KR20030084742A - Method for Recovering a Polymer - Google Patents

Abstract

An object of the present invention is to provide a method for recovering polymer particles having a small particle size and a constant particle diameter from a polymer latex containing an ABS resin or the like. The method for recovering the polymer of the present invention comprises a molding step of forming a mixture of polymer latex and a coagulant obtained by a static mixer or the like into a solid having a diameter of 0.5 to 15 mm, and adding and stirring the solid mixture to hot water of 50 ° C. or higher. A solidification step of solidifying and dividing, and a separation step of filtering and separating the solidified polymer particles. The recovered polymer particles have a particle size distribution in which particles having a particle size of 0.5 to 4 mm are 70 to 95 mass% with respect to the whole.

Description

Recovery Method for Polymers {Method for Recovering a Polymer}

The present invention relates to a method for recovering a polymer from a polymer latex containing an ABS resin or the like obtained by emulsion polymerization, and more particularly, to a method for recovering polymer particles having a small particle size and a constant particle size.

As a method of recovering a polymer from the polymer latex, a method of obtaining a powdery polymer by dehydration and drying after coagulation by adding a coagulant to the polymer latex has been conventionally performed. In this conventional method, solidification of the polymer latex is performed by supplying the polymer latex and the coagulant aqueous solution to a coagulation bath filled with hot water at a predetermined temperature (predetermined temperature determined by the desired particle diameter) and stirring in the coagulation bath. However, in this method, since the fine particles are generated and the particle size distribution of the recovered polymer particles is increased, (1) dehydration is poor in the dehydration step after the coagulation step, and (2) the fine particles are blocked in the separation and drying step. Productivity is reduced, (3) the loss by the leakage and scattering of fine particles is large, (4) the volume specific gravity becomes small, a large storage volume is needed, (5) the facilities for preventing dust explosion, etc. are needed, (6) When entering into a kneading machine such as an extruder, fine particles are scattered, and segregation occurs inside the extruder, resulting in poor mixing properties, resulting in poor molding.

An object of the present invention is to recover polymer particles having a small particle size and a constant particle diameter from a polymer latex.

The inventors have determined that a predetermined amount obtained by mixing a polymer latex and an aqueous coagulant solution

It has been found that a polymer mixture containing almost no fine particles can be recovered by making a creamy mixture in a concentration range into a yarn having a predetermined diameter and separating and solidifying the creamy mixture of the yarn by stirring in hot water.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of a structure of a polymer recovery apparatus.

It is explanatory drawing which shows the structure of the mixer unit of a static mixer.

It is a schematic diagram which shows the structure of another polymer recovery apparatus.

4 is a schematic diagram showing the configuration of a polymer recovery device used in Example 1. FIG.

<Explanation of symbols for the main parts of the drawings>

10 mixer

11 die

12 bulkhead

20 coagulation tank

21 axis of rotation

22 stirring wings

30 wet grinder

40 dehydrator

50 dryers

100 solid mixture

The present invention is shown below.

1.A method for recovering polymer particles from polymer latex,

A molding step of mixing the polymer latex and the coagulant into a solid shape having a diameter of 0.5 to 15 mm, a solidification step of solidifying and dividing the solid mixture into hot water and stirring, and a separation step of filtering and separating the solidified polymer particles. A method for recovering a polymer, characterized by the above-mentioned.

2. The method for recovering the polymer according to the first method, wherein the solid content concentration of the mixture is 15 to 40 mass%.

3. The method of the first method, wherein the temperature of the mixture is (Tm-60) ° C or higher and (Tm-10) ° C or lower when the Vicat softening temperature of the polymer to be recovered is Tm. Recovery method of the polymer in the range.

4. The method for recovering a polymer according to the first method, wherein the amount of the coagulant used is 1 to 10 parts by mass based on 100 parts by mass of the polymer.

5. The method of recovering polymer according to the first method, wherein the mixture is obtained by a static mixer.

6. The method of recovering polymer according to the first method, wherein the mixture is obtained by a single screw extruder or a twin screw or more multi screw extruder.

7. The method for recovering the polymer according to the first method, wherein the temperature of the hot water is at least (Tm-30) ° C and is at most (Tm + 30) ° C.

8. The method for recovering polymer according to the first method, wherein the solid mixture is cut into predetermined lengths and then charged into hot water.

9. The method for recovering polymer according to the first method, wherein the recovered polymer particles have a particle size distribution in which particles having a particle size of 0.5 to 4 mm are 70 to 95 mass% with respect to the whole.

According to the present invention, the mixture of the polymer latex and the coagulant is made into a solid shape having a diameter of 0.5 to 15 mm, and this is divided into almost uniform lengths by adding the mixture to hot water and stirring, so that the particle size contains little fine particles because it solidifies. Constant polymer particles can be obtained and can be recovered.

When solid content concentration of the said mixture is 15-40 mass%, when a solid mixture is thrown into hot water, a solidification process can be advanced, without causing mold deformation.

In addition, when the temperature of the mixture is above (Tm-60) ° C and below the range of (Tm-10) ° C, since the mixture has an appropriate viscosity, it does not cause mold deformation when the solid mixture is added to hot water. The coagulation process can be advanced.

When the usage-amount of the said coagulant is 1-10 mass parts with respect to 100 mass parts of said polymers, solidification of a polymer latex can be advanced efficiently.

When the mixture is obtained by a static mixer, a mixture in a good mixed state can be obtained, and the solidification can be efficiently performed in a subsequent step.

Moreover, when the said mixture is obtained by a single screw extruder or a biaxial or more multi-screw screw extruder, the mixture in a favorable mixing state can be obtained, and the solidification can be performed efficiently in a subsequent process.

When the temperature of the hot water is (Tm-30) ° C or more and (Tm + 30) ° C or less, solidification of the polymer latex can be efficiently proceeded.

When the solid mixture is cut into a predetermined length and then introduced into hot water, polymer particles having a more uniform particle size can be obtained.

Moreover, according to this invention, the dehydration property in the dehydration operation | work in a separation process can be improved, a blockage can be prevented, and the loss of a polymer can be reduced. In addition, the storage volume can be reduced by increasing the volume specific gravity of the recovered polymer particles. In addition, it is possible to prevent molding defects due to segregation of the fine particles in the molding machine since no equipment for preventing dust explosion is required and fine particles are not scattered during injection into a molding machine such as an extruder.

Hereinafter, the present invention will be described in detail.

The present invention relates to a method for recovering polymer particles from a polymer latex, comprising a molding step of mixing a polymer latex and a coagulant into a solid shape having a diameter of 0.5 to 15 mm, and a solidification step of solidifying and dividing the solid mixture into hot water and stirring the mixture. And a separation step of separating the solidified polymer particles by filtration.

In addition, polymers applicable in the present invention include (i) acrylonitrile-butadiene-styrene resin (ABS resin), acrylonitrile-butadiene-α-methylstyrene resin (heat resistant ABS resin), acrylonitrile-butadiene-N-phenyl Maleimide resin (heat resistant ABS resin), acrylonitrile-ethylene-propylene-diene-styrene resin (AES resin), methyl methacrylate-butadiene-styrene resin (MBS resin), high-impact polystyrene resin (HIPS resin), Resins such as graft copolymers such as acrylonitrile-acrylate-styrene resin (AAS resin), (ii) styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), and rubber such as acrylic rubber Hard polymers such as a type polymer, (iii) acrylic resin, polystyrene, styrene-methyl methacrylate (MS resin), and styrene-acrylonitrile copolymer (AS resin).

The said polymer latex is obtained by emulsion polymerization, and solid content concentration is 20-50 mass% normally. On the other hand, as said coagulant, what is conventionally used for coagulation of a polymer latex, For example, inorganic acids, such as hydrochloric acid, a sulfuric acid, nitric acid, organic acids, such as acetic acid, formic acid, a citric acid, and metal salt of these acids are mentioned. As this metal salt, inorganic salts, such as calcium chloride, aluminum chloride, aluminum sulfate, magnesium sulfate, organic salts, such as calcium acetate and aluminum acetate, are mentioned, for example. This metal salt can be used as it is, and can also be used after melt | dissolving in water etc. The said coagulant can be used individually by 1 type or in combination of 2 or more types.

The addition amount of the coagulant is preferably 1 to 10 parts by mass, more preferably 1 to 5 parts by mass with respect to 100 parts by mass of the polymer in consideration of the solid content concentration of the polymer latex and the coagulation value of the polymer. If the amount of the coagulant added is less than 1 part by mass, the polymer latex cannot be sufficiently solidified. On the other hand, if it exceeds 10 parts by mass, waste is generated because the required amount of the coagulant is exceeded. Here, the "coagulation value" is a polymer latex having a predetermined solid content concentration and a coagulant having a different solid content concentration, and after a certain period of time, the minimum concentration (concentration after mixing) at which precipitation occurs when precipitation formation is confirmed. Say.

The method of mixing the polymer latex and the coagulant is not particularly limited, but the method of mixing the polymer latex and the coagulant separately by mixing them in a mixer, the method of adding the coagulant to the polymer latex and mixing the method, and the method of adding the polymer latex to the coagulant and mixing them, etc. Can be mentioned. By these methods, it can become a creamy form preferably. Although mixing conditions are not specifically limited, It is preferable to select temperature in consideration of the non-cut softening temperature of the polymer to be recovered. When the non-cut softening temperature of this polymer is set at Tm ° C, the temperature at the time of mixing is preferably (Tm-60) ° C to (Tm-10) ° C, more preferably (Tm-55) ° C to (Tm- 15) ° C, more preferably (Tm-50) ° C to (Tm-20) ° C. When this temperature is lower than (Tm-60) C, it disperse | distributes as microparticles | fine-particles in a coagulation | solidification tank by a coagulation | solidification process, and among the polymer particle collect | recovered, a lot of fine particles are made and particle size distribution becomes large. On the other hand, when it is higher than (Tm-10) ° C, the viscosity of the mixture tends to be high, so it may be difficult to obtain a solid mixture having a diameter of 0.5 to 15 mm. Moreover, in order to make it the said temperature, a polymer latex and a coagulant can be pre-warmed and a mixer can also be heated. Moreover, it is preferable to also maintain the obtained mixture at the said temperature.

The mixer used for mixing the polymer latex and the coagulant is not particularly limited, and examples thereof include a static mixer, a single screw extruder, a two or more multiaxial screw extruder, and the like. In this invention, it is preferable to use a static mixer, a single screw extruder, or two or more multiaxial screw extruders as said mixer. These mixers may be in longitudinal or transverse arrangement. In the case where the mixer is arranged vertically, the mixture extruded from the mixer can be directly put into the coagulation bath by providing a coagulation bath at a position below the outlet side (lower end) of the mixer. In the case of the transverse arrangement of the mixer, a facility for guiding the mixture into the coagulation bath is required separately. In the case of using a screw extruder as the mixer, an interlocking twin screw extruder is preferable from the standpoint of mixing performance and extrusion stability.

Here, the static mixer, which is an example of the mixer, is configured by connecting a plurality of mixer units in series.

The cylindrical end face shape of each mixer unit is circular, for example, It is not limited to this, It can be an elliptical form, a polygonal shape, etc. In order to move the resulting mixture while mixing the polymer latex and coagulant press-fitted into the barrel by a pump or the like, the partition walls in the barrel need to be twisted as they face the barrel direction. The torsion angle, that is, the angle at which the partition wall rotates from one end face to the other end face of the cylinder of the mixer unit, for example, is 90 degrees, 180 degrees, or the like, but may be an angle other than these. Further, the end face of the partition wall on the outlet side of the mixer unit at the front end and the end face of the partition wall on the inlet side of the mixer unit at the next stage are connected so as to intersect.

Solid content concentration of the mixture which consists of a polymer latex and a coagulant becomes like this. Preferably it is 15-40 mass, More preferably, it is 20-40 mass%, More preferably, it is the range of 25-35 mass%. If the solid content concentration of the mixture is less than 15% by mass, it becomes a slurry, not a cream, and it is difficult to obtain a solid mixture, and the polymer particles to be recovered have a large amount of fine particles and a large particle size distribution. On the other hand, when it exceeds 40 mass%, since the viscosity of a mixture tends to become high, it may be difficult to obtain the solid mixture of diameter 0.5-15 mm.

The creamy mixture of the polymer latex and coagulant in the mixer is extruded from a generally circular or elliptical hole provided at the outlet side of the mixer, and has a diameter of 0.5 to 15 mm, preferably 0.5 to 10 mm, more preferably 1 To a 5 mm solid mixture (molding process). In addition, this "diameter" is a broad meaning including the maximum length of an outer diameter.

This solid mixture may be continuous but may be cut to a predetermined length at the time of extrusion. In the case of cutting to a predetermined length, the length is preferably 1 to 10 mm, more preferably 1 to 5 mm. The cutting method is not particularly limited, and there are a method of using a cutter, a method of using a fluid cutter, and the like. Moreover, it is preferable to make the temperature at the time of extrusion of the solid mixture into the temperature at the time of mixing of the polymer latex and coagulant demonstrated above.

Thereafter, the solid mixture is introduced into hot water (warmed water) in a coagulation bath and stirred (coagulation step). This solid mixture can be brought into contact with the atmosphere and can be introduced in hot water and extruded in hot water.

The temperature of the hot water is preferably (Tm-30) ° C to (Tm + 30) ° C, more preferably (Tm-20) ° C to (Tm + 20) ° C, still more preferably (Tm-10) ° C to (Tm + 10) ° C. When this temperature is lower than (Tm-30) ° C, the solid mixture is not solidified in the state in which it is introduced, and is dispersed as fine particles in a coagulation bath, and tends to increase the number of fine particles in the recovered polymer particles. In addition, coagulation baths having the same or different temperature can be installed in series in multiple stages. In this case, it is preferable that the temperature of the hot water be increased by the coagulation bath at the rear stage. Thereby, since solidification of a solid mixture advances gradually, the polymer particle which is smaller in fine-grained particle | grains and has a constant particle diameter is obtained.

In addition, the hot water may be hot water including a coagulant or a coagulation aid.

The solid mixture is solidified (coagulated) at the same time as it is introduced into hot water, and is further divided immediately when stirred to form a single thread or granular form. Stirring conditions are not specifically limited. Moreover, as a stirring blade used for stirring, it can be what can divide | disconnect the said solid-form mixture into single-bed form or a granular form in hot water efficiently, and is not specifically limited. For example, stirring blades, such as a paddle wing, a padra wing, a turbine wing, a bland margin wing, a max blend wing, and a full zone wing, can be used.

The polymer particles obtained by the coagulation step are separated by filtration (separation step) using a filter or the like, then dehydrated and dried to be recovered. In addition, filtration separation and dehydration may be performed simultaneously.

As a filtration separation means, a belt filter, a vacuum belt filter, etc. are mentioned. Centrifugal dehydrator etc. are mentioned as dehydration means. Moreover, an airflow dryer, a fluid dryer, a rotary dryer, etc. are mentioned as drying means. The drying temperature (refers to the airflow temperature) is usually (Tm-50) ° C to Tm ° C, preferably (Tm-40) ° C to (Tm-1O) ° C. When the polymer is an ABS resin, the drying temperature is preferably 50 to 100 ° C, more preferably 70 to 95 ° C.

According to the present invention, the recovered polymer particles may have a particle size distribution of particles having a particle diameter of 0.5 mm or less, preferably 20 mass% or less, more preferably 15 mass% or less, and still more preferably 10 mass% or less with respect to the whole. have. Moreover, the particle | grains exceeding 0.5 mm of particle diameters are preferably 80 mass% or more, More preferably, it is 85 mass% or more, More preferably, it can be set as 90 mass% or more. Moreover, the particle | grains in the range of 0.5-4 mm of particle diameters are 70-95 mass% with respect to the whole, Preferably it is 75-95 mass%, More preferably, it can be set as 80-92 mass%. The particles having a particle diameter of 0.1 mm or less are preferably 1% by mass or less, and more preferably 0.5% by mass or less with respect to the whole.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated using drawing.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows an example of a structure of a polymer recovery apparatus. This recovery apparatus is provided with the mixer 10 which installed the static mixer which connected five stage mixer units in the vertical direction, and the coagulation tank (1st coagulation tank) 20 in which hot water was entered. In addition, a wet mill 30, a second solidification tank 20a, and the like may be provided at the rear end of the first solidification tank 20, and the dehydrator 40, the dryer 50, and the like may be provided in this order.

The wet grinder 30 and the 2nd coagulation tank 20a (in FIG. 1, 21a shows the rotating shaft of a stirring blade, 22a shows a stirring blade) may be omitted, and it can further expand as needed. It may be. That is, when the solid mixture 100 extruded from the mixer 10 is uniformly divided in the first coagulation tank 20 in order to make it constant to a desired size, and this can be solidified, the wet grinder 30 and (Or) The second coagulation bath 20a can be omitted. In addition, when the solid mixture is gradually solidified, a fine grinder 30 and / or a second coagulation tank 20a are installed in order to sufficiently reduce the fine particles to uniformly and uniformly size the polymer particles. If necessary, it can be installed in multiple stages.

The static mixer is configured by connecting a mixer unit in five stages in FIG. 1, but is not limited thereto. As long as it can fully mix a polymer latex and a coagulant, four or less stages may be sufficient and six or more stages may be sufficient as it.

In addition, each mixer unit constituting the static mixer has a cylindrical shape of an end face circular shape as shown in FIG. 2, and guides the spiral mixture by dividing the mixture of polymer latex and coagulant passing through the inside into two cylinders. One partition 12 is provided. The partition wall 12 is provided to be twisted in the direction of the cylinder to obtain a mixture of the polymer latex and the coagulant passing through the cylinder in a spiral manner, and its twist angle, that is, one end face of the cylinder (end face on the inlet side) The angle at which the partition wall 12 is twisted from to the other end surface (end surface on the exit side) is 180 degrees in the example of FIG. 2. That is, it is twisted so that half rotation may be carried out from the end surface of an entrance side to the end surface of an exit side. This twist angle is not limited to 180 degrees, and may be, for example, 90 degrees, 270 degrees, 360 degrees, or the like. In order to show the state which the partition 12 is twisted gradually, the end surface 12i of the partition at the entrance side is shown to FIG. 2 (X), and the cut end surface 12c of the partition at the center part of the cylinder is shown to FIG. 2 (Y). 2 (Z) shows the end face 12o of the partition wall at the outlet side, respectively.

Each mixer unit is connected so that the partition 12 may cross | intersect at the front end side and the back end side. In other words, the partition wall end face on the outlet side of the mixer unit at the front end and the partition wall end face on the inlet side of the mixer unit at the rear end are connected so as to have a positional relationship intersecting with each other. For this reason, the mixture of the polymer latex and the coagulant which passed through the mixer unit on the front side as two fractions is also classified into two when it enters the mixer unit on the rear side, and as a result, it is classified into four at that time. As the number of stages of the mixer unit goes through, the number of fractions increases and is sufficiently mixed.

In addition, as an example of FIG. 2, the partition wall 12 of each mixer unit is a single plate-shaped member having a curved shape, and therefore has a function of classifying a mixture of polymer latex and a coagulant into two, but it is not necessarily one sheet. For example, a member having a shape having a function of classifying a mixture of a polymer latex and an aqueous solution of a coagulant into three parts (a member having a radially orthogonal cutting end surface extending radially in three directions at the same angle from the cylindrical axis). It may be. It may also be a member of a shape having an action of dividing into four or more (a member having a shape in which the cut end surface orthogonal to the cylindrical axis extends radially in four directions at the same angle from the cylindrical axis).

Moreover, in order to make the temperature of the mixture which consists of a polymer latex and a coagulant into said preferable temperature range, a static heat source can be provided in a static mixer.

The mixture obtained as described above is extruded in a solid form from a plurality of holes (each having a diameter of about 0.5 to 15 mm in diameter) of the die 11 at the bottom of the mixer 10.

Hot water is contained in the coagulation tank 20 into which the solid mixture 100 is introduced. The temperature of this hot water is preferably (Tm-30) 占 폚 to (Tm + 30) 占 폚. In this hot water, a coagulant or a coagulation aid can be added in advance. The coagulation bath can be installed in two or more stages as shown in FIG. 1, in which case the temperature of the hot water of the first coagulation bath 20 is set relatively low, and the coagulation bath is gradually set higher so as to gradually solidify the solid mixture 100. It is possible to advance the polymer particles with less finely divided particles and have a smaller particle size distribution.

Although not shown, the coagulation tank 20 is provided with the stirring blade 22 which rotates by transmitting the driving force from a drive source (motor) through the rotating shaft 21. As shown in FIG. By the rotation of the stirring blade 22, the solid mixture introduced into the coagulation bath 20 from the mixer 10 into the coagulation bath 20 is divided into a single threaded or granular form.

As the wet mill 30 of the rear end side of the coagulation tank 20, a conventionally well-known thing can be used and since it demonstrates a conventionally well-known function, further description is abbreviate | omitted. Similarly, the dehydrator 40 and the dryer 50 can also use a conventionally well-known thing, and since it exhibits a conventionally well-known function, further description is abbreviate | omitted.

It is a schematic diagram which shows the structure of the polymer recovery apparatus different from FIG. In this recovery apparatus, a screw extruder is used as the mixer 10a. The rest of the configuration is the same as that in Fig. 1, and the same reference numerals are used to denote the description thereof.

The screw extruder used in the polymer recovery apparatus of FIG. 3 is a single screw, but this is an example, and a screw extruder of two or more axes can be used. When using a twin screw extruder, the interlocking type is preferable from the standpoint of mixing performance and extrusion stability.

<Example>

Hereinafter, an Example is given and this invention is demonstrated concretely. In addition, in an Example and a comparative example, a part and% are a basis of weight unless there is particular notice.

<Example 1>

By the polymer recovery apparatus of the structure shown in FIG. 4 using the latex (solid content concentration 35%) containing ABS resin of 90 degreeC of non-cut softening temperature, and magnesium sulfate aqueous solution (solid content concentration 10%) which is a coagulant, ABS resin particles were recovered. That is, polymer particles were recovered by a polymer recovery device using a static mixer as a mixer.

In addition, the polymer recovery apparatus used in this Example 1 differs from the polymer recovery apparatus shown in FIG. 4 in the following points. In other words, the mixer unit has four stages. Moreover, the internal diameter of the static mixer as the mixer 10 is 8 mm, the number of the holes of the die 11 provided in the exit side of the static mixer is three, and the diameter of each hole is 6 mm, respectively.

Initially, the latex and the coagulant were introduced into the static mixer at a rate of 30 liters / hour and 2.1 liters / hour, respectively (usage amount of 2 parts of magnesium sulfate relative to 100 parts of the polymer included in the latex) and at 50 ° C. Mixed. Thereafter, the obtained mixture was extruded from the die provided on the outlet side of the static mixer as a solid mixture (solid content concentration was 33.4%, temperature was 50 ° C) and hot water in the coagulation bath 20 with stirring blades (temperature 90 In)). Subsequently, the stirring blade was rotated at the rotation speed of 120 rpm in this coagulation tank 20, and the average residence time was made into 0.5 hour. It was confirmed that the real mixture was parted by this stirring. Thereafter, the solidified polymer particles were separated by filtration, dried at 80 ° C. for recovery, and the particle size distribution of the polymer particles was measured. The results are shown in Table 1.

<Example 2>

ABS resin particle | grains were collect | recovered by the polymer collection | recovery apparatus of the structure shown in FIG. 3 using the latex and coagulant in the said Example 1. That is, the polymer particle was collect | recovered by the polymer recovery apparatus which used the longitudinally arranged twin screw extruder as the mixer 10a.

In addition, the polymer recovery apparatus used in this Example 2 differs strictly from the polymer recovery apparatus shown in FIG. 3 in the following two points. That is, (1) there is no 2nd coagulation tank 20a, and (2) a screw extruder is an interlocking biaxial | shaft. In addition, the screw diameter of the screw extruder is 251 mm, the screw L / D is 4 (L is 10 cm), the number of holes of the die 11 installed at the outlet side of the screw extruder is 50, and the diameter of each hole is 2 mm.

Initially, the latex and the coagulant were introduced into the screw extruder at a rate of 30 liters / hour and 2.1 liters / hour, respectively (usage amount of magnesium sulfate 2 parts per 100 parts of the polymer included in the latex), and 50 캜. Mixed in. Thereafter, the obtained mixture was extruded from the die provided on the outlet side of the screw extruder as a solid mixture (solid content concentration was 33.4%, temperature was 50 ° C), and hot water in the coagulation bath 20 with stirring blades (temperature 90 In)). Next, in this coagulation tank 20, the stirring blade was rotated at the rotation speed of 120 rpm, and the average residence time was made into 0.5 hour. It was confirmed that the real mixture was parted by this stirring. Thereafter, the solidified polymer particles were collected by filtration, and the particle size distribution of the polymer particles was measured. The results are shown in Table 1.

Comparative Example

ABS resin particle | grains were collect | recovered by the conventionally well-known collection | recovery apparatus using the latex and coagulant in the said Example 1. That is, the polymer particle was collect | recovered by the polymer collection | recovery apparatus of the structure which did not use the mixer 10 in FIG.

The latex, the coagulant and water (temperature 30 ° C.) were each 30 liters / hour, 2.1 liters / hour, 2.1 liters / hour (the amount equivalent to 2 parts of magnesium sulfate per 100 parts of polymer included in the latex), and 9.9 Into the coagulation bath 20 (temperature 90 degreeC), without mixing, the stirring blade was rotated at the rotation speed of 120 rpm, the average residence time was made 0.5 hour, and the latex was solidified at the speed of liter / hour. Thereafter, the solidified polymer particles were collected by filtration, and the particle size distribution of the polymer particles was measured. The results are shown in Table 1.

As is clear from Table 1, in the comparative example, 65% of particles of 0.5 mm or less were produced, and among them, 33% of fine particles of 0.1 mm or less were contained. On the other hand, Examples 1 and 2 had almost no fine particles of 0.1 mm or less, and the particles of 0.5 to 4 mm were 85% and 90%, respectively. Therefore, according to this invention, polymer particles with few fine particles and constant particle size can be recovered.

In the present invention, a molding step of mixing a polymer latex and a coagulant obtained by a static mixer or the like into a solid shape having a diameter of 0.5 to 15 mm, and a solidification step of solidifying and dividing the solid mixture into 50 ° C or more of hot water and stirring, By providing the separation process which isolate | separates the obtained polymer particle by filtration, the polymer particle which hardly contains a fine particle can be collect | recovered.

Claims (9)

A method for recovering polymer particles from polymer latex, A molding process in which the mixture of the polymer latex and the coagulant is in a solid shape having a diameter of 0.5 to 15 mm, a solidification process in which the solid mixture is poured into hot water and stirred, and solidified and separated, and the solidified polymer particles are separated by filtration. A process for recovering a polymer, comprising a separation step. The method for recovering a polymer according to claim 1, wherein the solid concentration of the mixture is 15 to 40 mass%. The method of recovering a polymer according to claim 1, wherein the temperature of the mixture is (Tm-60) ° C or higher and (Tm-10) ° C or lower when the non-cut softening temperature of the polymer to be recovered is Tm. . The method for recovering a polymer according to claim 1, wherein the amount of the coagulant used is 1 to 10 parts by mass based on 100 parts by mass of the polymer. The method of claim 1, wherein the mixture is obtained by a static mixer. The method of claim 1, wherein the mixture is obtained by a single screw extruder or a two or more multiscrew screw extruder. The method for recovering a polymer according to claim 1, wherein the temperature of the hot water is at least (Tm-30) ° C and at most (Tm + 30) ° C. The method of recovering a polymer according to claim 1, wherein the solid mixture is cut into a predetermined length and then charged into hot water. The method for recovering a polymer according to claim 1, wherein the recovered polymer particles have a particle size distribution in which particles having a particle size of 0.5 to 4 mm are 70 to 95 mass% with respect to the whole.