KR102390536B1 - Twin Screw Extrusion Dryer - Google Patents

Abstract

The present invention relates to a screw-type compression dehydration method capable of efficiently removing water from an acrylic rubber polymer containing water while maintaining physical properties of the acrylic rubber polymer, and increasing productivity; and a copper screw-type dehydrator. The dehydrator of the present invention comprises a plurality of partitioned compression zones, and temperatures for each zone are repetitively heated or cooled to increase coagulation efficiency.

Description

Twin Screw Extrusion Dryer

The present invention relates to a screw-type compression dehydration method capable of efficiently removing water from an acrylic rubber polymer containing water while maintaining physical properties of the acrylic rubber polymer and increasing productivity, and a copper screw-type dehydrator.

As for the conventional dehydration of polymers by suspension polymerization, other methods, such as fluid drying, are common, and most of them are dried by the same method even today. In the case of using such an airflow or fluidized dryer, in the drying process, a large amount of thermal energy is required to evaporate moisture after the liquid component is removed with a centrifugal dehydrator, etc., and the loss is large, and thermal deterioration of the resin is accelerated. In this case, since it is obtained as a powder, it takes a lot of energy, but there is also a problem of dust explosion, and there are problems such as blocking of the flowing powder or difficulty in handling.

In order to solve this problem, after removing most of the moisture from the slurry of the vinyl polymer obtained by suspension polymerization by a filter or a centrifugal dehydrator, the undried hydrous polymer is mixed with a dehydrating unit having a plurality of slits and at least one vent opening There is known a method for recovering a polymer that is supplied to a twin-screw extruder consisting of a barrel equipped with a barrel and a screw inserted into the barrel, is compressed and dehydrated inside, and is simultaneously plasticized and continuously extruded in a molten state at the tip nozzle of the copper extruder. The effect is still insufficient.

In addition, the dehydration efficiency is still not good, which may cause vapors in the kneading or melting stage afterward, and there are still disadvantages that require a lot of energy.

The present invention solves the above problems, has excellent drying efficiency, does not cause carbonization in the drying process, and increases the internal pressure due to water still present in excess at the rear end in the compression drying process, and also increases the pressure Provided is a dewatering device and a dewatering process for acrylic rubber that does not have foam cells inside the final produced pellets, and does not cause a problem of reducing the surface uniformity of the product during blending and processing with other thermoplastic resins after pelletization. In addition, it is to provide a new method that solves the problem that the inside of the extrusion dehydrator rises during the dehydration process, which lowers the stability of the machine operation,

Accordingly, the present invention is to provide an extrusion drying method and a drying apparatus using a new twin screw for solving the above problems.

As a result of research to achieve the above object, the agglomerated mixture of acrylic rubber polymerization prepared through emulsion polymerization (in the form of a polymerized slurry containing water, rubber particles and various additives) was mixed with the raw material input part of the screw-type extrusion dryer and pressed A twin-screw screw inserted into the barrel having a barrel comprising a section (compression zone), a primary dewatering slit zone, a squeezing zone, and an arrangement of a secondary slit zone, a kneading zone, a vacuum discharge zone and a pelletizing zone The present invention was completed by providing an extrusion dryer having a.

In addition, the present invention relates to the raw material input part, compression part, and primary dehydration slit of a screw-type extrusion dryer for agglomerated mixture of acrylic rubber polymerization (in the form of a polymerized slurry containing water, rubber particles and various additives) prepared through emulsion polymerization. An extrusion dryer having a barrel including an arrangement of a zone, a squeezing zone, a second slit zone, a kneading zone, a third slit zone, a vacuum discharge zone and a pelletizing zone, and having a twin screw inserted into the barrel By providing the present invention was completed.

One aspect of the present invention is a twin screw type extrusion dryer, wherein the dryer is a compression zone in which the acrylic slurry is aggregated by increasing the temperature, a first slit zone having a dehydration function to discharge liquid water, and dehydration by squeezing the first slit zone A twin screw type for drying and pelletizing an acrylic rubber slurry including a first squeezing zone that provides a back pressure to An extrusion dryer is provided.

As mentioned above, by adopting the temperature program for each section of the present invention, the screw element of the squeeze zone and the temperature program of the compression zone, the reduced pressure discharge part, etc. in combination, it can be manufactured in the form of pellets, not in powder form, with excellent dehydration effect, The effect of easy handling can be achieved.

In addition, the polymer can be easily obtained in the form of pellets through a simple improvement of the conventional twin screw extruder, and due to the increase in the internal dehydration effect, an excellent effect of sufficiently lowering the moisture content is achieved even when manufactured in the form of pellets rather than powder form. do.

Therefore, handling is easy, and when kneading with other thermoplastic resins using the acrylic rubber in the form of pellets of the present invention, the kneading effect and dispersing effect are excellent, and it can also have advantages in processing that minimizes an additional dehydration step.

1 is a schematic configuration diagram of an extrusion dryer of the present invention.
2 is a schematic view of the element of the screw and the element of the squeezing zone.

Hereinafter, the present invention will be described in more detail through embodiments or examples including the accompanying drawings. However, the following specific examples or examples are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

Also, unless defined otherwise, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description herein is for the purpose of effectively describing particular embodiments only and is not intended to limit the invention.

Also, the singular forms used in the specification and appended claims may also be intended to include the plural forms unless the context specifically dictates otherwise.

Also, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

One aspect of the present invention is a twin screw type extrusion dryer, wherein the dryer is a compression zone in which the acrylic slurry is aggregated by increasing the temperature, a first slit zone having a dehydration function to discharge liquid water, and dehydration by squeezing the first slit zone A twin screw type for drying and pelletizing an acrylic rubber slurry including a first squeezing zone that provides a back pressure to An extrusion dryer is provided.

In one aspect, the compression zone may be divided into a plurality of compartments, and the temperature of each zone may be maintained at 60 to 150° C. to dry and pelletize the acrylic rubber slurry that promotes the aggregation of the slurry.

In one aspect, the temperature of the compression zone may be increased to 60 ~ 150 ℃, more specifically 70 ~ 100 ℃ to increase the coagulation efficiency by drying and pelletizing the acrylic rubber slurry by heating and cooling.

According to the present invention, the semi-molten acrylic rubber is extruded into strands through the die of the head, cut into pellets through the die, and packaged.

In addition, in the present invention, the depth of the screw channel at the rear end of each slit zone is lower than the channel depth of the screw at the front end, so that the dehydration effect in each slit zone can be further enhanced.

In addition, the present invention is a screw element of the squeezing zone to have a seal ring shape (see Fig. 2(b)) in which a channel is not formed as a cylinder shape to increase the compression efficiency, so that the dehydration effect in the first slit zone It may be characterized in that it is increased by 10% or more, more preferably by 20% or more.

In the above description, the channel means the distance from the bottom surface formed between each element to the top of the element in FIG. 2( a ).

In addition, the present invention is also characterized by further increasing the dehydration effect in the squeezing zone by performing a temperature program in the compression zone to alternately increase the temperature and the cooling, thereby further increasing the aggregate size of the fed aggregates. By adopting a compression zone divided into a plurality of cooling and heating zones for temperature, it is possible to further increase the dehydration effect.

In addition, the present invention is programmed within 60 ~ 150 ℃ or maintained at 60 ~ 150 ℃ in the compression zone, and the temperature of the first slit zone, the first squeezing zone and the second squeezing zone is raised to 100 ~ 250 ℃ After dehydration, by setting the temperature at 10 to 50 ° C lower than the temperature of the second squeezing zone in the kneading zone, while preventing fusion due to melting, pulverize by kneading and crush into powder or small lumps in the second slit zone or It is possible to facilitate dehydration from the ventilation zone to the vapor phase. If the temperature is not lowered, it is not good because it is fused by partial melting, thereby reducing the efficiency in which water evaporates in the vapor phase in the third slit zone or the ventilation zone and is removed.

Hereinafter, the present invention will be looked at in more detail.

In the present invention, the compression zone is formed of a plurality of temperature setting zones, and by increasing the temperature to 60 to 150° C. by introducing the acrylic rubber slurry, the size of the aggregate of the aggregated input slurry is increased, more preferably in the compression zone. When the temperature program is carried out and the temperature rise and the cooling are alternately increased to further increase the aggregate size of the fed agglomerates to further increase the dehydration effect in the squeezing zone, it is preferred because it has a better dehydration effect. That is, by adopting a compression zone divided into a plurality of cooling and heating zones for temperature, it is possible to further increase the dehydration effect. If the temperature program is not set, it is possible to increase the size of the agglomeration by maintaining each zone at 60~150℃, but it is more preferred because repeating the cooling temperature increase with the temperature program significantly improves the dehydration effect.

In the compression zone, this agglomeration size is increased and then transferred to the next stage by a twin-screw screw.

After passing through the compression zone, the acrylic rubber mixture sufficiently agglomerated at high temperature removes 30% or more, preferably 50% or more of the water in the first slit zone. The primary slit zone delays the transport speed by increasing the height of the barrel of the squeezing zone present at the rear end of the primary slit zone for the slurry agglomerate flowing in from the compression zone, thereby rotating while squeezing the aggregate of the primary slit zone. Dehydration proceeds while passing through the slit formed in the slit zone.

Therefore, another feature of the present invention is that the dehydration efficiency is further increased by controlling the height of the barrel of the squeezing zone to further reduce the forward speed. In the primary slit zone, it is possible to achieve a dehydration rate of 50 wt% or more, preferably 60 wt% or more, and more preferably 70 wt% or more, and when the height of the barrel of the squeezing zone is not increased, it is usually about 30 wt%. Although it has a dehydration rate in the present invention, since it has a remarkably high dehydration rate, it is good that there is no need to have an additional drying step due to the generation of steam at the rear end or the low content of the final dried pellets.

In addition, in the first squeezing zone, the temperature is increased from that of the compression zone, and by raising the temperature to 100 to 250 ℃, the rubber aggregate to be squeezed in the primary is partially melted, and the compression of the squeeze zone is further improved to increase the dehydration efficiency. It is also a feature of the present invention. In general, when the temperature of the compression zone is 100℃, if the temperature of the primary squeezing zone is maintained at 160~180℃, the dehydration efficiency is also increased, and the dehydration efficiency is further increased by discharging as steam along with dehydration through the primary slit. can do it

The resin dehydrated in the first slit zone by the first squeezing zone is put into the kneading zone, at this time, in the kneading zone, it is set at a lower temperature than the partially melted state in the first squeezing zone and pulverized into powder. , it is transferred to the secondary slit zone again, and the height of the barrel is adjusted to be higher than the height of the barrel in the squeezing zone in the secondary squeezing zone located at the rear end of the secondary slit zone, and squeezed in the secondary squeezing zone for additional dehydration and water contained in the resin that has passed through the secondary squeezing zone is further dehydrated through a reduced pressure dehydration ventilation device to remove 95 wt% or more, preferably 98 wt% or more of water or unreacted monomers.

After that, the dehydrated resin powder is cut by a die head to make pellets.

In addition, as described above, the present invention includes a temperature control means for controlling the temperature of the compression unit, the squeezing unit, the kneading unit, and the head die unit. It is also characterized by further increasing the dewatering efficiency at the slit by setting higher than the height of the forward advancing screw of

In addition, the present invention may further include a dehydration step by further providing a tertiary slit zone after the kneading zone if necessary.

An example of the present invention may be described as shown in FIG. 1 . 1, when acrylic rubber sludge containing 40 to 70 wt% of water is put into the raw material inlet of the barrel, for example, ABS graft polymer containing 30 to 40% of water is When it is put into the raw material inlet of the barrel, it is sent forward by the rotation of the twin-screw screw. The compression zone consists of a plurality of sections, and each section may be programmed with a different temperature or may be programmed with the same temperature. The temperature of each section is set in the range of 60~150℃, and the larger the temperature deviation, the better the cohesive effect is, for example, if the temperature is repeated like 100℃, 70℃, 100℃, 70℃ In this case, the agglomeration effect of the slurry is better and the dehydration effect can be further increased in the slit zone or squeezing zone at the rear end. can do. However, in the case of a temperature program, energy consumption can be large, so it is good to keep it at a constant temperature. for example.

After accelerating agglomeration in the compression zone, the shape of the screw of the primary squeezing zone located at the rear end of the primary slit zone is changed to the shape of a screw element in another barrel zone, for example, an RFV element (FIG. 2(a)). By adopting a screw having a different shape of a seal ring (see Fig. 2(b)), the dewatering efficiency of the primary slit zone is significantly increased. By giving the change of the screw element of the squeezing zone as described above, the depth of the channel of the same or similar RFV element adopted other than the squeezing zone of the present invention is made thin to give squeezing. Effect, for example, can bring about an increase in the dehydration effect of 10% or more, preferably 20% or more. With such an increase in the dehydration effect, the temperature of the cylinder of the squeezing zone or the kneading zone located at the rear end is raised to 150 ° C. or more, for example, 160 to 230 ° C., and the secondary or 3 It may have the effect of allowing it to be discharged as vapor rather than as water in the primary slit zone. If a sufficient dehydration effect cannot be obtained in the primary slit zone, it is still dehydrated in a liquid form such as water in the secondary and tertiary slit zones. Therefore, problems such as lengthening the dehydration process or adding a process for dehydration with steam may appear.

After that, the primary dehydrated resin is put into the kneading zone, and in the kneading zone, the temperature is maintained at a lower temperature than the primary squeezing zone and high shear force is applied to partially melt and pulverize the resin, and to prevent resin deterioration and die face cutting. After cutting, it is possible to prevent the pellets from aggregating at high temperatures, and also to prevent fusion due to melting, which can further promote dehydration in the next stage of vacuum ventilation. The powder or flake acrylic rubber polymer obtained in the kneading step can be obtained, and it is usually kneaded by keeping the temperature of the squeezing zone lower than the temperature of the squeezing zone of the previous stage by kneading and pulverized into a powder.

In addition, a second slit zone is formed between the kneading zone and the shear squeezing zone, and the second slit zone is dehydrated in a vapor phase by back pressure by kneading. The reason for dehydration in the vapor phase is that the temperature of the squeezing zone and the kneading zone can be sufficiently increased and the dehydration efficiency can be increased in the first slit zone.

After the resin dehydrated by steam in the second slit zone is kneaded, it is ventilated under vacuum or reduced pressure in the reduced pressure discharge zone, and then pelletized through a die head. The temperature of the decompression zone is set to be the same as the temperature of the kneading zone, and the remaining water or unreacted monomers are recovered and separated by reducing the pressure.

In addition, the present invention may further include the step of additionally discharging water in a vapor state by additionally introducing a third slit zone between the kneading zone and the reduced pressure discharge zone. In this case, even if the squeezing zone after the third slit zone is not additionally installed, the remaining trace amount of moisture can be sufficiently discharged as steam, so a special device may not be required.

The resin powder that has passed through the reduced pressure discharge zone of the present invention is compressed in a head die, partially melted, and then cut and pelletized while discharging to a strand.

As described above, the present invention has been described with specific details and limited examples and drawings, but these are only provided to help a more general understanding of the present invention, and the present invention is not limited to the above embodiments, and the present invention is not limited to the above embodiments. Various modifications and variations are possible from these descriptions by those of ordinary skill in the art.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and not only the claims described below, but also all of the claims and all equivalents or equivalent modifications to the claims will be said to belong to the scope of the spirit of the present invention. .

C1: raw material input part, C1 ~ C5: compression zone
C6: 1st slit zone C7 ~ C8 1st squeezing zone
C9: Second slit zone C10: Kneading zone
C11: 3rd slit zone C12 ~ C14 decompression discharge zone
C15 : die head
C10 ~ C14: 2nd squeezing zone

Claims (3)

As a twin screw type extrusion dryer, the extrusion dryer provides a compression zone in which the acrylic slurry is agglomerated by increasing the temperature, a first slit zone having a dehydration function to discharge liquid water, and a back pressure for dehydration by squeezing the first slit zone A twin screw type extrusion dryer for drying and pelletizing acrylic rubber slurry including a first squeezing zone, a second slit zone for discharging vapor phase water, a kneading zone, a reduced pressure discharge zone, and a die head for pelletizing,
The compression zone is divided into a plurality of compartments, and the temperature of each compression zone is alternately raised and cooled at 60 to 150° C. to increase the coagulation efficiency. A twin screw type extrusion dryer for drying and pelletizing the acrylic rubber slurry. The method of claim 1,
A twin screw type extrusion dryer for drying and pelletizing acrylic rubber slurry that is dehydrated by raising the temperature of the first squeezing zone to 100 to 250°C. 3. The method of claim 2,
A twin-screw type extrusion dryer that dries and pellets the acrylic rubber slurry in which the temperature of the kneading zone is set 10 to 30°C lower than the temperature of the first squeezing zone.

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