KR102144877B1 - Method for preparing eco-friendly aromatic vinyl-vinyl cyanide compolymer - Google Patents

Abstract

The present invention relates to a method for preparing an eco-friendly aromatic vinyl-vinyl cyanide copolymer, and more particularly, by contacting a pellet-type aromatic vinyl-vinyl cyanide copolymer with carbon dioxide (CO ₂ ) in a supercritical fluid state, the Extracting a volatile organic compound (VOC) in the copolymer (S1); 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 the volatile organic compound (S2), and when contacting 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 (S2) step has a volatile organic compound content of weight %. It relates to a method for producing an aromatic vinyl-vinyl cyanide copolymer of 1,700 ppm or less as a standard.

Description

Manufacturing method of eco-friendly aromatic vinyl-vinyl cyanide copolymer {METHOD FOR PREPARING ECO-FRIENDLY AROMATIC VINYL-VINYL CYANIDE COMPOLYMER}

The present invention relates to a method for producing an eco-friendly aromatic vinyl-vinyl cyanide copolymer, and more particularly, to a pellet-type aromatic to significantly reduce the residual amount of volatile organic compounds (VOC) remaining in the pellets of the aromatic vinyl-vinyl cyanide copolymer. It relates to a method for producing a vinyl-vinyl cyanide copolymer.

Copolymers of aromatic vinyl compounds such as styrene and vinyl cyanide compounds such as acrylonitrile are excellent in transparency, chemical resistance, and mechanical properties, and are molded materials with excellent mechanical properties such as hardness, tensile properties, molding shrinkage and impact resistance. It is widely used in industrial fields.

The copolymer of the aromatic vinyl compound and the vinyl cyanide compound may be prepared using various polymerization methods such as emulsion polymerization, bulk polymerization, and solution polymerization, but in emulsion polymerization, impurities such as emulsifiers and flocculants remain in the polymer, resulting in thermal stability, etc. There is a problem that causes a decrease in the mechanical properties of, and it is generally manufactured by bulk polymerization or solution polymerization.

Meanwhile, in the aromatic vinyl-vinyl cyanide copolymer prepared by the bulk polymerization or solution polymerization, volatile organic compounds (VOCs) such as unreacted monomers or solvent components remain in the polymer, and are desorbed to remove them. It must go through a devolatilization process. However, since the volatile organic compound trapped in the polymer vaporizes at a temperature much higher than the boiling point when it exists in a pure state, the devolatilization process has to be performed under high temperature/high vacuum conditions. There is a problem in that the temperature during volatilization is close to the glass transition temperature of the polymer and may cause a decrease in physical properties of the polymer.

However, even through the high temperature/high vacuum devolatilization process as described above, the unreacted monomer or solvent component in the polymer still remains at a concentration of several thousand ppm, which is a level that is difficult to cope with the increasingly strengthening environmental regulations. In order to satisfy this, the concentration of the volatile organic compound in the polymer must be lowered to a level of several hundred ppm or less.

KR 1998-0073126 A

The present invention was devised to solve the problems of the prior art, and a pellet-type aromatic vinyl-vinyl cyanide copolymer for remarkably reducing the residual amount of volatile organic compounds (VOC) remaining in the pellets of the aromatic vinyl-vinyl cyanide copolymer It is an object of the present invention to provide a method of manufacturing.

According to an embodiment of the present invention for solving the above problems, the present invention provides a pellet-type aromatic vinyl-vinyl cyanide copolymer in contact with carbon dioxide (CO ₂ ) in a supercritical fluid state, Extracting a volatile organic compound (VOC) (S1); 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 the volatile organic compound (S2), and when contacting 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 (S2) has a volatile organic compound content of weight %. It provides a method for producing an aromatic vinyl-vinyl cyanide copolymer of 1,700 ppm or less as a standard.

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

Hereinafter, the present invention will be described in more detail to aid in understanding the present invention.

The terms or words used in the description and claims of the present invention should not be construed as being limited to their usual or dictionary meanings, and the inventor appropriately explains the concept of terms in order to explain his own invention in the best way. Based on the principle that it can be defined, it should be interpreted as a 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 a volatile organic compound (VOC) in the copolymer by contacting a pellet-type aromatic vinyl-vinyl cyanide copolymer with carbon dioxide (CO ₂ ) in a supercritical fluid state. ) Extracting (S1); 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 the volatile organic compound (S2), and the step of (S1) Upon contact, carbon dioxide in a supercritical fluid state may have 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 (S2) step contains a volatile organic compound. It may be 1,700 ppm or less based on this weight %.

In the present invention, the term'pellet' refers to a spherical, elliptical, cylindrical, or polyhedral type that can be obtained by extruding the dried copolymer after polymerization of an aromatic vinyl-vinyl cyanide copolymer. It can mean a coalescence aggregate.

According to an embodiment of the present invention, the pellet-type 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, for example, one or more selected from the group consisting of styrene, α-methylstyrene, p-methylstyrene, and vinyltoluene, and the vinyl cyanide compound is, for example, acrylonitrile, methacrylonitrile, and ethacryl. It may be one or more selected from the group consisting of ronitrile. The'derived repeating unit' of the present invention may represent a component, a structure, or the substance itself derived from a substance. In another example, the repeating unit derived from the aromatic vinyl compound may be included 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, and the repeating unit derived from the vinyl cyanide compound is the copolymer It may be included in 0.1 to 50% by weight, 10 to 50% by weight, or 10 to 40% by weight based on the coalescence.

According to an embodiment of the present invention, the pellet-type aromatic vinyl-vinyl cyanide copolymer may have a pellet length or average particle diameter of 0.3 mm to 4.0 mm, 0.3 mm to 2.0 mm, or 0.3 mm to 0.5 mm, and this range The removal rate of the volatile organic compound in the pellet is very excellent.

On the other hand, the pellet may be, for example, a spherical, elliptical, cylindrical or polyhedral shape, the length of the pellet may mean the length of the longest axis of the cylindrical or polyhedral pellet, the average particle diameter of the pellet is the average of the spherical It may mean a particle diameter, an average particle diameter according to an elliptical spherical long axis diameter, or an average particle diameter according to a diameter of a cross section of a cylindrical pellet.

As another example, when the pellet has an oval spherical shape, a cylindrical shape, or a polyhedral shape, an aspect ratio according to 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 an embodiment of the present invention, the pellet-type 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/ It may be cm ³ to 1.1 g/cm ³ , and within this range, the removal rate of the volatile organic compound in the pellet is very excellent.

According to an embodiment of the present invention, when contacting the step (S1), the pressure may be 74 bar or higher, and the temperature may be 31.1 °C or higher. The pressure and temperature may be a supercritical fluid condition of carbon dioxide for using carbon dioxide as a supercritical fluid state, and in order to prevent phenomena that may deteriorate the properties of the aromatic vinyl-vinyl cyanide copolymer, the contact is It can be carried out at a pressure of 74 to 180 bar and a temperature of 31.1 to 90 °C, or a pressure of 74 to 130 bar and a temperature of 31.1 to 60 °C.

On the other hand, the pressure and temperature may be carried out through heating after injection of the pellet-type aromatic vinyl-vinyl cyanide copolymer and carbon dioxide in a pressure vessel, for example, and the heating may be performed by heating a heating coil and a heating tape. ), a heating circulator, or the like.

In addition, the contact may be performed for 1 to 3 hours, 1 to 2 hours, or 1 to 1.5 hours, for example, and within this range, the pellet-type aromatic vinyl-vinyl cyanide copolymer and carbon dioxide in a supercritical fluid state are sufficiently By contacting, there is an effect of extracting volatile organic compounds in the pellet-type aromatic vinyl-vinyl cyanide copolymer as much as possible.

In another example, when contacting the step (S1), carbon dioxide in a supercritical fluid state has a density of 0.1 g/cm ³ to 0.8 g/cm ³ , 0.15 g/cm ³ to 0.6 g/cm ³ , 0.15 g/cm ³ to 0.45 g/cm ³ , or 0.17 g/cm ³ to 0.44 g/cm ³ , and within this range, the volatile organic compounds present in the pellet have high solubility in carbon dioxide in a supercritical fluid state, and thus the volatility in the pellet The removal rate of organic compounds has a very excellent effect, and in particular, the density of carbon dioxide in a supercritical fluid state may be 0.3 g/cm ³ to 0.44 g/cm ³ , and within this range, the volatile organic compounds in the pellets There is an effect that can be extracted with a removal rate of 40% or more.

In another example, the contact in step (S1) may be carried out including an entrainer, and specific examples of the co-solvent are methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-heptanol, 2-heptanol, n-hexane, cyclohexane, toluene, diethyl ether, tetrahydrofuran, tetrahydropyran, acetone, propanone, 2-butanone, methyl ethyl ketone, and two or more thereof It may be a polar solvent selected from the group consisting of a mixture, and in this case, there is an effect of more effectively extracting volatile organic compounds present in the pellet by increasing the dissolving power of carbon dioxide in a supercritical fluid state.

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

On the other hand, the aromatic vinyl-vinyl cyanide copolymer production method of the present invention volatile carbon dioxide in a supercritical fluid state including the volatile organic compound in addition to the step (S1) and separation step (S2) of extracting the volatile organic compound in the pellet. Separating the organic compound and gaseous carbon dioxide (S3); And reusing the gaseous carbon dioxide as carbon dioxide in a supercritical fluid state for extracting a volatile organic compound (S4). The separation of the step (S3) may be carried out by lowering the pressure of carbon dioxide in a supercritical fluid state containing a volatile organic compound to less than 74 bar and lowering the temperature to 20 to 26 °C, and the lower pressure and lower temperature conditions of 74 bar Less than and 20 to 26 °C may be exemplary conditions of pressure and temperature for changing carbon dioxide in a supercritical fluid state into a gaseous state, and specific examples are 50 bar or less and 20 to 26 °C, or 10 bar or less and 20 to 26 It may be °C.

When carbon dioxide is reused according to steps (S3) and (S4), after extracting volatile organic compounds in step (S1), carbon dioxide is not discharged into the atmosphere, so that environmental problems such as greenhouse gases can be prevented in advance. In addition, the separated unreacted monomer can be reused for a later polymerization reaction, and volatile organic compounds can be continuously extracted from reuse of previously supplied carbon dioxide without additional supply of carbon dioxide. Economical and productivity when using large-scale facilities This has an excellent effect.

As another example, the steps (S1) and (S2) may be performed in a continuous process. In the continuous process, in the step (S1), carbon dioxide in a supercritical fluid state for contact with the pellet-type aromatic vinyl-vinyl cyanide copolymer is continuously flowed, and after the contact and extraction of the volatile organic compound, the (S2) In the step, it may mean continuously separating carbon dioxide in the state of a supercritical fluid containing a volatile organic compound. This is a process for preventing the extraction amount of the volatile organic compound from being limited when carbon dioxide in the supercritical fluid state in the extraction device for performing the steps (S1) and (S2) becomes saturated with the dissolving power of the volatile organic compound. As such, when the continuous process is followed, the removal rate of the volatile organic compound in the pellet is very excellent.

On the other hand, in order to perform the continuous process, in order to maintain the supercritical fluid state of carbon dioxide, the temperature and pressure of the extraction device must be maintained, and the temperature is such that the extraction device is placed in a thermostat, or the jacket is When carbon dioxide is injected into the extraction device, it can be maintained through a heat exchange device such as a preheater, and the pressure is controlled by valve control and a back pressure regulator when carbon dioxide is injected. Can be maintained through the device.

Hereinafter, the present invention will be described in more detail by examples. However, the following examples are for illustrative purposes only, and the scope of the present invention is not limited thereto.

Example

Example 1

A cylindrical SAN pellet (manufactured by LG Chem, product name 82TR) having a length of 3.5 mm and an average particle diameter of 2.0 mm was used.

Example 2

Cylindrical SAN pellets with a length of 1.4 mm and an average particle diameter of 1.8 mm (manufactured by LG Chem, product name 82TR) were used.

Example 3

A cylindrical SAN pellet (manufactured by LG Chem, product name 82TR) having a length of 0.8 mm and an average particle diameter of 0.7 mm was used.

Example 4

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

Experimental Example 1

Volatile organic compound extraction was performed according to the following procedure using the pellets of Examples 1 to 4, and the content of the volatile organic compound in the pellet before extraction and the content of the volatile organic compound in the pellet after extraction were measured by gas chromatography (GC). Measurements were made and the results are shown in Table 1 below.

* Volatile organic compound extraction sequence

1) The pellets of Examples 1 to 4 were respectively added to a pressure vessel.

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

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

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

5) After sufficiently contacting for the above time, the valve was opened to transfer carbon dioxide in the supercritical fluid state to a separator, and a pellet from which the volatile organic compound was extracted was obtained.

6) After the transfer of carbon dioxide in the supercritical fluid state to the separator was completed, the temperature and pressure of the separator were lowered and lowered to room temperature and atmospheric pressure to separate volatile organic compounds and 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, in the case of extracting the volatile organic compound in the pellet according to the present invention, it was confirmed that the volatile organic compound in the pellet can be removed at a removal rate of 1,200 ppm or less and 45% or more. In particular, it was confirmed that the smaller the length and the average particle diameter of the pellet, the higher the removal rate of the volatile organic compound in the pellet, and the residual amount was extremely reduced.

Experimental Example 2

In order to confirm the change in the removal rate of the volatile organic compound depending on the carbon dioxide density in the pressure vessel, the volatile organic compound in the pellet was extracted in the same manner as in Experimental Example 1, using the pellet of Example 1, The carbon dioxide density was adjusted to the density shown in Table 2.

division Example 1 Carbon dioxide density in pressure vessel (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 extracting the volatile organic compound in the pellet, it was confirmed that the higher the carbon dioxide density in the pressure vessel, the higher the removal rate of the volatile organic compound in the pellet, and the residual amount was extremely reduced.

Claims (10)

A step of extracting a volatile organic compound (VOC) in the copolymer by contacting the pellet-type aromatic vinyl-vinyl cyanide copolymer with carbon dioxide (CO ₂ ) in a supercritical fluid state (S1); 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 the volatile organic compound (S2),
Upon contact of the step (S1), carbon dioxide in a supercritical fluid state has a density of 0.3 g/cm ³ to 0.44 g/cm ³ ,
The pellet-type aromatic vinyl-vinyl cyanide copolymer separated in the step (S2) has a volatile organic compound content of 1,700 ppm or less based on wt%,
The pellet-type 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. delete The method of claim 1,
The pellet-type aromatic vinyl-vinyl cyanide copolymer is an aromatic vinyl-vinyl cyanide copolymer having a length or average particle diameter of 0.3 mm to 4.0 mm. The method of claim 1,
The pellet-type aromatic vinyl-vinyl cyanide copolymer has a bulk density of 0.7 g/cm ³ to 1.5 g/cm ³ of an aromatic vinyl-vinyl cyanide copolymer. The method of claim 1,
When contacting the step (S1), the pressure is 74 bar or higher, and the temperature is 31.1° C. or higher. The method of claim 1,
The method for producing an aromatic vinyl-vinyl cyanide copolymer in which the contact of step (S1) is carried out including an entrainer. The method of claim 6,
The co-solvent is methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-heptanol, 2-heptanol, n-hexane, cyclohexane, toluene, diethyl ether, tetrahydrofuran, A method for producing an aromatic vinyl-vinyl cyanide copolymer, which is a polar solvent selected from the group consisting of tetrahydropyran, acetone, propanone, 2-butanone, methylethylketone, and mixtures of two or more thereof. The method of claim 1,
The method for preparing the aromatic vinyl-vinyl cyanide copolymer comprises the step (S3) of separating carbon dioxide in a supercritical fluid state including the volatile organic compound into a volatile organic compound and carbon dioxide in a gaseous state (S3). Copolymer manufacturing method. The method of claim 8,
The aromatic vinyl-vinyl cyanide copolymer manufacturing method comprises the step of reusing the gaseous carbon dioxide as carbon dioxide in a supercritical fluid state for extracting volatile organic compounds (S4). The method of claim 1,
The (S1) and (S2) steps are a method for producing an aromatic vinyl-vinyl cyanide copolymer that is carried out in a continuous process.