KR20150065345A - Extruding apparatus for recycling polymer - Google Patents

Abstract

The present invention relates to an extruding apparatus consisting of a raw material supplying device and an extruder where supplied flake through the raw material supplying device is continuously transferred in a low direction of the extruding apparatus by a screw, and high temperature flake is transferred to a melting point area past a softening point while injecting dried inert gas which is heated in the melting point or before or after the melting point area into a cylinder, thereby being expected to remove moisture and impurity by exhausting the injected inert gas after the inert gas passed the area of supplying raw materials in an opposite direction of injecting the flake.

Description

[0001] EXTRUDING APPARATUS FOR RECYCLING POLYMER [0002] BACKGROUND OF THE INVENTION [0003]

The present invention relates to an extrusion apparatus for recycling waste polyethylene terephthalate (PET) recovered after being used in beverage containers, food containers, etc., including bottled water bottles,

In the present extrusion apparatus comprising the raw material supply device and the extruder, a process for removing the moisture absorbed in the flakes before the flakes are melted proceeds from the viewpoint of suppressing the hydrolysis of the flakes to be recycled. The flakes are placed in the raw material supply device under vacuum And the flakes supplied to the extruder are transferred under vacuum and heated while being heated to flush the moisture absorbed on the surface and inside of the flakes with a heated inert gas and degassing the water in the opposite direction of transport of the flakes before hydrolysis takes place, It is possible to provide an extrusion apparatus which does not require a drying treatment.

PET (PTE) materials are widely used polymer resins with a wide range of applications, particularly beverage containers or bottles, and food packaging containers,

Polycondensation polymers typified by such PET (polyethylene terephthalate) resins have characteristics such as excellent heat resistance, weather resistance, mechanical properties, transparency, and the like.

On the other hand, as environmental problems have arisen, many materials, especially plastics, have been required to be recycled. In response to such social demands, recycling of PET materials used in beverage containers, bottles,

Furthermore, in the case of the recycled PET material, recycling is preferable for the production of the PET container which can be applied in the same manner as the PET before use even if it is recycled, and it is preferable that the recycled resin can be suitably used for food. And impurities are severely limited in order to make this application.

Therefore, discussions are under way on recycling apparatus or method of PET material which can remove impurities and ensure safety in recycling.

Next, the recycling process of the PET material proceeds to a process of collecting used PET, melting it, removing impurities from the molten resin and regenerating it as a reusable resin. Thus, the process of recycling the PET material includes a pretreatment process And the main treatment process.

Impurities including water during regeneration of the recovered waste polymer are factors that inhibit the production of high quality polymers.

In the present invention, in the removal of impurities, particularly moisture, water removal, which had to be carried out in a separate step before entering the main processing step, can be performed in the main processing step without a pre-removing operation, thereby simplifying the recycling process, And an object of the present invention is to provide an extrusion apparatus for obtaining a high quality polymer.

Next, the pretreatment step is a step of collecting the used PET material and preparing it to a state before the melting, and usually refers to a process of collecting used PET material, pulverizing it into a small flake state, washing and drying.

The flakes which have undergone the pretreatment process are melted in the main treatment process and removed after the impurities are removed. In particular, the flakes subjected to the pretreatment process must be sufficiently dried as described above before the main treatment process.

The polyester flakes which have undergone the pretreatment process must be dried in order to combine moisture during storage and transportation due to hygroscopicity and heated in a dryer at a temperature of 160 ° C to 180 ° C in order to remove moisture, Or more.

In addition, the polyester flake absorbs moisture due to its hygroscopic properties and has a moisture content of 1% by weight. When such a flake is put into an extrusion device for the main treatment process, hydrolysis may lead to a large viscosity loss.

Therefore, it is usually necessary to carry out a pre-drying step before the addition to the extruder, and thus drying is required to ensure that the moisture content of the flakes is up to 0.01% by weight. Moreover, such pre-drying is important because it leads to an increase in viscosity rather than a decrease in intrinsic viscosity (IV) of the polymer in the next step of the process.

Meanwhile, Korean Patent No. 10-1278570 (2013.06.19) entitled " Apparatus for recycling recovered waste polymer and recycling method using the apparatus ", Patent No. 10-1298068 (Aug. 13) " Apparatus for recycling recovered waste polymer ".

It is an object of the present invention to provide an extrusion apparatus capable of recycling a waste polymer as a high-quality recycled polymer even if a pre-drying process is not performed in the main process.

Of course, the above-mentioned patent can obtain a regenerated polymer having a high intrinsic viscosity from which impurities are removed in the regeneration of the waste polymer rather than the other related patents (Patent No. 10-0866356, Patent No. 10-2012-0058572, etc.) However,

It is an object of the present invention to provide a regenerated polymer having a higher intrinsic viscosity by solving the problems that may be caused by the above-mentioned patent.

On the other hand, "Preparation and Decontamination Method", Published Patent No. 10-0926606 (2009.11.05) "Apparatus for filling extruder with pretreated thermoplastic material", Published Japanese Patent Application No. 10-2012-0102165 Lt; / RTI >

The patent application 10-2012-0102165 relates to a process for the treatment and detoxification of thermoplastic materials and the removal of contaminants or impurities from such materials which are heated and mixed under vacuum in at least one receiving tank, Discloses a method of introducing a rinsing medium into a receiving tank so that contaminants can be removed efficiently, quickly, and possibly completely, in an extruder after being subjected to a crushing process and then introduced into an extruder to remove impurities in the molten resin. And to expect the effect to be made.

And, in the patent No. 10-0926606, a pre-treated thermoplastic material is introduced into an extruder, with a container provided with a rotary tool provided for the pretreatment of the material, each container having a discharge opening for the fluid material, This discharge opening for the material has a structure in which a fluid is fluidly connected to the fill opening of the extruder, which ultimately discloses an apparatus for filling an extruder with a pretreated thermoplastics material.

However, both of the above two prior arts disclose a configuration in which a waste flake is subjected to a pre-drying process before being injected into an extrusion apparatus, that is, a separate tank is provided, and a pre-drying process of waste flakes is carried out to introduce flakes into the extruder It can be understood that the pre-drying process is indispensably required.

Further, in the case of the above-mentioned two prior arts, it is preferable that the heating temperature for heating the flakes in the receiving tank is set to be lower than the softening point temperature and the melting point temperature (240 ° C) of the flakes, This is because there is a problem in that fusion-bonding phenomenon easily occurs.

Particularly, when such fusion occurs, excessive force is applied to the rotating body rotating in the receiving tank, and smooth supply to the inside of the extruder through the receiving tank becomes impossible.

For this reason, in the extrusion apparatuses including the above-mentioned two prior arts, there is a limit in that the temperature in the receiving tank must be set to be higher than the softening point temperature and lower than the melting point temperature.

Therefore, in the extrusion apparatus for recycling the recovered waste polymer according to the present invention, the waste polymer can be recycled without using a pre-drying process, which is essentially required in the main process, and even if flakes are introduced into the extrusion apparatus, There is a first object of the present invention to provide an extrusion apparatus which can efficiently remove a resin material.

Another object of the present invention is to provide an extrusion apparatus capable of achieving the above object by simply changing the internal structure of the extrusion apparatus.

In addition, in order to provide an extruding device capable of dehydrating moisture and impurities at a temperature higher than the melting point temperature, regardless of the melting point temperature, compared with the conventional extrusion apparatuses in which melt- As a result,

As a result, the equipment required for the process or the process is simplified compared to the existing recycling process, and the polymerization degree of the polycondensation polymer is raised even if the pre-drying operation is not essential, so that the product can be used as a high quality product suitable for the food container It is an object of the present invention to provide an apparatus for recycling waste polymers.

According to an aspect of the present invention, there is provided an extrusion apparatus for recycling a waste polymer,

A raw material feeding device into which a flake for recycling is injected; and an extruder for removing impurities while the melted flakes are heated and extruded,

And vacuum sucking is performed in the extruder up to a melting point or a region around the melting point to degas moisture in the flakes.

And the inert gas is injected into the region around the melting point or the melting point in the extruder.

Further, the injected inert gas is a heated dry gas, and the injection is performed at a pressure equal to or higher than the pressure in the cylinder.

Further, the extruder is extruded while maintaining the vacuum in the extruder at a constant value of less than 100 mbar.

According to the extrusion apparatus for recycling the waste polymer according to the present invention,

Since the flakes supplied to the extruder are continuously conveyed in the downstream direction of the extruder by the screws provided in the extruder, even if the flake particles are fused to each other due to the elevated temperature, there is no problem in transferring the raw materials, It is expected that the effect of dehydrating moisture and impurities at a temperature higher than the melting point temperature can be anticipated, regardless of the melting point temperature,

The flake is folded into the melting point region after passing through the plasticizing zone, and it is expected that the inert gas is injected in the region before and after the melting point, and that the inert gas is injected into the extruder in the direction opposite to the transfer of the flake, The bar,

Ultimately, it is possible to solve the problem that the viscosity of the resin is lowered by minimizing the hydrolysis by degassing the water before the polymer is melted and hydrolysis occurs, and it is possible to provide a high-quality polymer for recycling.

1 is a schematic view for explaining a recycling process in which the present invention is included.
2 is a view showing an extrusion apparatus according to the present invention.
3 is a view showing an extrusion apparatus according to another embodiment of the present invention.
4 is a view showing an extrusion apparatus according to still another embodiment of the present invention.

Hereinafter, an extrusion apparatus for recycling a waste polymer according to the present invention will be described in more detail with reference to the drawings.

FIG. 1 schematically shows a pretreatment process and an extrusion process in a recycling process. As described above, in the pretreatment process, the waste polymer is processed into a flake by pulverization after collection of waste materials, , An extrusion process is carried out in which a flake having undergone the pre-treatment process is injected into the extrusion apparatus to cause an action such as melting,

In the conventional process, a pre-drying process for removing moisture before the extrusion process to be introduced into the extrusion apparatus was required,

According to the extrusion apparatus for recycling the waste polymer according to the present invention, the pre-drying process itself, which is essential in the existing main processing, is not required, and this moisture removal operation is performed not only in the melting process of the flakes in the extrusion apparatus There is a technical feature in that it is possible to solve the problem that the viscosity of the resin is lowered by minimizing the hydrolysis by degassing the water before the polymer is melted and hydrolysis occurs, and it is possible to provide a high quality polymer for recycling.

In the present extrusion apparatus comprising the raw material supply device 10 and the extruder 20, the flakes supplied to the extruder 20 through the raw material supply device 10 are continuously conveyed by the screw 200 in the downstream direction of the extruder, The inert gas injected into the cylinder by injecting the inert gas H1 in the melting point region or in the region before or after the melting point is injected into the cylinder by the elevated temperature of the flame, So that the degassing is carried out in the opposite direction, that is, after passing the extruder raw material supply point 25 in the reverse direction.

Particularly, the above-described degassing removes water and impurities including inert gas in the cylinder through the suction means 140, thereby solving the problem that the viscosity in the resin drops due to hydrolysis in the extrusion apparatus.

The impurity used in the present invention refers to a variety of harmful substances, including moisture, which generally refers to a substance that not only lowers viscosity during molding of a recycled material but also acts harmful to human bodies, and the extrusion apparatus according to the present invention includes It is intended to obtain a high quality recycled polymer capable of efficiently removing impurities including moisture even in the absence of the preliminary moisture removing operation and reaching the target viscosity.

The recycling apparatus according to the present invention can be applied not only to PET but also to a process of recycling a polymer having high hygroscopicity. It does not mean that the PET is applied only to PET recycling. Therefore, in the following, Petra is referred to as a polymer, not a specific material.

2 to 4 schematically show an extrusion apparatus according to the present invention used for progressing an extrusion process,

The extrusion apparatus according to the present invention comprises a raw material feeder 10 into which a flake f for recycling is fed, and an extruder 10 for removing impurities as a result of heating and melting the flake f supplied through the raw material feeder 20).

Particularly, the flakes passing through the raw material supply device 10 are supplied to the extruder 20, heated and melted to a molten resin state, and extruded while removing impurities including moisture in the process of passing the molten resin through the extruder 20 ,

The flakes fed to the extruder are prevented from hydrolyzing due to moisture when the polymer is melted by removing the moisture absorbed in the flakes under vacuum to the melting or melting point region.

The flakes supplied to the extruder 20 through the raw material supply device 10 are transferred to the melting point region through the plasticizing zone and the moisture absorbed in the flakes is evacuated to the outside through the vacuum suction in the course of reaching the region before and after the melting point,

When the flakes are supplied to the extruder 20 and are transferred to the melting point region, the flakes to be transferred are gradually heated to the melting point temperature, and the moisture absorbed in the flake surface and the flakes heated from the heated temperature is immediately evaporated, .

Particularly, the moisture at the elevated temperature in the extruder 20 may cause deterioration of the polymer due to hydrolysis, so that the polymer is degassed under vacuum to degas moisture and impurities before being hydrolyzed, thereby positively affecting the viscosity It is expected.

The extruder 20 includes a screw 200 that rotates in one direction for transferring flakes or melted resin through a plasticizing zone and a cylinder 230 in which a screw is accommodated.

The molten zone I and the metering zone IV may be divided into a melting zone I and a metering zone IV as shown in Figure 2 depending on the action performed in the extruder, Or may be divided into a melting zone I, a mixing zone II and a pressure reducing and degassing zone III and a weighing zone IV as shown in FIG. .

The melting zone is divided into a first melting zone (I-1) and a second melting zone (I-2) according to the zone in which the flakes are plasticized and melted,

A region from the plasticizing zone to the melting point region for the flake is designated as the first melting zone (I-1), and a region from the melting zone region to the melting molten resin region is designated as the second melting zone (I-2). Of course, the melting point region does not mean a region corresponding to the melting point temperature but is generally referred to as a region around the melting point.

The raw material supply device 10 includes a first supply part 110 having a first gate 115 for opening and closing a charging port into which a flake f is charged, And a second supply unit 120 having a second gate 125 for opening and closing,

The second supply part 120 is connected to the melting zone I of the extruder 20.

The molten zone I of the raw material feeder 10 and the extruder 20 communicating with the first feeder 110, the second feeder 120 and the second feeder 120 must be maintained in a vacuum state ,

To this end, first and second suction means (130, 140) for blocking oxygen and maintaining the vacuum are provided. In particular, the vacuum must be maintained in the raw material supply device and the extruder so as not to substantially reduce the pressure, and the oxygen must be kept airtight since the oxygen interruption, moisture removal, and separation of impurities directly affect the viscosity.

As shown in FIGS. 2 to 4, the cylinder 230 is positioned in the depressurizing and degassing zone III shown in FIG. 4 by bending the cylinder of the melting zone I, And an inner tooth cylinder 270 having an inner gear 235 on the inner side for gear interlocking. The screw is also distinguished from the screw located in the depressurization and degassing zone III shown in FIG.

As shown in FIG. 2, the extrusion apparatus according to the present invention may not include the pressure reducing and degassing zone III shown in FIG. 4, and in the case where the pressure reducing and degassing zone III is not provided, The gas addition injection (H2) and the mixing zone (II) are also omitted, and it is possible to proceed from the melting zone (I) directly to the metering zone (IV). Of course, such a structure is a possible part in removing impurities including moisture in the melting zone (I).

As shown in FIG. 3, the vacuum pump P is connected to the pre-cylinder of the metering zone IV after the melting zone I in the extruding apparatus of FIG. 2 according to the conditions of the polymer under the injection of the inert gas H1, You may.

That is, the molten zone (I) according to the present invention is a section where the flakes transferred through the raw material supply device (10) are heated and melted, and the molten resin passing through the molten zone (I)

Extruded through the metering zone IV immediately after melting as shown in Figure 2,

As shown in FIG. 3, after being melted and extruded through the metering zone IV through the degassing before entering the metering zone IV,

Is passed through the mixing zone II after melting as shown in Fig. 4, and is extruded through the metering zone IV after passing through the depressurization and degassing zone III. The mixing zone II is a zone where the molten resin is mixed with the inert gas H2. The inert gas H2 is injected into the extrusion unit through the injection hole to maximize the surface area for removing residual impurities.

Next, when the flake is put in without the pre-drying process, the internal temperature of the melting zone is increased by heating, and the moisture absorbed in the flake is generated. And the viscosity of the molten resin is lowered by hydrolysis with the above-mentioned water. In the case of the conventional extrusion apparatus, a pre-drying process is essentially required. In the present invention, it is not necessary to perform a separate pre-drying process in order to perform the moisture removing operation in the extrusion apparatus. There is one.

Accordingly, in the present invention, the water generated in the melting zone I is sucked through the second suction unit 140 provided at the extruder raw material supply point 25 and discharged to the outside, (140) is vacuum-sucked up to the melting zone (I) of the extruder, more specifically, to a region before or after the melting point or the melting point so that the moisture absorbed in the flake in the region escapes to the outside and prevents hydrolysis .

Since the flakes are generally sensitive to atmospheric oxygen or moisture, it is necessary to ensure that they are completely sealed in the feedstock and extruder. Therefore, by keeping the vacuum state, it is possible to prevent the inflow of oxygen or moisture in the atmosphere from the outside, and to discharge the moisture generated in the melted flakes and plasticized and melted in the melting zone I of the extruder.

In order to maintain the vacuum state of the raw material supply apparatus 10, the first and second supply units 110 and 120 are also required to maintain a vacuum. To this end, the first and second suction units 130, 140 and first and second slide gates 115, 125 for opening and closing the supply inlet, respectively.

The first and second slide gates 115 and 125 are devices for transferring flakes to the raw material supply device 10 so as to shut off oxygen and suck and discharge the moisture generated in the melting section of the extruder, And the first and second slide gates should be kept in a vacuum-tight closed state. In order to maintain such a vacuum state, the second suction means 140 must always be operated.

Then, the flake is transferred from the raw material supply device 10 to the extruder 20, and the moisture generated in the first melting zone I-1 is degassed together with the impurities by the vacuum suction of the second suction device 140, Vacuum within the apparatus and within the extruder is preferably kept below 100 mbar. More preferably, the vacuum in the raw material feeder and in the extruder is maintained at less than 10 mbar.

Next, in the extruding apparatus of the present invention, it is preferable that the inert gas H1 is injected into the cylinder 230 located in the melting zone I through the injection hole in order to more efficiently remove water and impurities. This is to remove moisture and impurities that are absorbed in the flakes to inhibit hydrolysis.

As the inert gas H1, nitrogen gas may be used, and it is preferable that the nitrogen gas injection in the cylinder 230 is located at a melting point or a point before or after the melting point.

When the inert gas H1 is injected at the point, the injected inert gas is passed through the extruder raw material supply point 25 in the opposite direction in which the flakes are transferred by the second suction means 140, .

The temperature of the inert gas H1 is preferably a dry inert gas heated to the same temperature as the temperature inside the cylinder 230 at the point where the inert gas is injected. This is because the temperature of the melt, In order to avoid such problems.

That is, since the inert gas at room temperature reduces the heat transfer of the flakes and the melt, a heat transfer higher than the set temperature is required. Therefore, in the present invention, the temperature of the melt can be maintained by using a heated inert gas and thermal decomposition of the polymer can be prevented by not applying high heat transfer. The temperature of the inert gas is preferably 100 ° C. or more and less than 300 ° C. Do.

Preferably, the inert gas is injected at a pressure higher than the internal pressure of the cylinder 230 at the point where the inert gas is injected. Do. Further, injecting the inert gas at a high pressure is preferable because the dispersion of the polymer and the gas becomes more uniform.

The flow rate of the inert gas is preferably 10 NL / min to 200 NL / min (NL is the volume (L) at 0 and 101.3 kPa) based on the material kg.

Next, as shown in FIG. 2, the extrusion apparatus according to the present invention may be extruded in a state where the flakes passing through the melting zone I are melted and immediately passed through the metering zone IV and the impurities are removed Degassing can be performed before passing through the metering zone IV, as shown)

As shown in FIG. 4, after the molten resin I is injected into the molten resin, the inert gas H 2 is injected into the molten resin and the molten resin is passed through the mixing zone II. After passing through the pressure reducing and degassing zone III, ). ≪ / RTI >

The operation and process from the mixing zone (II) shown in FIG. 4 are described in detail in the applicant's patent registration No. 10-01298068, and the description starting from the mixing zone (II) is disclosed in Patent Registration No. 10-01298068 It briefly explains the basic functions of each part.

The molten resin which has been removed in the molten zone I is transferred to the mixing zone II to be mixed with the inert gas or nitrogen gas in the mixing zone II and to the reduced pressure and degassing zone III Lt; / RTI > The removal of the impurities by the action of the inert gas is carried out in the depressurizing and degassing zone (III) which is formed next to the mixing zone (II), and the depressurizing and deaerating zone (III) is the zone in which the pressure is set below the atmospheric pressure.

In addition, the surface area of the molten resin is drastically increased in the decompression and degassing zone (III) to increase the degree of polymerization and increase the expansion and surface area according to the nitrogen injection in the mixing zone, thereby facilitating the removal of impurities including residual moisture do.

The molten resin mixed with the inert gas is supplied through the through hole 255 formed in the mixing zone II to the depressurization and degassing zone III, (III-1) which is atmospheric pressure or lower while passing through the pressure reducing zone 255, whereby the surface area is maximized and impurities can be removed.

A vacuum pump (P) is connected to the decompression and degassing zone (III), and impurities including water deaerated from the molten resin through the vacuum pump are sucked and discharged by a vacuum pump.

It is preferable that the pressure of the inert gas (H2) injected into the mixing zone II, that is, the nitrogen gas is injected at 50 kg / cm 2 to 200 kg / cm 2, and the temperature of the nitrogen gas is set to the temperature of the molten resin in the cylinder.

While the present invention has been described with reference to the accompanying drawings, it is to be understood that the present invention is not limited to the disclosed embodiments, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

Description of the Related Art [0002]
f: flake
10: Feeding device
110: first supply part 115: first slide gate
120: second supply part 125: second slide gate
130: first suction means 140: second suction means
20: extruder 25: extruder feed point
200: screw 230: cylinder
I: Melting zone II: Mixing zone III: Decompression and deaeration zone

Claims (5)

A raw material feeding device into which a flake for recycling is fed,
And an extruder in which the charged flakes are heated and melted and extruded to remove impurities,
Wherein a vacuum suction is performed in the extruder to a melting point or a region before or after the melting point to degas moisture in the flakes, thereby recycling the recovered waste polymer provided with the dehumidifying function. The extrusion apparatus according to claim 1, wherein an inert gas is injected into the region of the melting point or the melting point in the extruder, for recycling the recovered waste polymer provided with the dehumidifying function. The extrusion apparatus according to claim 2, wherein the injected inert gas is a heated dry gas. The extrusion apparatus recycles the recovered waste polymer having a dehumidifying function. 3. The extrusion apparatus according to claim 2, wherein the injected inert gas is injected at a pressure equal to or higher than a pressure in the cylinder. The extrusion apparatus for recycling the recovered waste polymer having a dehumidifying function according to claim 1, wherein the raw material supply device and the extruder are extruded while maintaining a vacuum of less than 100 mbar.

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