SPECIFICATION
METHOD FOR PRODUCING POLYTHIOL COMPOUND, POLYMERIZABLE COMPOSITION
FOR OPTICAL MATERIAL, AND USES THEREOF
5
TECHNICAL FIELD
[OOOl]
The present invention relates to a method for producing a
polythiol compound, a polymerizable composition for optical
10 materials, and uses thereof.
BACKGROUND ART
[0002]
Plastic lenses are lightweight, not easily breakable and
15 tintable as compared with inorganic lenses. Therefore, in recent
years, plastic lenses have rapidlybeeninwide use inopticaldevices
such as spectacle lenses and camera lenses.
[0003]
It has become necessary for resins for plastic lenses to have
20 more enhanced performances, and there have been demands for an
increase in the refractive index, an increase in the Abbe number,
a decrease in specific gravity, an increase in heat resistance, and
the like. Thus, a varlety resin materials for lenses have been
hitherto developed and used.
25 [0004]
Among others, optical materials formed from
polythiourethane-based resins have high refractive index and high
Abbe numbers, and are excellent in impact resistance, tintability,
processability, and the like. Polythiourethane-based resins are
obtained by allowing polythiols to react with polyiso (thio) cyanate
compounds and the like.
5 [0005]
It is required that in the case of being used in plastic lenses,
polythiourethane-based resins be less color, have excellent resin
colors, and be transparent. If the quality of polythiol is poor,
the quality of the resin thus obtainable may also be poor.
10 The method for producing a polythiol is exemplified in the
following patent documents.
[0006]
Patent Document 1 or 2 describes a method of obtaining a
particular polythiol compound by reacting 2-mercaptoethanol with
15 epichlorohydrin, reacting the compound thus obtained with thiourea
to obtain an isothiuronium salt, and then hydrolyzing the
isothiuronium salt.
[0007]
Patent Document 3 describes a method for producing a polythiol
20 compound, the method including adjusting the amount of particular
impuritiesthatarecontainedin2-mercaptoethanoltoapredetermined
range.
Patent Document 4 describes a method for producing a polythiol
compound, the method including adjusting the content of calcium that
25 is contained in thiourea to a predetermined range.
Patent Document 5 describes a method for producing a polythiol
compound, the method including adjusting the content of calcium that
is contained i n t h i o u r e a , and t h e amount of p a r t i c u l a r i m p u r i t i e s
t h a t a r e contained i n 2-mercaptoethanol, t o predetermined ranges.
RELATED DOCUMENT
PATENT DOCUMENT
5 [0008]
[Patent Document11 JapaneseUnexaminedPatent PublicationNo.
2-270859
[PatentDocument2] JapaneseUnexaminedPatent PublicationNo.
7-252207
[Patent Document 31 Pamphlet of I n t e r n a t i o n a l Publication No.
WO 2007/129449
[Patent Document 41 Pamphlet of I n t e r n a t i o n a l Publication No.
WO 2007/129450
[Patent Document 51 Korean P a t e n t PublicationNo. 2010-0078120
15
DISCLOSURE OF THE INVENTION
[0009]
However, i n t h e case where a p l a s t i c l e n s formed from a
polythiourethane-based r e s i n is produced using a p o l y t h i o l compound
20 t h a t is obtainable by t h e methods described these documents, t h e r e
is room f o r an improvement i n q u a l i t y such as color, transparency
and s t r i a t i o n .
[OOlO]
There have been cases, i n which even i f t h e r e is no problem i n
25 t h e product q u a l i t y when a p l a s t i c l e n s is produced using a p o l y t h i o l
compound obtained by small-scale production, t h e q u a l i t y of t h e
p o l y t h i o l compound f l u c t u a t e s between d i f f e r e n t production batches
when a p o l y t h i o l compound is produced continuously and repeatedly
i n the production i n an actual i n d u s t r i a l scale. Furthermore, there
have been occasions i n which when a p l a s t i c lens is produced using
such apolythiolcompound, a p l a s t i c l e n s having a p r o b l e m i n q u a l i t y
5 such as color, transparency and o p t i c a l homogeneity i s obtained.
That is, the efficiency percentage (number of i t e m s of q u a l i t y
p r o d u c t / t o t a l number of produced i t e m s ) , which includes p l a s t i c
lenses t h a t s a t i s f y the product q u a l i t y described above among the
p l a s t i c lenses obtainable from a p o l y t h i o l compound, has decreased
10 i n some cases.
[00111
However, t h e r e havebeen occasions inwhich d e f e c t i v e p o l y t h i o l
compounds occur i n l a r g e q u a n t i t i e s without its cause being
understood. Furthermore, t h e r e h a v e b e e n a n i s s u e t h a t anevaluation
15 of the q u a l i t y of a p o l y t h i o l compound as a monomer is d i f f i c u l t ,
based on the chemical analysis r e s u l t s of the p o l y t h i o l compound,
and judgment must be made based on the evaluation of a p l a s t i c lens
t h a t can be a c t u a l l y obtained from the polythiol compound. A
polythiolcompound with which a p l a s t i c lens having a desiredproduct
20 q u a l i t y cannot be obtained i n i n d u s t r i a l production, cannot be used
as a monomer. Therefore, it is very important, i n view of the
i n d u s t r i a l production efficiency of the polythiol compound and in
view of economic e f f i c i e n c y , t o e s t a b l i s h a method f o r producing a
polythiol compound by which a p l a s t i c lens product having a d e s i r e d
25 product q u a l i t y can be stably obtained.
[00121
It is because a p l a s t i c lens formed from a thiourethane resin
is produced at a rate of one sheet of lens per batch. Specifically,
first:, a thiourethane-based polymerizable composition is injected
into a glass type mold, the polymerizable composition is polymerized
under heating to cure, and then the cured product is released from
5 the glass type mold. Thus, one sheet of lens is produced. That is,
in order to obtain one sheet of a thiourethane-based plastic lens,
many processes and operations are needed. Furthermore, if a
thiourethane-based plastic lens is not proved to have a desired
product quality, it is difficult to reuse the plastic lens as a
10 thiourethane resin, unlike those products formed fromthermoplastic
resins and the like. Therefore, it is very important to establish
a method for producing a polythiol compound by which a plastic lens
product having a desired product quality can be stably obtained, in
view of the industrial production efficiency of plastic lenses and
15 in view of economic efficiency.
Therefore, inthe case of continuously andrepeatedlyproducing
a polythiol compound in an industrial scale, it is necessary to
establish amethod for producing a polythiolcompoundwith excellent
20 production stability, by which a polythiol compound that is used as
a raw material for plastic lenses having a desired product quality
is stably obtained without any fluctuation in the product quality
of the polythiol compound between different production batches.
[00141
25 The present invention can be described as follows.
[I] A method for producing a polythiol compound, the method
comprising:
a step for reacting 2-mercaptoethanol with an epihalohydrin
compound represented by the following formula (1)
[0015]
5 [00161
wherein X represents a halogen atom,
at atemperatureof 10°Cto 50°Ctoobtainapolyalcoholcompound
represented by the following formula (2);
[0017]
a step for reacting the polyalcohol compound represented by
formula (2) thus obtained with thiourea in the presence of hydrogen
chloride to obtain an isothiuronium salt;
a step for adding, while maintaining a reaction solution
15 containing an isothiuronium salt thus obtained at a temperature of
15OC to 60°C, aqueous ammonia to the reaction solution within 80
minutes to hydrolyze the isothiuronium salt to obtain a polythiol
compound represented by the following formula (5);
and
a step for adding hydrochloric acid which is a concentration
of 25% to 36% to a solution containing the polythiol compound thus
5 obtained, washing the solution at a temperature of 10°C to 50°C to
purify the polythiol compound.
[2] The method for producing a polythiol compound according to [I],
compound comprises:
10 a step for reacting 2-mercaptoethanol with the epihalohydrin
compound represented by formula (1) at a temperature of 10°C to 20°C
to obtain a compound represented by the following formula (3);
100181
and
a step for r e a c t i n g t h e compoundrepresentedby formula (3) with
2-mercaptoethanol a t a temperature of 10°C t o 50°C t o obtain the
polyalcohol compound represented by formula ( 2 ) .
5 [3] Amethod forindustrialmanufactureofapolythiolcompound,
using the method according t o [ I ] or [ 2 ] .
[ 4 ] A polymerizable composition for o p t i c a l materials,
comprising a polythiol compound obtained by the method according t o
any one of [ I ] t o [3].
10 [5] A molded product obtained by curing the polymerizable
composition for o p t i c a l materials according to [4].
[6] A p l a s t i c lens comprising the molded product according t o
[51.
[0020]
15 In addition, washing according t o the invention means a process
of s t i r r i n g andmixing an organic layer containing aproduct inwater
or an aqueous acid or a l k a l i solution, causing the mixture t o stand
s t i l l , subsequently separating the mixture t o liquid-liquid
p a r t i t i o n , and thus obtaining an organic layer containing a reaction
20 product. Water washing means washing using water, acid washing means
washing using an acidic aqueous solution, and a l k a l i (aqueous
ammonia) washing means washing using an aqueous a l k a l i solution
(aqueous ammonia) .
[0021]
2 5 When a polythiol compound t h a t is obtainable from the method
forproducingapolythiolcompoundoftheinventionis used, a p l a s t i c
lens formed from a polythiourethane-based r e s i n having excellent
quality such as color, transparency and striation can be obtained.
Furthermore, according to the invention, even in the case where a
polythiol compound is produced repeatedly in actual production on
an industrial scale, no fluctuation occurs in the product quality
5 of the polythiol compound between different production batches, a
plastic lens having adesiredproductqualitycanbe stablyobtained,
and a production method for a polythiol compound with excellent
production stability can be provided. Furthermore, a polythiol
compound which is suitable as a raw material for plastic lenses can
10 be stably supplied. Furthermore, when apolythiolcompoundobtained
by such a method is used, the product yield and the efficiency
percentage of the product thus obtainable can be improved.
DESCRIPTION OF EMBODIMENTS
The "method for producing polythiol compounds including
4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane as a main
component (hereinafter, simply a polythiol compound)'' of the
invention will be described based on the following exemplary
20 embodiment.
[0023]
The method for producing a polythiol compound of the present
exemplary embodiment can include the steps described below.
Step A: 2-mercaptoethanol is reacted with an epihalohydrin
25 compound represented by the following formula (1) at a temperature
of 10°C to 50°C, and thus a polyalcohol compound represented by the
following formula (2) is obtained.
(I,
X
[0025]
(wherein X represents a halogen atom)
[0026]
Step B: The polyalcohol compound obtained in step A is reacted
with thiourea in the presence of hydrogen chloride, and thus an
isothiuronium salt is obtained.
Step C: While a reaction solution containing the isothiuronium
salt obtained in step B is maintained at a temperature of 15OC to
60°C, aqueous ammonia is added to the reaction solution within 80
minutes, the isothiuronium salt is hydrolyzed, and thus a polythiol
compound represented by the following formula (5) is obtained.
15 [0027]
[00281
Step D: Hydrochloric acid which is a concentration of 25% t o
36% is added t o the solution containing the polythiol compound
5 obtained in step C, the solution is washed a t a temperature of 10°C
t o 50°C, and the polythiol compound is purified.
[00291
According t o the production method of the present exemplary
embodiment, a p l a s t i c l e n s formedfromapolythiourethane-basedresin
10 produced using a polythiol compound t h a t is obtained by performing
step A, step C and step D in p a r t i c u l a r within the scope of the
invention, has excellent quality such as color, transparency and
s t r i a t i o n . Furthermore, according t o the production method of the
present exemplary embodiment, even in the case where a polythiol
15 compoundis repeatedlyproducedinactualproduction on an i n d u s t r i a l
scale, a polythiol compound having a desired product quality can be
stably obtained without any fluctuation i n the product quality of
thepolythiolcompoundbetween differentproductionbatches, and the
production s t a b i l i t y is excellent. The production method of the
20 present exemplary embodiment is p a r t i c u l a r l y useful as a method for
i n d u s t r i a l manufacture of a polythiol compound.
Hereinafter, the various processes w i l l be described i n
sequence.
[0030]
(Step A)
In step A, 2-mercaptoethanol is reacted with an epihalohydrin
compoundrepresentedbythe following formula ( I ) , a n d t h e r e b y a t r i o l
compound represented by the following formula (2) can be obtained
as a polyalcohol compound.
[0031]
[0033]
In the formula ( I ) , X represents a halogen atom which may be
15 a fluorine atom, a chlorine atom, a bromine atom or an iodine atom,
and is preferably a chlorine atom.
[0034]
Inthepresentexemplaryembodiment, the r e a c t i o n c a n b e c a r r i e d
out at a temperature in the range of 10°C to 50°C, preferably 15OC
to 50°C, and more preferably 2S°C to 4S°C. When the reaction
temperature is lower than 10°C, the reaction does not sufficiently
proceed throughout the reaction process, and unreacted elements may
5 be retained in the reaction system, causing the reaction to proceed
suddenly. When the reaction temperature is higher than 50°C, the
color of the lens may be deteriorated. That is, when the reaction
temperature is in the temperature range described above, excellent
controllability of the reaction is attained, and the color of the
10 plastic lens thus obtainable is also excellent.
The reaction can be carried out for 2 hours to 12 hours, and
preferably 3 hours to 10 hours.
[0035]
The reaction can be carried out, for example, in the following
15 manner. First, 2-mercaptoethanolandabase areadded, ifnecessary,
to water or a lower alcohol solvent such as methanol or ethanol,
subsequently an epihalohydrin is added dropwise thereto, and thus
areaction is carriedout. The reactiontemperature andthe reaction
time are preferably adjusted to be in the ranges described above.
20 The reaction time includes the time for the dropwise addition of the
epihalohydrin, and the temperature of the reaction solution at the
time of the dropwise addition needs to be adjusted to the reaction
temperature. The use amount of 2-mercaptoethanol is necessarily
equal to or more than 1.8 moles and equal to or less than 3 moles
25 relative to 1 mole of the epihalohydrin, and the use amount is
preferably equal to or more than 1.8 moles and equal to or less than
3 moles, andmore preferablyequalto ormorethan1.9moles and equal
to or less than 2.1 moles, relative to 1 mole of the epihalohydrin.
[00361
Examples of the base include metal hydroxides such as sodium
hydroxide and potassium hydroxide; metal carbonates such as sodium
5 carbonate and potassium carbonate; and tertiary amines such as
triethylamine and tributylamine. However, from the viewpoints of
reactivity and economic efficiency, sodium hydroxide is most
preferred. The use amount ofthebase is, in the case of amonovalent
base, equal to or more than 0.5 moles and equal to or less than 2
10 moles, and preferably equal to or more than 0.9 moles and equal to
or less than 1.1 moles, relative to 1 mole of the epihalohydrin. In
the case of a divalent base, the use amount of the base is preferably
an amount equivalent to a half the use amount of the monovalent base.
The base can be used as an aqueous solution, an alcohol solution or
15 the like, and when the base is used as a solution, the concentration
of the base can be appropriately selected.
[00371
Furthermore, in addition to the method described above, a trio1
compoundrepresentedbyformula (2) canalsobeobtainedbyatwo-steps
20 reaction of first producing a diol compound represented by the
following formula (3), and then adding 2-mercaptoethanol dropwise
thereto.
In this method, first, 2-mercaptoethanol is reacted with the
epihalohydrin compound represented by formula (1) described above,
25 and thus a compound represented by the following formula (3) is
obtained.
[00381
[0039]
The reaction temperature is 10°C to 20°C. The reaction time is
about 2 hours to 10 hours.
5 [0040]
Subsequently, the compoundrepresentedbyformula (3) is reacted
with 2-mercaptoethanol, and thus a trio1 compound represented by
formula (2) is obtained. The reaction temperature is 10°C to 50°C,
preferably 15°C to 50°C, and more preferably 25OC to 45OC. The
10 reaction time is about 2 hours to 12 hours.
When these processes are carried out in the temperature ranges
described above, excellent controllability of the reaction is
attained, and the color of the plastic lens thus obtainable is also
excellent.
15 [00411
The method can be carried out specifically in the following
manner.
First, an epihalohydrin is added dropwise into
2-mercaptoethanol and if necessary, water, or a lower alcohol such
20 as methanol or ethanol and a catalytic amount of a base in an aqueous
solution or lower alcohol solution of methanol or ethanol. The
reaction temperature and the reaction time are preferably adjusted
to be in the ranges described above. The use amount of
2-mercaptoethanolinthe solutionto whichthe epihalohydrinis added
dropwise is equal to or more than 1 mole and equal to or less than
5 3 moles, and preferably equal to or more than 1 mole and equal to
or less than 2 moles, relative to 1 mole of the epihalohydrin.
Furthermore, a catalyticamount ofthebase is used, andtheuseamount
of the base is, in the case of a monovalent base, equal to or more
than 0.001 moles and equal to or less than 0.1 moles with respect
10 tothe epihalohydrin. In the case of a divalent base, the use amount
is preferably an amount equivalent to a half the use amount of the
monovalent base. The base can be used as an aqueous solution, an
alcohol solution or the like, and when the base is used as a solution,
the concentration of the base can be appropriately selected. As an
15 epihalohydrin is added dropwise to the solution, a diol compound
represented by formula (3) is obtained.
[0042]
Subsequently, the epihalohydrin is added such that the amount
of 2-mercaptoethanol is equal to or more than 1.5 moles and equal
20 to or less than 3.0 moles relative to 1 mole of the epihalohydrin,
and if there is a deficit, 2-mercaptoethanol is further added, and
a deficit of the base is added to the epihalohydrin such that the
amount of the base is equal to or more than 1.0 mole and equal to
or less than 2.0 moles. Thus, a polyalcohol compound represented
25 by formula (2) can be obtained. The reaction temperature and the
reaction time are preferably adjusted to the ranges described above.
100431
In regard to the synthesis of the diol compound represented by
formula ( 3 ) , the reaction temperature in the case of using a strong
base such as sodium hydroxide is appropriately adjusted to equal to
or higher than 10°C and equal to or lower than 50°C. If the reaction
5 temperature is too high, the base added in a catalytic amount is
consumed in a reaction which produces a polyalcohol compound from
the diol compound, and there is a possibility that the yield of the
diol form may decrease
100441
(Step B)
Next, the polyalcohol compound represented by formula (2) that
has been obtained in step A is reacted with thiourea in the presence
of hydrogen chloride, and thus an isothiuronium salt is obtained.
[0045]
15 Specifically, thiourea is added to the polyalcohol compound
represented by formula (2) in an amount of 2.7 moles or more,
preferably equal to or more than 2.7 moles and equal to or less than
6.0 moles, and more preferably equal to or more than 2.9 moles and
equal to or less than 3.2moles, relative to lmole ofthe polyalcohol
20 compound, and thus the components are reacted with each other. The
reaction is carried out in the presence of hydrogen chloride in an
amount of 3 moles or more, preferably equal to or more than 3 moles
and equal to or less than 12 moles, and more preferably equal to or
more than 3 moles and equal to or less than 5 moles, relative to 1
25 mole of the polyalcohol compound, at a temperature in the range of
from room temperature tothe reflux temperature, and preferably 90°C
to120°C, forabout1hourto10hours. Anisothiuroniumsaltcompound
is formedbythereactionbetweenapolyalcoholcompoundandthiourea.
When hydrogen chloride is used, a sufficient rate of reaction is
obtained, and also, coloration of the thiol compound and the color
of the plastic lens thus obtainable can be controlled. Regarding
5 the hydrogen chloride, an aqueous solution of hydrochloric acid or
hydrogen chloride gas can be used. When an aqueous solution of
hydrochloric acid is used, the concentration can be appropriately
selected.
[0046]
(Step C)
Aqueous ammonia is added to a reaction solution containing the
isothiuronium salt obtained in step B, and the isothiuronium salt
is hydrolyzed. Thus, a polythiol compound is obtained. As the
polythiol compound, a polythiol compound containing
15 4-mercaptomethyl-l,8-dirnercapto-3,6-dithiaoctane represented by
the following formula (5) as a main component can be obtained.
[0047]
[0048]
Specifically, while a reaction solution containing the
isothiuronium salt is maintained at a temperature in the range of
15OC to 60°C, preferably 31°C t o 55OC, and more preferably 31°C to
45OC, aqueous ammoniais addedtothe reactionsolution for 80minutes
or less, preferably70minutes or l e s s , andmorepreferably20minutes
t o 60minutes. It is preferable i f the time forwhich aqueous ammonia
5 is added is shorter, but i n view of the capacity of the f a c i l i t i e s
such as the cooling capacity, the time is s e t t o the range of the
time period described above.
[0049]
Whenahydrolyticreactionis carriedoutunder suchconditions,
10 plasticlenseshavingadesiredproductqualitycanbestablyobtained
in continuous production on an i n d u s t r i a l scale. That is, when t h i s
polythiol compound is used, p l a s t i c lenses formed from a
polythiourethane-basedresinhavingexcellentqualitysuchas color,
transparency and s t r i a t i o n can be obtainedwith a stabilizedproduct
15 quality. That i s , the product yield or the efficiency percentage
of the product can be improved by the hydrolytic reaction of the
present exemplary embodiment.
[0050]
It ispreferabletoaddanorganicsolventbeforeaqueous ammonia
20 is added. When an organic solvent is added, the product quality such
as color o f t h e p l a s t i c l e n s e s t h u s obtainableisimproved. The amount
o f t h e organic solvent addedis appropriately selected depending on
the kind of the solvent or t h e l i k e , but the organic solvent can be
added in an amount of 0.1 to 3.0 times, and preferably 0.2 to 1 . 0
25 times the amount of the thiuronium s a l t r e a c t i o n s o l u t i o n . Examples
of the organic solvent include toluene, xylene, chlorobenzene, and
dichlorobenzene. Fromtheviewpointofthe e f f e c t s describedabove,
toluene is preferred.
100511
Aqueous ammonia canbe addedin an amount of, interms of ammonia
(NH3), 1 mole or more, preferably equal to or more than 1 mole and
5 equal to or less than 3 moles, and more preferably equal to or more
than 1.1 moles and equal to or less than 2 moles, relative to 1 mole
of the use amount of hydrogen chloride described above, within the
addi~iontimed escribedabove. The concentration of aqueous ammonia
can be adjusted to 10% to 25%. Furthermore, ammonia gas can also
10 be used instead of aqueous ammonia. ' In the case of adding ammonia
gas in substitution of the entirety or a portion of aqueous ammonia,
the reaction canbe carriedoutunderthe same conditions (useamount,
addition time, and addition temperature) as those in a case where
aqueous ammonia is used.
In the present exemplary embodiment, ammonia (NH3) is added at
a rate of addition of 1.25 mol%/min or more, preferably equal to or
more than 1.25 mol%/min and equal to or less than 3.75 mol%/min, and
more preferably equal to or more than 1.38 mol%/min and equal to or
20 less than 2.5 mol%/min, relative to 1 mole of hydrogen chloride. In
the present process, it is not necessary to add ammonia continuously
at theabove-described rate, andit is acceptable if the average rate
of addition of the addition time described above is included in this
range.
25 After aqueous ammonia is added, the hydrolytic reaction is
carried out continuously at a temperature in the range of from room
temperature to the reflux temperature, and preferably 30°C to 80°C,
for about 1 hour t o 8 hours.
[00531
(Step D)
In the present exemplary embodiment, the polythiol compound
5 obtained i n step C is purified by washing.
[00541
Specifically, acid washing and then several times of water
washing can be carried out. Water washing can also be carried out
before acid washing, a n d a l k a l i washing c a n a l s o b e c a r r i e d o u t a f t e r
10 acid washing. The number of water washing can be reduced by a l k a l i
washing. Impurities and the l i k e can be e f f i c i e n t l y removed by the
washing process. When purification by such washing is performed,
t h e c o l o r of the p l a s t i c lenses obtained from the polythiol compound
is improved, and high quality p l a s t i c lenses with reduced occurrence
15 of clouding and s t r i a t i o n can be produced with a high yield, while
the efficiency percentage is also improved. Examples of preferred
embodiments include a method of performing water washing-acid
washing-water washing-alkali washing-water washing a f t e r
hydrolysis; amethodofperformingacid~.rashing-~iaterwashing-alkali
20 washing-water washing; and a method of performing acid washing-water
washing. The respective washing processes may be repeated several
times .
[00551
Acid washing can be carried out by adding hydrochloric acid t o
25 the solution containing the polythiol compound thus obtained. The
concentration of hydrochloric acid can be adjusted t o 25% t o 36%,
and preferably 30% to 36%. When the concentration of hydrochloric
acid i s lower than 25%, clouding may occur i n t h e p l a s t i c lens due
t o impurities and the l i k e . Furthermore, the temperature of acid
washing can be s e t t o 10°C to 50°C, preferably 15OC to 50°C, more
preferably 20°C to 50°C, and even more preferably 30°C to 45OC.
5 When the concentrationof hydrochloric acidand the temperature
conditions a r e s a t i s f i e d , p l a s t i c lenses having excellent color and
reduced clouding can be obtained with a high product yield, and the
efficiency percentage i s also improved.
[0056]
10 Water washing can be achieved by using degassed water having
an oxygen concentration of 5 mg/L or l e s s .
Examples of the method for producing degassed water include a
method of purging dissolved oxygen by bubbling nitrogen; a method
of purging dissolved oxygen by a heating treatment; and a method of
15 purging dissolved oxygen by vacuum degassing. However, there are
no p a r t i c u l a r limitations on the method as long a s t h e oxygen
concentration can be adjusted to 5 mg/L or l e s s .
Thereby, color or clouding t h a t causes a problem in o p t i c a l
materials such as p l a s t i c lenses can be e f f e c t i v e l y suppressed.
20 [0057]
Furthermore, a l k a l i washing can be carried out by adding an
a l k a l i n e aqueous solution, and s t i r r i n g themixture atatemperature
i n the range of 20°C t o 50°C for 10 minutes to 3 hours. The alkaline
aqueous solution is preferably aqueous ammonia. Furthermore, the
25 concentrationof aqueous ammoniacanbe s e t to O.l%tolO%p, referably
0.1% to 1%, and more preferably 0.1% to 0.5%.
[0058]
Also for acid washing and a l k a l i washing, when water having an
oxygen concentration of 5 mg/L or l e s s is used, color or clouding
t h a t causes a problem in o p t i c a l materials such a s p l a s t i c lenses
can be e f f e c t i v e l y suppressed.
5 [00591
After step D, a solvent removal process, and i f necessary, a
low boilingpoint-compoundremoval process, a f i l t e r i n g p r o c e s s , and
a d i s t i l l a t i o n process are c a r r i e d o u t , andthus a polythiolcompound
containing 4-mercaptomethyl-l,8-dimercapto-3,6-dithiaoctane canbe
10 obtained as a polythiol compound.
The solvent removal process is aprocess of removing the organic
solvent a t normal pressure or under reduced pressure. The degree
of pressure reduction and the temperature may be appropriately
selected depending on the solvent used or the l i k e , however it is
15 preferable t o carry out the solvent removal process under reduced
pressure and a t 100°C or lower, and preferably 85°C or lower.
[00601
The low boiling point compound removal process is a process of
removinganyincludedlowboilingpoint compounds a t normal pressure
20 or under reduced pressure, a f t e r the solvent removal process. The
degreeof pressure reductionand the temperaturemaybeappropriately
selected depending on the solvent used or t h e l i k e , however it is
preferabletocarryouttheloriboilingpointcompoundremovalprocess
under reduced pressure and a t 100°C or lower, and preferably 85'C
25 or lower. At t h a t time, the process may also be carried out while
an i n e r t gas such as nitrogen gas is blown i n .
[00611
The filtering process is a process of removing solids such as
salts by filtration. The method for filtration or the like is
appropriately selected, for example filtration under reduced
pressure or filtration under added pressure using a membrane filter
5 or a cartridge filter can be used. It is preferable to carry out
the process using a filter having a pore size of 5 pm or less, and
preferably 2 pm or less.
[0062]
Thedistillationprocess is aprocess ofpurifyingthepolythiol
10 compound by distillation. The degree of pressure reduction and the
temperature may be appropriately selected depending on the solvent
used or the like, however it is preferable to carry out the
distillation process under reduced pressure and at 250°C or lower,
and preferably 200°C or lower.
15 In addition, the production process of the present exemplary
embodiment can be carried out in air, but it is preferable to carry
out the entire process in a nitrogen atmosphere, from the viewpoint
of color.
2 0
The polymerizable composition for optical materials according
to the present exemplary embodiment includes a polythiol compound
for optical materials obtained by the method described above, and
a polyiso(thio)cyanate compound.
25 [0064]
The polyiso (thio)c yanate compound is not particularly limited
aslongas it is acompoundhavingatleasttwoormoreiso(thio)cyanate
groups in one molecule, and specific examples include aliphatic
polyisocyanate compounds such as hexamethylene diisocyanate,
1,5-pentane diisocyanate, 2,2-dimethylpentane diisocyanate,
2,2,4-trimethylhexane diisocyanate, butene diisocyanate,
5 1,3-butadiene-l,4-diisocyanate, 2,4,4-trimethylhexamethylene
diisocyanate, 1,6,11-undecane triisocyanate, 1,3,6-hexamethylene
triisocyanate, 1,8-diisocyanato-4-isocyanatomethyloctane,
bis (isocyanatoethyl) carbonate, bis (isocyanatoethyl) ether, lysine
diisocyanate methyl ester, and lysine triisocyanate;
alicyclic polyisocyanate compounds such as isophorone
diisocyanate, bis(isocyanatomethyl)cyclohexane,
dicyclohexylmethane diisocyanate, cyclohexane diisocyanate,
methylcyclohexane diisocyanate, dicyclohexyl dimethylmethane
isocyanate, 2,5-bis (isocyanatomethyl) -bicycle [2.2.1] heptane,
15 2,6-bis (isocyanatomethyl)- bicycle [2.2.1]h eptane,
3,8-bis(isocyanatomethyl)tricyclodecane,
3,9-bis(isocyanatomethyl)tricyclodecane,
4,8-bis(isocyanatomethyl)tricyclodecane,
4,9-bis(isocyanatomethyl)tricyclodecane,
20 bis(4-isocyanatocyclohexyl)methane,
1,3-bis( isocyanatomethyl)c yclohexane, and
1,4-bis(isocyanatomethyl)cyclohexane;
polyisocyanate compounds having aromatic ring compounds, such
as 1,2-diisocyanatobenzene, 1,3-diisocyanatobenzene,
25 l,4-diisocyanatobenzene, tolylene diisocyanate,
2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, ethylphenylene
diisocyanate, lsopropylphenylene diisocyanate, dimethylphenylene
diisocyanate, diethylphenylene diisocyanate, diisopropylphenylene
diisocyanate, trimethylbenzene triisocyanate, benzene
triisocyanate, biphenyl diisocyanate, toluidine diisocyanate,
4,4'-methylenebis(pheny1 isocyanate),
5 4,4'-methylenebis(2-methylphenyl isocyanate),
bibenzyl-4,4'-diisocyanate, bis(isocyanatophenyl)ethylene,
bis(isocyanatomethyl)benzene, m-xylylene diisocyanate,
bis (isocyanatoethyl)b enzene, bis (isocyanatopropyl)b enzene, a,a ,a ',
a'-tetramethylxylylene diisocyanate, bis(isocyanatobutyl)benzene,
10 bis(isocyanatomethyl)naphthalene, bis(isocyanatomethylpheny1)
ether, bis(isocyanatoethy1) phthalate, and
2,5-di(isocyanatomethy1)furan;
sulfur-containing aliphatic polyisocyanate compounds such as
bis(isocyanatomethy1) sulfide, bis(isocyanatoethy1) sulfide,
15 bis (isocyanatopropyl) sulfide, bis (isocyanatohexyl) sulfide,
bis(isocyanatomethyl)sulfone, bis(isocyanatomethy1) disulfide,
bis(isocyanatoethy1) disulfide, bis(isocyanatopropy1) disulfide,
bis(isocyanatomethylthio)methane, bis(isocyanatoethylthio)methane,
bis(isocyanatomethylthio)ethane, bis(isocyanatoethylthio)ethane,
20 1,5-diisocyanato-2-isocyanatomethyl-3-thiapentane,
1,2,3-tris(isocyanatomethylthio)propane,
1,2,3-tris(isocyanatoethylthio)propane,
3,5-dithia-1,2,6,7-heptane tetraisocyanate,
2,6-diisocyanatomethyl-3,5-dithia-1,7-hen diisocyanate,
25 2,5-diisocyanatomethylthiophene, and
4-isocyanatoethylthi0-2,6-dithia-1,8-octane diisocyanate;
aromatic sulfide-based polyisocyanate compounds such as
2-isocyanatophenyl-4-isocyanatophenyl sulfide,
bis(4-isocyanatophenyl) sulfide, bis(4-isocyanatomethylphenyl)
sulfide;
aromatic disulfide-based polyisocyanate compounds such as
5 bis (4-isocyanatophenyl) disulfide,
bis(2-methyl-5-isocyanatophenyl) disulfide,
bis(3-methyl-5-isocyanatophenyl) disulfide,
bis(3-methyl-6-isocyanatophenyl) disulfide,
bis(4-methyl-5-isocyanatophenyl) disulfide, and
10 bis(4-methoxy-3-isocyanatophenyl) disulfide;
sulfur-containing alicyclic polyisocyanate compounds such as
2,5-diisocyanatotetrahydrothiophene,
2,5-diisocyanatomethyltetrahydrothiophene,
3,4-diisocyanatomethyltetrahydrothiophene,
15 2,5-diisocyanto-l,4-dithiane, 2,5-diisocyantomethyl-l,4-edithiane,
4,5-diisocynato-1,3-dithiolane,
4,5-bis(isocyantomethy1)-1,3-dithiolane, and
4,5-diisocyantomethyl-2-methyl-1,3-dithiolane;
aliphatic polyisothiocyanate compounds such as
20 1,2-diisothiocyanatoethane and 1,6-diisothiocyanatohexane;
alicyclic polyisothiocyanate compounds such as cyclohexane
diisothiocyanate; aromatic polyisothiocyanate compounds such as
1,2-diisothiocyanatobenzene, 1,3-diisothiocyanatobenzene,
1,4-diisothiocyanatobenzene, 2,4-diisothiocyanatotoluene,
25 2,5-diisothiocyanato-m-xylene, 4,4'-methylenebis(pheny1
isothiocyanate), 4,4'-methylenebis(2-methylphenyl isothiocyanate),
4,4'-methylenebis(3-methylphenyl isothiocyanate),
4,4'-diisothiocyanatobenzophenone,
4,4'-diisothiocyanato-3,3'-dimethylbenzophenone, and
bis(4-isothiocyanatophenyl) ether;
carbonyl polyisothiocyanate compounds such as 1,3-benzene
5 dicarbonyl diisothiocyanate, 1,4-benzene dicarbonyl
diisothiocyanate, and (2,2-pyridine)-4,4-dicarbonyl
diisothiocyanate; sulfur-containing aliphatic polyisothlocyanate
compounds such as thiobis(3-isothiocyanatopropane),
thiobis(2-isothiocyanatoethane), and
10 dithiobis(2-isothiocyanatoethane);
sulfur-containing aromatic polyisothiocyanate compounds such
as l-isothiocyanato-4-[(2-isothiocyanato)sulfonyl]benzene,
thiobis(4-isothiocyanatobenzene),
sulfonyl(4-isothiocyanatobenzene), and
15 dithiobis(4-isothiocyanatobenzene); sulfur-containing alicyclic
polyisothlocyanate compounds such as 2,5-diisothiocyanatothiophene
and 2,5-diisothiocyanato-1,4-dithiane; and
compounds having isocyanato groups and isothiocyanato groups,
such as 1-isocyanato-6-isothiocyanatohexane,
20 1-isocyanato-4-isothiocyanatocyclohexane,
1-isocyanato-4-isothiocyanatobenzene,
4-methyl-3-isocyanato-1-isothiocyanatobenzene,
2-isocyanato-4,6-diisothiocyanato-1,3,5-triazine,
4-isocyanatophenyl-4-isothiocyanatophenyl sulfide, and
25 2-isocyanatoethyl-2-isothiocyanatoethyl disulfide.
[00651
Preferredexamples ofthepolyiso(thio)cyanate compoundinclude
aliphatic polyisocyanate compounds such as hexamethylene
diisocyanate, 1,5-pentane diisocyanate, isophorone diisocyanate,
bis(isocyanatomethyl)cyclohexane, dicyclohexylmethane
diisocyanate, 2,5-bis(isocyanatomethy1)-bicyclo[2.2.l]heptaner
5 2,6-bis (isocyanatomethyl)- bicycle [2.2.1]h eptane,
1,3-bis(isocyanatomethyl)cyclohexane, and
1,4-bis(isocyanatomethyl)cyclohexane; andpolyisocyanate compounds
havingaromaticringcompounds, suchasbis(isocyanatomethyl)benzene,
10 m-xylylene diisocyanate, 1,3-diisocyanatobenzene, tolylene
diisocyanate, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene,
4,4'-methylenebis(pheny1 isocyanate).
[0066]
Furthermore, halogen-substituted forms such as
15 chlorine-substituted forms and bromine-substituted forms,
alkyl-substituted forms, alkoxy-substituted forms,
nitro-substituted forms, prepolymer type modified forms associated
with polyhydric alcohols, carbodiimide-modified forms,
urea-modified forms, biuret-modified forms, dimerized ortrimerized
20 reaction products and the like of those compounds described above
can also be used. These compounds may be used alone, or mixtures
of two or more kinds may be used.
[0067]
Regarding the polythiol compound used in the polymerizable
25 composition for optical materials, other polythiol compounds for
optical materials can also be used in addition to the polythiol
compounds for optical materials obtained by the method described
above.
Preferred examples ofthe otherpolythiolcompounds for optical
materials include aliphatic polythiol compounds such as
methanedithiol, 1,2-ethanedithiol, 1,2,3-propanetrithiol,
5 pentaerythritol tetrakis(2-mercaptoacetate), pentaerythritol
tetrakis(3-mercaptopropionate), bis(mercaptoethy1) sulfide,
5,7-dimercaptomethyl-l,ll-dimercapto-3,6,9-trithiaundecane,
4,7-dimercaptomethyl-l,ll-dimercapto-3,6,9-trithiaundecaneJ
4,8-dimercaptomethyl-l,ll-dimercapto-3,6,9-trithiaundecanet
10 2,5-dimercaptomethyl-l,4-dithiane,
tetrakis(mercaptomethylthiomethyl)methane,
tetrakis(2-mercaptoethylthiomethyl)methane,
tetrakis(3-mercaptopropylthiomethyl)methane,
bis (2,3-dimercaptopropyl) sulfide,
15 2,5-dimercaptomethyl-l,4-dithiane, 2,5-dimercapto-l,4-dithiane,
2,5-dimercaptomethyl-2,5-dimethyl-1,4-dithiane,
1,1,3,3-tetrakis (mercaptomethylthio)p ropane,
1,1,2,2-tetrakis(mercaptomethy1thio)ethane and
4,6-bis (mercaptomethylthio)- 1,3-dithiane.
20 [0068]
The use ratio of the polythiol compound and the
polyiso(thio)cyanate compound is not particularly limited, however
usually, the molar ratio of SH group/NCO group is in the range of
0.5 to 3.0, preferably in the range of 0.6 to 2.0, and more preferably
25 intherangeof0.8to1.3. Whentheuseratiois intherangedescribed
above, various performances such as the refractive index and heat
resistance that are required in optical materials such as plastic
lenses and transparent materials can be satisfiedin a well-balanced
manner.
[0069]
For the purpose of improving various properties, operability
5 and polymerization reactivity of the polythiourethane-based resin
of the invention, other substances may be added in addition to the
polythiol compound and iso(thio)cyanate compound that form the
urethane resin. For example, in addition to the urethane-forming
raw materials, one kind or two or more kinds of active hydrogen
10 compounds represented by amine or the like, carbonate compounds,
estercompounds, metals, metaloxides, organometallic compounds, and
inorganic substances may also be added.
[0070]
Furthermore, various substances suchas a chainextending agent,
15 a crosslinking agent, a photostabilizer, an ultraviolet absorber,
an oxidation inhibitor, an oil-soluble dye, a filler, and a mold
releasingagentmayalsobeaddedaccordingtothepurpose, similarly
to known molding methods. In order to adjust the rate of reaction
to a desired value, thiocarbamic acid S-alkyl ester, or a known
20 reaction catalyst that is used in the production of
polythiourethane-based resins may also be appropriately added.
Regarding the reaction catalyst, thiocarbamic acid S-alkyl
ester, or a known reaction catalyst that is used in the production
of polythiourethane-based resins can be appropriately added.
25 Examples of the reaction catalyst include dialkyltin halides
such as dibutyltindichloride anddimethyltindichloride; dialkyltin
dicarboxylates suchasdimethyltindiacetate, dibutyltindioctanoate,
and dibutyltin dilaurate; dialkyltin dialkoxides such as dibutyltin
dibutoxide and dioctyltin dibutoxide; dialkyltin dithioalkoxides
such as dibutyltin di(thiobutoxide); dialkyltin oxides such as
di(2-ethylhexy1)tin oxide, dioctyltin oxide, and
5 bis(butoxydibuty1tin) oxide; and dialkyltin sulfides such as
dibutyltin sulfide. Suitable examples include dialkyltin halides
such as dibutyltin dichloride and dimethyltin dichloride.
[0071]
Furthermore, for the purpose of modifying the resin, resin
10 modifying agents such as a hydroxyl compound, an epoxy compound, an
episulfide compound, an organic acid and an anhydride thereof, and
an olefin compound containing a (meth) acrylate compound or the like
may also be added. Here, the resin modifying agent is a compound
which regulates or enhances properties suchas refractive index, Abbe
15 number, heatresistanceandspecificgravity, andmechanical strength
such as impact resistance of a material formed from a
thiourethane-based resin.
[0072]
Furthermore, the polymerizable composition for optical
20 materials of the present exemplary embodiment may include a bluing
agent as necessary. The bluing agent has an absorption band in the
wavelength range of from orange color to yellow color in the visible
light region, andhas a functionofregulatingthe color of anoptical
material formed from a resin. More specifically, the bluing agent
25 contains a substance which displays from blue color to violet color.
[0073]
There are no particular limitations on the bluing agent that
is used in the polymerizable composition for o p t i c a l materials of
thepresentexemplaryembodiment, andspecificexamplesincludedyes,
fluorescent brightening agents, fluorescentpigments, and inorganic
pigments. The bluing agent is appropriately selected among those
5 t h a t can be used as bluing agents, in accordance with the properties
required from o p t i c a l components, r e s i n color, and t h e l i k e . These
bluing agents may be used respectively alone, or two or more kinds
may be used i n combination.
[0074]
Among these bluing agents, from the viewpoint of s o l u b i l i t y i n
the polymerizable composition and the viewpoint of transparency of
t h e o p t i c a l m a t e r i a l t h u s obtainable, a dye is preferred.
[0075]
From the viewpoint of the absorption wavelength, the bluing
15 agent is preferably a dye having a maximum absorption wavelength of
equal t o or more than 520 nm and equal t o or l e s s than 600 nm, and
more preferablya dye having amaximumabsorptionriavelengthof equal
t o or more than 540 nm and equal t o or less than 580 nm.
Furthermore, fromtheviewpointofthe s t r u c t u r e o f t h e compound,
20 an anthraquinone-based dye is preferred.
[0076]
There are no p a r t i c u l a r limitations on the method for adding
the bluing agent, and it is preferable t o have the bluing agent added
in advance t o the monomer system. Regarding the method, various
25 methods suchasamethodofdissolvingthebluingagentinthemonomer,
and a method of preparing a master solution containing a high
concentration of the bluing agent, and adding the bluing agent by
dilutingthemastersolutionriiththemonomerusedoranotheradditive,
can be employed.
[0077]
Specifically, the polymerizable composition for optical
5 materials of the present exemplary embodiment is obtained as a mixed
solution, bymixingthepolythiolcompoundobtainedbytheproduction
method described above and a polyiso(thio)cyanate compound, with
other components as necessary. This mixed solution is subjected to
defoaming by an appropriate method according to necessity,
10 s u b s e q u e n t l y i n j e c t e d t h e m i x e d s o l u t i o n i n t o a m o l d , andpolymerized
b y s l o r . r l y h e a t i n g u s u a l l y f r o m a l o r i t e m p e r a t u r e t o a h i g h t e m p e r a t u r e .
[0078]
A molded product formed from the polythiourethane-based resin
obtainable by curing the polymerizable composition of the present
15 exemplary embodiment in this manner has features such as a high
refractive index, low dispersibility, excellent heat resistance and
durability, light weight, and excellent impact resistance. Also,
the molded product has satisfactory color, and is suitable as a raw
material for optical materials such as spectacle lenses and camera
20 lenses, and transparent materials.
[0079]
Furthermore, a plastic lens obtained by using the
polythiourethane-basedresinofthepresentexemplaryembodimentmay
also be subjectedtophysicalandchemicaltreatments such as surface
25 polishing, antistatic treatment, hard coating treatment,
non-reflective coating treatment, staining treatment, and dimming
treatment, in order to perform improvements such as prevention of
reflection, impartation of high hardness, enhancement of abrasion
resistance, enhancement of chemical resistance, impartation of
anti-fogging, and impartation of fashionability.
5 EXAMPLES
[0080]
Hereinafter, the present invention will be described in more
detail based on Examples, however the invention is not intended to
be limited to these.
10 [0081]
In the following Examples, properties were measured by the
following measurement methods.
APHA: This is a method for indicating the color, and the color
was determinedusingstandardliquids preparedbydissolvingreagents
15 of platinum and cobalt, and determining a standard liquid dilution
having a color density equivalent to that of the color of the sample
by making a comparison. Thus, the "degree" of the color was defined
as the measured value.
Water content: A sample was dissolved in toluene, and water
20 measurement was carried out using a Karl-Fischer Water Titrate.
Viscosity: The viscosity was measured according to JIS K7117.
Refractive index: The refractive index was measured at 20°C
using a digital refractometer, RA-600, manufactured by Kyoto
Electronics Manufacturing Co., Ltd.
25 Ammonium content: The sample was dissolved in chloroform and
extracted with water, and the ammonium content was measured by ion
chromatography.
Acidcontent: Thesamplewasdissolvedinasolvent, thesolvent
was t i t r a t e d using a methanol solution of KOH, and t h e a c i d content
was calculated as a HC1 content.
Lossdegreeoftranspareancyofresin:A9-mmplatewasproduced
5 under the conditions f o r t h e p l a s t i c lens production o f t h e Examples,
andthe loss degree oftranspareancywas measured using a loss degree
oftranspareancyanalyzer (manufacturedbyHayashiCo., Ltd.; LUMINAR
ACE LA-150SE).
Resin Y I : This i s a yellow index for color evaluation, and
10 is measured with a colorirneter. A 9-mm p l a t e was produced under the
conditions f o r the p l a s t i c lens production of the Examples, and the
Y I value was measured using a colorimeter (CR-400) manufactured by
Konica Minolta, Inc.
S t r i a t i o n : A lens was produced under the conditions f o r the
15 p l a s t i c lens production of the Examples, and the lens was visually
observed under a high pressure mercury lamp. A sample in which no
s t r i p e d p a t t e r n was observed was rated as 0, and a sample i n which
a s t r i p e d p a t t e r n was observed was rated as X.
[0082]
2 0 Furthermore, degassedvraterata dissolvedoxygenconcentration
of 2 ppm was obtained by bubbling nitrogen into water and thereby
purging dissolved oxygen.
[0083]
[Example A-l]
(Synthesis of polythiol compound containing
4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane as main
component)
In a r e a c t o r , 124.6 p a r t s by weight of 2-mercaptoethanol and
18.3 p a r t s by weight of degassed water (dissolved oxygen
concentration: 2 ppm) were introduced. 101.5 p a r t s by weight of a
32 wt%aqueous solutionofsodiumhydroxidewas addeddropwisethereto
5 over 40 minutes at 12OC t o 35OC, and then 73.6 p a r t s by weight of
epichlorohydrin was added dropwise t h e r e t o over 4.5 hours at 29°C
t o 36OC. Subsequently, t h e mixture w a s s t i r r e d f o r 40 minutes.
Production o f 1,3-bis(2-hydroxyethy1thio)-2-propanol was confirmed
from NMR d a t a .
331.5 p a r t s b y w e i g h t o f 35.5%hydrochloricacidwas introduced,
and then 183.8 p a r t s by weight of thiourea having a p u r i t y of 99.90%
was introduced. The mixture rias s t i r r e d f o r 3 hours under r e f l u x
a t llO°C, and thereby a r e a c t i o n which forms thiuronium s a l t was
c a r r i e d out. The r e a c t i o n mixture was cooled t o 45OC, and then 320.5
15 p a r t s by weight of toluene xias added t h e r e t o , and t h e mixture was
cooled t o 31°C. 243.1 p a r t s by weight of a 25 wt% aqueous ammonia
s o l u t i o n was introduced over 44 minutes a t 31°C t o 4 l o C , and a
h y d r o l y t i c r e a c t i o n was c a r r i e d out by s t i r r i n g t h e mixture f o r 3
hours a t 54OC t o 62OC. Thus, a toluene s o l u t i o n of a p o l y t h i o l
20 containing 4-mercaptomethyl-1,8-dimercapto-3,6-dithaoctne as a
main component was obtained. 162.8 p a r t s by weight of 35.5%
hydrochloric a c i d was added t o t h e toluene s o l u t i o n , and thus t h e
toluene s o l u t i o n was a c i d washed f o r 1 hour at 35"C t o 43'C. 174.1
p a r t s by weight of degassed water (dissolved oxygen concentration:
25 2ppm) wasadded, a n d w a s h i n g f o r 3 0 m i n ~ t e s a t 3 5 ~ C t o 4 5 ~ C r . ~ a s c a r r i e d
out two t i m e s . 162.1 p a r t s by weight of 0.1% aqueous ammonia was
a d d e d t h e r e t o , andthemixturergaswashedfor 30minutes. 1 7 4 . 2 p a r t s
by weight of degassed water (dissolved oxygen concentration: 2 ppm)
was added thereto, and washing for 30 minutes at 35'C to 45"C was
carried out two times. Toluene and a trace amount of water were
removed under heating at reduced pressure, and then the residue was
5 filtered under reduced pressure using a 1.2 pm PTFE type membrane
filter, and thus 205.0 parts by weight of a polythiol compound
containing 4-mercaptomethyl-l,8-dimercapto-3,6-dithiaoctane as a
main component was obtained. The properties of the polythiol
compound thus obtained are shown in Table-1.
(Measurement of viscosity of polymerizable composition)
52 parts by weight of m-xylylene diisocyanate, 0.015 parts by
weight of dibutyltin dichloride as a curing catalyst, 0.10 parts by
weight of ZELEC UN (trade name, product of Stepan Company; acidic
phosphoric acid ester), and 0.05 parts by weight of BIOSORB 583
15 (manufactured by Kyodo chemical Co., Ltd.; ultraviolet absorbent)
rveremixedanddissolvedat20°C. 48 parts byweightofthepolythiol
compound containing
4-mercaptomethyl-1,8-dimercapto-3,6-dithaoctan as a main
component thus obtained was introduced and mixed, and thus a mixed
20 uniform solution was obtained. The time of preparation of the mixed
uniform solution was defined as 0 hour, and the viscosity after 7
hours was measured with a B type viscometer. The viscosity after
7 hours of the polymerizable composition was used as an index of the
rate of polymerization. An evaluation was conducted such that a
25 sample having a viscosity value of 250 mPa.s or less was rated as
0, and a sample having a viscosity value of 1000 mPa.s or more was
rated as X. The results are shown in Table-2.
[0084]
The results of an elemental analysis and an NMR analysis of
4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane will be shown.
Elemental analysis (as C ~ H ~ ~ S S )
CHS analysis values : 32.12 6.19 61.69 Calculated values : 32.27
6.19 61.53 'H NMR (CDC13)
a, = 1.74 to 1.91 (3H, m, SH)
2.70 to 3.00 (13H, m, CH)
[0085]
I3C NMR ( i n C D C l s )
(Production of p l a s t i c lens)
52 p a r t s by weight of m-xylylene diisocyanate, 0.015 p a r t s by
5 weight of d i b u t y l t i n dichloride as a curing c a t a l y s t , 0.10 parts by
weight of ZELEC UN (trade name, product of Stepan Company; acidic
phosphoric acid e s t e r ) , and 0.05 p a r t s by weight of BIOSORB 583
(manufactured by Kyodo chemical Co., Ltd.; u l t r a v i o l e t absorbent)
weremixedanddissolvedat20°C. 48 partsbyweightofthepolythiol
10 compound containing
4-mercaptomethyl-l,8-dimercapto-3,6-dithiaoctane as a main
component thus obtained was introduced and mixed, and thus a mixed
uniform solution xias obtained. This uniform solution was subjected
to defoaming for 1 hour a t 600 Pa, and then the uniform solution rias
15 f i l t e r e d using a 1 pm TEFLON (registered trademark) f i l t e r .
Subsequently, the filtered solution was injected into a mold formed
from a glass mold and a tape. This mold was introduced into an oven,
the temperature was slowly increased from 10°C to 120°C, and
polymerization was carried out for 20 hours. After completion of
5 the polymerization, the mold was taken out from the oven, and a resin
was obtained by releasing the product from the mold. The resin thus
obtained was further subjected to annealing for 3 hours at 120°C.
The properties of the lens thus obtained are shown in Table-2.
[0088]
[Examples A-2 to A-101
Polythiol compounds containing
4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane as a main
component were respectivelyproducedinthe samemanner as in Example
A-1, except that the production conditions describedin Table-l were
15 used. The properties of the polythiol compounds thus obtained are
shown in Table-1. Furthermore, the viscosities after 7 hours of the
polymerizable compositions were measured, and plastic lenses were
produced, inthe samemanner as inExampleA-1. The results are shown
in Table-2.
20 [0089]
[Example B-11
(Synthesis of polythiol containing
4-mercaptomethyl-l,8-dimercapto-3,6-dithiaoctane as main
component)
25 In a reactor, 124.6 parts by weight of 2-mercaptoethanol and
18.3 parts by weight of degassed water (dissolved oxygen
concentration: 2 ppm) were introduced. 101.5 parts by weight of a
32rit%aqueous s o l u t i o n o f sodiumhydroxidewas addeddropwisethereto
over 40 minutes a t 12OC t o 35OC, and then 73.6 p a r t s by weight of
epichlorohydrin w a s added dropwise t h e r e t o over 4.5 hours at 28OC
t o 36'C. Subsequently, t h e mixture was s t i r r e d f o r 40 minutes.
5 Production of 1,3-bis (2-hydroxyethylthio) -2-propanol was confirmed
from NMR d a t a .
Next, 183.7 p a r t s b y w e i g h t o f t h i o u r e a h a v i n g a p u r i t y o f 99.90%
was introduced, and 108.6 p a r t s by weight of hydrogen c h l o r i d e gas
having a p u r i t y of 90.7% tias blown t h e r e i n . The mixture was s t i r r e d
10 f o r 3 hours under r e f l u x a t llO°C, and thereby a r e a c t i o n which forms
thiuronium s a l t was c a r r i e d out. The r e a c t i o n mixture was cooled
t o 45OC, and then 320.5 p a r t s by weight o f t o l u e n e w a s added t h e r e t o ,
and t h e mixture was cooled t o 31°C. 216.7 p a r t s by weight of a 25
wt% aqueous ammonia s o l u t i o n was introduced over 29 minutes at 31°C
15 to40°C, andahydrolyticreactionwas carriedoutbyagingthemixture
f o r 3 hours a t 54OC t o 63OC. Thus, a toluene s o l u t i o n of a p o l y t h i o l
containing 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane as a
main component was obtained. 162.9 p a r t s by weight of 35.5%
hydrochloric acid was added t o t h e toluene s o l u t i o n , and thus t h e
20 toluene s o l u t i o n was a c i d washed f o r 1 hour a t 34OC t o 43°C. 174.2
p a r t s by weight of degassed water (dissolved oxygen concentration:
2 ppm) was added t h e r e t o , and washing f o r 30 minutes at 35OC t o 45OC
was c a r r i e d out two times. 162.8 p a r t s by weight of 0.1% aqueous
amrnoniawas a d d e d t h e r e t o , andwashingwas c a r r i e d o u t f o r 30minutes.
25 174.2 p a r t s by weight of degassed water (dissolved oxygen
concentration: 2 ppm) was added t h e r e t o , and washing f o r 30 minutes
at34OCto 45"Cwas c a r r i e d out two t i m e s . Toluene a n d a t r a c e amount
of water were removed under heating at reduced pressure, and then
the residue was filtered under reduced pressure using a 1.2 pm PTFE
type membrane filter, and thus 205.0 parts by weight of a polythiol
compound containing
5 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane as a main
component was obtained. The properties of the polythiol compound
thus obtained are shown in Table-1. Measurement of the viscosity
of the polymerizable composition was carried out in the same manner
as in Example A-1. The results are shown in Table-2.
10 Identification of
4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane was carried out
in the same manner as in Example A-1, and the same results were
obtained.
[00901
15 (Production of plastic lens)
52 parts by weight of m-xylylene diisocyanate, 0.015 parts by
weight of dibutyltin dichloride as a curing catalyst, 0.10 parts by
weight of ZELEC UN (trade name, product of Stepan Company; acidic
phosphoric acid ester), and 0.05 parts by weight of BIOSORB 583
20 (manufactured by Kyodo chemical Co., Ltd.; ultraviolet absorbent)
weremixedanddissolvedat20°C. 48 partsbyweightofthepolythiol
compound containing
4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane as a main
component thus obtained was introduced and mixed thereto, and thus
25 a mixed uniform solution was obtained. This uniform solution was
subjected to defoaming for 1 hour at 600 Pa, and then the uniform
solution was filtered using a 1 pm TEFLON (registered trademark)
f i l t e r . Subsequently, t h e f i l t e r e d s o l u t i o n w a s i n j e c t e d l n t o a m o l d
formed from a glass mold and a tape. This mold was introduced i n t o
an oven, the temperature was slowly increased from 10°C t o 120°C,
and polymerization was carried out for 20 hours. After completion
5 of the polymerization, the mold was taken out from the oven, and a
r e s i n was obtainedby releasing the product fromthemold. The r e s i n
thus obtainedwas furthersubjectedtoannealing f o r 3 hours at12O0C.
The properties of the lens thus obtained are shown in Table-2.
[0091]
[Examples B-2 t o B-101
Polythiol compounds containing
4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane as a main
component were respectivelyproducedinthe samemanner as inExample
B-1, except t h a t the production conditions described in Table-1 were
15 used. The properties of the polythiol compounds thus obtained are
shown in Table-1. Furthermore, t h e v i s c o s i t i e s a f t e r 7 hours of the
polymerizable compositions were measured, and p l a s t i c lenses were
produced, in the samemannerasinExampleB-1. The r e s u l t s areshown
in Table-2.
20 [0092]
Example A-l
Example A-2
Example A-3
Example A-4
Example A-5
Example A-6
Example A-7
Example A-8
Example A-9
Example
A-I0
Condition I
Reaction
temperature
Condition
Peed
temperatu
re
Peed time
Condition 111 Monomer analysis values
Acid Acid Color Specific Acidity Water
concentrati washing gravity
on temperatu
Refract
ive
index
C, a 3
C -I m 0
m m
rl c
0 m .-I
C m -Ac cm
5 8 m 3
a,
o r d a
Q .rl a m u
a 7 m
U 0
u a , u
9 .d
2 0 - U I m o
c.l 4
a, s
U G U
O Q O
IC( u
U a
mob
5 w c
"
--I m U
V C O
--I 0 'L a .-I
C Q m
0 --I C
0 - 6 0 c
C O O
0 U .-I
.A a
+ J a c u a o
m a u
a, lL
G5 .. .. .. H H H
H H H
d C C
0 0 0
--I .rl .d
C , Q Q
-A -4 -d a a a
C C C
0 0 0
U v U

[0094]
[Examples C-1 to C-12 and Comparative Examples A-1 to A-51
Polythiol compounds containing
4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane as a main
5 component were respectivelyproducedinthe samemanner as inExample
A-1, except that the production conditions described in Table-3 were
used. The viscosities after 7 hours of the polymerizable
compositions were measured, and plastic lenses were produced, in the
same manner as in Example A-1. The results are shown in Table-3.
10 [0095]
Example C-l r-
Condition I
Reaction
temperature
Condition I1
feed
temperaccre
feed time
minutes
Acid washing
temperature
Viscosity
after 7 h ( * I
Resin evaluation
Color LOSS degree of Striation
transparency
Example C-7
Example C-2
Example C-3
Example C-4
Example C-5
Example C-6
Example C-8
Example C-9
1 26-29 1 32-43 35.5 1 18-22 / 4.3 1 20 I O I
47-50
27-29
26-31
28-30
Example C-10
Example C-ll
32-43
15
37-40
51-55
Example C-12
32
35
38
35
35.5
35.5
35.5
35.5
38-43
36-40
35-39
37-44
0
0
0
0
4.2
4.4
4.4
4.3
19
19
18
19
0
0
0
0
U [O
0 U
4 0
m
s w 3
u [O
.-I c
0
[O X @ -4
a,
-I [O
C, N m
a 2
C d m 0
0 a
a, [ O m r C ,
d $2 rd
O m m U
CId C. 4 2 [ O
m o m
,a, , 3
o m a
C,
N m
.rl w u
a m u o m 3 m
u 0 (0 2
Q a , U U U
7 . 4 3 0 ? T o
I m o s m
CY m 2 - ; 6
U C U
o C , o : 2
w C, U a
[ O O h % Z
C w c 0
0 h -1
. - I [ O u C , C , e o . - I w
- I o w m o a -d 0
C C , o ] U [ O
0 - d m U u a o . 4 2
C OCC ., d s 2 0 0 . 4 6
.rl
0 a 2 0 -
U a , O C Q
m a , u m
a, lL C1 a .. .. m I, .. H .d m H
H H = I : h
co co Co a~ :[ O
-4 d 0
C , C , C , ' " u
.-I --I -4 a a a 4 .: C C C - s
o o o *
u u u - m
[00961
As discussed above, high quality plastic lenses were obtained
by using the polythiol compounds of Examples. On the other hand,
in Comparative Examples, there was a problem with at least one of
5 color, loss degree of transpareancy, and striation, so that plastic
lenses having satisfactory quality were not obtained.
Furthermore, the polymerizable composition containing the
polythiol compound of Comparative Example A-4 had a viscosity after
7 hours of 1000 mPa.s or more, and thus it was made clear that the
10 production stability of plastic lenses was affected thereby.
At the time of actual production, it is necessary to consider
that the volume efficiency (inconvenience such as precipitation
during operation), stirrability, and a cooling operation may be
needed when the operation temperature is too low as compared with
15 the precedingprocess. Fromthis viewpoint, in regard to Conditions
I1 (introduction of aqueous ammonia at the time of the hydrolytic
reaction), it is preferable to select the operation temperature to
be 15°C or higher, and in regard to Conditions I11 (hydrochloric acid
washing), it is preferable to select the operation temperature to
20 be l.O°C or higher.
[00971
From the above results, it was made clear that when a polythiol
compound obtained by allowing 2-mercaptoethanol to react with an
epihalohydrin compound at a temperature of 10°C to 50°C under
25 Conditions I; adding aqueous ammonia within 80 minutes while
maintaining the reaction liquid at a temperature of 15OC to 60°C to
hydrolyze an isothiuronium salt under Conditions 11; adding
hydrochloric acid a t a concentration of 25% t o 36% t o a solution
containing a polythiol compound; washing the solution a t a
temperature of 10°C t o 50°C; and thereby purifying the polythiol
compound under Conditions 111, is used, a p l a s t i c lens formed from
5 apolythiourethane-basedresinhavingexcellentqualitysuchas color,
transparency, andstriationcanbeproduced. Furthermore, according
t o the present invention, it was made clear t h a t even i n the case
where a polythiol compound is repeatedly producedin the production
i n a n a c t u a l i n d u s t r i a l scale, p l a s t i c l e n s e s havingadesiredproduct
10 quality are stably obtained without any fluctuation i n the product
quality of the polythiol compound between d i f f e r e n t production
batches.
[0098]
This application claims p r i o r i t y from Japanese Patent
15 Application No. 2012-179896 f i l e d August 1 4 , 2012, the e n t i r e
disclosure of which is incorporated herein by reference.
[0099]
The invention includes the following embodiments.
[ a l l A method for producing a polythiol compound, comprising:
2 0 a step for reacting a polyalcohol compound with thiourea i n the
presence of hydrogen chloride t o obtain an isothiuronium s a l t ; and
a s t e p f o r adding, while maintaining a reaction solution
containing the isothiuronium s a l t thus obtained a t a temperature of
20°C to 60°C, aqueous ammonia t o the reaction solution within 80
25 minutes, thereby hydrolyzing the isothiuronium s a l t t o obtain a
polythiol compound.
[a21 The method for producing a polythiol compound according
to [all, further including, after the step for hydrolyzing the
isothiuronium salt to obtain a polythiol compound,
a step for adding hydrochloric acid which is a concentration
of 25% to 36% to the solution containing the polythiol compound thus
5 obtained, washing the solution at a temperature of 20°C to 50°C to
purify the polythiol compound.
[OlOO]
[a31 The method for producing a polythiol compound according
to [all or [a2], further including, before the step for reacting the
10 polyalcohol compound with thiourea to obtain an isothiuronium salt,
a step for reacting 2-mercaptoethanol with an epihalohydrin
compound represented by the following formula (1) at a temperature
of 2OC to 50°C to obtain a polyalcohol compound represented by the
following formula (2) .
(wherein X represents a halogen atom)
[a41 The method for producing a polythiol compound according
to [a3], wherein the step for reacting 2-mercaptoethanol with an
epihalohydrin compound includes
a step for reacting 2-mercaptoethanol with an epihalohydrin
5 compound represented by the following formula (1) at a temperature
of 2OC to 20°C, and thereby obtaining a compound represented by the
follorring formula (3) ; and
(wherein X represents a halogen atom)
a step for reactingthe compound representedby formula (3) with
2-mercaptoethanol at a temperature of 10°C to 50°C to obtain a
polyalcohol compound represented by the following formula (2).
[a51 The method for producing a polythiol compound according
to [a31 or [a4], wherein the polythiol compound is
[a63 The method for producing a polythiol compound according
to [all or [a2], further including, before the step for reacting the
polyalcohol compound with thiourea to obtain an isothiuronium salt,
a step for reacting 2-mercaptoethanol with an epihalohydrin
10 compound represented by the following formula (1) at a temperature
of 2OC to 20°C, and thereby obtaining a compound represented by the
following formula (3) ; and
(wherein X represents a halogen atom)
a step for reactingthe compoundrepresentedbyformula (3) with
sodium sulfide to obtain a polyalcohol compound represented by the
following formula (4) .
[a71 The method for producing a polythiol compound according
to [a6j, wherein the polythiol compound includes one kind or two or
more kinds selected from the group consisting of
10 4,7-dimercaptomethyl-l,ll-dimercapto-3,6,9-trithiaundecane, and
[a81 Amethodforindustrialmanufacture ofapolythiolcompound,
using the method according to any one of [all to [a7].
[a91 A polymerizable composition for optical materials,
15 comprising a polythiol compound obtained by the method according to
any one of [all to [a8j.
[a101 A molded product obtained by curing the polymerizable
composition for optical materials according to [ag].
[all] A plastic lens comprising the molded product according
to [a10].

CLAIMS
1. A method for producing a polythiol compound, comprising:
a step for reacting 2-mercaptoethanol with an epihalohydrin
5 compound represented by the following formula (1) at a temperature
of 10°C to 50°C to obtain a polyalcohol compound represented by the
following formula (2);
(wherein X represents a halogen atom)
a step for reacting the polyalcohol compound represented by
formula (2) thus obtained with thiourea in the presence of hydrogen
chloride to obtain an isothiuronium salt;
a step for adding, while maintaining a reaction solution
15 containing the isothiuronium salt thus obtained at a temperature of
15OC to 60°C, aqueous ammonia to the reaction solution within 80
minutes, thereby hydrolyzing the isothiuronium salt to obtain a
polythiol compound represented by the following formula (5); and
a step for adding hydrochloric acid which is a concentration
of 25% to 36% to the solution containing the polythiol compound thus
obtained, washing the solution at a temperature of 10°C to 50°C to
5 purify the polythiol compound.
2. The method for producing a polythiol compound according to claim
1, wherein the step for reacting 2-mercaptoethanol with the
epihalohydrin compound comprises:
10 a step for reacting 2-mercaptoethanol with the epihalohydrin
compound represented by formula (1) at a temperature of 10°C to 20°C
to obtain a compound represented by the following formula (3); and
a step forreactingthe compoundrepresentedbyformula (3) with
15 2-mercaptoethanol at a temperature of 10°c to 50°C to obtain the
polyalcohol compound represented by formula ( 2 )
3. Amethodforindustrialmanufactureofapolythiolcompound, using
the method according t o c l a i m , l or 2.
5
4 . A poiymerizable composition f o r o p t i c a l materials, comprising
a polythi'ol compound obtalned by the method according t o any one of
claims 1 to 3 .
10 5. Arnoldedproductobtainedbycuringthepolymerizable composition
for o p t i c a l . m a t e r i a l s according t o claim 4 .
6. A p l a s t i c lens comprising the molded product according t o claim 5.