
Q0
Shears
25r
Pea s rength N/om-.|>O
Q-I
I
5
r151‘?
___|g ~—-Ione ~ téu-—---'*
‘ ____________, , ‘_ _ ___‘_ - ———.. —~ Q‘
-0- bIend1-u— blend2
0 *"“ 1 _ ’i"— 1 * '—1 ‘ W*;;*""' i ‘:3 ‘ ‘ I‘ _;fl'0 1 2 3 4 5Weeks of storage
Fig.43.13 Effect of storage on peel strength
200 e» (1 »180
....x
U’)Q
....\-hrCD
._aPOQ
-AQQ
80
60
tr
J
_ 4- ‘_—_-4-‘-;—;4~_
t
|
|
i
|
.
- -+
-4~
'\
.!
1
—-0- blend1
-—I—~ blend2
F" __ . to ~<-~~»~ 0
0 1 2" — ‘ i _ MI _ _ 7 *fi.__ '" ’A’*__1 "V '71‘ i
Weeks of storage
Fig.4.3.14 Variation on shear strength on storage ofadhesives
3 4 5 6
Table 4.3.1 shows the number of flex cycics to failure of the adhesive joints The adhcswcs
based on thcmtoplastic elastomcr solutions withstand much larger number of cycles than
oommcrcial adhesive.
I25
Table 4.3.1 Flex cycles after leather joints failed~~— -—_i W f_i' __ _- ——— ii _ _ _, I I H _ _ ____ __ ,___,, __ _i~ --V-_ -- '7 V V . — V 7 — '--— ——— ' '
N/cm N/cmAdhesive joint '5 Adhesive type if Peel strength, Shear strength,
I
Blend I
Blend 2
Y Comm- I
.___ ._+_.4_4_4_‘;r
Leather to leather 2I
Comm.2Blend I
2 Blend 2" I Comm.l ‘Leather to plastic A,
Comm.2 7
I6464
53656
200
20646
10246
43264
150
IO489
2 _.-T-__;..--_. , - . .-_Ts.._T.._.-.__.._._.Above I lakh
Above I lakh
I600
83456
Above l lakh
Above I lakh
I 500
64346
I
Table 4.3.2 shows the peel and shear strength of different leather components jointed
using these adhesive solutions. These are the main components used in leather products. In all
the types of adhesives thermoplastic elastomer based adhesives show better adhesion for bonding
applications in leather product industry.
Table 4.3.2 Adhesive strength of different foot wear components
._. _.___ _ . _ ______.__|
2 2 r "fi;*::lr"""** r r "IiI Blendl 1‘ Blend 2 C0|nm.2 2“Adhesivet Peel . Shear I Peelp I N/cm N/em N/cm
bl
I? joint i . I I;; Shear L Peel5 Nkm L Nkm
H
Shear
N/cm
‘r’-—"-'—'"—'-'—"—— — e"---~ - B I B ' _rI | 'IA =22 I 83I21 asi
I. I8 51 .I I5 L 61 .A I 20 i 42E L ‘A
\-OO¢\lO\U'1-F>~UJl\J-~
30
30
32
28
2 I
29
I 23 39 2525é; A I4 35 ;E; 20 3 64 47Ii. . " .. ..1. ..
3O0
an
.128!6| Q62.I 92 3I 48 t=I492A435‘ 8| II! . . . ..
l0
20
I2
2]
I4
23
22
IO
ll
.___ __ __i___ __._t ______.i..__.__--—-i--V--V-77 —'i'—-,-v ~ V - i
30
43
4|33
50
30
3l
Z8
32i_i__________i____ _ Hriii ._i__ ____ __i_____ ___ ll‘ __ ____ _ _ __ _i__; L
I26
l -Upper leather to upper lather; 2- Upper leather to sole leather; 3- upper leather to NR sole;
4- Upper leather to SBR sole; 5 -Upper leather to M/C sole; 6 -WC.‘ to NR sole; 7 »M/(.' to SBR
sole; 8 -Upper leather to plastic sole," 9- Sole leather to plastic sole.
Table 4.3.3 shows the peel and shear strength of upper leather to plastic soles jointed
using the adhesives before and after exposed to different environments.
Table 4.3.3 adhesion strength retention of leather to plastic soles. Peel (N/cm)and
If W’ a S S. . l T :7 ‘ L_ WQVT 73 B!¢"<!1_ s_ Blend? J Comte-13 3 t_
i Peel i Shear ll Peel Shear Peel n Shear i"
Shear (N/cm!) strength.I i; i L S; l lJY—— -- *;_.l :33.” ~ -. - _ a- ~34 ‘Li _: if3 r 3' it 3' "3"3 Normal ll l4 1: 35 l‘ 25 ii 43 l0 1: 28 lf, Water l l ‘ i1-_ —-- ~ —— —- _ -
soaking ‘ll 4' 35 23 l 40 , 7 t 18 3P‘ Hot water 5; E , lllg r t ,A soaking V 5 ~ 32 i 9 it 4l 3 t 9 ll- I , Ageing 39 J 36 10 1 42 l 5 i 20' ‘ti 2 l. I~ t| - I
l Quickstic 11 T" 33 1 23 ti 40 4 i I8 it..__ _s i___ e ' ‘ sConclusions
I. Thermoplastic elastomer solutions can be used as eflicient adhesives in leather product
industry.
2. Themioplastic elastomer based adhesives show much superior bonding compared to
commercial adhesives.
3. Thermoplastic elastomcr adhesive solutions show better resistance to different environment
oompared to commercial adhesives.
4. The shelf life of the thennoplastic elastomcr based adhesives ure found to be vet}-' good
I27
References
l.K. Palanivelu, Leathers, p46, July I997.
2.D. Briggs, Hand Book of Adhesion, D. E. Packham (ed), Longrnan Group, Ltd., p461,
U. K (I992).
3. KJ- Kedlaya, Leaxhers, ll, no.8, p70, (1995).
4. H. Pagel and E. R- Luchnm Adhesive Age, 34, (Oct 1981).
5. Leathers, I2, no.4, p49, (I996).
6. Lealhers, I3, no.6, p 56, (1997).
7. N. R. Legge and H. E. Schroedr, Thermoplastic Elastome1"s- A Comprehensive
Review, Hanser Publicaiions, New York (I987).
8. L. F. Ramos De Valle and R. R. Ramirez, Rubb. Chem. & Teehnol, 55, 1328 (1982).
9. D. W. Aubrey and M. Sl'lCfl'lff, J. Polym. Sci, Chem. Ed, l8, p 2597 (1980).
10. I. Sl-;eist(Ed) , Hand Book of Adhesives, 2"’ odn, Van Nostrand Reinhold Co. New
York, ( I977).
l27A