KR20180033690A - Method for preparing eco-friendly aromatic vinyl-vinyl cyanide compolymer - Google Patents

Abstract

The present invention relates to a preparation method of an eco-friendly aromatic vinyl-vinyl cyanide copolymer. More specifically, the present invention relates to the preparation method of an aromatic vinyl-vinyl cyanide copolymer, the preparation method comprising: a step (S1) of contacting a pellet type aromatic vinyl-vinyl cyanide copolymer with carbon dioxide (CO_2) of a supercritical fluid state to extract volatile organic compounds (VOCs) in the copolymer; and a step (S2) of separating the pellet type aromatic vinyl-vinyl cyanide copolymer from which the VOCs are extracted and carbon dioxide of the supercritical fluid state including the VOCs, wherein carbon dioxide of the supercritical fluid state has a density of 0.1 to 0.8 g/cm^3 when the pellet type aromatic vinyl-vinyl cyanide copolymer comes into contact with carbon dioxide in the step (S1), and the pellet type aromatic vinyl-vinyl cyanide copolymer separated in the step (S2) contains the VOCs in an amount of 1,700 ppm or less based on weight percentage. The preparation method according to the present invention has an effect of remarkably reducing a remaining amount of VOCs remaining in pellets of the aromatic vinyl-vinyl cyanide copolymer.

Description

METHOD FOR PREPARING ECO-FRIENDLY AROMATIC VINYL-VINYL CYANIDE COMPOLYMER [0002]

TECHNICAL FIELD The present invention relates to a process for producing an aromatic vinyl-cyanide vinyl copolymer, and more particularly, to a process for producing an aromatic vinyl-cyanide vinyl copolymer having a pellet type aromatic Vinyl-vinyl cyanide copolymer.

A copolymer of an aromatic vinyl compound such as styrene and a vinyl cyanide compound such as acrylonitrile has excellent transparency, chemical resistance and mechanical properties and is a molding material excellent in mechanical properties such as hardness, tensile property, shrinkage ratio and impact resistance It is widely used in industry.

The copolymer of the aromatic vinyl compound and the vinyl cyanide compound can be produced by various polymerization methods such as emulsion polymerization, bulk polymerization and solution polymerization. However, emulsion polymerization causes impurities such as emulsifier and coagulant to remain in the polymer, , And it is generally produced by bulk polymerization or solution polymerization in general.

On the other hand, also in the aromatic vinyl-cyanide vinyl copolymer produced by the bulk polymerization or solution polymerization, volatile organic compounds (VOC) such as unreacted monomers or solvent components remain in the polymer, It must undergo a devolatilization process. However, since the volatile organic compounds trapped in the polymer are vaporized at a temperature much higher than the boiling point when they are present in a pure state, the devolatilization process is generally carried out under high temperature / high vacuum conditions. However, There is a problem that the temperature during the volatilization is close to the glass transition temperature of the polymer, which may lead to deterioration of the physical properties of the polymer.

However, even though the high-temperature / high-vacuum devolatilization process is performed as described above, unreacted monomers or solvent components in the polymer still remain at a concentration of several thousand ppm, which is a difficult level to cope with increasingly stringent environmental regulations , The concentration of the volatile organic compounds in the polymer should be lowered to several hundred ppm or less in order to satisfy the requirement.

KR 1998-0073126 A

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art described above, and it is an object of the present invention to provide a pellet-shaped aromatic vinyl-cyanide vinyl copolymer for reducing the residual amount of volatile organic compounds (VOC) remaining in pellets of an aromatic vinyl- And a method for producing the same.

According to one embodiment of the present invention for solving the above problems, the present invention provides a method for producing an aromatic vinyl-vinyl cyanide copolymer, which comprises contacting a pellet type aromatic vinyl-vinyl cyanide copolymer with carbon dioxide (CO ₂ ) Extracting a volatile organic compound (VOC) (S1); And separating the pelletized aromatic vinyl-vinyl cyanide copolymer from which the volatile organic compound has been extracted and carbon dioxide in a supercritical fluid state including a volatile organic compound (S2). In the step (S1) , The carbon dioxide in the supercritical fluid state has a density of 0.1 g / cm ³ to 0.8 g / cm ³ , and the pellet type aromatic vinyl-vinyl cyanide copolymer separated in the step (S 2) has a volatile organic compound content of% Based on the total amount of the aromatic vinyl-vinyl cyanide copolymer.

According to the present invention, there is an effect of remarkably reducing the residual amount of volatile organic compounds (VOC) remaining in the pellets of the aromatic vinyl-cyanide vinyl copolymer.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

The terms and words used in the description of the present invention and in the claims should not be construed to be limited to ordinary or dictionary terms and the inventor should appropriately interpret the concept of the term appropriately The present invention should be construed in accordance with the meaning and concept consistent with the technical idea of the present invention.

The method for producing an aromatic vinyl-vinyl cyanide copolymer according to the present invention comprises contacting a pellet-type aromatic vinyl-vinyl cyanide copolymer with carbon dioxide (CO ₂ ) in supercritical fluid state to form a volatile organic compound (VOC (S1); And separating the pelletized aromatic vinyl-vinyl cyanide copolymer from which the volatile organic compound has been extracted and carbon dioxide in a supercritical fluid state including a volatile organic compound (S2), wherein the step (S1) In contact, supercritical carbon dioxide may have a density of from 0.1 g / cm ³ to 0.8 g / cm ³ , and the pellet type aromatic vinyl-vinyl cyanide copolymer separated in the step (S 2) has a volatile organic compound content May be not more than 1,700 ppm based on the weight%.

The term " pellet " in the present invention means a copolymer of an aromatic vinyl-vinyl cyanide copolymer and an aromatic vinyl-vinyl cyanide copolymer after extrusion of the dried copolymer, May refer to aggregate aggregates.

According to one embodiment of the present invention, the pellet-like aromatic vinyl-vinyl cyanide copolymer may include a repeating unit derived from an aromatic vinyl compound and a repeating unit derived from a vinyl cyanide compound. The aromatic vinyl compound may be at least one selected from the group consisting of styrene,? -Methylstyrene, p-methylstyrene, and vinyltoluene. Examples of the vinyl cyanide compound include acrylonitrile, methacrylonitrile, And rhenitrile. The 'derived repeating unit' of the present invention may be a constituent, a structure derived from a substance, or the substance itself. As another example, the repeating unit derived from an aromatic vinyl compound may be contained in an amount of 50 to 99.9% by weight, 50 to 90% by weight, or 60 to 90% by weight based on the copolymer, 0.1 to 50% by weight, 10 to 50% by weight, or 10 to 40% by weight based on the weight of the coalescence.

According to one embodiment of the present invention, the pellet type aromatic vinyl-vinyl cyanide copolymer may have a length or an average particle size of the pellets of 0.3 mm to 4.0 mm, 0.3 mm to 2.0 mm, or 0.3 mm to 0.5 mm, The removal efficiency of the volatile organic compounds in the pellets is very excellent.

For example, the pellets may be spherical, elliptic spherical, cylindrical or polyhedral, and the length of the pellets may mean the length of the longest axis of the cylindrical or polyhedral pellets, The average particle diameter according to the particle diameter, the elliptical spherical major axis diameter or the average particle diameter according to the diameter of the cross section of the cylindrical pellet.

As another example, when the pellet is elliptical, cylindrical or polyhedral, the aspect ratio along the longest axis and the shortest axis of the pellet may be 0.5 to 10, 0.5 to 5, or 0.5 to 2.

According to one embodiment of the present invention, the pelletized aromatic vinyl-vinyl cyanide copolymer has a bulk density of 0.7 g / cm ³ to 1.5 g / cm ³ , 1.0 g / cm ³ to 1.2 g / cm ³ , or 1.05 g / cm to ³ may be 1.1 g / cm ^3, it has a very excellent effect removal of volatile organic compound in the pellets within this range.

According to an embodiment of the present invention, when the contact is made in step (S1), the pressure may be 74 bar or more and the temperature may be 31.1 ° C or more. The pressure and temperature may be supercritical fluid conditions of carbon dioxide to utilize carbon dioxide in a supercritical fluid state and in order to prevent phenomena that may degrade the properties of the aromatic vinyl-cyanide vinyl copolymer, A pressure of 74 to 180 bar and a temperature of 31.1 to 90 占 폚, or a pressure of 74 to 130 bar and a temperature of 31.1 to 60 占 폚.

The pressure and the temperature may be, for example, carried out by heating the pellet-shaped aromatic vinyl-vinyl cyanide copolymer and carbon dioxide in a pressure vessel, and the heating may be performed using a heating coil, a heating tape ), A heating circulator, or the like.

The contact may be carried out for 1 to 3 hours, 1 to 2 hours, or 1 to 1.5 hours, for example. In this range, pellet type aromatic vinyl-vinyl cyanide copolymer and carbon dioxide in supercritical fluid state are sufficiently To thereby extract the volatile organic compound in the pellet-type aromatic vinyl-vinyl cyanide copolymer as much as possible.

As another example, upon contacting in step (S1), the carbon dioxide in the supercritical fluid state may have a density of from 0.1 g / cm ³ to 0.8 g / cm ³ , from 0.15 g / cm ³ to 0.6 g / cm ³ , from 0.15 g / cm ^{3 3} to 0.45 g / cm ³ , or 0.17 g / cm ³ to 0.44 g / cm ^3. Within this range, the volatile organic compounds present in the pellets are highly soluble in carbon dioxide in the supercritical fluid state, The removal efficiency of the organic compound is remarkably excellent. Particularly, the density of carbon dioxide in the supercritical fluid state can be 0.3 g / cm ³ to 0.44 g / cm ³ , and within this range, the volatile organic compounds in the pellet It is possible to extract at a removal rate of 40% or more.

As another example, the contacting in the above step (S1) may be carried out with an entrainer, and in specific examples, the co-solvent may be methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, Butanone, methyl ethyl ketone, and a mixture of two or more thereof, for example, aliphatic alcohols such as methyl alcohol, ethyl alcohol, propanol, 1-heptanol, 2-heptanol, n-hexane, cyclohexane, toluene, diethyl ether, tetrahydrofuran, tetrahydropyrane, In this case, the solubility of carbon dioxide in the supercritical fluid state is further increased to effectively extract the volatile organic compounds present in the pellets.

According to an embodiment of the present invention, the content of the volatile organic compound in the pellet type aromatic vinyl-vinyl cyanide copolymer separated in step (S2) is 1,700 ppm or less, 100 ppm to 1,700 ppm, 1650 ppm, or 100 to 900 ppm, and it has an effect of improving the processability in molding while satisfying the environmental regulation within this range. As another example, the removal rate of the volatile organic compounds of the pelletized aromatic vinyl-vinyl cyanide copolymer separated in the step (S2) may be 10% or more, 20% or more, 30% or more, 40% or more, Within this range, there is an effect of improving workability at the time of molding. As a specific example, the removal rate may be 46% to 90%, or 46% to 70%, and the processability during molding is greatly improved while satisfying the environmental regulation within this range.

The method for producing an aromatic vinyl-vinyl cyanide copolymer according to the present invention may further comprise the steps of extracting volatile organic compounds in the pellets (S1) and separating step (S2), and further adding carbon dioxide in a supercritical fluid state including the volatile organic compounds to volatile organic compounds Separating the organic compound into gaseous carbon dioxide (S3); And reusing carbon dioxide in the gaseous state as carbon dioxide in a supercritical fluid state for extracting the volatile organic compound (S4). The separation in step (S3) may be carried out by depressurizing the carbon dioxide of the supercritical fluid state containing the volatile organic compound to less than 74 bar and lowering the temperature to 20 to 26 DEG C, And 20 to 26 占 폚 may be exemplary conditions of pressure and temperature for changing the carbon dioxide in the supercritical fluid state to the gaseous state and specific examples are 50 bar or less and 20 to 26 占 폚 or 10 bar or less and 20 to 26 Lt; 0 > C.

When the carbon dioxide is reused according to the steps (S3) and (S4), carbon dioxide is not discharged into the atmosphere after the extraction of the volatile organic compound in the step (S1), so that an environmental problem such as greenhouse gas can be prevented in advance And the separated unreacted monomer can be used again in the polymerization reaction. Further, it is possible to continuously extract volatile organic compounds from the re-use of the supplied carbon dioxide, without supplying any additional carbon dioxide, This has an excellent effect.

As another example, the steps (S1) and (S2) may be performed in a continuous process. In the continuous process, carbon dioxide in a supercritical fluid state for contacting with the pelletized aromatic vinyl-vinyl cyanide copolymer is continuously flowed in step (S1), and after contacting and extracting the volatile organic compound, May mean continuously separating the carbon dioxide in the supercritical fluid state including the volatile organic compound in the step (a). This is because, in the case where the carbon dioxide in the supercritical fluid state in the extraction device for performing the steps (S1) and (S2) is in a state where the solubility of the volatile organic compound becomes saturated, . According to the continuous process, the removal efficiency of the volatile organic compounds in the pellets is remarkably excellent.

In order to carry out the continuous process, the temperature and the pressure of the extraction device must be maintained in order to maintain the supercritical fluid state of the carbon dioxide. The temperature may be adjusted by placing the extraction device in a thermostatic chamber, And the carbon dioxide can be maintained through a heat exchanger such as a preheater when the carbon dioxide is injected into the extraction device. The pressure can be controlled by controlling the pressure during the injection of carbon dioxide, such as the valve control and the back pressure regulator Can be maintained through the device.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following examples are for illustrative purposes only and are not intended to limit the scope of the invention.

Example

Example 1

Cylindrical SAN pellets (product name: 82TR, manufactured by LG Chemical Co., Ltd.) having a length of 3.5 mm and an average particle diameter of 2.0 mm were used.

Example 2

A cylindrical SAN pellet (product name: 82TR, manufactured by LG Chemical Co., Ltd.) having a length of 1.4 mm and an average particle diameter of 1.8 mm was used.

Example 3

Cylindrical SAN pellets (product name: 82TR, manufactured by LG Chemical Co., Ltd.) having a length of 0.8 mm and an average particle diameter of 0.7 mm were used.

Example 4

Cylindrical SAN pellets (product name: 82TR, manufactured by LG Chemical Co., Ltd.) having a length of 0.3 mm and an average particle diameter of 0.3 mm were used.

Experimental Example 1

Using the pellets of Examples 1 to 4, volatile organic compounds were extracted according to the following procedure, and the content of volatile organic compounds in the pellets before extraction and the content of volatile organic compounds in the pellets after extraction were measured by gas chromatography (GC) The results are shown in Table 1 below.

* Volatile Organic Compounds Extraction Sequence

1) Each of the pellets of Examples 1 to 4 was charged into a pressure vessel.

2) After closing the pressure vessel, gaseous carbon dioxide was fed through the valve until the density of carbon dioxide in the pressure vessel became 0.44 g / cm ³ .

3) After the supply of the carbon dioxide was completed, heating was performed using a heating coil until the temperature reached 60 ° C and 125 bar with the valve closed.

4) The temperature and the pressure were maintained for 2 hours so that the supercritical carbon dioxide and the pellets of Examples 1 to 4 sufficiently contacted.

5) After sufficient contact for the above-mentioned time, the valve was opened to transfer the carbon dioxide in the supercritical fluid state to the separator, and then the volatile organic compound-extracted pellets were obtained.

6) After the transfer of the carbon dioxide in the supercritical fluid state to the separator, the temperature and pressure of the separator were lowered and lowered at room temperature and atmospheric pressure to separate the volatile organic compound and the gaseous carbon dioxide.

7) The separated gaseous carbon dioxide was transferred to a separate carbon dioxide storage tube for supplying carbon dioxide to the pressure vessel for reuse as supercritical carbon dioxide for extraction.

division Example One 2 3 4 Before extraction (ppm) 2,000 2,200 3,000 2,800 After extraction (ppm) 1,100 1,200 1,100 850 Removal rate (%) 45 46 63 70

As shown in Table 1, when the volatile organic compounds in the pellets were extracted according to the present invention, it was confirmed that the volatile organic compounds in the pellets could be removed at a removal rate of 1,200 ppm or less and 45% or more. Particularly, it was confirmed that the smaller the length and the average particle size of the pellets, the higher the removal rate of the volatile organic compounds in the pellets, and the remaining amount thereof was extremely reduced.

Experimental Example 2

In order to confirm the change in the removal rate of the volatile organic compounds according to the density of carbon dioxide in the pressure vessel, the pellets of Example 1 were used to extract volatile organic compounds in the pellets in the same manner as in Experimental Example 1, The density of carbon dioxide was adjusted to the density shown in Table 2.

division Example 1 Carbon dioxide in a pressure vessel density (g / cm ³⁾ 0.17 0.28 0.35 0.44 Before extraction (ppm) 1,340 2,360 2,240 2,000 After extraction (ppm) 1,120 1,650 1,320 1,100 Removal rate (%) 20 30 41 45

As shown in Table 2, when the volatile organic compounds in the pellets were extracted, the higher the density of carbon dioxide in the pressure vessel was, the higher the removal rate of the volatile organic compounds in the pellets was, and the residual amount thereof was extremely reduced.

Claims (10)

(S1) of contacting a pellet type aromatic vinyl-vinyl cyanide copolymer with carbon dioxide (CO ₂ ) in supercritical fluid state to extract volatile organic compounds (VOC) in the copolymer; And
Separating the pellet type aromatic vinyl-vinyl cyanide copolymer from which the volatile organic compound is extracted and carbon dioxide in a supercritical fluid state including a volatile organic compound (S2)
Wherein (S1) of carbon dioxide in the supercritical fluid state, upon contact of the step is a density of 0.1 g / cm ³ to 0.8 g / cm ^3,
The method for producing an aromatic vinyl-vinyl cyanide copolymer according to claim 1, wherein the content of the volatile organic compound in the pellet-like aromatic vinyl-vinyl cyanide copolymer is not more than 1,700 ppm. The method according to claim 1,
Wherein the pelletized aromatic vinyl-vinyl cyanide copolymer comprises a repeating unit derived from an aromatic vinyl compound and a repeating unit derived from a vinyl cyanide compound. The method according to claim 1,
Wherein the pellet-type aromatic vinyl-vinyl cyanide copolymer has a pellet length or an average particle diameter of 0.3 mm to 4.0 mm. The method according to claim 1,
Wherein the pelletized aromatic vinyl-vinyl cyanide copolymer has a bulk density of 0.7 g / cm ³ to 1.5 g / cm ³ . The method according to claim 1,
The method for producing an aromatic vinyl-vinyl cyanide copolymer according to claim 1, wherein the pressure is 74 bar or more and the temperature is 31.1 ° C or more. The method according to claim 1,
Wherein the contacting in step (S1) is carried out with an entrainer. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 6,
The co-solvent may be selected from the group consisting of methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-heptanol, 2-heptanol, n-hexane, cyclohexane, toluene, diethyl ether, Vinyl cyanide copolymer is a polar solvent selected from the group consisting of tetrahydropyran, acetone, propanone, 2-butanone, methyl ethyl ketone, and a mixture of two or more thereof. The method according to claim 1,
The method for producing an aromatic vinyl-vinyl cyanide copolymer according to claim 1, wherein the aromatic vinyl-vinyl cyanide copolymer comprises a step (S3) of separating carbon dioxide in a supercritical fluid state containing the volatile organic compound into volatile organic compounds and gaseous carbon dioxide ≪ / RTI > 9. The method of claim 8,
The method for producing an aromatic vinyl-vinyl cyanide copolymer according to claim 1, wherein the aromatic vinyl-vinyl cyanide copolymer is prepared by reacting carbon dioxide in gaseous state with carbon dioxide in a supercritical fluid state for extracting volatile organic compounds (S4). The method according to claim 1,
Wherein the steps (S1) and (S2) are carried out in a continuous process.