Adhesive-Free Lamination Technique using a Plasma Surface ...

3. Results and discussion
The AS of each combination of the films is shown in
table 2. All combinations of untreated films were not
stuck only by the heat-press. While the AS values of the
treated films did not exceed the industrial required values,
they showed hopeful high values.
Fig. 3 shows the treatment time dependence of the AS
of PET/LDPE treated in reactor a). Since this result was
one of the previous study results and PET was pulled in
the 180º peel test, these AS values were bigger than that
of table 2. As shown in Fig. 3, we obtained no clear dependence
of the AS on the treatment time. Thus, we tried
to use the reactor b) which was able to treat the films for a
quite short time.
Fig. 4 is the AS of PET/LDPE treated with the reactor
b). The AS at 10 s was stronger than that of table 2. This
reason was considered that the discharge density of the
reactor b) (52 Wcm -3 ) was higher than that that the reactor
a) (6.3 Wcm -3 ). Fig. 5 shows the AS of PET/LDPE treated
with the reactor b) with different discharge power. The
maximum AS value is attained at shorter treatment time in
higher power (20W) compared with lower power (10W)
treatment. But still the maximum value is lower than that
of required value (RV).
This result indicated that several tens of milliseconds
treatment time in high density plasma suffices for the adhesive-free
lamination technique. So we need high density
and short time treatment using high frequency discharge
such as RF pulse modulated discharge.
Fig. 6 shows the variation of the adhesive strength of
PET/LDPE as a plasma treatment time with different discharge
frequency in the same power (10W). The adhesive
strength was improved only by RF discharge even in the
same power. They indicated that enough adhesive strength
300
Table 2. The adhesive strength of each combination
treated with 100 kHz discharge.
Adhesive strength / Nm -1
Films Plasma gas
UT PT RV
PET/LDPE N 2 /He
87 300
NY/LDPE N 2 /He 434 500
0
PET/PP He 98 300
NY/PP He 186 500
*UT, untreated; PT, plasma treated; RV, required value.
*Reactor, a); treatment time, 15 s; Power, 100 W, 100
kHz.
Adhesive strength / Nm -1
250
200
150
100
50
0
0.001 0.01 0.1 1 10
Treatment time / s
Fig.4. The variation of the adhesive strength as a function
of the N 2 /He plasma treatment time. Sample, PET/LDPE;
reactor, b); Power; 10 W, 100 kHz.
Adhesive strength / Nm -1
200
100
0
0 20 40 60 80 100
Treatment time / s
Fig 3. The variation of the adhesive strength as a function
of the N 2 /He plasma treatment time. Sample, PET/LDPE;
reactor, a); Power; 100 W; 100 kHz, N 2 , 50 sccm.
Adhesive strength / Nm -1
300
250
200
150
100
50
0
20W
10W
0.001 0.01 0.1 1
Plasma treatment time / s
Fig.5 Adhesion strength as a function of treatment time
with different discharges power. 100kHz, 10W, 20W.