JPH0584204B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a coagulation method and apparatus for obtaining a polymer solid from a polymer latex. It relates to coagulation methods and devices. [Prior art] Polymer latex obtained by emulsion polymerization (hereinafter referred to as
It is abbreviated as latex. ), the latex is introduced into a coagulant solution (hereinafter abbreviated as coagulant) and the formed polymer particles are separated. This coagulation operation is usually performed as shown in Figure 3.
Putting the latex into the coagulating liquid in the stirring tank 60,
This is done by stirring with a stirrer 62 and then aging in a ripening tank 64. In addition, 6 in Figure 3
Reference numeral 6 is a pressure aging tank, which performs more sufficient aging. The suspension after the aging treatment is dehydrated and dried to form a powder. In addition, instead of mechanical stirring, there is a method in which latex is injected into the upward flow of the coagulating liquid in a vertical pipe (Japanese Patent Laid-Open No. 18602/1982), or a method in which both the latex and the coagulating liquid are atomized and brought into contact with each other. (Unexamined Japanese Patent Publication No. 58-87102
etc.) are also known. In general, in such latex coagulation operations, it is important to form particles that can be economically advantageously operated after coagulation. In other words, it is important to adjust the properties of the particles obtained in the coagulation operation to suit the purpose of the post-processing, and specifically, it is important to appropriately select the particles, particle size distribution, bulk density, moisture content, hardness, or porosity. If these conditions are inappropriate, washing, dehydration, drying, sieving, etc. after the coagulation step will not work properly, which is extremely disadvantageous industrially. [Problems to be Solved by the Invention] However, the powdery copolymer particles recovered by the conventional method have extremely small particle diameters, so that they may clog the filter cloth or dry out in the subsequent separation process. There are problems such as a decrease in yield due to the scattering of fine particles during the process, a decrease in workability due to difficulty in measuring during bagging, and a decrease in production efficiency for Banbury, Ruder, etc., and extremely poor productivity and operability in the subsequent process. . Furthermore, the generation of dust causes deterioration of the working environment and air pollution due to exhaust from dryers and the like. Such a problem is also common to JP-A-56-18602. Furthermore, in the method disclosed in JP-A-58-87102, since the latex and the coagulation method are brought into contact through the association of fine particles, the reaction rate is slow and there is a risk that the reaction may be non-uniform. [Means and effects for solving the problems] The present invention is capable of forming a latex by causing a coagulating liquid to flow down onto a liquid film on a conical inclined surface and continuously dropping the latex onto the falling liquid film. In this method, a polymer latex and a coagulant are brought into contact with each other to obtain polymer solid particles. coagulation of a polymer, characterized in that the coagulant solution is caused to flow down so as to form a coagulant solution, and the polymer latex is brought into contact with the coagulant by continuously dropping the polymer latex onto the flowing coagulant solution. a pressure vessel having a liquid outlet at the bottom; a truncated conical tray installed approximately in the middle of the pressure vessel with its axial direction being vertical; a polymer latex receiver installed at a position above the pressure vessel; piping for supplying polymer latex to the polymer latex receiver installed through the shell of the pressure vessel; installed on the bottom of the vessel,
a nozzle for dropping polymer latex onto the upper surface of the center side of the tray; and a coagulant solution receiver connected to the lower surface of the center opening of the tray so that the liquid can overflow from the edge of the opening of the tray. , a pipe for supplying a coagulant solution to the coagulant solution receiver installed through the shell of the pressure vessel; an opening level of the coagulant solution supply pipe and an upper edge level of the center opening of the tray; An apparatus for coagulating polymer latex, comprising: a baffle plate for upward flow of coagulating liquid, provided at a level between [Function] In the present invention, after the latex is made into predetermined droplets using a nozzle, it is brought into contact with the coagulating liquid, and since the contact state between each dropped particle and the coagulating liquid is uniform, the particle size and Polymer particles with uniform diameter distribution, bulk density, hardness, porosity, etc. can be obtained. Hereinafter, the configuration of the present invention will be explained in more detail. The latex used in the present invention may be any polymerized latex made by ordinary emulsion polymerization, and specifically, styrene, α-
(Co)polymer latex obtained by polymerizing one or more vinyl monomers consisting of monovinylidene aromatic compounds such as methylstyrene, vinyl cyanide compounds represented by acrylonitrile, (meth)acrylic acid esters, etc. , a butadiene-based copolymer of butadiene and a vinyl monomer, or a graft copolymer latex of polybutadiene and at least one of the above vinyl monomers, etc.
These latexes may be used alone or in combination with
There is no problem even if more than one type of polymer latex is mixed. Various latex coagulants can be used as the coagulant, specifically inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, organic acids such as formic acid, oxalic acid, acetic acid, or alkali metals, alkaline earth metals, etc. of these acids.
A metal salt made of aluminum or the like is used, and this is dissolved in an appropriate solvent (usually water) to form a coagulating liquid. The type and concentration of the coagulant are determined by the coagulability of the latex or the coagulant's ability to coagulate. In the coagulation method of the present invention, the latex is dropped in the form of droplets onto the liquid film of the coagulation liquid.
In this case, the inner diameter of the nozzle used for dispersing the latex is preferably about 1 to 10 mm, particularly about 3 to 5 mm. The amount of latex dropped is preferably about 10 to 50%, especially about 30 to 40%, of the amount of coagulation liquid flowing down. The coagulating liquid flows down in the form of a liquid film on the inclined surface of the tray, and the angle of this inclined surface is 0 to 90 degrees, especially 5 to 90 degrees.
It is preferable to set the angle to about 20°, and the length of the slope where the latex flows down is 50 to 200 mm, especially 50 to 100 mm.
It is preferable to set it to about mm. The distance between the latex receiver and the tray is 50 to 300 mm.
mm Especially preferred is 150 to 200 mm. It is preferable that the coagulating liquid flows on such a tray to a thickness (depth) of about 5 to 15 mm, especially about 8 to 12 mm. It should be noted that the upper part of the tray is narrower, so the thickness of the coagulating liquid becomes larger and becomes thinner towards the bottom. In the present invention, the flow rate is determined so that the thickness of the coagulating liquid falls within the above range at the lower end of the tray. It is preferable that the mixed liquid of the coagulating liquid and the latex is then maintained at a predetermined temperature and allowed to pass through a tube, or is aged by being gently stirred in a tank. That is, through this aging, the coagulating liquid penetrates into the interior of the latex droplets, resulting in sufficient coagulation. [Example] Hereinafter, the present invention will be described in further detail with reference to an example device shown in the drawings. FIG. 1 is a longitudinal sectional view of a latex coagulating apparatus according to an embodiment of the present invention. Reference numeral 10 denotes a pressure vessel, which has a cylindrical shape with a lid and a bottom and a relatively low tower height with the cylinder axis in the vertical direction. This pressure vessel consists of the shell 1
2 and the lower shell 14 at their flange portions 12.
a, 14a are connected by tightening bolts. A truncated conical tray 16 is installed at a substantially middle position within the pressure vessel 10 with its conical axis oriented vertically. . In addition, this tray 1
6 is supported by a coagulation liquid receiver 18, which will be described next. That is, at the edge of the central opening of the tray 16, there is a short cylindrical skirt portion 2 that hangs vertically downward.
0 is integrally provided by welding or the like, and the upper end of a cylindrical solidified liquid receiver 18 with an open bottom is fitted into the lower end of the skirt portion 20. A seal member (not shown) is interposed at the joint between the lower end of the skirt portion 20 and the upper end of the receiver 18 to prevent leakage of the coagulated liquid. A bracket 22 whose base end is fixed to the inner surface of the side wall of the lower shell 14 extends from a plurality of directions, for example three directions, toward the center of the lower shell 14, and has a coagulation liquid receiver 18 at its tip. The side circumferential surface of the coagulation liquid receiver 18 and the tray 16 installed above the coagulation liquid receiver 18 are thereby supported by the pressure vessel 10 . A coagulation liquid supply pipe 24 is connected to the coagulation liquid receiver 18 . This supply pipe 24 is connected to the lower shell 1
4 and the coagulation liquid receiver 18 side wall, and the end protruding to the outside of the lower shell 14 has a
A flange 24a for piping connection is provided.
Further, the other end of the supply pipe 24 is inserted into the coagulation liquid receiver 18, and a coagulation liquid outlet 26 is opened on the lower surface thereof, and the distal end thereof is sealed with a seal plate 28. The middle of the supply pipe 24 is bent into a crank shape, and a short stay 30 is fixed to the higher end of the supply pipe 24 to support the end of the tray 16. Reference numeral 32 denotes a current plate, which is a punch plate in this embodiment, and is installed horizontally across the vicinity of the upper edge of the coagulation liquid receiver 18. A latex receiver 34 is installed above the tray 16. In this embodiment, the latex receiver 34 is a circular, flat-bottom, dish-shaped container, and is connected to the pressure vessel 10 via a bracket 36 whose base end is fixed to the lower shell 14, the bottom surface of which is horizontal. It is attached so as to be coaxial with the tray 16. On the bottom surface of the latex receiver 34, nozzles 38 for discharging latex are provided at equal radial positions and at equal intervals with respect to the center of the bottom surface. In this embodiment, the nozzles 38 are arranged in two rows on a double concentric circle, and are arranged so that the latex flowing out from each nozzle 38 becomes droplets and falls onto the inclined surface of the tray 16. ing. A latex supply pipe 40 is installed above the latex receiver 34. This latex supply pipe 40 is installed in the vertical direction and extends outside the pressure vessel 10 through a dome 42 provided at the top of the pressure vessel 10 and a seal plate 44 sealing the dome 42. Further, the lower end of the latex supply pipe 40 extends below the liquid level in the latex receiver 34, so that the lower end can be immersed in the latex stored in the latex receiver 34. Note that 46 is an outlet provided at the bottom of the pressure vessel 10, and 48 is a leg for installing the pressure vessel 10. In the coagulation device having such a configuration, the coagulation liquid introduced from the supply pipe 24 flows downward into the receiver 18 from the opening 26, and then rises in the receiver 18 as an upward flow. After being subjected to a rectifying action by the rectifying plate 18 and having a substantially uniform upward flow velocity in the horizontal cross section, it evenly overflows from the center opening edge of the tray 16, and the tray 1
6. Flows down the upper surface in the form of a liquid film. On the other hand, the latex is supplied from the supply pipe 40 into the receiver 34, and is dropped from the nozzle 38 under the tray 16 in the form of droplets. Then, it flows down on the tray 16 together with the coagulating liquid, and flows down from the outer peripheral edge of the lower end of the tray 16. This falling flow further flows down the inner surface of the lower seal 14 and reaches the outlet 46.
It is then taken out of the pressure vessel 10. In this embodiment, the latex is dropped from the nozzle 38 onto the tray 16 with a uniform diameter, and each of the dropped latex droplets comes into contact with the coagulating liquid under substantially the same conditions. . That is, each latex droplet is in contact with the coagulating liquid for approximately the same amount of time, and the difference in the falling velocity of the coagulating liquid is approximately the same for each droplet. Moreover, since the liquid droplets are not subjected to vigorous stirring unlike in conventional apparatuses, the droplets do not break, and coagulated particles with uniform diameter and uniform properties can be obtained. Furthermore, by setting the diameter of the nozzle 38 to an appropriate value, particles having an appropriate particle size can be obtained. FIG. 2 is a system diagram showing the overall configuration of a coagulation apparatus incorporating the embodiment apparatus of FIG. 1. That is, at the bottom outlet of the pressure vessel 10, there is a ripening tube 5 disposed horizontally or with a gentle downward slope.
0 is connected, and further downstream there is a ripening tank 52.
is connected. Then, the latex droplets that have come into contact with the coagulating liquid in the pressure vessel 10 exit the outlet 46 and then enter the ripening tube 5.
0 at a low flow rate, and then introduced into the aging tank 52 and gently stirred by the stirring blades 54 to solidify the latex droplets. The stirring blades 54 are used to stir the latex particles slowly within the aging tank 52 so that they do not settle, and do not damage the latex particles. The aged particles are sent to the next step by a pump 56 and piping 58. Next, manufacturing examples will be described. Example 1 Using the apparatus shown in Figure 1, α-methylstyrene
A latex consisting of 75 wt% acrylonitrile and 25 wt% acrylonitrile was coagulated under the conditions shown below and in Table 1. Pressure vessel inner diameter 1.3 m Tray outer diameter 1.1 m Tray inner diameter 0.45 m Tray inclination angle 10° Total length of ripening tube 40 m Maturing tube inner diameter 100 mm (0.1 m) Aging tank capacity 7500 Inner diameter of nozzle 38 4 mm Number of nozzles 38 130 pieces Removed from the aging tank The resulting suspension was dehydrated by centrifugation and further dried in a drier to obtain a dry powder. The measurement results of the particle size distribution are shown in Table 2. Comparative Example 1 In the conventional apparatus shown in FIG. 3, latex was coagulated under the conditions shown below and in Table 3 using the same sample as in the example. The resulting slurry was dehydrated and dried in the same manner as in Example 1, and its particle size distribution was measured. The results are shown in Table 2. From Table 2, it is clear that according to the present invention, particles having a relatively large diameter and having a uniform particle size can be obtained. On the other hand, in the comparative example, the majority was fine powder. In addition, when the shapes of the particles obtained in Example 1 and Comparative Example 1 were observed under a microscope, it was found that the particles in the Examples had almost perfect spherical shapes, whereas about half of the particles in the Comparative Examples had irregular shapes. It was recognized that

【table】

【table】

[Table] [Effects] As described above, according to the present invention, latex particles having a uniform diameter and homogeneous properties can be produced. Furthermore, since the latex droplets come into contact with the downstream flow of the coagulating liquid, the reaction efficiency is high and there is no decrease in yield.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the embodiment device, FIG. 2 is a system diagram of the embodiment device, and FIG. 3 is a configuration diagram of the conventional device. 10...pressure vessel, 16...tray, 18...
Coagulated liquid receiver, 32... Current plate, 34... Latex receiver, 46... Outlet, 50... Ripening tube, 52...
...Aging tank.

Claims (1)

[Scope of Claims] 1. In a method for obtaining polymer solid particles by bringing a polymer latex into contact with a coagulant, the coagulant is brought into contact with the coagulant so as to form a liquid film on a tray having a downwardly expanding conical inclined surface. 1. A method for coagulating a polymer, which comprises causing a solution to flow down and continuously dropping the polymer latex onto the flowing coagulant solution to bring the polymer latex into contact with a coagulant. 2. The coagulation method according to claim 1, further comprising the step of aging the coagulant solution containing the polymer latex after flowing down the tray. 3. A pressure vessel having a liquid outlet at the bottom, a truncated conical tray installed approximately in the middle of the pressure vessel with its axial direction being vertical, and a portion above the tray within the pressure vessel. a polymer latex receiver installed at the pressure vessel; piping installed through the shell of the pressure vessel for supplying polymer latex to the polymer latex receiver; provided on the bottom,
a nozzle for dropping polymer latex onto the upper surface of the center side of the tray; and a coagulant solution receiver connected to the lower surface of the center opening of the tray so that the liquid can overflow from the edge of the opening of the tray. , a pipe for supplying a coagulant solution to the coagulant solution receiver installed through the shell of the pressure vessel; an opening level of the coagulant solution supply pipe and an upper edge level of the center opening of the tray; A coagulating apparatus for polymer latex, comprising: a baffle plate for upward flow of a coagulating liquid provided at a level between the coagulating liquid and the coagulating liquid; 4. The coagulation according to claim 3, characterized in that a ripening tube having a heating means is connected to the outlet of the pressure vessel, and a ripening tank having a stirring means is further connected to the ripening tube. Device.