Polymerizable composition for optical material
An embodiment relates to a polymerizable composition for an optical material and a polythiourethane-based compound prepared therefrom. The polythiourethane-based compound is excellent in appearance with low generation rates of stirae and bubbles.
1. A polymerizable composition, which comprises 1 to 5 types of a polyisocyanate compound, 1 to 5 types of a polythiol compounds, and a catalyst represented by the following Formula 1,
wherein R calculated by the following Equation 1 is a real number of 9.5 to 19.5:
R
=
10
×
(
A
B
+
Q
)
[
Equation
1
]
In the above Equation 1,
A
=
∑
i
=
1
n
(
4200
N
i
×
f
i
)
,
f
i
=
(
m
i
W
i
o
i
)
/
C
,
and
C
=
∑
i
=
1
n
(
m
i
W
i
o
i
)
,
n is the number of kinds of the polyisocyanate compound,
N i is the content (% by weight) of NCO in the i-polyisocyanate compound,
m i is the number of functional groups in the i-polyisocyanate compound,
W i is the amount (g) of the i-polyisocyanate compound added,
o i is the weight average molecular weight (g/mole) of the i-polyisocyanate compound,
B=Σ j=1 l ( S j ×P j )
1 is the number of kinds of the polythiol compounds,
S j is the equivalent weight (g/eq.) of the j-polythiol compound,
P
j
=
(
u
j
V
j
t
j
)
/
Z
-
Z
=
∑
j
=
1
l
(
u
j
V
j
t
j
)
,
u j is the number of functional groups in the polythiol compound,
V j is the amount (g) of the j-polythiol compound added,
t j is the weight average molecular weight (g/mole) of the j-polythiol compound,
Q
is
The
molecular
weight
of
the
substituent
E
of
the
compound
represented
by
the
formula
1
(
g
/
mol
)
×
g
×
D
The
molecular
weight
of
the
compound
represented
by
the
following
formula
1
(
g
/
mol
)
×
K
×
1000
In the above Formula 1,
E is a halogen compound,
F is an aliphatic hydrocarbon having 1 to 30 carbon atoms or an aromatic hydrocarbon having 6 to 30 carbon atoms,
h and g are each independently an integer of 1 to 4,
h+g is 4,
K is the amount of the compound represented by the above Formula 1 based on 100 of the total amounts of the polyisocyanate compound and the polythiol compound,
D is the rate of change in the viscosity of the polymerizable composition with respect to time and is a value derived from Equation 2 defined as follows:
In y =In G+D×x [Equation 2]
In the above Equation 2,
x is the elapsed time (hours) from the preparation of the composition to the measurement of viscosity, which ranges from 5 to 24,
y is the viscosity (cps) of the polymerizable composition at 10° C. after time x, and
G is the initial viscosity of the polymerizable composition at 10° C.
2. The polymerizable composition of claim 1 , wherein A is a real number of 80 to 120, and B is a real number of 80 to 115.
3. The polymerizable composition of claim 1 , wherein D is a real number of 0.08 to 0.25.
4. The polymerizable composition of claim 1 , wherein R is a real number of 9.8 to 18.
5. The polymerizable composition of claim 1 , wherein E is at least one selected from the group consisting of fluorine (F), chlorine (Cl), bromine (Br), and iodine (I).
6. The polymerizable composition of claim 1 , wherein F is an alkyl group having 1 to 10 carbon atoms.
7. The polymerizable composition of claim 6 , wherein F is methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, or t-butyl.
8. The polymerizable composition of claim 1 , which has a viscosity of 1,000 cps (centipoise) or more after it stands at 10° C. for 24 hours.
9. The polymerizable composition of claim 1 , wherein when the polymerizable composition is made into a specimen having a diameter of 75 mm and a thickness of 10 mm, it has a generation rate of bubbles of 0 to 10% and a generation rate of striae of 0 to 8%.
10. The polymerizable composition of claim 1 , which comprises 1 to 3 types of a polyisocyanate compound and 1 to 4 types of a polythiol compound.
11. A polythiourethane-based compound prepared from the polymerizable composition of claim 1 .
12. An optical material molded from the polythiourethane-based compound of claim 11 .
13. The optical material of claim 12 , which has a refractive index of 1.55 to 1.70 for light at 546 nm and an Abbe number of 25 to 45.