Method for removing odor-causing substances from resin

Abstract

The present invention provides a method for removing odor-causing substances from a resin. The method comprises: a step in which a resin and a sub / supercritical fluid are introduced into a twin-screw extruder; a step in which the introduced resin and sub / supercritical fluid form a mixture in the twin-screw extruder; and a step in which odor-causing substances are extracted from the mixture and removed, wherein the sub / supercritical fluid is at least one selected from alcohol, acetone, and water.

Description

Method for removing odor-causing substances from resin

[0001] The present invention relates to a method for removing off-odor-causing substances from a resin. More specifically, the present invention relates to a method for removing off-odor-causing substances from a resin in a short period of time through continuous extrusion.

[0002] Odor characteristics are important when using resin. In particular, recycled resins may be unusable due to severe odors. Conventional methods for reducing odor include the batch process (hot air flush) or heating drying (dry hopper). However, these methods have the disadvantage of requiring a long time due to their batch nature and large equipment volume.

[0003] Methods for removing off-odor-causing substances using single-screw extruders have been studied. However, in the case of single-screw extruders, the screw is constructed as a single unit, making it difficult to change the screw once manufactured; furthermore, since the residence time within the extruder is linked to the RPM, it is difficult to adjust each component.

[0004] Meanwhile, although there is a method to remove contaminants from polymers using supercritical carbon dioxide, existing methods have the disadvantage of being time-consuming and having reduced removal efficiency.

[0005] Related prior art is KR 10-0351785.

[0006] The objective of the present invention is to provide a method for effectively removing odor-causing substances from resin continuously over a short period of time.

[0007] Another objective of the present invention is to provide a method for removing off-odor-causing substances from resin using a conventional twin-screw extruder without using a batch process (hot air flush), a heating dryer (dry hopper), or complex equipment.

[0008] Another objective of the present invention is to provide a method for effectively removing off-odor-causing substances by changing extrusion conditions according to the type of resin.

[0009] Another objective of the present invention is to provide a method for producing a resin with reduced odor using the above method and a resin produced therefrom.

[0010] The above and other objectives of the present invention can all be achieved by the present invention described below.

[0011] 1. One aspect of the present invention relates to a method for removing off-odor-causing substances from a resin. The method comprises the steps of: introducing a resin and a sub-supercritical fluid into a twin-screw extruder; forming a mixture within the twin-screw extruder with the introduced resin and sub-supercritical fluid; and extracting and removing off-odor-causing substances from the mixture, wherein the sub-supercritical fluid is selected from one or more of alcohol, acetone, and water.

[0012] 2. In the above 1 embodiment, the off-flavor-causing substance may include TVOCs (Total Volatile Organic Compounds) having 6 to 16 carbon atoms.

[0013] 3. In the above 1 to 2 embodiments, the twin-screw extruder is equipped with a first inlet and a second inlet, the first inlet may introduce resin, and the second inlet may introduce sub-supercritical fluid.

[0014] 4. In the above 1 to 3 embodiments, the twin-screw extruder can maintain a temperature of 100 to 400 ℃ and a pressure of 1 to 200 bar.

[0015] 5. In the above 1 to 4 embodiments, the sub / supercritical fluid in the mixture may comprise 0.1 to 20 wt%.

[0016] 6. In the above 1 to 5 embodiments, the off-flavor-causing substance may be discharged through the vent at the rear end of the twin-screw extruder or collected through the vent and recycled.

[0017] 7. In the above 1 to 6 embodiments, the TVOCs removal rate according to Formula 1 below may be 20% or more:

[0018] [Equation 1]

[0019] TVOCs removal rate = (V0-V1) / V0 * 100

[0020] (In Equation 1, V0 is the TVOCs content of the resin before extrusion (ppm), and V1 is the TVOCs content of the resin after discharge from the extruder (ppm).)

[0021] 8. Another aspect of the present invention relates to a method for manufacturing a resin with reduced off-odor. The method comprises the steps of: feeding a resin into a twin-screw extruder to melt it; mixing the molten resin with a sub- / supercritical fluid injected into the twin-screw extruder to form a mixture; extracting and removing off-odor-causing substances from the mixture; and discharging the resin from which the off-odor-causing substances have been removed through the discharge port of the twin-screw extruder to pelletize it.

[0022] 9. In the above 8 embodiments, the off-flavor-causing substance may include TVOCs having 6 to 16 carbon atoms.

[0023] 10. In the above 8 to 9 embodiments, the twin-screw extruder is equipped with a first inlet and a second inlet, the first inlet may introduce resin, and the second inlet may introduce sub-supercritical fluid.

[0024] 11. In the above 8 to 10 embodiments, the twin-screw extruder can maintain a temperature of 100 to 400 ℃ and a pressure of 1 to 200 bar.

[0025] 12. In the above 8 to 11 embodiments, the sub / supercritical fluid in the mixture may comprise 0.1 to 20 wt%.

[0026] 13. In the above 8 to 12 embodiments, the off-flavor-causing substance may be discharged through a vent at the rear end of the twin-screw extruder or collected through a vent and recycled.

[0027] The present invention provides a method for effectively removing off-odor-causing substances from a resin continuously and in a short period of time, using a conventional twin-screw extruder without using a batch method (Hot air flush), a heating drying (Dry Hopper), or complex equipment, and effectively removing off-odor-causing substances by changing the extrusion conditions according to the type of resin, and has the effect of providing a method for manufacturing a resin with reduced off-odor using the said method and a resin manufactured therefrom.

[0028] FIG. 1 is a reaction process diagram according to one embodiment of the present invention.

[0029] The present invention will be described in more detail below. Where terms such as 'comprising,' 'having,' and 'consisting of' are used in this specification, other parts may be added unless 'only' is used. Where a component is expressed in the singular, it includes cases where it includes the plural unless specifically stated otherwise.

[0030] In interpreting the components, even without separate explicit indication, they are interpreted to include an error range of approximately 5%.

[0031] In this specification, 'off-odor-causing substances' include TVOCs (Total Volatile Organic Compounds) having 6 to 16 carbon atoms.

[0032] FIG. 1 is a reaction process diagram according to one embodiment of the present invention. As shown in FIG. 1, a resin and a sub-supercritical fluid are fed into a twin-screw extruder (10). The twin-screw extruder (10) is equipped with a first inlet (11) and a second inlet (12). In one embodiment, the first inlet (11) may feed the resin, and the second inlet (12) may feed the sub-supercritical fluid. The first inlet (11) is connected to a hopper (1), and the resin may be supplied to the hopper (1). The second inlet (12) is connected to a pump or gas cylinder (2), and the sub-supercritical fluid is supplied to the pump or gas cylinder (2).

[0033] The above-mentioned twin-screw extruder (10) is a continuous extruder in which a barrel accommodating a twin screw and a motor driving the screw are connected. Each screw consists of multiple segments connected in a modular fashion, and each segment can be combined and used in sections according to the reaction raw material. Therefore, the screw can be changed according to the reaction raw material and reaction conditions, and the extrusion conditions can be easily changed in sections.

[0034] The above-described twin-screw extruder (10) is divided into melting, mixing, and discharge sections according to the flow of the injected resin, and each of these sections may have different temperatures, screw segments, etc. In the melting section, the injected resin is melted, and in the mixing section, the resin and sub / supercritical fluid are mixed. In the discharge section, a vent (13) is formed so that odor-causing substances can be discharged or collected and recycled. In a specific embodiment, the odor-causing substances discharged through the vent (13) can be captured by a trap (14). Additionally, the captured odor-causing substances can be transported to a hood (16) by a pump (15) and discharged.

[0035] An outlet (14) is formed at the end of the above-mentioned twin-screw extruder (10), through which the resin from which the off-odor-causing substance has been removed can be obtained in the form of pellets.

[0036] In a specific example, the twin-screw extruder maintains a temperature of 100 to 400°C and a pressure of 1 to 200 bar. Within this range, off-odor-causing substances can be easily extracted in a short time, thereby securing a TVOCs removal rate of 20% or more, preferably 35% or more. In a specific example, the twin-screw extruder may maintain a temperature of 150 to 300°C and a pressure of 1 to 150 bar.

[0037] There are no restrictions on the polymer resins that can be used in the extruder, and recycled resins are also possible. Examples include polyethylene, polypropylene, polyamide, polyester, polyvinyl chloride, polystyrene, cross-linked polyolefin, acrylic resin, styrene-acrylonitrile copolymer, ABS resin, etc., but are not necessarily limited thereto. These may be used individually or in combination of two or more types. The resins to be fed may be fed in a solid state, such as pellets.

[0038] The above sub-supercritical fluid is selected from one or more of alcohol, acetone, and water. When these are applied as sub-supercritical fluids, not only is the removal effect of TVOCs having 6 to 16 carbon atoms excellent, but handling and use are also advantageous. In a specific example, the alcohol may be a monovalent, divalent, or polyvalent alcohol having 1 to 10 carbon atoms. Preferred examples of the above sub-supercritical fluid include methanol, ethanol, propanol, butanol, pentanol, hexanol, acetone, or a combination of two or more of these.

[0039] The above sub- / supercritical fluid is mixed with the molten resin inside the extruder. Therefore, the fluid inside the extruder is in a sub- / supercritical state.

[0040]

[0041] *In a specific example, the sub / supercritical fluid may be mixed to be 0.1 to 20 wt% of the mixture of the sub / supercritical fluid and the resin. Within this range, extrusion processing is possible without damaging the inherent properties of the resin, and excellent TVOCs removal efficiency can be achieved. In a specific example, the sub / supercritical fluid may be 1 to 15 wt% of the mixture.

[0042] The method for removing odor-causing substances from a resin according to the method of the present invention may have a TVOCs removal rate of 20% or more, for example 35% or more, preferably 50% or more, according to Formula 1 below:

[0043] [Equation 1]

[0044] TVOCs removal rate = (V0-V1) / V0 * 100

[0045] (In Equation 1, V0 is the TVOCs content of the resin before extrusion (ppm), and V1 is the TVOCs content of the resin after discharge from the extruder (ppm).)

[0046]

[0047] Another aspect of the present invention relates to a method for manufacturing a resin with reduced off-odor. The method comprises the steps of: feeding a resin into a twin-screw extruder to melt it; mixing the molten resin with a sub- / supercritical fluid injected into the twin-screw extruder to form a mixture; extracting and removing off-odor-causing substances from the mixture; and discharging the resin from which the off-odor-causing substances have been removed through the discharge port of the twin-screw extruder and pelletizing it.

[0048] The above-mentioned twin-screw extruder may be the twin-screw extruder (10) of FIG. 1. There are no limitations on the polymer resins that can be used in the extruder, and recycled resins are also possible. Examples include polyethylene, polypropylene, polyamide, polyester, polyvinyl chloride, polystyrene, cross-linked polyolefin, acrylic resin, styrene-acrylonitrile copolymer, ABS resin, etc., but are not necessarily limited thereto. These may be used individually or in combination of two or more types.

[0049] The above sub-supercritical fluid is selected from one or more of alcohol, acetone, and water. When these are applied as sub-supercritical fluids, the removal effect of TVOCs having 6 to 16 carbon atoms is excellent. In a specific example, the alcohol may be an alcohol having 1 to 10 carbon atoms. Preferred examples of the above sub-supercritical fluid include methanol, ethanol, propanol, butanol, pentanol, hexanol, acetone, or a combination of two or more of these.

[0050] The resin fed into the above-mentioned twin-screw extruder (10) is melted in the melting section, and the melted resin is mixed with the sub-supercritical fluid injected into the above-mentioned twin-screw extruder (10) to form a mixture. At this time, the fluid inside the extruder may be in a sub-supercritical fluid state.

[0051] The above mixture is transferred to the discharge section at the rear end via the mixing section of the twin-screw extruder (10), and the odor-causing substance is extracted and removed through the vent formed in the discharge section. Subsequently, the resin from which the odor-causing substance has been removed is discharged through the discharge port of the twin-screw extruder and obtained in the form of pellets.

[0052] The above mixture may be mixed in a twin-screw extruder maintaining a temperature of 100 to 400°C and a pressure of 1 to 200 bar. Within this range, off-odor-causing substances can be easily extracted in a short time, thereby securing a TVOCs removal rate of 20% or more, preferably 35% or more. In a specific example, the twin-screw extruder may be at a temperature of 150 to 300°C and a pressure of 1 to 150 bar. Within this range

[0053] In a specific example, the sub / supercritical fluid in the mixture may comprise 0.1 to 20 wt%. Within this range, extrusion processing is possible without damaging the intrinsic properties of the resin, and excellent TVOCs removal efficiency can be achieved. In a specific example, the sub / supercritical fluid may comprise 1 to 15 wt% of the mixture.

[0054] The resin produced by the above method has significantly reduced residual TVOCs and does not produce odor.

[0055]

[0056] The present invention is to be explained more specifically through the following examples, but these examples are for illustrative purposes only and should not be interpreted as limiting the invention.

[0057]

[0058] Examples

[0059]

[0060] In the case where a partially cross-linked polyolefin resin containing a peroxide crosslinking agent is applied as the resin

[0061]

[0062] Example 1

[0063] A 30mm twin-screw extruder from SMPlatek was used to recycle a partially cross-linked polyolefin resin containing a peroxide crosslinking agent with 58 ppm of TVOCs. The polyolefin resin containing the crosslinking agent was fed into the first inlet of the twin-screw extruder and extruded at approximately 200°C. Supercritical ethanol was injected into the twin-screw extruder using a metering pump at a concentration of 3 wt% of the mixture, and the pressure inside the extruder was 20 bar. The processing temperature of the twin-screw extruder was maintained at approximately 200°C, with the sub / supercritical section set to 300°C and TVOCs discharged through a vent. The TVOCs content of the resin pellets produced from the outlet of the twin-screw extruder was measured and is shown in Table 1.

[0064]

[0065] Example 2

[0066] Water (H2O) was injected as a sub / supercritical fluid instead of ethanol at a content of 3 wt% in the mixture, and the procedure was performed in the same manner as Example 1 above, except that the pressure inside the extruder was 40 bar.

[0067]

[0068] Example 3

[0069] Acetone was injected as a sub / supercritical fluid instead of ethanol at a content of 4.5 wt% in the mixture, and the procedure was carried out in the same manner as Example 1 above, except that the pressure inside the extruder was 20 bar.

[0070]

[0071] Comparative Example 1

[0072] The procedure was performed in the same manner as Example 1, except that sub- / supercritical fluids were not used.

[0073]

[0074] Comparative Example 2

[0075] Carbon dioxide (CO2) was injected as a sub-supercritical fluid instead of ethanol at a content of 3 wt% in the mixture, and the procedure was carried out in the same manner as Example 1 above, except that the pressure inside the extruder was 20 bar.

[0076]

[0077] Comparative Example 3

[0078] The procedure was performed in the same manner as Example 1, except that a single-screw extruder was used instead of a twin-screw extruder.

[0079]

[0080] Evaluation method

[0081] (1) TVOCs: The sample was analyzed using the HSS-GC (Headspace GC) analysis method with HSS (PerkinElmer) GC (Agilent). After sampling for 30 minutes at a temperature of 150°C, the content of TVOCs with 6 to 16 carbon atoms was measured.

[0082] (2) TVOCs removal rate: The calculated value was obtained using Equation 1 below.

[0083] [Equation 1]

[0084] TVOCs removal rate = (V0-V1) / V0 * 100

[0085] (In Equation 1, V0 is the TVOCs content of the resin before extrusion (ppm), and V1 is the TVOCs content of the resin after discharge from the extruder (ppm).)

[0086]

[0087] A / Type of Supercritical Fluid Extruder TVOCs (ppm) TVOCs Removal Rate Example 1 Ethanol Biaxial 2458.6% Example 2 Water Biaxial 3244.8% Example 3 Acetone Biaxial 2360.3% Comparative Example 1 -Biaxial 93-60.3% Comparative Example 2 CO2 Biaxial 4915.5% Comparative Example 3 Ethanol Uniaxial 538.6%

[0088] As confirmed in the above examples, the resin obtained according to the method of the present invention showed a low residual TVOCs content and an increased TVOCs removal rate. On the other hand, Comparative Example 1, which did not apply a sub-supercritical fluid, showed an increase in TVOCs content compared to the resin before being fed into the extruder. Comparative Example 2, which applied CO2 as a sub-supercritical fluid, showed poor removal efficiency for TVOCs with 6 to 16 carbon atoms. Comparative Example 3, which applied a uniscrew extruder instead of a twinscrew extruder, showed poor TVOCs removal rate despite applying ethanol as a sub-supercritical fluid.

[0089]

[0090] When LLDPE is applied as the resin

[0091] Example 4

[0092] LLDPE containing 14 ppm of TVOCs was fed into the first inlet of a twin-screw extruder and melted by heating at 180°C. Supercritical ethanol was injected into the twin-screw extruder using a metering pump to a concentration of 3 wt% of the mixture, and the pressure inside the extruder was 20 bar. The processing temperature of the twin-screw extruder was carried out at approximately 180°C, and the processing temperature in the sub / supercritical section was set to 300°C, with TVOCs discharged through a vent. The TVOCs content of the resin pellets produced from the outlet of the twin-screw extruder was measured and is shown in Table 2.

[0093]

[0094] Example 5

[0095] Supercritical ethanol was injected into the mixture at a content of 6 wt%, and the procedure was performed in the same manner as Example 4 above, except that the pressure was 30 bar.

[0096]

[0097] Example 6

[0098] Supercritical ethanol was injected to a content of 9 wt% in the mixture, and the procedure was carried out in the same manner as Example 4 above, except that the pressure inside the extruder was 40 bar.

[0099]

[0100] Comparative Example 4

[0101] The procedure was performed in the same manner as Example 4, except that sub- / supercritical fluids were not used.

[0102]

[0103] The method for evaluating physical properties was performed in the same manner as above, and the results are shown in Table 2.

[0104]

[0105] A / Type of Supercritical Fluid Extruder TVOCs (ppm) TVOCs Removal Rate Example 4 Ethanol 3wt% Biaxial 935.7 Example 5 Ethanol 6wt% Biaxial 657.1 Example 6 Ethanol 9wt% Biaxial 471.4 Comparative Example 4 Biaxial 2257.1

[0106] As confirmed in the above examples, the resin obtained according to the method of the present invention showed a low residual TVOCs content and an increased TVOCs removal rate. On the other hand, Comparative Example 4, which did not apply a sub-supercritical fluid, showed an increase in TVOCs content compared to the resin before being fed into the extruder.

[0107] Simple variations or modifications of the present invention can be easily implemented by those skilled in the art, and all such variations or modifications are considered to be included within the scope of the present invention.

Claims

1. A method according to claim 8, wherein the twin-screw extruder is equipped with a first inlet and a second inlet, wherein the first inlet feeds resin and the second inlet feeds sub / supercritical fluid.

2. The method according to claim 1, wherein the off-flavor-causing substance comprises TVOCs having 6 to 16 carbon atoms.

3. The method according to claim 1, wherein the twin-screw extruder is equipped with a first inlet and a second inlet, wherein the first inlet feeds resin and the second inlet feeds sub / supercritical fluid.

4. The method according to claim 1, wherein the twin-screw extruder maintains a temperature of 100 to 400 ℃ and a pressure of 1 to 200 bar.

5. The method according to claim 1, wherein the sub- / supercritical fluid in the mixture comprises 0.1 to 20 wt%.

6. A method according to claim 1, wherein the off-odor-causing substance is discharged through a vent at the rear end of the twin-screw extruder or collected through a vent and recycled.

7. A method of any one of paragraphs 1 through 6 having a TVOCs removal rate of 20% or more according to Formula 1 below: [Equation 1] TVOCs removal rate = (V0-V1) / V0 * 100 (In Equation 1, V0 is the TVOCs content of the resin before extrusion (ppm), and V1 is the TVOCs content of the resin after discharge from the extruder (ppm).) 8. A method for manufacturing a resin with reduced off-odor, and the method The resin is fed into a twin-screw extruder and melted; The molten resin is mixed with a sub-supercritical fluid injected into the twin-screw extruder to form a mixture; The off-odor-causing substance is extracted and removed from the above mixture; and The resin from which the above-mentioned odor-causing substances have been removed is discharged through the discharge port of a twin-screw extruder and pelletized; A method comprising a step, wherein the sub / supercritical fluid is selected from one or more of alcohol, acetone, and water.

9. The method according to claim 8, wherein the off-flavor-causing substance comprises TVOCs having 6 to 16 carbon atoms.

10. A method according to claim 8, wherein the twin-screw extruder is equipped with a first inlet and a second inlet, wherein the first inlet feeds resin and the second inlet feeds sub / supercritical fluid.

11. The method according to claim 8, wherein the twin-screw extruder maintains a temperature of 100 to 400°C and a pressure of 1 to 200 bar.

12. The method according to claim 8, wherein the sub- / supercritical fluid in the mixture comprises 0.1 to 20 wt%.

13. A method according to claim 8, wherein the off-odor-causing substance is discharged through a vent at the rear end of the twin-screw extruder or collected and recycled.

Images