KR101971115B1 - Method for preparing ester polythiol with high yield - Google Patents

Abstract

According to an embodiment, by washing, with a tertiary amine aqueous solution, an ester polythiol composition manufactured by conducting a reaction of polyol with an excess thiol group-containing carboxylic acid under an acid catalyst, it is possible to effectively remove remaining thiol group-containing carboxylic acid and the acid catalyst, and also improve a yield of ester polythiol.

Description

METHOD FOR PREPARING ESTER POLYTHIOL WITH HIGH YIELD [0002]

The examples relate to a method for producing an ester polythiol composition used as a raw material for a polythiourethane-based optical material. The examples also relate to an ester polythiol composition prepared by the above method, a polymerizable composition containing the same, and an optical material obtained therefrom.

The plastic optical material is lightweight and easily broken compared to an optical material made of an inorganic material such as glass, and is excellent in dyeability. Therefore, it is widely used as an optical material such as a spectacle lens and a camera lens. In recent years, high performance of optical materials such as high transparency, high refractive index, low specific gravity, high heat resistance and high impact resistance has been demanded.

Among plastic optical materials, polythiourethane has excellent optical properties and mechanical properties and is widely used as an optical material. Polythiourethanes can be prepared by reacting polythiols with isocyanates, and lenses made from polythiourethanes are widely used because of their high refractive index, light weight, and relatively high impact resistance.

In recent years, attempts have been made to improve the impact resistance by using an ester polythiol having an ester group (-COO-) introduced into a polythiol in the production of a polythiourethane based optical material.

Such an ester polythiol is generally produced by adding a polyhydric alcohol and an excess amount of a thiol group-containing carboxylic acid to a nonpolar and aprotic solvent, reacting the mixture through azeotropic distillation under an acid catalyst, and then reacting the unreacted thiol group -Containing carboxylic acid is removed by washing with a basic aqueous solution.

For example, Korean Patent No. 1363198 discloses reacting a polyhydric alcohol with an excess of a thiol group-containing carboxylic acid to prepare an ester polythiol, followed by base washing to remove the carboxylic acid remaining in the reaction solution .

Further, in addition to such base washing, there is known a method of reacting a polyhydric alcohol with an excessive thiol group-containing carboxylic acid and removing the thiol group-containing carboxylic acid under vacuum without further purification, thereby producing an ester polythiol.

Korean Registered Patent No. 1363198 (Feb.

As described above, conventionally, in the course of preparing the ester polythiol, the base is washed with a base in order to remove the residual carboxylic acid, and metal basic materials such as sodium hydroxide, potassium hydroxide, sodium carbonate and the like are conventionally used have. However, such conventional types of bases can form salts with not only the desired thiol group-containing carboxylic acid but also ester thiol, so that the purification is not effective and thus there is a problem that a high yield can not be expected.

In addition, the method of removing the remaining thiol group-containing carboxylic acid through vacuum without the base cleaning as described above has a problem that it is difficult to completely remove the residual thiol group-containing carboxylic acid, although the production yield is high.

Also, the acid catalyst used in the synthesis of the ester polythiol also remains after the reaction to deteriorate the quality of the final product. Therefore, an effective method for removing the acid catalyst together is also required.

Thus, through the following examples, it is intended to provide a novel method for effectively removing residual thiol group-containing carboxylic acid and acid catalyst after synthesis of ester polythiol, thereby improving the yield and improving the quality of the final product.

According to one embodiment, there is provided a process for preparing an ester polythiol compound, comprising: (1) reacting 1 equivalent of a compound of the formula (1) and 1.01 to 2 equivalents of a compound of the formula (2) And (2) washing the crude ester polythiol composition with a tertiary amine aqueous solution to remove the compound of Formula 2 and the acid catalyst remaining in the composition. Provided:

[Chemical Formula 1]

(2)

In this formula,

R ₁ are each independently H, -CH ₃ or -CH ₂ CH ₃ ;

R ₂ are each independently -CH ₃ , -CH ₂ CH ₃ or -CH ₂ CH ₂ CH ₃ ;

p is 1 or 2;

m is independently an integer of 0 to 10;

each n is independently an integer of 1 to 4;

l and o are each independently 0 or 1;

Where n + l + o = 4.

According to another embodiment, there is provided an ester polythiol composition prepared by the above method, wherein the content of the compound of Formula 2 is 0.5% by weight or less.

According to this embodiment, an ester polythiol composition prepared by reacting a polyol with an excess of a thiol group-containing carboxylic acid under an acid catalyst is washed with a tertiary amine aqueous solution to remove unreacted residual thiol group-containing carboxylic acid and an acid catalyst The yield of the ester polythiol can be improved while effectively removing it.

Specifically, the tertiary amine has selective reactivity to form a salt with the thiol group-containing carboxylic acid without forming a salt with the ester polythiol. Therefore, by washing with an aqueous solution of the tertiary amine, the thiol group-containing carboxylic acid Can be removed by transferring the salt to the water layer. In addition, since the tertiary amine can form salts with the acid catalyst and can be removed together, it is possible to prevent deterioration in quality due to the residual catalyst.

As a result, the ester polythiol composition prepared according to the examples may be produced at a high yield, and the content of the thiol group-containing carboxylic acid contained therein may be very small.

The ester polythiol composition according to the present invention can be produced from polythiourethane having excellent properties such as refractive index, Abbe number, transparency, glass transition temperature, and yellowing degree by polymerization with isocyanate, It is useful in the field.

In the present invention, the term " ester polythiol " means a polythiol having at least one ester group (-COO-) in the molecule.

The term " ester polythiol composition " in the present invention means a composition comprising ester polythiol as a main component and other minor components.

Method for preparing ester polythiol composition

The method for producing an ester polythiol composition according to an embodiment includes the steps of (1) reacting 1 equivalent of a compound represented by the following formula (1) with 1.01 to 2 equivalents of a compound represented by the following formula (2) under acid catalysis to obtain a crude ester polythiol composition ; And (2) washing the crude ester polythiol composition with a tertiary amine aqueous solution to remove the compound of Formula 2 and the acid catalyst remaining in the composition:

[Chemical Formula 1]

(2)

In this formula,

R ₁ are each independently H, -CH ₃ or -CH ₂ CH ₃ ;

R ₂ are each independently -CH ₃ , -CH ₂ CH ₃ or -CH ₂ CH ₂ CH ₃ ;

p is 1 or 2;

m is independently an integer of 0 to 10;

each n is independently an integer of 1 to 4;

l and o are each independently 0 or 1;

Where n + l + o = 4.

Each step will be described in detail below.

(1) Preparation of unpurified ester polythiol composition

In the step (1), 1 equivalent of the compound of the formula (1) and 1.01 to 2 equivalents of the compound of the formula (2) are reacted under acid catalyst to obtain a crude ester polythiol composition.

The compound of formula (1) is a polyhydric polyol used for the synthesis reaction of ester polythiol.

Specific examples of the compound of Formula 1 include trimethylol propane, pentaerythritol, ditrimethylol propane, dipentaerythritol, trimethylolpropane ethylene oxide adduct, pentaerythritol ethylene oxide adduct, ditrimethylolpropane ethylene oxide adduct Water, dipentaerythritol ethylene oxide adduct, trimethylolpropane propylene oxide adduct, pentaerythritol propylene oxide adduct, ditrimethylolpropane propylene oxide adduct, dipentaerythritol propylene oxide adduct, and the like.

The compound of formula (2) is a thiol group-containing carboxylic acid used for the synthesis reaction of an ester polythiol.

Specific examples of the compound of Formula 2 include thioglycolic acid and 3-mercaptopropionic acid.

The compound of Formula 1 and the compound of Formula 2 are esterified to produce an ester polythiol composition.

In the above reaction, the compound of formula (2) is used in excess of the compound of formula (1).

For example, 1.01 to 2 equivalents, more preferably 1.05 to 1.15 equivalents, of the compound of formula (2) is used relative to 1 equivalent of the compound of formula (1).

Here, the equivalence means a molecular weight divided by the number of reactors.

The reaction between the compound of Formula 1 and the compound of Formula 2 is carried out under an acid catalyst.

As the acid catalyst, sulfuric acid, para-toluenesulfonic acid, sulfuric acid derivatives such as trifluorosulfonic acid are preferable.

Further, since water is generated as a by-product in the above reaction, it can be carried out by azeotropic distillation in a solvent which can be separated from water.

Specifically, the reaction between the compound of Formula 1 and the compound of Formula 2 may be carried out by azeotropic distillation in a nonpolar and aprotic solvent.

More specifically, as the solvent, hydrocarbon solvents such as benzene, toluene, xylene, hexane, heptane, octane and the like can be used.

Through the above process, an untreated ester polythiol composition is obtained.

In addition to the desired ester polythiol, the unreacted compound of Formula 2 and the acid catalyst remain in the untreated ester polythiol composition.

For example, the untreated ester polythiol composition may contain 0.1 to 10% by weight or 0.5 to 5% by weight of the compound of Formula 2.

In addition, the untreated ester polythiol composition may contain the acid catalyst in an amount of 0.001 to 1 wt%, or 0.01 to 0.5 wt%.

(2) Cleaning with tertiary amine aqueous solution

In the step (2), the above crude ester polyol composition is washed with an aqueous solution of tertiary amine to remove the compound of formula (2) and the acid catalyst remaining in the ester polythiol composition.

The cleaning may be performed, for example, by mixing the crude ester polythiol composition with an aqueous solution of the tertiary amine followed by removal of the aqueous layer. Wherein the crude ester polythiol composition contains a solvent or may be mixed with an aqueous solution of the tertiary amine after being mixed with a solvent.

The tertiary amine may be, for example, an aliphatic tertiary amine having good compatibility with water.

Specifically, the tertiary amine aqueous solution may be an aqueous solution of trimethylamine, triethylamine, tributylamine or pyridine.

The tertiary amine is used in the form of an aqueous solution dissolved in water, for example, as an aqueous solution diluted to a concentration of 1 to 15% by weight in water.

The aqueous solution of the tertiary amine removes the remaining compound of formula (2) and the acid catalyst at the time of washing the ester polythiol composition obtained in step (1).

Specifically, the tertiary amine forms a salt with the compound of Formula 2 and the acid catalyst. On the other hand, the tertiary amine does not react with ester polythiol, which is the main object contained in the crude composition.

Accordingly, the tertiary amine selectively reacts only with the compound of Formula 2 and the acid catalyst to form a salt. Thereafter, the salt formed is removed and transferred to the aqueous layer, whereby only the compound of Formula 2 and the acid catalyst in the crude composition can be selectively removed.

Thus, the selective reaction of the tertiary amine is due to the absence of active hydrogen in the molecule.

On the other hand, metal basic materials (for example, sodium hydroxide, potassium hydroxide, sodium carbonate, etc.) or amines having active hydrogen (primary amine, secondary amine) which have conventionally been used for similar purposes also react with ester polythiol So that effective purification is difficult and a high yield can not be expected.

The washing with the aqueous solution of the tertiary amine can be carried out until the pH of the aqueous waste solution after washing is 8 or more, or until the pH of the aqueous waste solution ranges from 7 to 8.

That is, if the aqueous waste solution after the washing has a pH of 8 or more, the compound of formula (2) and the acid catalyst may be considered to be completely converted into a salt form and removed.

(3) acid cleaning

After washing with an aqueous solution of the tertiary amine, tertiary amines may remain in the ester polythiol composition. The residual tertiary amine acts as a cocatalyst in a subsequent urethane reaction or the like to increase the reaction rate, thereby making it difficult to control the reaction.

Therefore, the step of washing the ester polythiol composition washed with the tertiary amine aqueous solution with an aqueous acid solution can be further roughened.

The pickling can be performed, for example, by mixing the ester polythiol composition with an aqueous acid solution and then removing the aqueous layer.

The aqueous acid solution may be, for example, an aqueous solution of sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid or nitric acid.

As an example, the acid aqueous solution may contain 1 to 10% by weight of hydrochloric acid, based on the total weight of the aqueous acid solution.

The cleaning with the acid aqueous solution may be performed until the pH of the aqueous waste solution after washing becomes 5 or less, for example, until the pH is in the range of 1 to 5.

That is, when the pH of the aqueous waste solution after the washing is 5 or less, it can be considered that the tertiary amine is removed.

(4) Brine cleaning

After rinsing with the acid solution, the acid component may remain in the ester polythiol composition. The acid component remaining as such can act as a catalyst poison in the subsequent urethane reaction and the like, thereby lowering the reaction efficiency.

Therefore, the step of washing the solution of the ester polythiol washed with the acid aqueous solution with brine may be further carried out.

The brine cleaning may be performed, for example, by mixing the ester polythiol composition with brine and then removing the water layer.

The salt water used herein may contain, for example, 5 to 20% by weight of salt based on the total weight of the salt water.

The washing with the brine can be repeatedly performed until the pH of the aqueous waste solution after washing becomes 6 or more, for example, until the pH is in the range of 6 to 7.

According to the above process, the ester polythiol can be synthesized at a high yield (e.g., 80% or more).

In addition, according to the above method, the content of the compound of formula (2) and the acid catalyst remaining in the final product may be very small.

Ester polythiol composition

According to an embodiment, there is provided an ester polythiol composition prepared by the above process.

The ester polythiol composition according to the embodiment contains an ester polythiol compound as a main component.

The ester polythiol compound may be a bifunctional or more polyfunctional, a trifunctional or more polyfunctional, or a polyfunctional or quaternary functional. For example, the ester polythiol compound may be a polythiol having 2 to 10, 2 to 8, 2 to 6, or 2 to 4 thiol groups in the molecule.

The ester polythiol may have at least one ester group (-COO-) in the molecule.

For example, the ester polythiol according to an embodiment may have a structure in which the carboxyl group of the compound of Formula 2 is condensed to the hydroxyl group of the compound of Formula 1 to form an ester group.

The ester polythiol compound content in the ester polythiol composition may be at least 90 wt%, at least 95 wt%, at least 97 wt%, at least 99 wt%, or at least 99.5 wt%.

In addition, the ester polythiol composition may contain a minor amount of other components, so that the content of the ester polythiol compound in the ester polythiol composition may be less than 100% by weight.

In the ester polythiol composition according to the embodiment, the content of the compound of Formula 2 is 0.5% by weight or less. More specifically, the content of the compound of Formula 2 in the ester polythiol composition may be 0.4 wt% or less, or 0.3 wt% or less.

Further, in the ester polythiol composition according to the embodiment, the content of the remaining acid catalyst may be 0.5% by weight or less. More specifically, the content of the acid catalyst in the ester polythiol composition may be 0.4 wt% or less, 0.3 wt% or less, 0.2 wt% or less, or 0.1 wt% or less.

Also, the ester polythiol composition according to the above example may have an ester polythiol purity of 50% or more. This purity may mean the percentage of the actual yield of the ester polythiol which should be theoretically obtained through the reaction with respect to the total weight of the ester polythiol composition obtained through the reaction of the compound of formula 1 and the compound of formula 2. [ have.

For example, the ester polythiol composition according to the above example may contain at least 50 wt%, for example, 50 to 99 wt%, of ester polythiol having 4 or more functionalities.

Further, in the ester polythiol composition according to the above-mentioned embodiment, the tertiary amine compound used in the purification hardly exists. For example, the content of the tertiary amine compound in the ester polythiol composition may range from less than 0.1% by weight to less than 0.01% by weight.

In addition, the polythiol according to an embodiment may have an APHA (American Public Health Association) color value in the range of 5 to 30, or in the range of 10 to 20.

In addition, the polythiol according to the embodiment may have a liquid refractive index (nd 25) in the range of 1.510 to 1.540, or in the range of 1.520 to 1.530.

Polymerizable composition

According to an embodiment, there is provided a polymerizable composition comprising said polythiol and isocyanate.

The polymerizable composition may contain the polythiol and the isocyanate in a mixed state or may contain the polythiol and the isocyanate in a separated state. That is, in the polymerizable composition, the polythiol and the isocyanate may be in a state of being in contact with each other or separated from each other so as not to contact each other.

The polymerizable composition may contain, as the polythiol, the ester polythiol composition according to the above embodiment in an amount of 100% by weight. In addition, if necessary, the polymerizable compound may further include a polythiol other than the ester polythiol composition as described above. In this case, the polymerizable composition may contain the ester polythiol composition in an amount of 5 to 70 parts by weight based on 100 parts by weight of the total polythiol.

The isocyanate may be a conventional one used for the synthesis of polythiourethane.

Specifically, the isocyanate is at least one member selected from the group consisting of isophorone diisocyanate, dicyclohexylmethane-4,4-diisocyanate, hexamethylene diisocyanate, 2,2-dimethylpentane diisocyanate, 2,2,4-trimethylhexane diisocyanate, 1,3-butadiene-1,4-diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 1,6,11-undecatriisocyanate, 1,3,6-hexamethylene triisocyanate, (Isocyanatoethyl) ether, 1,2-bis (isocyanatomethyl) cyclohexane, 1 (isocyanatomethyl) , 3-bis (isocyanatomethyl) cyclohexane, 1,4-bis (isocyanatomethyl) cyclohexane, dicyclohexylmethane diisocyanate, cyclohexane diisocyanate, methylcyclohexane diisocyanate, dicyclohexyl (Isocyanatoethyl) sulfide, bis (isocyanatohexyl) sulfide, bis (isocyanate) sulfide, bis (isocyanatoethyl) Bis (isocyanatomethylthio) methane, bis (isocyanatoethylthio) methane, bis (isocyanatomethyl) disulfide, bis (Isocyanatoethylthio) ethane, bis (isocyanatomethylthio) ethane, 1,5-diisocyanato-2-isocyanatomethyl-3-thiapentane, 2,5-diisocyanatothiophene , 2,5-bis (isocyanatomethyl) thiophene, 2,5-diisocyanatotetrahydrothiophene, 2,5-bis (isocyanatomethyl) tetrahydrothiophene, 3,4- Bis (isocyanatomethyl) tetrahydrothiophene, 2,5-diisocyanato-1,4-dithiane, 2,5- (Isocyanatomethyl) -1,4-dithiane, 4,5-diisocyanato-1,3-dithiolane, 4,5-bis (isocyanatomethyl) Oran, aliphatic isocyanate compounds including 4,5-bis (isocyanatomethyl) -2-methyl-1,3-dithiolane, and the like; (Isocyanatoethyl) benzene, bis (isocyanatoethyl) benzene, bis (isocyanatoethyl) benzene, bis (isocyanatoethyl) Examples of the aromatic diisocyanate compound include aromatic diisocyanates such as phenyl ether, phenylenediisocyanate, ethylphenylenediisocyanate, isopropylphenylenediisocyanate, dimethylphenylenediisocyanate, diethylphenylenediisocyanate, diisopropylphenylenediisocyanate, trimethylbenzene triisocyanate, Toluene diisocyanate, 4,4-diphenylmethane diisocyanate, 3,3-dimethyldiphenylmethane-4,4-diisocyanate, bibenzyl-4,4-diisocyanate, bis (isocyanato Phenyl) ethylene, 3,3-dimethoxybiphenyl-4,4-diisocyanate, hexahydrobenzene diisocyanate, hexahydrate Xylene diisocyanate, p-xylene diisocyanate, xylene diisocyanate, X-xylene diisocyanate, 1,3-bis (isocyanatomethyl) ) Cyclohexane, diphenylsulfide-2,4-diisocyanate, diphenylsulfide-4,4-diisocyanate, 3,3-dimethoxy-4,4-diisocyanatodibenzylthioether, bis Diisocyanate, diphenyldisulfide-4,4-diisocyanate, 2,2-dimethyldiphenyldisulfide-5,5-diisocyanatomethylbenzene) sulfide, 4,4-methoxybenzenethiolethylene glycol- Diisocyanate, 3,3-dimethyldiphenyldisulfide-5,5-diisocyanate, 3,3-dimethyldiphenyldisulfide-6,6-diisocyanate, 4,4-dimethyldiphenyldisulfide-5,5-diisocyanate , 3,3-dimethoxydiphenyl disulfide-4,4-diisocyanate, 4,4 -Dimethoxydiphenyl disulfide-3,3-diisocyanate, and mixtures thereof.

More specifically, as the isocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, toluene diisocyanate and the like can be used.

The polymerizable composition may further contain additives such as an internal release agent, an ultraviolet absorber, a polymerization initiator, a heat stabilizer, a color correcting agent, a chain extender, a crosslinking agent, a light stabilizer, an antioxidant, .

Examples of the internal release agent include a fluorine-based nonionic surfactant having a perfluoroalkyl group, a hydroxyalkyl group or a phosphate ester group; A silicone-based nonionic surfactant having a dimethylpolysiloxane group, a hydroxyalkyl group or a phosphate ester group; Alkyl quaternary ammonium salts such as trimethylcetylammonium salt, trimethylstearylammonium salt, dimethylethylcetylammonium salt, triethyldodecylammonium salt, trioctylmethylammonium salt, diethylcyclohexadodecylammonium salt; The acid phosphate ester may be used singly or in combination of two or more thereof.

Examples of the ultraviolet absorber include benzophenone, benzotriazole, salicylate, cyanoacrylate, oxanilide, and the like.

As the polymerization initiator, an amine-based, phosphorus-based, organosilicate-based, organic copper-based, organic gallium, organic zirconium, organic iron-based, organic zinc, and organic aluminum may be used.

Examples of the thermal stabilizer include metal fatty acid salts, phosphorus, lead, and an organosilicate, which may be used alone or in combination of two or more.

Polythiourethane-based optical material

The examples provide polythiourethane-based compounds obtained from the polymerizable composition as described above. The polythiourethane compound is prepared by polymerizing (and curing) the polythiol composition and the isocyanate compound. The reaction mole ratio of the SH group / NCO group in the polymerization reaction may be 0.5 to 3.0, specifically 0.6 to 2.0, more specifically 0.8 to 1.3. Within this range, the refractive index, heat resistance And the balance and the like can be improved. Further, in order to control the reaction rate, the above-mentioned reaction catalyst which is conventionally used for the production of polythiourethane may be added.

The embodiment provides a molded article obtained by curing the polymerizable composition and an optical material comprising the molded article. The optical material may be prepared by polymerizing and molding the polymerizable composition.

First, the polymerizable composition is degassed under reduced pressure, and then injected into a mold for optical material molding. Such degassing and mold injection can be performed, for example, at a temperature range of 20 to 40 캜. After injection into the mold, the polymerization is usually carried out by gradually heating from a low temperature to a high temperature.

The temperature of the polymerization reaction may be, for example, 20 to 150 ° C, and specifically 25 to 120 ° C. In order to control the reaction rate, a reaction catalyst which is usually used in the production of polythiourethane may be added, and specific examples thereof are as exemplified above.

Then, the polythiourethane-based optical material is separated from the mold.

The optical material may be in various shapes by changing the mold of the mold used in the production. Specifically, it may be in the form of a spectacle lens, a camera lens, a light emitting diode (LED), or the like.

The optical material may have a refractive index of 1.65 to 1.75 or 1.65 to 1.70.

The optical material may be an optical lens, specifically a plastic optical lens. The optical lens can be used for surface polishing, antistatic treatment, hard coat treatment, anti-reflection coat treatment, anti-reflection treatment, anti-reflection treatment, anti- A dyeing treatment, a dimming treatment, and the like.

The following more specific embodiments are illustrated.

Example: Preparation of ester polythiol

(1) Example 1

Step 1: Preparation of crude ester polythiol composition

63.0 g (0.46 mol) of pentaerythritol (99%), thioglycolic acid (hereinafter referred to as TGA, 99% of Diesell) were added to a Mentel 1L three-necked reactor equipped with a condenser, a stirring device, 187.4 g (2.03 mol) of p-toluenesulfonic acid, 0.8 g of para-toluenesulfonic acid and 466.4 g of toluene were charged and the reactor temperature was raised to 120 캜. The reaction by-product, water, was started to be discharged to Dean Stark while maintaining the reactor temperature at 110 to 115 ° C. After 4 hours of reaction, it was confirmed that 32.5 g of water was discharged, and the reaction was terminated. The reaction conversion rate calculated by the amount of discharged water was 97.5%. The toluene was distilled off under reduced pressure at 60 DEG C and 1 Torr, and 653.6 g of ethyl acetate was added to obtain a crude composition containing pentaerythritol tetramercaptoacetate (hereinafter PETMA).

Step 2: Purification using a tertiary amine aqueous solution

435.7 g of a 5% triethylamine aqueous solution was mixed with the crude PETMA composition obtained in the step 1, and the aqueous layer was removed from the separating funnel to confirm that the aqueous layer had a pH of 9. The obtained organic layer was mixed with 3% aqueous HCl solution and the aqueous layer was removed from the separating funnel to confirm that the pH of the aqueous layer was 2. The obtained organic layer was mixed with 435.7 g of 5% brine and the pH of the aqueous layer was checked while removing the aqueous layer from the separating funnel, and the operation was repeated until the pH was 6 or higher. The obtained organic layer was purified by vacuum distillation at 50 DEG C and 1 Torr to obtain final PETMA.

(2) Example 2

435.7 g of a 5% aqueous pyridine solution was mixed with the crude PETMA composition obtained in the procedure of Step 1 of Example 1 above, and the aqueous layer was removed from the separating funnel to confirm that the pH of the aqueous layer was 10. The obtained organic layer was mixed with 3% HCl aqueous solution, and the aqueous layer was removed from the separating funnel to confirm that the pH of the aqueous layer was 3. The obtained organic layer was mixed with 435.7 g of 5% brine, and the pH of the aqueous layer was checked while removing the water layer from the separating funnel and repeated until the pH was 6 or higher. The obtained organic layer was purified by vacuum distillation at 50 DEG C and 1 Torr to obtain final PETMA.

(3) Example 3

435.7 g of a 2% triethylamine aqueous solution was mixed with the crude PETMA composition obtained in the procedure of Step 1 of Example 1 above, and the aqueous layer was removed from the separating funnel to confirm that the aqueous layer had a pH of 8. The obtained organic layer was mixed with an aqueous 2% HCl solution and the aqueous layer was removed from the separating funnel to confirm that the pH of the aqueous layer was 4. The obtained organic layer was mixed with 435.7 g of 5% brine, and the pH of the aqueous layer was checked while removing the water layer from the separating funnel and repeated until the pH was 6 or higher. The obtained organic layer was purified by vacuum distillation at 50 DEG C and 1 Torr to obtain final PETMA.

Comparative Example: Preparation of ester polythiol

(1) Comparative Example 1

435.7 g of a 5% sodium hydroxide aqueous solution was added to the crude PETMA composition obtained in the procedure of Step 1 of Example 1 above and the aqueous layer was removed from the separating funnel to confirm that the pH of the aqueous layer was 8. The obtained organic layer was mixed with 3% HCl aqueous solution, and the aqueous layer was removed from the separating funnel to confirm that the pH of the aqueous layer was 4. The obtained organic layer was mixed with 435.7 g of 5% brine, and the pH of the aqueous layer was checked while removing the water layer from the separating funnel and repeated until the pH was 6 or higher. The obtained organic layer was purified by vacuum distillation at 50 DEG C and 1 Torr to obtain final PETMA.

(2) Comparative Example 2

435.7 g of a 5% aqueous ammonia solution was mixed with the crude PETMA composition obtained in the procedure of Step 1 of Example 1, and the aqueous layer was removed from the separating funnel to confirm that the pH of the aqueous layer was 8. The obtained organic layer was mixed with 3% HCl aqueous solution, and the aqueous layer was removed from the separating funnel to confirm that the pH of the aqueous layer was 4. The obtained organic layer was mixed with 435.7 g of 5% brine, and the pH of the aqueous layer was checked while removing the water layer from the separating funnel and repeated until the pH was 6 or higher. The obtained organic layer was purified by vacuum distillation at 50 DEG C and 1 Torr to obtain final PETMA.

(3) Comparative Example 3

(0.46 mol) of pentaerythritol (99%) and 339.0 g (3.68 mol) of TGA (99% of Diesels) were charged in a 1 liter three-necked reactor equipped with a stirrer, a cooling condenser, Mol) and 466.4 g of toluene were charged, and the reactor temperature was raised to 120 ° C. The reaction by-product, water, was started to be discharged to Dean Stark while maintaining the reactor temperature at 110 to 115 ° C. After 8 hours of reaction, it was confirmed that 30.1 g of water was discharged, and the reaction was terminated. The reaction conversion rate calculated by the amount of discharged water was 90.4%. The reaction solution was distilled under reduced pressure at 60 ° C and 1 Torr to remove toluene. Thereafter, the reaction solution was distilled again under reduced pressure at 110 DEG C and 5 Torr to remove residual TGA, thereby obtaining final PETMA.

Test Example

The ester polythiol prepared in the above Examples and Comparative Examples was evaluated according to the following procedure. The results are summarized in Table 1 below.

(1) Yield of ester polythiol

The yield of the ester polythiol synthesized in the above Examples and Comparative Examples was calculated as a percentage of the theoretical yield (200 g).

Yield (%) = (actual gain (g) / theoretical gain (200 g)) x 100

(2) Residual thioglycolic acid (TGA) content and product purity

The residual TGA content in the ester polythiol sample was measured using high performance liquid chromatography (HPLC, LC 20A, Shimazhu, Japan). At this time, a C18 reverse phase column (Ace 5, 250 X 4.6 mm, ACE-121-2548, particle size 5 μm) and a mixed solvent (CH ₃ CN: H ₂ O = 7: 3) , A UV wavelength of 240 nm, and an oven temperature condition of 40 占 폚. During the test, TGA was observed for about 2.4 minutes and tetrafunctional product was observed for 10.2 minutes. The content of TGA and the content of tetrafunctional products (product purity) were measured by area ratio to the total amount.

(3) APHA (American Public Health Association) color

The APHA of the ester polythiol sample was measured using a ColorQuest XE instrument from Hunterlab. At this time, the concentration of the standard solution prepared by dissolving the reagents of platinum and cobalt was data, and the APHA color value obtained by the comparison between the program and the sample solution was determined as a frequency (frequency). The smaller the measured value, the better the color.

(4) liquid refractive index

The liquid refractive index of the ester polythiol sample was measured at 25 캜 using Refractometer RA-600, a liquid refractometer of Kyoto Electronics Co.,

division Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 yield(%) 89.2 87.6 93.5 27.4 33.7 99.8 Residual TGA (%) 0.2 0.1 Not detected 1.1 0.9 3.1 APHA color 9 9 5 15 19 27 Liquid refractive index (nd 25) 1.5458 1.5459 1.5456 1.5412 1.5421 1.5393 Product Purity (%) 64.6 53.1 70.7 27.8 41.4 51.5

As shown in Table 1, the ester polythiol prepared according to Examples 1 to 3 had a high yield and purity, a low residual TGA content, and was excellent in APHA color and liquid refractive index. On the other hand, the ester polythiol prepared according to Comparative Examples 1 to 3 had a low yield, a low purity, a high residual TGA content, and was poor in terms of APHA color and the like.

Claims (12)

(1) reacting 1 equivalent of a compound represented by the following formula (1) and 1.01 - 2 equivalents of a compound represented by the following formula (2) under acid catalysis to obtain a crude ester polythiol composition;
(2) washing the crude ester polythiol composition with a tertiary amine aqueous solution to remove the compound of Formula 2 and the acid catalyst remaining in the composition;
(3) washing the ester polythiol composition washed with the tertiary amine aqueous solution with an aqueous acid solution until the pH of the aqueous layer waste solution after washing with the aqueous acid solution is less than 5; And
(4) The method of any one of (1) to (4), further comprising washing the washed ester polythiol composition with the aqueous acid solution, followed by repeated washing with the brine until the pH of the aqueous layer wastewater after washing is at least 6, Method for preparing ester polythiol composition:
[Chemical Formula 1]

(2)

In this formula,
R ₁ are each independently H, -CH ₃ or -CH ₂ CH ₃ ;
R ₂ are each independently -CH ₃ , -CH ₂ CH ₃ or -CH ₂ CH ₂ CH ₃ ;
p is 1 or 2;
m is independently an integer of 0 to 10;
each n is independently an integer of 1 to 4;
l and o are each independently 0 or 1;
Where n + l + o = 4.
The method according to claim 1,
Wherein the reaction of the compound of Formula 1 with the compound of Formula 2 is carried out by azeotropic distillation in a nonpolar and aprotic solvent.
The method according to claim 1,
Wherein the tertiary amine aqueous solution is an aqueous solution of trimethylamine, triethylamine, tributylamine or pyridine.
The method according to claim 1,
Wherein the cleaning with the tertiary amine aqueous solution is carried out until the pH of the water layer waste solution after cleaning becomes 8 or more.
The method according to claim 1,
Wherein the cleaning with the tertiary amine aqueous solution is carried out by mixing the crude ester polythiol composition with an aqueous solution of the tertiary amine and then removing the aqueous layer.
delete delete The method according to claim 1,
Wherein the acid aqueous solution is an aqueous solution of hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid or nitric acid.
delete delete 8. An ester polythiol composition prepared according to the process of any one of claims 1 to 5 and 8, wherein the content of the compound of formula (2) is 0.5% by weight or less:
(2)

In the above formula, p is 1 or 2.
12. The method of claim 11,
Wherein the ester polythiol composition contains at least 50% by weight of a tetrafunctional or higher ester polythiol.