A Study on the Weldability of Simultaneous Two-Axis Drawing Nylon I=ilm
Hiroshi KIMURA, * Takuzi YAMAGUCHI, * Masaki IMACHI, **
Masakazu TsuBoKAwA*, Noriyuki MOORI*,
(Received March 10, 1972)
In this paper we describe an experimental study to obtain the welding
conditions without losing the characteristic of simultaneous two-axis drawing
nylon film.
INTRODUCTION
227
The purpose of this paper is to clarify the characteristic of simultaneous two-axis
drawing nylon film and seeking after the possibilities of welding bond, making use
of the property of thermoplastic's. Namely, molecular chain oriented by simulta
neous two-axis drawing is considered to be set at random by welding, which causes
a great property change on both weld and heat affected zone, and thus the
characteristic of simultaneous two-axis drawing nylon film can be considered to be
done away with. The focus of the study, therefore, is to obtain the welding
conditions without losing the characteristic of simultaneous two-axis drawing nylon
filmY
EXPERIMENTAL RESULTS AND CONSIDERATION
Welding method used is heating plate weldingll • 2) and suitable conditions are set
up by studying the interrelation among heating plate shape, heating temperature,
welding pressure and welding time. Specimen used was simultaneous two-axis
drawing 6-nylon film, 0.025 mm in thickness. First, tensil strength and elongation
were recorded from tension tests on machine direction (M. D.), transverse direction
CT. D.), and a 45-degree angle direction, and microstructure was examined by X-ray
diffraction. Heat cycle influence was examined by giving heat influence from-196°C
(produced by liquid nitrogen) to 200°C (produced by hot air circulating dryer).
Specimen used in the tension test was JIS K6475 type-3 dambel type. Fig. 1 shows the
shape of welding specimen and peeling specimen. Fig. 2 & 3 shows the general structure
and important parts of welding apparatus made only for this experiments. The
suitable voltage necessary for the desired heating temperature is obtained from
* Dep. of Textile Eng.
** Textile Research Institute
228
(al JIS K 6745 Type-l
(b) Peeling test specimen. r= Welded part.
rr=:~ l' I i § =! (0) Tension test specimen.
Fig. 1 The Shape of Specimens .
.J, Pressure
A.C lOOV
Pyrometer bLIJ Cold junction I~oad
cell
1 ; Iron plate. 2 ; Asbestos. 3 Iron plate. 4 ; Heater. S Heating plate. 6 Specimen.
Recorder 7 Teflon. S i Rubber.
9 Fig. 2 Welding equipment.
i Iron plate.
Fig. 3 Heating apparatus.
A. C.lOO V regulated by slidac, and the temperature was detected from heating plate
by thermocouple. Welding pressure was
made based on lever principle and was
picked up by compression load cell and
was put into tensilon recorder. The
pressure was made quickly, and welding
time was recorded just after necessary pressure being obtained. Both up and
down side of specimen surface were cov
ered with O.18mm teflon film mixed with
glass clothes in order that specimen stick
to neither heating plate nor rubber plate.
Specimen was preheated just before the
experiment in the hot air circulating dryer at 50°C for 25 hr. for the sake of
'llO r O--------r
[~ !-----------!j ~-~-- 100
Type.l
~ ________________ ~-i
I=:; !-----~I 1----- 79 .
Type.2
Type. 3
Fig. 4 Heating plate.
229
getting better conditions. Bubbles born at welding time are thus avoided. Heating
plate attached to the welding apparatus is made of copper, and 3 different types in
shape are shown in fig. 4. Type 1 is for peeling specimen, type 2 is for manufacturing
tensile specimen, type 3 is for inspecting the differences of joint efficiency resulted
from the various shapes of heating plate. Changes of microstructure caused by
.. ~ '-"" ~ (/) !Ii <1! .... ~ <1! .... ::I +' U td .... r..
15
3 6 9 12 15 Fracture stress (kg/rnmz )
Fig. 5 Relation between fracture stress and directional property of base material.
100'---~--~--'----r---r---,--~------,
10 20 40 80 160 Jleating time (sec.J
Fig. 7 Effect of temperature. (200°C)
<If'
.~ td .... ~ <1! ....
.~ ~ ::>
100
80
60
40
20
Fig. 6 Relation between ultimate strain and directional property of base material.
100
I 0 0 0
0
50
5
0-----6--0----0
10
10 20 40 Immersion time (days)
Fig. 8 Fracture stress and ultimate strain of nylon film immersed in liquid nitrogen.
230
100~---r---"--r-----;------'
5~--+---4----~--------+------~
5~--4----+----~-------+----~
o~--~-~--~-----~---~ 10 20
Times of repetition
40
(times)
Fig. 9 Fracture stress and ultimate strain of nylon film exposed repeated temperature from -196°C to 200°C.
100
0- 0 0 <:5
50
10 20 40
Immersion time (days)
Fig 10 Joint efficiency of welded film immersed in liquid nitrogen.
influences described-above were exami
ned by stu ding the orientation changes
obtained from the comparison of diffrac
tion degree of X-ray diffraction photo
graphs taken on the plain films, by
penetration method. In case of 6-nylon,
diffraction patterns of (200) (002) side are
observed relatively strong. X-ray test
conditions were as follows. Voltage: 55KV.,
Electric current: 10mA. Distance between
specimens: 28mm. irradiation time: 2hr. X-ray apparatus: SHIMAZU analysis
type X-ray apparatus GX-l. Fig. 9,Fig. 10 show the relations between strength of
each direction and elongation obtained from tension test on specimen. Photo. 1 shows
the X-ray photographs taken from Thru Edge and End side of specimen. Figs. 5-6
explain that on great differences were observed both in strength and in elongation
on the test of M. D., T. D. and a 45 degree angle direction. This clarifies that the
specimen is twice as strong as that of non-drawing. Diffraction pattern of Thru. in
photo. 1 is of ring shape and that of Edge is almost the same as that of End, which
is the (typical) characteristics of simultaneous two-axis drawing. Thus, the experi
ments only on M. D. were to be done, and comparison of diffraction degree was to
be made using Edge X-ray diffraction photograph. Fig. 7 shows the result of prelim
inary experiment on heat influence caused by welding. No remarkable changes were
observed in reference to strength and elongation, after 40sec. heating at 200°C, which
clarifies that the specimen still keeps the characteristic of simultaoeous two-axis
drawing film. Fig.8 shows the result of thermal fatigue, no low-temperature fatigues
(at -196°C-at+ 20°C) were observed but high-low temperature fatigues (at -196°C-....
at+200°C) were in existence and S-N curve was recorded in proportion to repeated
number. Comparing the fatigue of repeating number 10 (total heating time 150sec.)
and that of 200°C 160sec., it is observed that fracture stress is in existence around
each 11 kg/mm point. That is to say, high-low temprature fatigue is similar to simple
231
heating fatigue. Photo. 2 is the X- ray diffraction photograph of both simple heating
fatigue specimen and high- low temprature fatigue specimen (at - 196°C-at+ 200°C) ,
which deny the micro- influence. Fig. 10 examines the changes of joint strength by
Photo. 1 X-ra y d iffract ion patterns.
Heating time: 80sec. Heat ing time: 160sec . Times of r epet it ion: 40t im es .
Photo. 2 X-ray d iffraction patterns.
232
" 23O'e
Welding time
Fig. 11 Relation between welding condition and peel strength.
Welding pressure (kg/cm 2 )
°O~------~------~------~------~
Welding time (sec.)
Fig.13 Relation between welding condition and peel strength.
I I at
i I t--------------+---
~~=----~;J:~,//--------r-- I-
'/~-'-" , " • " Welding time (sec.)
SOOf-- ~, r ~-O i---- - ----«>--- 10 -
o I ---<D-- 5
I ~' Weld~ng pressure (kg/em l )
Fig.15 Relation between welding conditions and peel strength.
Welding pressure
(kg/em2 }
---«)-- 10
----{])----
---.----0--
o~ ______ ~ ______ ~ ______ ~~ ____ ~
Fig. 12 Relation between welding condition and peel strength.
--<D-- I I
~ ~ , I
---e---"10 --0--- 10
I-----~···~~=-i~ I
I i I I ~
Fig.14 Relation between welding conditions and peel strength.
\\'elding pressure (kg/em l )
Fig. 16 Relation between welding conditions and peel strength.
dipping ultrasonic welding specimen in liquid nitrogen. Figs. 11---16 are the results of
peeling tests on specimen welded by type 1 heating plate. Specimens marked by ( • )
are ruptured in a welding boundary. From the experiments described above, follow
ing conditions are proved to be required in getting sufficient welding. Welding
temperature: 250°C, heating time for welding: 5sec, Welding pressure: 10kg/cm2•
The order of conditions mentioned also indicates the order of importance in getting
sufficient welding. Photos. 3---5 are X-ray diffraction photograghs of peeling test
specimen. In reference to photo. 3 at 230°C, no remarkable changes of molecular
233
Welding pre ss ur e : 20kg/ em 2 , 5 kg / em2
, 20kg / em 2
Welding time: 5 see . , 15sec. , 15sec.
Welding te mperatur e : 230·C , 230·C, 230·C
P hoto . 3 X- r ay diffr act ion pattern s.
Welding pressure: lOkg / em2 , 2 kg / em 2
, 10kg/ em 2
We lding t ime: 2 see . , 5 see . , 5 see .
Welding temperature : 250·C, 250·C , 250·C
Ph oto. 4 X- r ay diffracti on patte rns.
Welding pres s ur e : lOkg/ em 2 , 2 kg / em 2
, lOkg / em2
Welding time: 2 sec . , 5 sec . , 5 sec.
We ldin g te mperature: 270·C, 270·C , 270·C
Ph oto . 5 X- ray diffra e ti on patterns .
234
orientation are observed, but in photo. 4, at 250°C, some are observed to keep
primary orientation while others being observed to proceed its change of orientation
according to the welding condition, and in photo. 5, at 270°C, most of molecular
orientations are dissolved except a few case of welding time being short (2sec) ,
welding pressure lOkg/ cm2, and in this 'case orientation tendency being observed.
Mierostructure under great peeling strength welding condition (250°C, 5se'c, lOkg/ cm2)
dissolves almost all molecular orientations and keeps a little original orientation
tendency. From those results, fine welding joint, making use of simultaneous two
axis drawing nylon film, is considered to be possible. Further considerations being
made, comparing photos. 4 & 5 with others taken under the same welding condi
tions except welding temperature, which brought forth the interesting facts stated as
follows X- ray diffraction photogragh got at 250°C for 2sec'. load of lOkg/ cm2 clearly
shows the primary molecular orientation while considerable dissolution can be
observed at 270°C under the same conditions. Photograph taken at 250°C for 5sec.
load of 2 kg! cm2 shows lowering tendancy of orientation, and total dissolution of
orientation can be observed at 270°C under the same conditions. Further more,
photograph obtaind at 250°C for 5sec-. load of lOkg/ cm2 slightly keeps the orientation
" ,. } llrl'j ~ 1m.' sec .
';el.! lng"rcssurp Ow cm 2
\
--«r -
Fig, 17 Relation between welding cond it ions and joint efficiency.
We lding press ure: 4 kg / cm2 ,
Welding time : 5 sec . ,
Welding temperature: 250·C,
Weld l nq pr essure (kq / cm l )
.~ _ lO
- - -{J)- - .
F ig. 18 Relat ion between welding conditions and joint efficiency.
4 kg / cm2
5 sec .
270·C
Photo . 6 X - ray diffra c ti on patte rn s.
235
but orientation cannot be observed by any means at 270°C. Figs. 17 & 18 show the
results of tension test on specimen welded by type 2 heating plate. Excellent welding
was obtained at 250°C welding temperature, for 5sec. welding time, 4 kg/cm2 welding pressure, which has proved 90% welding
jOint efficiency. In Comparison to the
results of peeling test, this excellency
seems to be explained by the difference
of shape of heating plate (the welding
conditions are same except welding
pressure). Photo. 6 is the X-ray diffraction
photograph of tension test specimen. Most
of the primary molecular orientations
are kept at 250°C while the disorder of
molecular orientation being observed at
270°C. This clarifies that the considerable
difference on weld microstructure is pro-
1400 1200 1000 800 650 Wave number (ern-I)
Fig. 20 IR diagram
A B
c D
E F
G
we ld ing time : 5 sec.
~ -~·250·C S 501--------!--____ ...... -<D-.... 270.C type 3 -
aa~----------~------______ ~ ____ ~ Welding pressure (k.g/emJ:)
Fig.19 Relation between joint efficiency and welding pressure applied by various types of heating plates.
Welding conditions
Heating Pressure Heating temp. (kg/ern" ) time
(.oC) (sec. )
270 10 5 2
250 10 5 2
230 20 15 5
BaSe material
236
duced only by 20°C temperature difference under the same ·conditions. What is more,
the disorder of molecular orientation is observed in X-rar diffra'ction photograph of
peeling spe'Cimen, while primary orientation is kept on tension test specimen, which
can be also considered due to the difference of shape. That is to say, type 1 is
considered to have a great heat accumulation effect and, therefore, to give a great
heat influence on specimen. Upon this, in order to make a sufficient welding on weld
parts with keeping the orientation to some extent, type 3 heating plate has been
contrived, making use of characteristics of both type 1 and type 2 and put into
experiments. Fig. 19 shows the experimental results of type 3, explaining that it
provides relatively stable welding of more than 80% welding joint efficiency. Fig. 20
is the result of heating influence of welding examined by IR. Changes of transmittance
can be pointed out at CONH of wave number 1030, 930 (cm- l ).
CONCLUSION
The folloWing summary can be made from the results of the present experiments.
Welding of simultaneous two-axis drawing nylon film can be possible without losing
its characteristic, by choosing the proper welding conditions.
ACKNOWLEDGMENTS
The authors would like to express sincere thanks to Yunichika Co. Ltd. for
preparing to base materials.
Part of this work was presented at the Meeting of the Textile Machinery Society
of Japan, Osaka, March 1971.
REFERENCES
1) Hiroshi KIMURA: Welding of Plastics (Nikkan Koogyo Press Co. Ltd), p.109 (1967)
2) Hiroshi KIMURA: Foundation for the Heating welding of Plastics (Sanpo Co. Ltd.) (1971)
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