JPS58174401A - Method and apparatus for continuous coagulation of polymer latex - Google Patents

Abstract

PURPOSE:To obtain solid polymer having high slurry concentration, uniform particle size and excellent blocking resistance, by supplying a solution of a coagulant to the outer tube of a coagulating apparatus furnished with a double-walled tube, and supplying a polymer latex to the inner tube, thereby contacting both compnents instantaneously under specific condition. CONSTITUTION:The inner tube 2 is inserted into the outer tube 1 having one open end and one closed end leaving a gap between both tubes. The inner tube is made shorter than the outer tube. A guiding blade 8 is placed between the outer tube 1 and the inner tube 2. A solution of a coagulant is supplied through the outer tube 1, and at the same time, a polymer latex is supplied through the inlet port 3 attached at one end of the outer tube and through the inner tube 2 to the coagulating apparatus countercurrently to the coagulant solution. Both liquids are brought into contact instantaneously with each other in the coagulation chamber in the outer tube at the outlet part of the inner tube. The Reynolds number of the mixture of the polymer latex and the coagulant solution in the coagulation chamber 4 is maintained at 100,000-300,000, and the solid polymer concentration is kept to 3-25wt% during the coagulation operation to obtain the solid polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and an apparatus for continuously obtaining a polymer solid material from a copolymer tree and a coagulation method using a steel solidifying agent. Combined solids (
The purpose of the present invention is to provide a novel coagulating method and a coagulating device for polymer latex, which can be efficiently and easily produced using a simple device.

The coagulation method referred to here refers to the rubbery polymer 2 in a stabilized state.
The polymer latex is coagulated into particles using a coagulant 12 capable of destroying the micelles of rice cakes, such as a solution of an inorganic salt or an inorganic acid, an organic acid, or a hydrophilic polar solvent. It means obtaining a polymer in crumb form or other form.

A common industrial operation of the coagulation method is polymerization.

The coagulant solution and the coagulant solution are fed into a stirred tank, and the polymer latex is coagulated and flocculated by one-minute line drawing or continuous operation, and the tin polymer is made into crumb-like or other shapes, followed by solid-liquid separation, washing, and coagulation. The properties of the crumb produced during the coagulation process are extremely important in order to obtain a solid product that is of excellent quality through post-processing steps such as dehydration and drying.

That is, when the crumb contains many fine particles, problems arise in the solid-liquid separation step, such as a decrease in the operating rate O due to clogging and a decrease in yield due to the outflow of fine stems into the separation liquid. Furthermore, if coagulation is incomplete and uncoagulated polymer latex remains, it will be liberated in the subsequent post-processing process, which will not only hinder operations but also cause quality deterioration.

Furthermore, if the coagulated crumb has poor porosity, it will be difficult to wash and dry it. Furthermore, if the solidified crumb lacks strength, it will be broken into fine particles in subsequent steps, making stable operation difficult.

The properties of the crumb obtained through the coagulation operation, specifically, the particle size, particle size distribution, and porosity of the crumb.
The presence or absence of polymer latex in a non-coagulated state, as well as its resistance to polymerization and kinging, greatly affect the industrial operability of solid-liquid separation, washing, dehydration, and drying after the coagulation process, as well as the quality of the solid product obtained. be.

In the conventional coagulation operation using a stirring tank, which is generally carried out on an industrial scale, the control of the crumb size depends on the stirring intensity, and the shape and rotational speed of the stirring blade are important factors in determining the crumb size. Originally, the purpose of stirring is to mix the target substances appropriately. Ah, 1. Wapa. . . ,5. Yay. . Changing the stirring intensity for □ necessarily sacrifices the stable operation of the stirring tank, and requires a great deal of effort and expense to maintain and manage the rotating equipment. In coagulation when using a stirring tank, the capsules enclosing the polymer 2 and cubes are crushed by the stirring force to advance coagulation.
The crumb size will increase! It takes time to complete IM,
Therefore, the residence time in the stirring tank is forced to be extended, leading to an increase in the size of the stirring tank and the number of bases. Also, as mentioned above, the particle size distribution of crumb size depends on the stirring intensity, but it is almost impossible to make this stirring intensity uniform in the tank, so the particle size distribution is not wide. The generation of coarse crumbs and fine crumbs cannot be completely prevented.

On the other hand, as a coagulation method that replaces the stirring tank, tubular 1IA1! A coagulation method using a D device (4I 18602/18602, 18623/1983) has been proposed, but this method also has the following problems.

ω It is extremely difficult to control the particle size of crumbs obtained by coagulation. That is, depending on the properties of the polymer latex to be coagulated, there are many cases where there are extremely many fine crumbs, or where the crumbs are formed into blocks and there are many coarse crumbs.

■ In order to prevent the formation of fine crumbs, it is difficult to increase the Reynolds number (i.e. flow rate) of the mixed liquid in the coagulation equipment, and when there is a large amount of polymer latte or crumbs to be coagulated, the coagulation equipment is extremely large. It's K of K.

G) To prevent coarse crumbs, use a low crumb concentration W that is economically disadvantageous (for example, 0.1 to 2.5 weight) in the coagulation chamber! (hereinafter referred to as slurry concentration) and 41 cannot be used.

Therefore, the present inventors developed a coagulation method and a coagulation device that can increase the slurry concentration in the coagulation in a tubular coagulation device and prevent the formation of coarse crumbs that lack porous properties due to the formation of coarse crumbs due to the formation of coarse crumbs that lack porous properties. As a result of intensive research with the aim of achieving this goal, the present invention has been completed.

That is, the present invention uses a coagulation device having a double tube, supplies a coagulant solution from one side to the other through the outer tube of the coagulation device, and simultaneously supplies the polymer latex through the inner tube in parallel to the coagulant solution. In a method for obtaining a polymer solid from a polymer latex by bringing the two into instant contact with each other through a flow of water and K,
A polymer characterized in that the operation is performed under conditions in which the Reynolds of the mixed solution of the polymer latex and the coagulant solution in the coagulation chamber is 100,000 to 300,000, and the polymer solid concentration is 3 to 25% by weight. Continuous coagulation of latex.

・■ Main body cylinder 1 with one end (A) pierced and the other end) opened, and main body cylinder 1 so that there is a gap between the end (A) side of main body cylinder 1 and main body cylinder 1. Inserted.

An inner cylinder 2 that is shorter than the main cylinder 1, a good guide vane 8 provided between the main cylinder 1 and the inner cylinder 2, and a supply port 3 provided at the end (to) of the main cylinder 1.
, supplying polymer latex to the inner cylinder 2, supplying a coagulant solution to the main cylinder from the supply port 3, and coagulating both solutions at the front end of the inner cylinder 2 in the main cylinder 1 A device for coagulating polymer latex which has been brought into contact in chamber 4 is provided.

First, a further aspect of the coagulation operation of the present invention will be explained with reference to FIG. IK. The coagulation device shown in the figure has a main body cylinder 1 with a circular cross section and an inner tube 2 therein.

Polymer latex A and coagulant solution B are supplied from supply nozzles 2 and 3 to the coagulation chamber 4, where they are coagulated and formed, and discharged from the discharge section 7, followed by solid-liquid separation (not shown). Sent to the post-processing process of washing, dehydration, and drying. The polymer latex is passed through the outlet 5 of the inner tube 2 into the coagulation chamber 4.
When the polymer latex is allowed to flow out at a constant flow rate in parallel with the flow of the coagulant solution, the polymer latex momentarily contacts the coagulant solution supplied from the nozzle 3 in the form of droplets, and once becomes a group of fine particles. , diffuse in the flow direction and in the direction perpendicular to the flow within the coagulation chamber 4, but each diffusion distance is restricted by the flow velocity of the fluid in the coagulation chamber and the wall 6 of the coagulation chamber, and
:11 The fine particles are formed into a round rod shape with a cross section similar to that of the coagulation chamber 4 due to their own adhesive properties, resulting in nine crumbs. In the coagulation chamber, the coagulant solution is constantly flowing in the gap between the wall of the coagulation chamber and the formed crumb, so there is no contact between the crumb and the wall, and therefore the polymer does not adhere to the wall in the coagulation chamber. , no deposition occurs. In FIG. 1, guide vanes 8 are installed in the inner tube 2, but the guide vanes 8 may not be provided in the double tube coagulation apparatus used in the method of the present invention.

The feature of the present invention is that even at high slurry concentrations, it is possible to suppress crumb formation and obtain crumbs of appropriate particle size.
The coagulation conditions for this purpose are as follows.

When the coagulant solution comes into contact with the polymer latex, it is usually well rectified9, and the Reynolds number Fi in the coagulation chamber of the mixture of coagulant solution and polymer latex is 100,00.
0~300,000. Good I L<1t150,000
It is necessary to set it to ~300,000, if it is less than 100,000, there is a risk of crumbling.
If it exceeds 00, the effect of forming crumbs will be lost. (
Here, the Reynolds number is ρ DU? /μ, where D is the inner diameter of the coagulation chamber, U is the flow rate of the mixed liquid, ρ is the density of the mixed liquid, and V is the viscosity of the mixed liquid. ) Next, the fine particles obtained above are shaped into a suitable ram size depending on the slurry concentration in the coagulation chamber, the constraints of the wall of the coagulation chamber, and the flow state. Tsut,b
Crumb formation is determined by the balance between the adhesive force of the particles themselves and the dispersion force caused by the flow. Therefore, when the slurry concentration is high, crumbs with a dense structure and a small distance between particles can be obtained. When the slurry concentration is low, a shibbolus structure with a large interparticle distance is obtained, but this leads to the formation of fine crumbs. Therefore, the slurry concentration in the coagulation chamber is 3
-25% by weight, preferably 5-15% by weight. 3-
It is difficult to prevent the formation of fine crumbs when the
If the time exceeds 25 seconds, it is difficult to prevent the generation of coarse crumbs.

To adjust the slurry concentration, the solid content concentration of the polymer latex is usually adjusted to 1 ml using a known method.

There are no particular restrictions on the fluidity of the coagulant solution as long as it comes into contact with the polymer latex in a sufficiently rectified state.

Here, the rectified state refers to the flow state of the coagulant solution in a state where the influence of turbulence at the inlet of the coagulation tube has disappeared.

Under normal solidification conditions, it is expressed near the inner tube outlet 5,
D is the inner diameter of the outer tube, d is the outer diameter of the inner tube, υ' is the flow rate of the coagulant solution, μ' is the density of the coagulant solution, and μ' is the viscosity of the coagulant solution. ) Also, the Reynolds number in the inner tube 2 of polymer latex is usually 5,000 or more.

The coagulated fIK8 resin ## of the present invention is suitably applied to rubbery polymer latex made by conventional emulsion polymerization. Specifically, steel/butadiene rubber (8BR)
, acrylonitrile-butadiene rubber (NBR),
Examples include latexes such as J7'tadiene rubber, acrylic rubber, vinyl acetate copolymer rubber, chloropre/rubber, or mixtures thereof. Any coagulant may be used as long as it has the ability to coagulate the polymer latex. Known coagulants are aqueous solutions of acids and salts. Suitable acid aqueous solutions include sulfuric acid, hydrochloric acid, phosphoric acid, acetic acid, etc. alone or in combination. A suitable aqueous solution of salt is Ca(NOs)m,
It is a single or mixed aqueous solution of Ale (Son)s, NaCl, etc. Other known coagulants are organic solvents, such as ketones (eg acetone), alcohols (eg ethyl alcohol, methyl alcohol, etc.) and mixtures thereof. How much coagulant to use? It is determined by the solidity or coagulation ability of the coagulant. Therefore, when an aqueous solution of an acid or salt is used, the concentration of the acid or salt is not constant for the reasons mentioned above.

When carrying out the present invention, the temperature of the raw materials supplied to the coagulation device is usually 307 mL each for polymer latex and coagulant solution.
The temperature is 90°C, preferably 40-80°C.

A preferred coagulation device of the invention is sealed at one end;
Main body cylinder 1 with the other end (c) open, end of main body cylinder 1 (to)
An inner tube 2 shorter than the main tube 1 inserted into the main body IK with a gap between it and the main tube 1 from the side, a guide vane 8 provided between the main tube 1 and the inner tube 2, and a guide blade 8 of the main tube 1 The end (a) consists of a supply port 3 for the coagulant solution.

The length of the inner tube 2 is n in FIG. (Suzuwachi n
(m) The front end of the inner tube 2 is the coagulation chamber 4.

Inside! The preferred ratio Fi of the inner diameter of the main body cylinder 1 to the outer diameter of the main body cylinder 1 is
It is 2 to 10 times.

Guide vanes are provided on the outer surface of the inner tube 2 in the gap between the main body cylinder l and the inner tube 2. A preferable guide vane 8 has a structure that gives a swirling flow to the flow of the coagulant solution, as shown in FIG.
This is a spiral guide vane 8 shown in FIG. In the blade, the pitch (5 in FIG. 1) Fi is usually 1 to 10 times the distance 11h between the main body tube 1 and the inner tube 2, and the height HFi allows the inner tube 2 to be pulled out from the main body tube 1. is determined to be.

The number of pitches is usually l pitches or more. In FIG. 1, the spiral guide blade 8 is a single type with one blade, but it may also be a double type with two blades (see FIG. 2), a triple type with three blades, or the like.

When a spiral guide vane is used, the flow of the coagulant solution becomes a swirling flow, so that the coagulant solution envelops the coagulant fine particles that produce acid after contact with the polymer latex. Block formation in the radial direction can be suppressed.

The outlet of the inner tube 2 is also arranged downstream of the coagulant solution supply nozzle 3.

Coagulant solution supply nozzle 30 and polymer latte.

The distance is such that the time it takes for the combined latex to reach the outlet of the inner tube is 0.2 seconds or more. The diameters of the main body cylinder 1 and the inner tube 2 are determined by the Reynolds number in the coagulation chamber of the mixed solution of coagulant solution and polymer latex, etc., but a practical internal diameter of the main body cylinder Fiis ~ 150 μp is appropriate. . Coagulation chamber length #
'i (m in the figure) is determined by the residence time of the mixed solution (i.e. crumb forming time), and the preferred residence time of the mixed solution is 0.5 to 20 seconds.

The method and apparatus of the present invention result in the following advantages.

(1) Even when coagulating a high crumb slurry concentration that cannot be performed using a general tubular # placement method, it is possible to obtain a coagulated mass of an appropriate size that is highly porous.

■ Because it can coagulate at a high crumb slurry concentration, it is inexpensive.

(3) Since only a small amount of dilution water is required, the cost of transporting dilution water is reduced, and the loss of coagulant can be reduced, resulting in a significant reduction in the running cost of coagulation. ' As described above, an industrially advantageous coagulation process can be completed by the coagulation method and coagulation apparatus according to the present invention, and its industrial value is great.

The present invention will be specifically described below with reference to Examples.

8.1-Voice, outer diameter 10.5 + wm8) Cyacrylonitrile-butadiene rubber (JSRN23 manufactured by Japan Synthetic Rubber Co., Ltd.
The polymer latex (25°C) of 08) was fed at a rate of 3°C per hour, and the aqueous coagulant solution (8°C) adjusted to have magnesium silosulfate at 6% by weight relative to the polymer solids was fed through the nozzle 3.
0°C) is supplied in the range of 0.4-20 m'/hour1, and the solidified slurry has an average residence time of 10.0 m' at that temperature. The properties of the crumb obtained after being sufficiently stabilized were placed in a stirring tank (not shown, with an inner diameter of 1 m12 and a variable speed stirrer with 2 stages of 3 propellers) as shown in Table 1. . The polymer latex open body cylinder used had an inner diameter of 23 mm, and its length was adjusted so that the average residence time of the mixed solution in the coagulation chamber was 0.6 seconds. Also, the length of the tens shown in the figure is 500 square meters. The spiral guide vane has a single structure with a pitch (D) of 5oIw11 and a height of H)4-.

(Hereinafter referred to as Crater) Table 1 As shown in Table 1, it can be seen that the particle size distribution of crumbs varies depending on the Reynolds number of the mixed liquid in the coagulation chamber. In the table, the crumb moisture content (dry base) is used as a substitute for the porous nature of the crumb, and is expressed on a dry rubber basis by measuring the moisture contained in the crumb after draining the sample for 30 seconds. It is something that Ri2
The larger the value of the water content, the more porous the material.

Example 2, Comparative Example 2 Using the same equipment as in Example 1 except for removing the guide vane 8 from the equipment in Example 1, the latex flow rate in Experiment No. 2 in Table 1 was set to 1 to 17 m'/HR. Coagulation was performed under the same conditions as in Example 1 except for the changes.The results are shown in Example 2.
Table 2 As shown in Table 2, it can be seen that the particle size distribution of crumbs varies depending on the Reynolds number of the mixed liquid in the coagulation chamber.

Example 3, Comparative Example 3 Using the apparatus of Example 1 and under the same flow rate conditions as Experiment No. 2 in Table 1, the slurry chain degree (weight S) in the coagulation chamber ranged from 2.5 to
The solid content concentration of the polymer latex was adjusted to 35 cm, and coagulation was performed.

The results are shown in Table 3. As shown in the table, it can be seen that the flow diameter distribution of 2 mm varies depending on the slurry concentration in the coagulation chamber.

The properties of the resulting crumb are such that the higher the slurry concentration in the coagulation chamber, the denser the internal structure of the crumb and the lower the moisture content of the syfram.

Conversely, when the slurry concentration is low, the crumb becomes porous and has a high moisture content.

Example 4, Comparative Example 4 Using the apparatus of Example 2, under the same flow rate conditions as Experiment No. 4 in Table 2, the slurry concentration (heavy weight) in the coagulation chamber was 25 to 3.
The solid content concentration of the polymer latex was adjusted so that the solid content of the polymer latex was 500 mm.

The results are shown in page 41. From the table, it can be seen that the particle size distribution of crumbs varies depending on the slurry concentration in the coagulation chamber.

(Ysu bottom @ et al.) A test similar to Experiment No. 1.2 using the polymer latex of Example 5 was conducted. (However, in Experiment No. 11, the coagulation apparatus of Example 2 was used.) However, the coagulant aqueous solution used was an aqueous solution containing magnesium sulfate adjusted to 10% by weight based on the polymer solids. The results are shown in Table 5.

(Hereinafter referred to as rack b) Table 5 shows that the crumb properties are exactly the same in shape and moisture content as in the case of acrylonitrile-butadiene rubber, with no uncoagulated latex and a sharp particle size distribution without containing fine particles. I got something.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view of one example of the coagulation apparatus of the present invention. FIG. 2 shows an example of a two-blade structure. 2. Polymer latex supply nozzle (inner tube) 3. Coagulant solution supply nozzle 4. Coagulation chamber 7. Discharge section 8 ...Guidance plate □A...Polymer latex □B...Coagulant solution

Claims (1)

[Claims] ■ Using a coagulation device having a double tube, the coagulant solution is supplied from one side to the other through the outer tube of the coagulation device, and (4) the polymer latex is supplied to the coagulant solution through the inner tube. In a method of obtaining a polymer solid from a polymer latex and a coagulant solution by bringing them into instant contact by supplying them in parallel flow, the Reynolds number of the mixture of polymer latex and coagulant solution in the coagulation chamber is 100ρ00. - aoo, ooo, and a continuous coagulation method of a polymer latex, which operates under conditions where the lateral change of the polymer solids is from 3 to 25% by weight. ■ , One end mark is sealed and the other end (- is opened, nine main body cylinder 1, main body #1 inserted into main cylinder 1 so that there is a gap between the end mark side and main body cylinder 1) short inner cylinder 2
, a good guide vane 8 provided between the main cylinder 1 and the inner cylinder 2, a supply port 3 provided at a small part of the main cylinder 1, a hollow, a polymer tube and a rice cake to the inner cylinder 2, and a supply. 3, a coagulant solution is supplied from the main body cylinder IK, and both liquids are brought into contact with each other in a coagulation chamber 4 at the front end of the inner cylinder 2 in the main body cylinder 1.