JP3029075B2 - Method and apparatus for producing resin powder with low residual vinyl monomer content by steam treatment of vinyl chloride resin slurry - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vinyl chloride resin (hereinafter "PVC") containing vinyl monomers such as unreacted vinyl chloride monomer (hereinafter sometimes abbreviated as "VC") as residual vinyl monomer. The present invention relates to a method for producing VC having a low residual VC content by removing VC from a slurry, and an apparatus used therefor.

More specifically, the present invention introduces a treated PVC slurry containing unreacted VC into a treatment passage formed on a perforated plate shelf, and transmits steam from below through the pores of the perforated plate. while injecting into the slurry, conical with respect to the liquid surface a different water vapor from above the slurry surface
In addition, in some cases while suppressing foam generation of the processed PVC slurry by intermittently injected (foam), eliminating the bubbles generated without could be suppressed early (defoaming)
It is allowed by an apparatus that is used method and its producing stable low PVC residual VC content consisting of keeping the flow state.

[0003]

2. Description of the Related Art PVC, also known as polyvinyl chloride, is a resin having excellent properties both chemically and physically. The production is usually carried out by polymerizing VC in an aqueous medium by a suspension polymerization method, an emulsion polymerization method or a bulk polymerization method. Among them, the suspension polymerization method and the emulsion polymerization method are widely used. In both methods, the polymerization reaction is stopped when a certain polymerization conversion rate, generally 80-95%, is reached, the aqueous medium is mechanically separated from the polymer slurry obtained, and hot air drying or other The aqueous medium is removed by various drying methods to obtain a polyvinyl chloride (PVC) powder.

[0004] in an aqueous medium which is separated at each stage of the
Also, in the exhaust from the dryer is also still a small amount of VC in PVC powder immediately after drying remaining. However, from the viewpoint of environmental protection, it is desirable to reduce the amount of residual VC as much as possible.

In the step of removing or recovering the unreacted monomer, the slurry to be treated is placed on a perforated plate shelf of a treatment tower equipped with a perforated plate shelf in which a processing passage is formed in a groove shape and divided by partition walls. Introducing water vapor from below through the pores of a perforated plate has been proposed (Japanese Patent Application Laid-Open No. 54-869).
3 and JP-A-56-22305). In this treatment, VC contained in PVC powder or PVC slurry is vaporized and separated by being put on steam introduced from below a perforated plate tray.

[0006]

In the above-mentioned treatment method, the PVC slurry to be treated on the perforated plate tray is foamed by the introduction (spray) of water vapor from below and overflows the partition wall. Undesirable situations often occur, such as the situation that flows into the downcomer pipe and the situation that enters the condenser via the VC discharge pipe. As a result, VC is still present in the product PVC particles flowing out of the outlet of the treatment equipment.
Cause a situation in which the remaining in a high-level of the amount to.

Further, the PVC particles adhered to the inner wall of the processing apparatus (tower) are deteriorated by being exposed to high-temperature steam for a long time due to the foaming due to the foaming. If mixed with, it may cause foreign matter.

The object along with it suppresses foaming of the above conventional process is a situation that occurs in the treatment tower (processor) of the present invention, by extinguishing once resulting foam without could be suppressed at an early stage The object of the present invention is to eliminate the obstacles of the conventional method.

[0009]

The present inventors have presumed the causes of the above-mentioned obstacles as follows: The bubbles generated by steam-treating the PVC slurry to be treated on a perforated plate tray are PVC particles. the generation of the bubble is a bubble of desorbed VC and water vapor from the interior Accordingly, the volume of the processed PVC slurry on the perforated plate apparent expands, the partition walls partitioning the groove-like processing channel as a result A situation may occur in which the fluid overflows and flows into the downcomer pipe, and if it proceeds further, it enters the condenser via the VC extraction pipe.

As a result of study based on the above presumption, the present inventors have arrived at the present invention which requires that the following three conditions be simultaneously satisfied. That is, according to the present invention defined in claim 1, the above-mentioned problems can be solved and the effects of the present invention can be sufficiently exhibited: 1) By introducing steam from below the perforated plate shelf, Thereby, the PVC slurry on the tray is stirred; 2) water vapor is conically sprayed from above the liquid level of the PVC slurry to the liquid level; 3) scattered matter from the PVC slurry or coagulated matter after volatilization. Is washed with warm water.

The present inventors have made intensive efforts to solve the above problems, and have completed the present invention described below. That is, in the present invention, when treating the PVC slurry to be treated in the tower-type treatment apparatus equipped with the perforated plate shelves, a process of injecting steam into the slurry through pores from below the perforated plate shelves . Continue
Over during the period, steam injection mechanism provided separately above the slurry surface for example, the residual by processing the processed PVC slurry comprising injecting steam against the treatment PVC slurry liquid surface from the nozzle The present invention relates to a method for producing a resin powder having a low vinyl monomer content and an apparatus used for the method.

As described above, the effect of separately jetting steam from above the liquid surface of the treated PVC slurry so as to exert a pressing force as uniformly as possible on the liquid surface is as follows.
Lies in extinguishing the bubbles generated without could be suppressed and the suppression of foam generation in the VC slurry, resulting as a residual V
PVC with a low C content can be produced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto.

FIG. 1 shows a perforated-plate-type tower-type treatment apparatus ("13" in FIG. 3) for carrying out the method of the present invention, in which a PVC slurry to be treated containing unreacted residual VC is stored. It is a schematic plan view of the perforated plate shelf 1 which performs a VC removal process. This perforated plate shelf 1 is usually formed with a perforated plate as a bottom plate of the processing passage as shown in FIG. 2, and a large number of pores are provided through the perforated plate shelf. Water vapor is passed through the pores from the lower side of the perforated plate shelf 1 through the pores.
Injected into C slurry.

The upper surface of the perforated plate shelf 1 has partition walls 20 to
23 are staggered (staggered). The role of the partition walls 20 to 23 is to make the flow of the PVC slurry to be treated introduced onto the perforated plate shelf 1 stay on the perforated plate shelf 1 for a predetermined time. As a result, the PVC to be treated is heated by the heat supplied from the steam injected through the pores.
Unreacted VC (residual VC) in the slurry is stripped, and water or the like, which is the medium of the PVC slurry to be treated, is removed by evaporation.

FIG. 2 is a schematic longitudinal sectional view of a tower type processing apparatus for further understanding the state of the processing system. In FIG. 2, it is apparent that a plurality of rows of partition walls 2 (collectively 20, 21, 22 and 23, etc.) rise from the upper surface of the perforated plate shelf 1 to partition the contained PVC slurry to be treated. Will be taken care of. FIG. 2 shows a perforated plate shelf 1
Is located at the top of the tower type processing apparatus.
When the perforated plate shelf 1 is located at or below the second stage, the left end section is the lower end of the downflow pipe from another perforated plate shelf (not shown) located immediately above the perforated plate shelf 1 Will be located. Further, a hot water injection ring 6 with an injection nozzle is installed below the shelf plate immediately above, and every time a predetermined time elapses, hot water is injected from the injection nozzle to wash the inside of the VC removal tower. Detailed configuration of hot water injection ring 6 with injection nozzle
For details on the deformation and specific operating conditions, see the separate section below.
Is described in

The PVC slurry to be treated introduced into the left end section of the perforated plate shelf 1 of FIG. 2 is subjected to steam treatment while flowing along the partition wall 20 in the direction of the drawing, and the body plate is formed at the end of the partition wall 20. 3 reached, subjected to steam treatment while flowing folded in the right partition wall 21 to the back direction, flows down tube this condition is formed by and the partition wall 23 is repeated tower wall 4
To reach. P to be processed after processing in perforated plate shelf 1
The VC slurry flows into a perforated plate shelf (not shown) immediately below via the downflow pipe 4, and reaches the outlet 11 of the processing apparatus 13 in FIG. 3 while repeatedly receiving the above-described processing.

In the present invention, in addition to the conventional treatment in which the PVC slurry to be treated is only treated on the perforated plate shelf 1 by steam injected from below the perforated plate shelf, the entire process is carried out. Over the period, steam is also jetted onto the slurry surface from the steam jet nozzle 5 separately provided above the surface of the PVC slurry to be treated.

Injection pressure of water vapor from above in the present invention
The force is usually 1 kgf at the outlet of the steam injection nozzle 5.
/ Cm²(Abs.)13 kgf / cm
² (Abs.) Or less, Preferably 1.1 to 11 kgf /
cm²(Abs.). If the injection pressure is too low
As a result of the lack of water vapor holding energy,
The steam will not be able to exhibit the expected foam extinction ability.Conversely
With a high injection pressure, the liquid level of the PVC slurry to be treated
As a result of the water vapor hitting the surface of the slurry
Induce foaming.

The amount of steam injected is 50 to 400 kg / h per m ² , preferably on the basis of the area of the perforated tray.
It is appropriate to select from 80 to 250 kg / h . When the injection amount is 45 kg / h / m ² or less, the defoaming effect is insufficient, and when the injection amount is 405 kg / h / m ² , the amount of steam used exceeds the required amount. Injection of steam is usually performed continuously, but may be performed intermittently. When performing intermittently, it is appropriate to perform so that the actual injection amount of water vapor falls in the above range. A method in which intermittent injection is repeated periodically may be suitable for adoption.

The structure of the steam injection nozzle 5 for eliminating bubbles (defoaming) or suppressing (suppressing bubbles) according to the present invention is uniform at any point on the surface of the treated PVC slurry flowing on the perforated plate 2. It is important that the injected steam be distributed to the water. This requirement is that when the steam injection nozzle 5 is installed near the center of the perforated plate shelf 1, the locus of the steam becomes longer as the distance from the center increases, and the temperature (holding heat energy) can decrease. It starts with trying to compensate as much as possible.

The installation position of the steam injection nozzle 5 is
It is preferable to select the height of the slurry from 50 to 1000 mm above the surface of the VC slurry in order to obtain a sufficient effect. If the steam jet nozzle 5 is installed at a position that is too low, it is difficult to jet steam uniformly to the surface of the PVC slurry to be treated. If the water vapor injection nozzle 5 is installed at a position that is too high, the height of the entire processing apparatus 13 may be increased more than necessary.

The apex angle (θ) of the conical surface formed by the steam group sprayed from above with respect to the surface of the PVC slurry to be treated is usually in the range of 60 to 150 degrees , preferably 100 to 135 degrees. P to be processed existing on the shelf 1
It is preferable to set so that the action of the steam can be applied as uniformly as possible to any part of the liquid surface of the VC slurry.
When the action of the steam is unevenly applied, local foaming is caused in the PVC slurry to be treated, resulting in a reduction in the defoaming effect.

The following are examples of the structure of the water vapor injection nozzle 5 that meets this demand: The diameter of the injection nozzle is increased in proportion to the distance from the center of the perforated plate shelf.・ Increase the number of holes of the injection nozzle in proportion to the distance from the center of the perforated plate shelf. ・ Use a wide-angle conical nozzle (conical nozzle with a large vertical angle θ) .

The body plate 3 and the partition walls 20 and 20 of the tower-type processing apparatus for processing the PVC slurry to be processed according to the present invention.
And the perforated plate constituting the bottom plate of each processing passage between the partition walls 21 and 22, and the partition walls 22 and 23 must have the following functions:-The PVC to be processed existing thereon The slurry does not flow down through the pores, and does not substantially block the pores. The PVC slurry to be treated is formed by allowing steam to pass therefrom over a long period of time and uniformly at any place. Be able to send it inside.

Further, the processing passage is required to have a slurry outflow path such as the downflow pipe 4 as shown in FIG. 2 and the PVC slurry extraction pipe 11 as shown in FIG.

In order to exhibit the above function, the diameter (inner diameter) of each pore provided in the perforated plate shelf is usually 5 mm or less, preferably 0.5 to 2 mm, most preferably 0.7 mm.
Set to に 1.5 mm. In addition, the opening ratio of each perforated plate shelf (= total pore area / perforated plate area; aka “opening ratio”) is 0.01 to 10%, preferably 0.04 to 4%.
%, Most preferably 0.2 to 2%.

When the opening ratio is significantly lower than the above lower limit, a state occurs in which the PVC particles present in the PVC slurry to be treated on the perforated plate tray are not sufficiently stirred. The cause is that the energy supplied by the water vapor injected from below into the PVC slurry to be treated through the pores of the perforated plate is insufficient for the intended stirring. Conversely, when the opening ratio of the perforated plate is significantly higher than the upper limit, the phenomenon that the treated PVC slurry existing on the perforated plate flows down from the pores (liquid leakage).
Or the excess water vapor is consumed even if the liquid does not leak.

In order to allow the PVC slurry to be treated to stay on the perforated plate constituting the perforated plate shelf 1 for a time required for the treatment, the processing passages (the partition walls 20, 21, 22, and 23) are required.
, Etc.) are formed in a series of long grooves. The streamline of the processing passage formed by the groove-shaped passage is appropriately selected from a ninety-nine-fold type (sheep-intestine type), a spiral type, a wicker type or a star type (radial type) as shown in the drawings, depending on the situation. it can.

In short, the processing path is such that the PVC slurry to be processed forms an extrusion flow while the following conditions are realized and maintained.
Moving upwards is sufficient for expressing the effect of the present invention. -The PVC slurry to be treated loaded on the perforated plate shelf is not accompanied by vigorous bubbling on the perforated plate shelf.-The time during which each PVC particle stays on the perforated plate shelf is made uniform; The PVC particles are uniformly suspended in the liquid medium and do not cause local uneven distribution.

The above-mentioned various partition walls 20, 21, 22 and 2
3 or the like, the perforated plate shelf 1 provided with the passage for treating the PVC slurry to be treated is provided in the treatment apparatus 13 of the present invention (including a tower type) in one or more stages. The effects of the present invention can be obtained by applying the improved mechanism and processing method.

When the processing apparatus of the present invention is provided with two or more perforated plate shelves (for example, 1 and 1a), the perforated plate shelves directly above the perforated plate shelves 1a located at the lower stage A hot water injection ring 6 is provided below the lower surface 1 and the lower surface of the perforated plate shelf 1 and the inner wall surface of the body plate connected thereto are connected to the hot water injection ring 6.
It is necessary to wash with hot water injected from the hot water injection nozzle provided . The hot water injection ring 6 may be formed by shaping a hot water pipe into a ring shape, and providing an appropriate number of injection nozzles and an appropriate number of injection nozzles for injecting hot water in a desired direction toward the lower surface of the shelf 1 and the inner wall of the body plate. The direction of hot water injection is such that the angle (γ) at which the axis of each hot water injection nozzle intersects the vertical direction is 10 °.
It is preferable to set the angle to about 60 degrees.

The hot water injection ring 6 may have a planar shape such as the Greek letter Ω type or Φ type, or the spiral type, star type or sheep intestine type (99-fold). It can be a type. The maximum diameter of the hot water injection ring 6 may be set so that the outer edge of the ring 6 is located inside the inner wall of the body plate 3 of the tower. However, if the inner wall of the body plate 3 is too close, there is a risk that the PVC particles and the like that are washed off may block the gap. In order to prevent such a situation, it is sufficient to set the outer diameter of the hot water injection ring 6 so as to be at least 20 mm inward from the inner wall of the body plate 3. It is preferable that the outer diameter of the hot water injection ring 6 is usually 150 to 2,000 mm when viewed from the inner diameter of the tower of a commonly used tower processing apparatus.

Here, the temperature of the hot water to be injected is PVC
Rally temperature ± 10 ° C, preferably the slurry temperature ±
7 ° C, more preferably ± 5 ° C of PVC slurry temperature.
Preferably .

The hot water injection is preferably performed at intervals of 90 minutes or less.
Or residual vinyl at intervals of 60 minutes or less
Preferred for producing resin powder with low monomer content
No. Further, the hot water injection is performed for 1 second or more, preferably 5 seconds.
ec or more to reduce residual vinyl monomer content
It is preferable for producing a resin powder. In another aspect, the
The hot water injection amount is 0.1 to 50 m ³ / h / m ² per operation.
Resin powder with low residual vinyl monomer content
Is preferred for production. Here, per operation means
Meaning one injection from each injection nozzle
You. That is, a plurality of injection nozzles are bored in the injection ring 6.
The temperature with multiple hot water injection nozzles
In the water injection ring 6, the total amount of hot water to be injected (total
(Hot water injection amount) is the injection amount per injection nozzle and its injection
It is the product of the number of injection nozzles.

The shape of the opening of the injection nozzle provided on the hot water injection ring 6 can be appropriately selected from circular holes, oval holes, slits and the like according to the purpose of use. Here, the maximum diameter of the circular hole or oblong holes are usually 1 to 8 mm, while the maximum length of the slit is preferably also chosen to normal 1 to 8 mm.

On the other hand , if the above-mentioned steam jetting mechanism 5 is passed from above to the surface of the PVC slurry to be treated existing on the perforated plate shelf 1, the steam can be jetted uniformly . Of course, the perforated plate shelf 1 having the above-described processing passage
Is a multi-stage assembly in the processing apparatus, that is, 1, 1a, 1
Usually used in arrangements such as b and 1c.

The case where the processing apparatus of the present invention is of the tower type will be described. The inner diameter (inner diameter: D) of the tower is also equal to the tower height (H).
There are no special restrictions. Normally tower inner diameter (D) 300 ~ 3
If it is set to 000 mm, preferably 500 to 2000 mm, it is suitable for most uses. Also, [ Tower height (H)
/ Tower inner diameter (D) ] ratio is selected such that H / D = usually 2 to 20, preferably 5 to 15.

The treated PVC slurry of the present invention contains, in addition to the aqueous dispersion medium and the PVC particles (powder), residual VC monomers to be removed therefrom.
The slurry may further contain a suspending agent, such as polyvinyl alcohol (P), added to the polymerization system during polymerization for resin production.
VA), carboxymethylcellulose (CMC), and the like, a buffer, a particle size adjusting agent, a scale adhesion inhibitor, an antifoaming agent, and the like.

PVC is a polymer of VC, which is a bonding unit of a molecular chain constituting a resin, and is an abbreviation of polyvinyl chloride, which is also called vinyl chloride resin. VC is an abbreviation for vinyl chloride (monomer).

However, the PVC to be treated in the present invention is V
The concept is not limited to a homopolymer of C, but includes a copolymer of VC with another vinyl monomer, a graft polymer of VC to an olefin polymer, and a composition of two or more of these. A typical example of PVC is a polymer containing 50% by weight or more of a VC unit as a constituent unit of the polymer.

Here, the term "vinyl monomer" is a concept including various kinds of: carboxylic acid esters of vinyl alcohol such as vinyl acetate; vinyl ethers such as alkyl vinyl ether; and unsaturated carboxylic acid. Esters such as acrylates and methacrylates; vinylidene halides such as vinylidene chloride and vinylidene fluoride; unsaturated nitriles such as acrylonitrile (also called "acrylonitrile"); olefins such as ethylene and propylene.

It is desirable to remove any amount of VC monomer remaining in the PVC slurry to be treated. The treated PVC slurry to which the method and the treatment apparatus of the present invention are applied usually contains 500 to 40000 ppm of VC absorbed or adsorbed by PVC particles. The concentration of PVC in the PVC slurry (hereinafter sometimes simply referred to as “slurry concentration”) is set to 5 to 45% by weight, preferably 10 to 40% by weight. If the upper limit is significantly exceeded, the fluidity of the PVC slurry to be treated is deteriorated. If the lower limit is significantly decreased, the capacity of the treatment apparatus (tower type) of the present invention is reduced, and the
There is no particular increase in removal capacity.

When the PVC slurry to be treated is subjected to steam treatment on the perforated plate shelf 1 provided with the outflow pipe 4, the lower limit of the slurry temperature is usually 60 ° C., preferably 70 ° C., and most preferably 80 ° C. Choose. On the other hand, the upper limit of the temperature of the PVC slurry to be treated is usually 130 ° C., preferably 120 ° C., and most preferably 110 ° C.

When the temperature of the PVC slurry to be processed is 60 to 130 ° C., the pressure in the processing apparatus is about 0. 2-3 kgf / cm ² (abs). PV to be treated
With the increase of the temperature of the C slurry, P in the slurry
VC is easily vaporized from the VC particles accompanying the water vapor.
However, if the temperature is too high, the PVC particles in the slurry will be colored or thermally degraded.

In addition to the above-mentioned slurry to be processed, the following slurry may be applied to the method and the processing apparatus of the present invention: During the completion of the polymerization reaction, the pressure in the reaction system is reduced to normal pressure. A PVC slurry obtained by releasing the slurry in the system to the storage tank in step 1.-A PVC slurry obtained by stopping the polymerization reaction at a stage of an arbitrary polymerization rate and opening the slurry in the system to the storage tank as it is.

When the PVC slurry to be treated of the present invention is charged above the perforated plate shelf 1 provided with the treatment passages described above, it is desirable that the slurry be preheated to 50 to 100 ° C. This preheating is performed on the treated PVC discharged from the processing equipment.
It is practical to do this by heat exchange between the slurry and the incoming PVC slurry to be treated. This heat exchange also cools the discharged PVC slurry and achieves a temperature reduction to a suitable discharge temperature of 60-120C.

The lower limit of the residence time of the PVC slurry to be treated in the processing apparatus is 1 min, preferably 2 min, most preferably 3 min, and the upper limit of the residence time is about 60 min.
min. Can be highly remove residual VC monomer from PVC particles to be treated PVC slurry with the setting a longer residence time of the processed PVC slurry residence time
If the length is too long, coloring (discoloration) and thermal deterioration of the PVC particles are caused.

The amount (flow rate) of the PVC slurry to be treated to be introduced into the treatment apparatus of the present invention is preferably 0.1 to 300 m ³ / h per 1 m ^{2 based on the} area of the perforated plate constituting each perforated plate shelf. Is adjusted to 1 to 100 m ³ / h.

The amount of steam introduced (sprayed) from below the perforated plate shelf mounted on the treatment apparatus of the present invention is 1 to 100 kg / h, preferably 5 to 50 kg / h per m ^{3 of the} PVC slurry to be treated. is there. The purpose of this steam introduction is to:-heat the PVC slurry to be treated and maintain it at a predetermined temperature;-sufficiently agitate the PVC slurry to be treated to prevent the contained PVC particles from settling out;-PVC to be treated. It promotes evaporation and transfer of VC remaining in the slurry into the gas phase.

In particular, prevention of sedimentation of PVC particles in the PVC slurry to be treated is important in the following two points: uniforming the residence time of each PVC particle contained in the PVC slurry to be treated ( residual V in residual VC and liquid medium residence time distribution narrow the) content in PVC particles
Promotes C removal.

In order to achieve each of the above objects, it is important to appropriately select the amount of steam introduced from below the perforated shelf. If the amount of introduced steam is too small, the desired state cannot be realized. On the other hand, if the introduced amount of water vapor is too large, flooding may occur in addition to intense splashing of the PVC slurry to be treated. Nevertheless, the processed P
The effect of removing VC in the VC slurry is not particularly improved.

[0053]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

[0054]

Example 1 The shape shown in FIG. 1 (pore diameter of the perforated plate: 1.3 m)
m, opening ratio 0.3%), and using a perforated plate-type tower-type processing apparatus assembled as shown in FIG.
Slurry [PVC (average degree of polymerization = 1300); PVC concentration 30% by weight, residual VC monomer concentration 30000 ppm
(PVC weight basis; subsequent units of VC concentration)]
The monomer treatment was performed based on the apparatus and process shown in FIG.

[0055] treated PVC slurry amount that can be charged into the upper side of the porous plate made tray 1 used were tower type processor 13 per stage 0.87 m ^3, the interval of the porous plate made trays 1600m
m, PVC slurry on each perforated plate shelf with a diameter of 1500 mm
The Lee solution depth was about 500 mm, and the width of the processing passage (for example, the interval between the partition walls 21 and 22) was 200 mm.

From the slurry tank 14 in FIG.
PVC slurry to be treated and preheated to 80 ° C
Into the top chamber 8 of the processing apparatus 13 shown in FIG.
Charged at m ³ / h and located above the slurry
From the steam injection nozzle 5 to the surface of the PVC slurry to be treated
Injects water vapor into a cone with an apex angle of about 120 degrees
2.5 kgf / cm ² (abs.) And injection amount 96 kg
/ (H / m ² ), the slurry in each stage is locally uneven
It was sprayed (evenly) so as not to cause a balance . In parallel with it
Then, steam (temperature of 110
℃ superheated steam) was introduced at a flow rate of 600 kg / h. At this time, the residence time of the PVC slurry to be treated was 10 minutes.

The PVC slurry to be treated is supplied to the treatment apparatus 1 shown in FIG.
After being loaded into the 3, water vapor while flowing the processing path of the porous plate made of tray 1 on the side in order to lower side, is introduced from below through the pores provided in the bottom plate of the perforated plate made tray 1 At 10
Heated to 0 ° C., the perforated plate shelf 1a provided thereunder from the downflow pipe 4 located at the end of the processing passage of the perforated plate shelf 1
To the receiving tank 16 through the slurry outlet pipe 11 and the slurry pump 19 from the lowermost stage of the processing apparatus 13.

In this process, the PVC slurry is transferred to the heat exchanger 17.
To 50 ° C. The VC content (concentration) in the discharged PVC slurry was 1 ppm or less. Further, the mixed vapor of water and VC generated in the tower top chamber 8 of the treatment device 13 exits the tower and enters the condenser 15, where the condensed water and VC are separated by liquid separation.

During the entire period of the above-mentioned PVC slurry treatment, steam is continuously supplied from above the surface of the PVC slurry to be processed through the steam injection nozzle 5 to a pressure of 2.5 kgf / cm ² Abs. In addition to suppressing the generation of bubbles in the slurry liquid phase by spraying, it is generated without being suppressed
Bubbled bubbles were eliminated as much as possible . Steam injection amount at this time was set to 1 m ² per 96 kg / h with a porous plate of area.

At the time of the above-mentioned PVC treatment, the hot water injection ring 6
The flow rate of hot water from each perforated plate shelf to 0.5 m ³ / h / stage,
When the tower was washed by spraying at an interval of 10 minutes at a total amount of 2 m ³ / h over 5 seconds onto the inner wall surface of each stage and the lower surface of the perforated plate shelf directly above, the product (PVC powder) contained burnt matter (PVC powder). Foreign matter; as a result of adhering to the inner wall surface of the body plate and heating for a long time, thermally deteriorated PVC particles, etc.) were not observed. Table 1 shows the results.
Shown in

[0061]

Comparative Example 1 In the process of Example 1, the injection from the steam injection nozzle 5 was stopped, and the other conditions were the same as in Example 1.

As a result, the PVC slurry to be treated foamed and the residual VC concentration in the PVC slurry at the treated PVC slurry outlet 11 reached 300 ppm (based on PVC). Also, 30 minutes after the start of operation, the P
VC was deposited and clogged, and operation became impossible. In addition, 78 burns (foreign matter) were generated in the product (PVC powder) per 100 g of PVC. The results are shown in Table 1.

[0063]

Comparative Example 2 In the process of Example 1, the operation of injecting the hot water from the hot water injection ring 6 was stopped, and the other conditions were the same as in Example 1.

As a result, the treated PVC slurry outlet 1
1 the residual VC concentration in the PVC slurry was 1 ppm
(PVC standard), but P in product (PVC powder)
122 burns (foreign matter) were generated per 100 g of VC. The results are shown in Table 1.

[0065]

Comparative Example 3 The same operation as in Example 1 was performed except that the apex angle of the steam injection nozzle 5 was set to 45 degrees from above the surface of the PVC slurry to be treated over the entire period of the PVC slurry treatment.

As a result, the water vapor injected from the water vapor injection nozzle was jetted to the center of the perforated plate shelf, and as a result, bubbles were generated from the surface of the PVC slurry not in contact with the water vapor, and P at PVC slurry outlet 11
The residual VC concentration in the VC slurry is 260 ppm (PVC
Criteria). In addition, 15 minutes after the start of operation,
As a result of the accumulation of PVC and clogging, operation became impossible. In addition, PVC100 in the product (PVC powder)
67 burns (foreign matter) were generated per shot. The results are shown in Table 1.

[0067]

Example 2 Hot water was supplied from a hot water injection ring 6 to each of the perforated plate shelves at a flow rate of 0.2 m ³ / h / stage for 10 min.
Injection to the following locations over the interval c (total injection amount 0.8 m ³
/ H), and the same operation as in Example 1 was performed, except that the inside of the column was washed. Here, each location in the tower refers to the inner wall surface of each shelf and the lower surface of the perforated plate shelf located immediately above.

As a result, the treated PVC slurry outlet 11
, The residual VC concentration in the PVC slurry at 1 ppm or less (PVC standard) was reduced, but two burns (foreign matter) were generated in the product (PVC powder) per 100 g of PVC. The results are shown in Table 1.

[0069]

[Embodiment 3] Hot water was supplied from a hot water injection ring 6 to each perforated plate shelf at a flow rate of 0.05 m ³ / h / stage for 5 s at 10 min intervals.
ec to the following places (total injection amount 0.2m
³ / h), and the same operation as in Example 1 was performed, except that the inside of the column was washed. Here, each place in the tower is
It refers to the inner wall surface of each shelf and the lower surface of the perforated plate shelf located immediately above.

As a result, the treated PVC slurry outlet 11
, The concentration of residual VC in the PVC slurry was reduced to 1 ppm or less (PVC standard), but 34 burns (foreign matter) were generated in the product (PVC powder) per 100 g of PVC. The results are shown in Table 1.

[0071]

Embodiment 4 Hot water was supplied from a hot water injection ring 6 to each perforated plate shelf at a flow rate of 1.5 m ³ / h / stage for 10 sec at 5 min intervals.
c to the following locations (total injection amount: 6.0 m ³ /
h) The same operation as in Example 1 was carried out, except that the inside of the column was washed. Here, each location in the tower refers to the inner wall surface of each shelf and the lower surface of the perforated plate shelf located immediately above.

As a result, the treated PVC slurry outlet 11
The concentration of residual VC in the PVC slurry at 1 ppm or less (based on PVC) and the PV in the product (PVC powder)
The number of burns (foreign matter) generated per 100 g of C reached 0, but the concentration of the treated PVC slurry was reduced to 23 wt%. Due to the decrease in the concentration of the treated PVC slurry, the load in the step of dewatering the PVC slurry increased. The results are shown in Table 1.

[0073]

Embodiment 5 Throughout the entire period of the PVC slurry treatment, a spray pressure of 5.0 kgf / cm ² (Abs.) Is applied from above the surface of the treated PVC slurry through the steam spray nozzle 5 to a uniform and uniform surface density. Water vapor was sprayed so as to suppress the generation of bubbles in the slurry liquid phase, and the generated bubbles that could not be suppressed were eliminated as much as possible. At this time, the steam injection amount was 153 kg / on the basis of the area of the perforated plate (/ m ² ).
The same operation as in Example 1 was performed except that h was set.

As a result, the outlet 1 of the treated PVC slurry
1 the residual VC concentration in the PVC slurry was 1 ppm
Below (PVC standard) and products (PVC standard)
The number of burns (foreign matter) per 100 g of PVC in the powder) was suppressed to zero. The results are shown in Table 1.

[0075]

Embodiment 6 Throughout the entire period of the PVC slurry treatment, a spray pressure of 11.0 kgf / cm ² (Abs.) Is applied from above the surface of the PVC slurry to be treated through the steam spray nozzle 5 to a uniform surface density. Water vapor was sprayed so as to suppress the generation of bubbles in the slurry liquid phase, and the generated bubbles that could not be suppressed were eliminated as much as possible. In this case, the steam injection amount was 226 kg based on the area of the perforated plate (/ m ² ).
The same operation as in Example 1 was performed except that / h was set.

As a result, the outlet 1 of the treated PVC slurry
1 the residual VC concentration in the PVC slurry was 1 ppm
The number of burned substances (foreign matter) per 100 g of PVC in the product (PVC powder) was eight. In this case, because the injection amount was increased by setting the injection pressure of the steam high,
In addition to the rippled surface of the PVC slurry, bubbles (about 100 to 150 mm in diameter) were generated. The results are shown in Table 1.

[0077]

According to the method and the processing apparatus of the present invention,
The following effects can be obtained. -The PVC slurry to be treated on the perforated plate shelf hardly foams even when water vapor is injected from below, and substantially neither overflows the partition wall nor flows into the downcomer pipe. -Undesirable situations such as a situation where the VC monomer enters the condenser via the extraction pipe from the top of the tower are prevented.-The amount of the VC monomer remaining in the PVC particles discharged from the outlet of the treatment device is at a predetermined level. The foaming of the PVC slurry to be treated is substantially suppressed, and the following ripple effect is also accompanied: The situation where PVC particles are entrained in the foam is almost completely eliminated. Almost no occurrence of adhering to PVC. Very little occurrence of deterioration of PVC particles due to prolonged exposure to water vapor. There is almost no generation of foreign matter due to mixing of degraded PVC particles and the like.

[0078]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a plan view of a perforated plate shelf constituting a processing apparatus used in the method of the present invention.

FIG. 2 is a schematic longitudinal sectional view of a perforated plate shelf portion constituting a processing apparatus used in the method of the present invention.

FIG. 3 is a conceptual system diagram showing the steps of the method of the present invention and the configuration of a processing apparatus.

[Explanation of symbols]

DESCRIPTION OF REFERENCE NUMERALS 1 Uppermost shelf made of perforated plate incorporated in the treatment apparatus of the present invention 2 Perforated plate incorporated in the treatment apparatus of the present invention 3 Body plate forming the outer shell of the tower type treatment apparatus of the present invention 4 Treatment of the present invention Downstream pipe from the downstream end of the perforated plate shelf incorporated in the apparatus 5 Steam injection nozzle provided above the perforated plate shelf incorporated in the processing apparatus of the present invention 6 Built in the processing apparatus of the present invention Hot water injection ring 7 PVC slurry inlet to be processed into the uppermost perforated plate shelf incorporated in the processing apparatus of the present invention 8 Tower chamber in the processing apparatus of the present invention 9 Bottom chamber in the processing apparatus of the present invention 9 10 Mixed steam outlet from the top of the processing apparatus of the present invention 11 Treated PVC slurry outlet from the lowest perforated plate shelf incorporated in the processing apparatus of the present invention 12 Steam introduction to the bottom of the processing apparatus of the present invention Mouth 13 Main body of processing apparatus of the present invention 14 Treated PVC slurry treated PVC discharged from the apparatus of the condenser 16 the invention of mixed vapor exiting from the processor overhead of the slurry tank 15 present invention to be charged into the processing apparatus of the invention
Slurry receiving tank 17 Heat exchanger installed in processing apparatus of the present invention 18 Slurry pump for charging treated PVC slurry to processing apparatus of the present invention 19 Slurry pump for discharging processed PVC slurry from processing apparatus of the present invention Reference Signs 20 partition wall incorporated in the processing apparatus of the present invention 21 partition wall incorporated in the processing apparatus of the present invention 22 partition wall incorporated in the processing apparatus of the present invention 23 partition wall incorporated in the processing apparatus of the present invention 1a Second-stage perforated plate shelf 1b incorporated in the processing apparatus of the present invention 3rd perforated plate shelf 1c incorporated in the processing apparatus of the present invention 4th stage ( Γ the crossing angle between the injection nozzle axis of the hot water injection ring and the vertical direction θ the apex angle of the water vapor injected downward from the steam injection mechanism in the conical surface

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Seiichi Uchida 2-2-1-606 Masago, Mihama-ku, Chiba City, Chiba Prefecture (56) References JP-A-56-22305 (JP, A) JP-A-54 -8693 (JP, A) JP-A-54-131687 (JP, A) JP-A-54-62171 (JP, A) JP-A-3-65202 (JP, A) (58) Fields investigated (Int. . ^7, DB name) C08F 6/00 - 6/24 C08F 14/06 B01D 19/02

Claims (23)

(57) [Claims] 1. A method of heating and stirring a vinyl chloride resin slurry containing a residual vinyl monomer with water vapor introduced from below, and spraying water vapor from above the liquid surface of the slurry onto the liquid surface. Washing the scattered matter or the coagulated matter after volatilization by hot water injection, thereby producing a resin powder having a low residual vinyl monomer content. 2. The method according to claim 1, wherein the pressure of the steam injected from above the slurry liquid level is higher than 1 kgf / cm ² (Abs.) At the injection start point. A method for producing a low amount of resin powder. 3. The method according to claim 1, wherein
The injection pressure of the water vapor injected from above the slurry was set at 1.
A method for producing a resin powder having a low residual vinyl monomer content of 1 to 11 kgf / cm ² (Λbs.). 4. The method according to claim 1, wherein water vapor injected from above the slurry is superheated steam, and the residual vinyl monomer content is low. 5. The method according to claim 1, wherein the slurry is subjected to a treatment until the slurry is finished.
A method for producing a resin powder having a low residual vinyl monomer content, wherein the resin powder flows in a state similar to an extrusion flow during the period . 6. The method according to claim 1, wherein the temperature of the slurry is kept at 70 to 150 ° C. and the resin powder has a low residual vinyl monomer content. 7. The method according to claim 1, wherein the apex angle θ of the conical surface of the water vapor sprayed in a conical shape from above the liquid surface of the slurry is 30 to 150. Resin powder production method with low residual vinyl monomer content. 8. The residual vinyl monomer content according to claim 1, wherein the amount of steam supplied also from below to the slurry is from 1 to 100 kg / h / m ² per operation. Low resin powder production method. 9. The method according to claim 1, wherein the temperature of the hot water to be sprayed is ± 10% of the temperature of the slurry.
A method for producing a resin powder having a low residual vinyl monomer content at ℃. 10. The method according to claim 1, wherein the hot water injection is performed at intervals of 90 minutes or less. 11. The method according to claim 1, wherein the hot water injection is performed at intervals of 60 minutes or less. 12. wherein A method according to any one of claims 1 to 11, lower resin powder production method of residual vinyl monomer content to perform hot water injection 1 sec or more. 13. The method according to claim 1, wherein the hot water injection is carried out for 5 seconds or more. 14. The method according to claim 1, wherein the injection amount of hot water is 0.1 to 50 m per operation.
^A method for producing a resin powder having a low residual vinyl monomer content of ³ / h / m ² . 15. In order to separate and remove the vinyl monomer from the residual vinyl monomer-containing vinyl chloride resin slurry,
An apparatus for producing a resin powder having a low residual vinyl monomer content, which is provided with the following means (a) to (e): (a) one or more resin powders provided in the column; (B) a passage for processing the slurry provided on the shelf made of perforated plate, (c) means for introducing steam from below the treatment passage, (d) above the surface of the slurry liquid (E) A hot water injection ring which is located below the perforated plate shelf just above the perforated plate shelf and injects hot water upward from the horizontal. 16. The apparatus according to claim 15, wherein the processing passage for the slurry forms a series of passages which are divided in a groove shape by partition walls on a perforated plate shelf, and the surface of the slurry liquid is formed. A resin powder having a low residual vinyl monomer content, characterized by being provided with a mechanism for injecting water vapor from above into the liquid surface at an apex angle (θ) of an injection cone surface of 30 to 150 degrees. manufacturing device. 17. The apparatus according to claim 15, wherein the pores provided on the perforated plate shelf have an average diameter of 5 m.
m, a device for producing a resin powder having a low residual vinyl monomer content of not more than m. 18. The apparatus according to claim 15, wherein the opening ratio of the perforated plate tray (= total pore area / total pore area).
An apparatus for producing a resin powder having a low residual vinyl monomer content having a total area of a perforated plate of 0.01 to 10%. 19. The apparatus according to claim 15, wherein the steam injection mechanism is a resin powder having a low residual vinyl monomer content located at a height of 50 to 1000 mm above the slurry liquid level. manufacturing device. 20. The resin powder having a low residual vinyl monomer content according to claim 15, wherein the injection nozzle of the hot water injection ring is located 50 to 500 mm below a perforated plate shelf directly above. Body manufacturing equipment. 21. The apparatus according to claim 15, wherein the hot water injection ring is a ring-shaped body made of a pipe and having a maximum diameter of 150 to 2000 mm, and is flat on a pipe wall.
An apparatus for producing a resin powder having a low residual vinyl monomer content and having a plurality of through holes having an average diameter of 1 to 8 mm. 22. The apparatus according to claim 15, wherein the hot water injection ring is a substantially ring-shaped member having a maximum diameter of 150 to 2000 mm formed of a pipe and a maximum width of 1 to 8 mm in a pipe wall. For producing a resin powder having a low residual vinyl monomer content and having a plurality of slits. 23. The apparatus according to claim 15, wherein the intersection angle (γ) between the injection nozzle axis of the hot water injection ring and the vertical direction is 10 to 60 degrees. Production equipment for low resin powder.