J. Pac .Sci. Tech. Vol.30 No.6㸦2021㸧

Original Paper㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼㹼

Effects of Processing Conditions on Tearing Characteristics of Zipper
Lines of E-Flute Corrugated Paperboard (Dependency of Length ofConnecting Portions, Width of Zipper Band, Phase Shift of Dashed Lines
and Tearing Velocity on Tearing Characteristics)
Shigeru NAGASAWA*ᄃ, Kouhei ISHII* and Itaru KOBAYASHI*
A structure of zipper band is used for opening a cover or splitting a panel by tearing the zipper dashed lines,
which are processed by using a repeatedly nicked (perforation formed) wedge blade. To arrange the geometricaldesign parameters of the zipper band of a package box, the tearing characteristics of the zipper-connecting portions
must be clarified. Herein, to investigate the tearing strength and the success rate of connecting portions (uncut
zones) of corrugated board in the fabrication machine direction, the length of connecting portions, the width ofzipper band, the phase shift angle between two dashed lines, and the pulling velocity of the cramped end of thezipper band were changed in the tearing test of the zipper band. The experimental results show that the outside(lower side) liner was de-laminated and tore protrusion occurred at the connecting portions in the band area. For
the upper critical length of connecting portions, at which the success rate became zero, the upper bound tearing
strength was obtained and is related to the Elmendorf-like tearing value by the uniaxial tensile test.
.H\ZRUGVzipper pull tab, nick, peeling, delamination, grainy, tearing, upper/lower critical length, Elmendorf tearing
strength

,QWURGXFWLRQ
To easily open a closed packaging box, amethod for tearing the zipper band (zipper pulltab) is implemented on the flap of the packaging
box. A zipper band for opening a flap of box
normally consists of two parallel dashed lines,
which are perforations for tearing. There are
empirically various cutting patterns of zipper
band for each manufacturer. However, there areno public designing methods and theoreticalinvestigations on the mechanics of the tearing
characteristics of zipper bands. Regarding the
failure behavior of paper, the mode III tear test(out-of-plane shearing) as the Elmendorf test 1 , 2 ) ,in which the tear propagates across the sheet
parallel to the direction of the initial slit, is
known and standardized (e.g., TAPPI, T414).
Since this test method evaluates the tearstrength of a plain thin paper or paperboard, acertain finite length of the uncut zone should be*analyzed to determine its fracture behavior. In
a study by Yamauchi et al. 3 ) , the Elmendorf tearindex was statistically equal to the tear index oftensile testing of thin papers. Namely, an outof-plane tearing of paper using the tensile
testing method shows a similar tearing
resistance as that of the Elmendorf testing.
Nagasawa et al. investigated the tearing tensile
force and breaking modes of the connecting
portions (uncut zones) of a 310g/m 2 whitecoated recycled paperboard, while varying
some parameters, such as the pitch of the nicks
and the profile of entry guide parts 4 ) .
Consequently, it was reported that appropriate
guiding routes embedded in the band zone
contributed to the truncation of connecting
portions when the band’s perforation was
across the grain direction. The upper or lower
critical length of connecting portions, at which
the tearing success rate of connecting portions

Nagaoka University of Technology, Dept. of Mechanical Eng.,

ᄃ Corresponding author, ditto. 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan,

TEL/FAX:+81-258-47-9701, Email:snaga@mech.nagaokaut.ac.jp㸫㸫Effects of Processing Conditions on Tearing Characteristics of Zipper Lines of E-Flute Corrugated Paperboard (Dependency of Length ofConnecting Portions, Width of Zipper Band, Phase Shift of Dashed Lines and Tearing Velocity on Tearing Characteristics)

zipper are as follows: length of dashed- cutting
line =5mm, connecting portions’ length (uncut
zones) a n =2, 2.5, and 3mm, zipper band widthb =12, 15, 20, and 25mm, and phase shift angle
T p =0°, 90°, and 180°.
Herein, the band strip is composed of two
dashed lines of a n +5mm (cutting line) with thephase shift angle T p , as shown in Fig.2 (b). The
difference between the left part and right partwas calculated as ( T p /360)(a n +5).
anc

Cramped end
for pulling

115

Unit: mm5b52

Left part
Right part
Machine direction

10(a) Layout and size of specimen for tearing testbbecame zero or started to decrease, wasreported, and the effects of the inclined pulling
direction on the tearing success rate wasinvestigated for a 310g/m 2 paperboard 5 , 6 ) . Josip
Bota et al. compared different zipper tear strips(ZTS) and conducted a manual opening test 7 ) .
However, these reports were limited to a certain
paperboard thickness (t =0.3–0.4mm). Besides,
studies on the tearing behavior of corrugatedboards have not been conducted.
Herein, to reveal the effects of the processing
conditions (the length and width of connecting
portions, the inclined pulling direction, thephase shift and the tearing velocity) on the
breaking modes and the tearing success rate ofconnecting portions (uncut zones) of an E-flute
corrugated board, a tearing test of zipper lines
was experimentally investigated when dashedcutting lines were across the flutes as I =0°(parallel to the fabricating machine direction of
the corrugated board).

Phase shift (difference) șp(b) Phase shift (difference) of two perforations

([SHULPHQWDO
6SHFLPHQV)LJ6SHFLPHQIRUWHDULQJWHVW)LJ shows a schematic illustration of the

double-faced corrugated board, which iscomposed of the upper (front side) liner, lower(backside) liner and the corrugated medium(CM). The nominal specifications of E-flute
board prepared are as follows: board height t=1.5mm, wave numbers of the CM 93 േ5 for
300mm (wavelength 3.4–3.1mm), Liners’ basis
weight 160g/m 2 , C5 liners’ thickness 0.220mm,
CM basis weight 115g/m 2 and CM thickness
0.166mm (JIS P 8118).

) L J   6 F K H P D W L F L O O X V W U D W L R Q R I F R U U X J D W H G 
SDSHUERDUG
)LJ shows the basic layout and size of the

The two dashed-cutting lines were
processed using a high-carbon-steel blade (NSK,KG 42417444), which had an angular apertureand crossing angle of 20.5° and 18.4°,
respectively. Since the cutting process was twoway as shown in )LJ , the end profile of the
cutting lines was made in the right-angle shape.
After processing two-way cutting, the upper
length of cutting L and the lower length of
cutting l became equal with each other. For theclamped end of the band for pulling up, thelength of the first cutting line c =15mm was
prepared, and the 10mm hatched was initiallyhand-bent at a right angle.
All experiments
were classified into two groups as follows. (i)When the phase shift affected the tearing
characteristics, b was fixed at 12mm, whereas
a n was chosen as 2–3mm. 7DEOH  arranges all
patterns. (ii) When b affected the tearing

specimen for the zipper band tearing test. The
parameters of the geometrical pattern of the㸫㸫

J. Pac .Sci. Tech. Vol.30 No.6㸦2021㸧

characteristics, T p was set as 0°, whereas a n was
set as 2–3mm. 7DEOH arranges all patterns.
Specimens were prepared in a room at an
average temperature of 296K and relative
humidity of 50% for 48h. The Number of
specimens was five for each zipper pattern.

7DEOH  3DWWHUQV RI ]LSSHU OLQHV LQ JURXS L 

([SHULPHQWDOPHWKRG

7DEOH  3DWWHUQV RI ]LSSHU OLQHV LQ JURXS LL  

EDQGZLGWK b =12mm.
Type of pattern

A

Length of uncut
zone an /mm
Angle of phaseshift Tp /㼻

B

C

D

2
0

E

F

G

2.5

90 1800HI

390 180090 180SKDVHVKLIW DQJOH T p =0°.
Type of pattern
Length of uncut
zone an /mm
Width of band
b /mm

)LJ7ZRZD\FXWWLQJRIVSHFLPHQ

(a) Pulling claw and X-stage(b) Fastening)LJ6FKHPDWLFVRIH[SHULPHQWDODSSDUDWXV)LJshows the experimental apparatus forthe tearing test of a corrugated board. The
apparatus is composed of a uniaxial tensile
testing apparatus with tearing velocity V and an
X-stage with horizontal moving velocity V. The
usual velocity was set as V =1mm/s. In contrast,
it was set as 0.5, 1 and 5mm/s for investigating
the velocity effect on tearing. Here, the angleof the pulling direction T a of the zipper band’s
clamped end was set as 90° against thehorizontal X-stage. Due to the restriction of themoving device, the total displacement of thezipper band’s clamped end was 40mm.

a

b

c

d

2
ϭϱ

ϮϬ

e

f

g

2.5
Ϯϱ

ϭϱ

ϮϬ

h

i

3
Ϯϱ

ϭϱ

ϮϬ

Ϯϱ

Consequently, five uncut zones (fivestages) were torn on the dashed lines of the Eflute specimen. When the specimen was
fastened using a window-opened steel plate at b
=12 and 15mm, the window’s width W was set
as 20mm, whereas for b =20 and 25mm, W was
set as 50mm, respectively.
In the tearing test, the relationship between
the tearing tensile force F and the displacementof the clamped end of the zipper band x wasmeasured for five stages of connecting portions.
The maximum peak tearing forces F p i (i=1,2,3,4
and 5) were detected from the response. During
the process, a digital camera recorded thetearing behavior of the specimen, and thesuccess rate of separation of five connecting
portions p S and the failure rate of separation at
any stage (i=1–5) p F i was investigated. Here,‫݌‬ௌ ൅ σହ௜ୀଵ ‫݌‬ி௜ = 1. When investigating thedependency of the tearing characteristics on the
tearing velocity, b was set as 12mm and fivespecimens were used for each velocity.

)XQGDPHQWDOWHDULQJVWUHQJWKTo evaluate the fundamental tearing
strength of the E-flute corrugated board in themachine direction (across flute), an Elmendorflike tearing strength test was conducted using auniaxial tensile device ( )LJ ).
with parameters: c =20mm, b =12mm, anda n = 90mm ( )LJ D ), was prepared and wastested (tearing test) under V =1.67mm/s. Five㸫㸫Effects of Processing Conditions on Tearing Characteristics of Zipper Lines of E-Flute Corrugated Paperboard (Dependency of Length ofConnecting Portions, Width of Zipper Band, Phase Shift of Dashed Lines and Tearing Velocity on Tearing Characteristics)

specimen were used for the test. This method
used a sufficiently long connecting portion toestimate the upper bound tearing strength of thezipper band 5 ) .

)LJ%HQGLQJPRPHQWUHVLVWDQFHRIQRQFUHDVHG (IOXWH ERDUG LQ SDUDOOHO WR
IOXWH
(a) Tensile for tearing (b) Specimen (Unit:mm)) L J Furthermore,   6 F K H P D W L F V  as
R I  W H DanotherU L Q J  W H V W fundamental
E\XQLD[LDOW H Qstrength
VLOH
tearing
test, a special tearing specimen)XQGDPHQWDOVWUHQJWKRIEHQGLQJPRPHQWA certain maximum peak-bending moment
is experimentally observed when considering acantilever bending of a band strip in themachine direction.
With a 10mm loading
position length from the clamped end of abending strength tester CST-J-1 8 ) , the bending
moment resistance of the E-flute corrugatedboard was measured with respect to the folding
angle. Using this bending moment response, themaximum
peak-bending
momentwasinvestigated, knowing the fundamental bending
strength at the first stage. )LJ (OPHQGRUIOLNH WHDULQJ IRUFH XVLQJWKH XQLD[LDO WHQVLOH VKRZQ LQ )LJZLWKSXOOLQJYHORFLW\RIPPV

5HVXOWVDQGGLVFXVVLRQ)XQGDPHQWDOWHDULQJVWUHQJWK) L J   shows examples of the line-bending
moment resistance M of the non-creased E-flute
board for the folding angle T =0°–90° when thebending line was parallel to the flute direction.
For T >10°, since the folded-inside liner was
buckled at a valley position of the intermediatewave layer, M was smaller than the maximum
peak M p e a k (2.9 N in average) at T p e a k (5.2° in
an average of five samples). M p e a k is related tothe bending resistance of the specimen at thefirst stage of the pull-up motion.
)LJ shows an example of the tearing force
response using the apparatus and specimen
shown in )LJ .

)LJ 7HDULQJ IRUFH UHVSRQVH RI ]LSSHUEDQG ZKHQ FKRRVLQJ D ORQJ XQFXW] R Q H R I   P P  Z L W K S X O O L Q J Y H O R F L W \ R I PPVDQG Ta =90°.

The tearing force F T S almost saturated as 9–
12 N for the clamped end’s displacement x =5–20mm. The maximum force at x=5–20mm wascollected to evaluate the Elmendorf-like tearing
strength from the test. The average maximum
tearing strength for five samples wasdetermined as 11.41N, with a standard
deviation of 1.25N.

㸫㸫

J. Pac .Sci. Tech. Vol.30 No.6㸦2021㸧
)LJ shows an example of the tearing force

F in )LJ when choosing a long connecting
portion (a n =90mm). Half of the maximum
tearing force F m a x /2 was determined as theaverage of 10.85N and with a standard
deviation of 0.95N. Here, F gradually decreased
at x >30mm due to the tearing failure. To acertain extent, in the tearing process, a periodic
change of F was observed as peak-to-peak'x p ൎO (as wave-length) )LJ ). )LJ and )LJ
show that F m a x /2 was almost equal to an
Elmendorf-like tearing strength F T S . Hence, thetearing strength of the E-flute corrugated board
in the machine direction was evaluated as F T S=11N with respect to the tearing line. As theearly maximum peak, a position of x b 0 =1.5mm,
F b 0 =4.8N was detected ( )LJ ). Since the arm
length of the pulling point was a projection of
the bent-up banda b 0 = ඥሺሺܿ െ ͳͲሻଶ െ ‫ݔ‬௕଴ ଶ ሻ ൎͻǤͻǡ with b=12mm, the bending moment of
F b 0 a b 0 was determined as 4.0Nmm/mm, whichappears to be equivalent to M p e a k ( )LJ ).
As a referenced investigation, theElmendorf tearing test using the uniaxial tensile
device was applied to a liner sheet of 160g/m 2(0.220mm thick), while varying the tearing
velocity V from 0.5 to 5mm/s. The tearing
strength in MD was 2.0–2.1 N, which gradually
increased with V. The strength of the prepared
E-flute corrugated board was about five times
stronger than that of the liner sheet. Here, thetearing strength of the liner sheet in CD was
1.5–2.0N for V =0.5–5mm/s. The results
indicated that the tearing strength of the raw
liner sheet increased as the tearing velocity
increased.

(IIHFWRIOHQJWKRIFRQQHFWLQJSRUWLRQVRQWHDULQJ
)LJ shows the side views of the pull-up

zipper band, with b =12mm, a n =2mm, and T p=0° (type A). )LJ shows the top views of torn
connecting portions when choosing types A, D,
and G: a n =2, 2.5 and 3.0mm at T p =0°, b =12mm.
)LJ shows the failure mode occurring at thethird stage during the tearing test in type D (a n

=2.5mm, T p =0°). The success rate of the tearing
separation p S was 100%, 80% and 0% for types
A, D and G, respectively.

(a) Peak(b) Peak(c) Folding
maximum force minimum force collapse
Fig.9 Side views of pull-up zipper band at
type A.

)LJ7RSYLHZVRIIURQWVLGHWRUQFRQQHFWLQJSRUWLRQVIRUW\SHV$'*

Namely, the upper critical length, at which p S=0, was a n = 3mm (a n /t=2), and the lower criticallength, at which p S started decreasing, wasa n =2mm (a n /t=1.33) for types A,D and G.

)LJ *HQHUDO YLHZ RI IDLOXUH PRGH RI
WHDULQJDWW\SH'

Torn protrusion occurred at the band andthe left/right-side area, although the band strip
seemed a little plucked. )LJ F and )LJ
show that the tearing failure mode started fromthe lower liner, outside the folded band strip.
This pull-out tendency of the band strip was
like that of a white-coated paperboard 5 , 6 ) .
)LJ shows representative examples of
the tearing tensile force F with respect to thedisplacement x with a n =2, 2.5 and 3mm at b
=12mm, T p =0° (A, D and G). At the early firststage (x=2–5mm) in )LJ , the peak minimum
force was detected. The similar peak minimum
forces were also detected in the second, third,㸫㸫Effects of Processing Conditions on Tearing Characteristics of Zipper Lines of E-Flute Corrugated Paperboard (Dependency of Length ofConnecting Portions, Width of Zipper Band, Phase Shift of Dashed Lines and Tearing Velocity on Tearing Characteristics)

an=2mm an=2.5mm
3rd
1st
2nd

15
10

Fp3

(an=2mm)Fp1

3KDVHVKLIWHIIHFWRQWHDULQJRII

an=3mm
5th stage
4th
Fp4

Fp2
Fp5

)LJ shows the success rate of the tearing
separation of connecting portions for all types
A–I in group (i). For a n =2.5mm, it was foundthat the phase shift of the cutting lines slightly
reduced the success rate.

100

0

0

Success rate of tearingpS /%5
Folding collapse Collapse under inclined
10
20
30
40
Displacement of cramped end of band x /mm)LJ 5HSUHVHQWDWLYH UHODWLRQVKLS EHWZHHQWHDULQJ IRUFH DQG GLVSODFHPHQW RI FUDPSHG
HQGRIEDQGVWULSIRUW\SHV$'*

2
0
12.1
1.1

F p = 11.08 (a n /t) 0 . 2 8
F p = 0.50(2F T S )(a n /t) 0 . 2 8




2.5

3

12.6
1.6

13.5
1.4

(1)

60

an=2.5mm

40

an=3.0mm

20
0

0

50
100
150
200
Phase shift Tp /㼻Failure rate of tearing pFi /%(i=1-5)1008060

Tp=0ι Tp=90ι
Tp=180ι

40
20
0

100

1st 2nd 3rd 4th 5thStage of connecting portion80

Tp=0ι Tp=90ι
Tp=180ι

60
40
20
0

1st 2nd 3rd 4th 5thStage of connecting portion(a) an=2.5mm(b) an= 3mm)LJ7HDULQJIDLOXUHUDWHIRUILYHVWDJHVZKHQFKRRVLQJW\SHV'±,
20

Tp=0ι

Tp=90ι

15
Fp2,1

Tp=180ιFp2 (Tp=0ι)
Fp2,2

10

5

7DEOH$YHUDJHWHDULQJIRUFHF S  $'* .

an /mm
Tp /㼻
Fp /N
Std.dev. /N

an=2.0mm)LJ 6XFFHVV UDWH RI WHDULQJ RI
F R Q Q H F W L Q J S R U W L R Q V I R U J U R X S  L  W \ S H V $ ,Tearing force F /Nfourth and fifth stages. The resistance can be
attributed to the plastic collapse 9 ) of the foldedband strip. After the folding collapse at eachstage, the tearing force reached F p i (i =1,2,3,4,
and 5). Although plastic collapse principally
occurred at every stage (connecting portion),
the first stage collapse was relatively larger
than that after the second stage due to a certain
inclined attitude of the pull-up band. Here, thefolded position and its resistance dispersed
among the specimens due to the periodic
rigidity of CM. The maximum peak forces also
disperse, as seen in )LJ . 7DEOH  shows theaverage maximum peak force F p and its
standard deviation for the five stages. The fullaverage force F p of five stages F p i (i=1–5) was
derived as approximation Eq.(1). Here, F p =൫σହ௜ୀଵ ‫ܨ‬௣௜ ൯Ȁͷ and F T S =11N as described in
section 3.1. The tearing force increased withthe length of connecting portions.

80

Failure rate of tearing pFi /%(i=1-5)

Tearing force F /N

20

0

0

10
20
30
40
Displacement of cramped end of band x /mm)LJ5HSUHVHQWDWLYHUHODWLRQVKLSEHWZHHQWHDULQJIRUFHDQGGLVSODFHPHQWRIFUDPSHG
HQGRI]LSSHUEDQGIRUW\SHV'(DQG)
)LJ shows that the failure rate of tearing
scattered in the five stages, whereas )LJ
shows a representative relationship between the㸫㸫

J. Pac .Sci. Tech. Vol.30 No.6㸦2021㸧

Success rate of tearing
pS /%

100

2

2.5

3

Tp /ι

90

180

90

180

90

180

Fp /N

10.6

8.9

11.4

10.0

13.3

10.7

Std.dev. /N

1.7

0.6

0.8

1.2

1.5

1.1

(a) Early peak(b) Late peak
)LJ 6FKHPDWLFV RI WZLVWHGSXOO EDQG E\
SKDVHVKLIWRIWZRGDVKHGFXWWLQJOLQHV(IIHFWRIEDQGZLGWKRQWHDULQJRII
To investigate the effects of band width on
the tearing characteristics, the width of theband strip was additionally chosen as b =15–25mm when T p was maintained as 0° (group ii).
)LJ shows the success rate of tearing p S ,whereas )LJ shows the failure rate of tearing
at any stage p F i (i =1–5) when changing b.

an=2.0mm60

an=2.5mm

40

an=3.0mm

20
0

0

5
10 15 20 25
Width of zipper band b /mm

30

FLJ 6XFFHVV UDWH RI WHDULQJ IRU W\SHV$'*DQGD±L
100

IRUW\SHV%&()+DQG, .
an /mm

80

80
60

100

b=12mmb=15mmb=20mmb=25mm40

Failure rate of tearing pFi /%(i=1-5)

7DEOH$YHUDJHWHDULQJIRUFHIRUILYHVWDJHVF S In )LJ , the three cases (a n =2, 2.5 and3.0mm) at b=12mm were rewritten from that ofT p =0° in )LJ . It was found that the tearing
success rate increased with the width of theband strip, and the tearing failure rate wasscattered for the five stages.

Failure rate of tearing pFi /%(i=1-5)tearing force and the displacement of theclamped end of the band strip when changing
T p =0°,90°, and180°. Comparing the non-zerophase shift T p =90, 180° with T p =0°, as seen in)LJ , the maximum peak F p i (i =2 was focusedin here) at non-zero phase shift was smaller
than that of the zero shift ( T p =0), and it was
divided into two peaks which were denoted as
F p 2 , 1 (early peak) and F p 2 , 2 (late peak). Thisphenomenon arises from the non-zero phaseshift of the two dashed-cutting lines ( )LJ ).
Calculating the full average of the fivemaximum peak forces F p = ൫σହ௜ୀଵ ‫ܨ‬௣௜ ൯Ȁͷ, 7DEOH 
was derived. For a n =2.5 and 3mm at T p =180°,
the maximum peak force was reduced about
21% from T p =0°. If the right-side tearing isisolated from the left side tearing, the expected
maximum peak force seems to be half of theforce at the synchronous state as T p =0°.
However, the real pulling force was interferedfrom the opposite side under a twisted mode of
the zipper band.

80
60
40

20

b=12mmb=15mmb=20mmb=25mm20

00

1st 2nd 3rd 4th 5thStage of connecting portion

1st 2nd 3rd 4th 5thStage of connecting portion(a) an =2.5mm(b) an =3mm

)LJ)DLOXUHUDWHRIWHDULQJIRUW\SHVD±L

The success rate increment tendency by the
band’s width was like that of a white-coatedpaperboard 6 ) . The bending stiffness of the band
increases as its width increases. In contrast, thetearing resistance (force) at a connecting
portion is determined by the length of theconnecting portion. This relation increases thebending curvature radius of the pull-up band
when increasing the band’s width. Thissituation was observed, as shown in )LJ .
)LJ D  (a n =3mm) is like )LJ D (a n =2mm)
with respect to the bending angle of the pull-up
band. For b =25mm, as shown in )LJ E , thebending angle of the pull-up band was about 61°
at the maximum peak force. Therefore, the inplane tensile stress of the outside layer of theband strip was reduced, compared to that of b
=12mm. Thus, the success rate of tearing seems
to increase with the width of the band strip.

㸫㸫Effects of Processing Conditions on Tearing Characteristics of Zipper Lines of E-Flute Corrugated Paperboard (Dependency of Length ofConnecting Portions, Width of Zipper Band, Phase Shift of Dashed Lines and Tearing Velocity on Tearing Characteristics)

7DEOH  6XFFHVV UDWH RI WHDULQJ RI
FRQQHFWLQJ SRUWLRQV IRU W\SHV ' *
ZKHQFKDQJLQJWKHWHDULQJYHORFLW\(a) b =12mm

a n (mm)
2.5
3
V (mm/s) Success rate p S (%)
0.5
80
0
1
80
0
5
90
70

(b) b =25mm)LJ6LGHYLHZVRISXOOXSEDQGVWULSDWW\SHV * DQG , (an=3mm).

Tearing force Fp /N

25

an=3.0mm201510

an=2.5mm

500

an=2.0mm(a) V =1mm/s

10
20
30
Width of zipper band b /mm)LJ 0D[LPXP SHDN IRUFH RI WHDULQJ IRUW\SHV$'*DQGD±L

For the tearing force against the width of theband, )LJ 0 shows F p (as a full average of fivestages) for types of A, D, G and a–i. Here, error
bars represent the standard deviation of samples.
F p increased as b due to the difference in thebending attitude. However, since the upperbound tearing force is expected as 2F T S =22N,
F p seems to settle down into a certain resistance< 2F T S as b increases. According to the resultof white-coated paperboard 6 ) , the tearing force
was determined by the length of a connecting
portion a n , but independent from b.

(IIHFWRIYHORFLW\RQWHDULQJRII
Regarding the tearing velocity effects on theseparation of connecting portions, as a plain liner
sheet of 160g/m 2 (0.220mm) was explained in

section 3.1, the tearing resistance and thedeformation of the E-flute specimen seem to beaffected by the velocity. 7DEOH  shows the
success rate of tearing for types D and G withthe tearing velocities V of 0.5, 1.0 and 5.0mm/s.

(b) V =5mm/s)LJ&RPSDULVRQRIVLGHYLHZVRISXOOXS
] L S S H U  E D Q G  Z K H Q  F K D Q J L Q J W K H  W H D U L Q J YHORFLW\DWW\SH'

The tearing state of V =0.5mm/s was notsensitive, compared to the case of V =1.0mm/s.
However, the tearing state of V =5mm/s varied,
and the success rate increased. )LJ shows theside views of the pull-up band when V =1.0 and
5.0mm/s at a n =2.5mm and b =12mm. Comparing)LJV  D) and E , the torn protrusion of E 
was seen as a small broken volume. Namely, apull-out deformation at the connecting portion
seems to be restricted by the tearing velocity or
the strain-rate of that region.

&RQFOXVLRQV
A plain zipper band without a guiding route
was prepared using a 160(upper liner)115(medium)-160(lower liner) g/m 2 E-flute
corrugated board (total height t =1.5mm). A
tearing test of the zipper band was conducted
while changing the length of connecting
portions a n , the width of band strip b, the angleof the phase shift of the two dashed-cuttinglines T p and the tearing velocity V. The
following conclusions were deduced from theexperiments.

㸫㸫

J. Pac .Sci. Tech. Vol.30 No.6㸦2021㸧

(1)

An in-plane tensile test based on
fundamental
tearing
strengthwas
conducted for an E-flute corrugated board
and a liner sheet in MD. The E-flute
corrugated board, which had a strength ofF T S  =11N, was about five times stronger
than that of the liner sheet.
(2) The relationship between the full averageof the maximum peak tearing force F p andthe normalized length of the connecting
portiona n /twasrevealed
usingexperimental approximation with an
exponentiation rule.
(3)       Ǧ    T  ൌ Ͳ°ǡ ͻͲ°, ͳͺͲ°ǡ          T  Ǥ       ǡ     T   ൌͳͺͲ°ǡ
  T   ൌͻͲ°Ǥ
ሺͶሻ        ͳʹǡͳͷǡʹͲǡʹͷǡ            ǡ     Ǥ(5) When the tearing velocity was increased
from 1 to 5mm/s, the success rate of tearing
at connecting portions of the E-flute
corrugated board was stably increased.

In many real problems, the tearingv e l o c i t y s e e m s t o b e l a rg e r t h a n t h a t o f t h i s
s t u d y. W h e n t h e t h i c k n e s s o f c o r r u g a t e db o a r d i s l a rg e r t h a n t h a t o f E - f l u t e , t h etearing behavior of zipper seems to bechanged. These geometrical and dynamice ff e c t s o n t h e t e a r i n g c h a r a c t e r i s t i c s s h o u l d
be investigated furthermore.



1RPHQFODWXUH
b: width of the band strip (pull tab), b=12,
15, 20, and 25 (mm)an: length of a connecting portion (uncutzone) along the cutting line
T p : a n g l e o f p h a s e s h i f t ( d i ff e r e n c e )between two dashed-cutting lines, Tp=

0, 90 and 180 (°)
F : tearing tensile force of the clamped endof the zipper bandx : displacement of the clamped band end in
the vertical direction
Fpi : the maximum peak tearing force at thei-th stage (the i-th connecting portion,i=1±5 was considered)Fp : average maximum peak tearing force fort h e f i v e s t a g e s , ൫σ૞࢏ୀ૚ ࡲ࢖࢏ ൯Ȁ૞pS : success rate (probability) of tearing
separation of connecting portions bypulling a clamped end of zipper bandp F i : failure rate of tearing at the i-thstage.
F T S : (Elmendorf-like) tearing strength
using uniaxial tensile test device
shown in )LJ5HIHUHQFHV㸧C .A.Bronkhorst, K.A.Bennet, Handbook of
Physical Testing of Paper, 1, p.388 (1983).
㸧M .B.Lyne, M.A.Jackson & A.E.Ranger, The
in-plane, Elmendorf, and edge tear strength
properties of mixed furnish papers, TAPPI,
55(6), p.924 (1972).
㸧T .Yamauchi, A.Tanaka, Tearing test for
paper using a tensile tester, Journal of Wood
Science, 48, p.532 (2002).
㸧S .Nagasawa, M.Uehara & C.Matsumoto,
Effects of guiding routes and grain directionof white-clay-coated paper board on tearing
characteristics of zipper pull tab (inJapanese), Journal of the Japan Society forTechnology of Plasticity, 59(685), p.15
(2018).
㸧S .Nagasawa, M.Uehara & C.Matsumoto,
Tearing characteristics of zipper pull tab of
paperboard (in Japanese), Proceedings of
26th annual congress of SPSTJ, p.140 (2017).
㸧S .Nagasawa, M.Uehara & C.Matsumoto,
Effects of mechanical conditions on tearing
characteristics of zipper band made of whiteclay-coated paperboard (Dependency oftearing characteristics on length ofconnecting portions, width of band and㸫㸫Effects of Processing Conditions on Tearing Characteristics of Zipper Lines of E-Flute Corrugated Paperboard (Dependency of Length ofConnecting Portions, Width of Zipper Band, Phase Shift of Dashed Lines and Tearing Velocity on Tearing Characteristics)

pulling direction), Journal of Advanced
Mechanical
Design,Systems
and
Manufacturing, 15(1), p. jamdsm0009 (2021).
㸧J . Bota, G. Petković, Evaluation of Zipper
Tear Strip Design Structure for Paperboard
Packaging, Proceedings of International
Symposium Graphic Engineering and Design-GRID 2020, At: Novi Sad, Srbija, p.299(2020).

㸧K atayama Steel Rule Die Inc., Crease Stress
Tester CST-J-1 (online), available fromhttp://diemex.com/sale/cst_e.html, (accessedon 17 February, 2021).
㸧H .Kudo, Plasticity, Morikita publishing,(1968), pp.16-19 (in Japanese).

㸫㸫

(Received 31 May 2021)(Accepted 21 October 2021)