802
Tr-electron
releasing
have
a
andelectron
and
where
Xand Ydenoteelectron
[I]
[II]
conjugated
and
system,
Dyes
withdrawing
substitu-
with both electron
concluded that
substituents,
withdrawing
They
donating
respectively.
of the molecule. Such molecules
ends
and
ents at
McRae’s
the modified
1,
[8],
prediction
opposite
contribution
have a
Equation
equation
structure
caused
of
of
in
[III]
dipole
transfer
changes
large
intramolecular
relationships permit
empirical
with solvents:
(cr) [5]:
charge
by
Åmax
where Av is the difference in
for
and
absorption frequency
to
of the cr band shifts
The
longer wavelengths
Åmax
+
in
and in the
solution
B)
gas
( ALo
Åmax
( vs)
(
v~);
with
of the solvents
[ 13].
polyamide
increasing polarity
Disperse dyes
which are
C
are
of solvent
constants,
independent
prop-
to
fabrics to
are often
applied
nDis the refractive index ofthe solvent measured
erties ;
of their excellent
to
because
ability
produce pale -shades
and
D
is the
con-
at the sodium
static dielectric
D-line;
effects
in color with
cover barm
Therefore,
[
1
].
changes
stant of the solvent. In
side
the
term on the
first
1,
Equation
will be
to both theoretical and
us information
decreasing
interesting
Cf
the
of the
contribution
right-hand
expresses
disper-
The
practical dyers.
spectral change gives
sion interaction of the
with the
and the last
solvent,
interactions.
dye
about
in the local
around the
in the
changes
polarity
dye
phenomenon
term
the
expresses
dipole-dipole
with
The
same
( 19].
polymer
decreasing
Cf
we
have
the
of
that
found, however,
Recently,
azo
J1m$X
also
basic data for
provides
computer color-matchingjobs.
the of
deriva-
4-aminoazobenzene
(4’-nitro,
6
dyes
nylon
decreasing dye
disperse
In this
we
study,
clarify
spectral
disperse
change
the nature of
on
film
to
shifts
tives) [II]
longer wavelengths
on
6
with
Then we
dyes
the
nylon
analyze
Cf.
with
in the
concentration
substrate,
(Cf)
for CI
3 and 5
shift
(abbre-
various
spectral
Disperse Orange
shown in
1. Wehave observed the
as
Figure
appreciable
6’-positions,
viated as
3
and
in detail
5)
Orange
through
shift for
with
chlorine
low
2’- and
at
atoms
dyes
since both
are
azo
with
methods,
dyes
(Orange
practical
or with
dyes
in
a
particularly
very
range.
Cf
structures
red
5).
3)
decreasing
simple
appreciable
in
shifts
with
Åmax
in
6
nylon
(Orange
Cf
Experimental
The
in
were identical to those used
and the solvents were
dyes
[ 15-18],
grade.
previous
studies
meric
spectrophoto-
drawn,
prepared
6
film was
Nylon
biaxially
Unitika Ltd. The film was treated in waterat 95°C for
by
25 hours before use.
The
film was
measurements
the same methodas that used
dyedusing
in
of
isotherms
and
17,
[ 15,
18]
sorption
the
concentration
of
in the
in the
in
profiles
[16],
dyes
dye
polymer
diffusion
studies
where
concentration
(Cf)
the
film
from saturation
zero.
ranged
approximately
mg)
(4-10 mL)
Cfto
The
in
the dried
film
was extracted with
at 80-90°C
(10-20
dye
aqueous
25%
solution
pyridine
1.
FIGtJRE
films:
of CI
in
5
6
Absorption
two or three
spectra
times. There
no
Disperse Orange
nylon
spectrum.
were
concentrations of the
a
dotted line is
the
of each
passing through
Åmax
extracts
The amountof
in the extract
by evaporation.
dye
was estimated
(10-25 mL)
colorimetrically.
Visible
ofthe
in solvents
and
or
absorption spectra
dyes
on the film
were measured on
a
Hitachi
U-3300
U-2000A
at
in
room
the
spectrophotometer
For
temperature
usual
ofthe
film
measurements
at
way.
spectral
dyed
1 x
various
was
each film
2.5
(
cm)
temperatures,
specimen
sandwiched
betweentwobrass blocks
cmwide
( 1.25