JPH03223303A - Production of particulate polymer - Google Patents

Abstract

PURPOSE:To obtain continuously a particulate polymer having a low fine powder content and a sharp particle size distribution by interposing a step of mixing with a codirectionally rotating twin screw kneader into a process for forming polymer particles from a polymer latex obtained by emulsion polymerization. CONSTITUTION:A process for forming polymer particles from a polymer latex obtained by emulsion polymerization, comprising adding a coagulant to the latex to form a polymer slurry and adding an organic liquid which is difficultly water-soluble and does not dissolve but can wet the polymer to the slurry, wherein at least either a step of mixing the polymer latex with the coagulant or a step of mixing the polymer slurry with the organic liquid applied with a codirectionally rotating twin screw kneader.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a method for producing a powdery polymer, and more specifically, a method for producing a powdery polymer with less fine powder and a sharp particle size distribution using a co-rotating twin-screw kneader. Regarding the manufacturing method of powdery polymers - (Prior art) Polymer latex obtained by emulsion polymerization method etc.
Generally, polymer particles with a particle size of 1 μm or less are covered with an emulsifier and exist as dispersed and suspended in water, and because the particle size is too small, it is difficult to directly separate solid and liquid and recover the polymer. Conventional methods for recovering the polymer from such polymer latex include: (1) directly separating it as powder using a spray dryer; (2) mixing salt or acid with the polymer latex and coagulating it; A commonly used method is to solidify the material by heating it to an elevated temperature, then dehydrate and dry it to recover it as powder.

Furthermore, in order to adjust the particle size of the obtained polymer particles,
■ A method of dispersing polymer latex in a specific solvent and coagulating it after spheroidizing it (Japanese Patent Application Laid-open No. 52-68285);
■ A method of granulating a slurry obtained by coagulating polymer latex by mixing an organic liquid that is poorly soluble in water and that does not dissolve the polymer but can wet it (Japanese Patent Publication No. 59-5610)
,■ It is poorly soluble in water and does not dissolve the polymer, but it can be obtained by heating! A method of mixing sclerosis and polymer latex in the presence of a coagulant (Japanese Patent Publication No. 59-5611), ■ Dispersing droplets of polymer latex in a coagulating atmosphere using a spray drying mechanism. A method of semi-solidifying, further solidifying in a coagulating liquid, and then dehydrating and drying (Japanese Patent Application Laid-Open No. 56-95905)
Publication No. 2), etc. have been proposed.

However, the method using a spray dryer requires a large amount of water to be evaporated and a large amount of drying energy to dry the polymer latex containing a large amount of water. There have been problems such as the particle size tends to be uneven and the particle size distribution becomes wide, it is difficult to control the particle size and bulk specific gravity, and the equipment cost is high.

In the coagulation and solidification method described in (2), when a normal seed-type or base-type coagulation and solidification device is used, the particle size distribution of the obtained polymer powder becomes wide; The handling of the powder and granules is difficult due to the large amount of
There is a problem in that if a few percent by weight of fine powder of less than m is mixed into the total particles, it causes dusting. and the average particle size is 1
It was never made less than 50 μm.

Method ① can control the particle size distribution and average particle size in the region where the particle size is 100 μm or more by spheroidization.
This is difficult on the small particle size side of 00 μm or less, and furthermore, it is necessary to treat a large amount of solvent used after the spheroidization treatment, and since the spherical latex particles are coagulated from the outside, coagulation becomes uneven and the polymer There was a risk of problems such as fish eyes occurring during processing. Method (2) is a method for producing a powdery polymer with a sharp particle size distribution, but it was not possible to arbitrarily control the average particle size while maintaining the sharp particle size distribution. In addition, in the method (■), although the amount is less than the method (■), 60 to 60 parts by weight per 100 parts by weight of the polymer.
In order to add 500 parts by weight of organic liquid, it still had the disadvantage that a large amount of organic liquid had to be treated.

Method (2) is also a method for producing powdery polymers with a sharp particle size distribution, but it is not possible to arbitrarily control the average particle size while maintaining the sharpness of the particle size distribution. In addition, method (2) also had the disadvantage that a large amount of organic liquid had to be treated in order to add 1 to 5 (volume ratio) of organic liquid to 1 volume of polymer.

Furthermore, in methods ① and ③, the addition of the organic liquid is done in batches, so the viscosity increases over time after the addition of the organic liquid, despite the addition of a suspending agent and a surfactant. It had an unstable granulation process in which it rose. For this purpose, the particle size distribution of the particles produced depends on the rotation speed of the stirrer,
It has been difficult to produce large quantities of particles with controlled particle size distribution and bulk specific gravity at low cost, as they are greatly influenced by the shape of the stirrer, the amount of organic liquid used, etc. Furthermore, the granulation behavior is different from continuous granulation by continuously supplying an organic liquid or the like, and it is no exaggeration to say that batch-type granulation is a different technology from continuous granulation.

Method (2) has the same mechanism as spray drying, so it is easy to obtain spherical powder, but it has drawbacks such as a limit to the particle size and the need for large equipment because it uses a gas phase for coagulation. was.

[Problem to be solved by the invention]

On the other hand, with the automation of powder weighing and the increasing size of storage and transportation equipment, problems such as blocking phenomena, where powder particles solidify together during storage, and clogging of transportation lines due to insufficient fluidity of powder, are becoming more common. Therefore, there is a strong desire to develop a granular polymer that is easy to handle. In addition, recently, the functions required of resins have increased, and a single polymer alone cannot meet the demands for higher functionality, so it is often used in combination with other polymers and modifiers. In such cases, storage,
It is necessary to appropriately control the particle size to avoid component fluctuations due to powder segregation during transportation.

On the other hand, when using polymers in combination with other materials,
Roughly melt and knead with an extruder or the like to increase the uniformity of the mixture. In such applications, it is necessary to minimize the number of particles with a particle size of 40 μm or less, which adversely affect the handling properties of the powder-grain polymer, and to make the powder-grain polymer as fine as possible in order to improve dispersion during mixing. . Thus, there has been a strong desire for a method for controlling the particle size of powdery polymers that can control the average particle size while keeping the particle size distribution sharp.

The present invention Previously, as a method for producing a powdery polymer that solved the problems of the above methods ① to ② and also met the above requirements, a polymer slurry obtained by first coagulating a polymer latex was used. , in a method of continuously granulating polymer particles by adding and mixing an organic liquid that is sparingly soluble in water and does not dissolve or wet the polymer, a specified range of temperature and abundance ratio of water and organic liquid during mixing. (PCT)
/JP88100974).

However, for certain polymer latexes, especially copolymer latexes containing a large amount of rubber components, PCT/JP88
When the manufacturing method of 100974 was applied and a stirring tank was used as a coagulation device, a problem arose in that the coagulation process became unstable. In other words, if the solid content concentration of the polymer slurry is increased during coagulation to improve productivity, if the coagulation temperature decreases, or if the amount of coagulant decreases, the slurry Instability occurred in that the viscosity increased, transportation became difficult, and the coagulator was prone to clogging.

Furthermore, when such latex containing a large amount of rubber components was coagulated using a stirred tank type coagulation device, the polymer particles (coagulated particles) produced by the coagulation became large, numbering several hundred or more.

As a result, when the obtained polymer particles are mixed with other materials, the polymer particles become difficult to disperse in other materials, resulting in problems such as deterioration of the appearance of the resin composition product.

In addition, copolymers and kraft polymers containing large amounts of rubber components have the problem that unless a large amount of organic liquid is used, granular polymers with large bulk specific gravity and good fluidity cannot be obtained.

An object of the present invention is to provide a method for producing a granular polymer suitable for continuously producing a granular polymer containing less fine powder and having a sharp particle size distribution.

[°Means to solve the problem]

That is, in the method for producing a powdery polymer of the present invention, a coagulant is added to and mixed with a polymer latex obtained by an emulsion polymerization method to form a polymer slurry, and then a water-resistant polymer is added to the polymer slurry. In a method of granulating polymer particles contained in a polymer slurry by adding and mixing an organic liquid that dissolves and does not dissolve the polymer or dissolves the polymer, the step of mixing a polymer latex and a coagulant and the polymer slurry It is characterized in that at least one of the mixing steps of the organic liquid and the organic liquid is carried out using a co-rotating twin-screw kneader.

[For production]

The method for producing a powdery polymer of the present invention includes a step of adding and mixing a coagulant to a polymer latex obtained by an emulsion polymerization method to coagulate the polymer latex to form a polymer slurry (
(hereinafter abbreviated as the coagulation step) and the polymer slurry thus obtained is mixed with an organic liquid that is sparingly soluble in water and does not dissolve the polymer but wets it. At least one of these steps is carried out using a co-rotating twin-screw kneader.

That is, the coagulation process is carried out using a co-rotating twin-screw kneader,
The subsequent granulation process is carried out using ordinary granulation equipment with mixing function.
For example, it may be carried out using an overflow type stirring tank, or conversely, the coagulation step may be carried out in a mixing tank equipped with stirring blades,
The subsequent granulation step may be carried out in a co-rotating twin-screw kneader. Alternatively, the coagulation step and the granulation step may be carried out in the same direction-rotating twin-screw kneader, or in this case, the coagulation step and the granulation step can be carried out continuously in the same co-rotating twin-screw kneader. It can also be implemented.

1 to 3 show an example of a co-rotating twin-screw kneader used in the method of the present invention.

In the method of the present invention, a twin-screw kneader having a figure-8 barrel cross section and two screws is used. A kneader or a single-screw extruder having only one screw has a poor ability to convey a polymer slurry and cannot obtain desired polymer particles.

Further, in the two-wheeled mixer used in the method of the present invention, it is necessary to use a co-rotating two-screw mixer in which the screws rotate in the same direction and the screws have a self-cleaning action. In a twin-screw kneading machine that rotates in different directions, it is difficult to make the screws self-cleaning, so the polymer in the polymer slurry tends to stick to the screw surface, causing the polymer to block the inside of the device. This makes stable operation difficult.

The screws to be placed in the kneading machine are of the double-thread type with a screw cross section as shown in Figure 4(a), or of the screw type as shown in Figure 4(b).
) can be used, but a double-thread type is preferable because it allows for a larger hold-up amount of the device.

Screw elements generally have five functions based on their functions: ■Forward conveyance, ■Reverse conveyance, ■Kneading, ■Progressive kneading with the functions of ■ and ■ above, and ■Reverse feed kneading with the functions of ■ and ■ above. It can be roughly divided into types. Figure 5(a)-(
Representative shapes of these five types of screw elements are shown in e).

Polymer latex, coagulant,
The part that supplies polymer slurry and organic liquid (hereinafter referred to as
The screw element located at the raw material supply port (referred to as the raw material supply port) is preferably an element of (1) forward conveyance or (2) forward conveyance which has a forward conveyance function, and (4) an element of forward conveyance is particularly preferable.

As for the total length of a portion of the screw of the co-rotating twin-screw kneader, the ratio L/D is preferably 2 or more, where L is the length of the screw and D is the outer diameter of the screw. However, if it is too long, it will be difficult to manufacture the device, so
The ratio L/D is preferably 40 or less, particularly 20 or less.

If the residence time is insufficient for one twin-screw kneader, it is preferable to use two or more co-rotating twin-screw kneaders connected in series. It is also possible to use an overflow type mixed species connected after the twin-screw kneader.

Note that the co-rotating twin-screw kneading machine referred to in the present invention also includes a device commonly referred to as a co-rotating twin-screw extruder.

In order to enhance the mixing effect of the screw, the rotational speed of the screw is desirably such that the speed of the portion where the seven screws are in contact with the inner surface of the barrel is 5 cm/sec or more, preferably 20 cm/sec or more.

The upper limit of the screw rotation speed is determined based on the mechanical strength of the device, but it is usually desirable to set it at 2000 revolutions/rotation or less.

The particle size of the powdery polymer product can be controlled by the configuration and rotation speed of the screw elements of the co-rotating twin-screw kneader used for mixing the polymer latex and coagulant. Screw element (C) in Figure 5
If the proportion of is increased and the kneading is strengthened, the particle size will become smaller. In addition, if the screw element configuration is the same,
The particle size becomes smaller by lowering the rotational speed of the screw and increasing the residence time.

The polymer latex used in the present invention is produced by a normal emulsion polymerization method, and contains an emulsifier, a polymerization initiator, other polymerization aids, etc., and may be a homopolymer, a copolymer, or Any graft copolymer latex may be used.

As the homopolymer and copolymer latex, aromatic vinyl compounds such as styrene, dichlorostyrene, α-methylstyrene; acrylonitrile J h h II
1-! -L II 11th ffi S
7? '-7ru L/ -++-nok Δ substance: Alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate; acrylic acid, vinyl chloride, vinylidene chloride, vinyl acetate Vinyl compounds such as: conjugated diolefins such as butadiene, chlorobrene, isoprene, and derivatives thereof; and homopolymers, copolymers, and latex mixtures of these polymers consisting of monomers such as ethylene glycol.

Further, examples of the graft copolymer latex include those obtained by grafting a monomer or a monomer mixture capable of forming a hard polymer onto an elastic backbone polymer.

Examples of the elastic backbone polymer constituting the graft copolymer latex include diene polymers such as butadiene, isoprene, and chloroprene; acrylic acid ester polymers in which the alkyl group has 4 to 10 carbon atoms such as butyl acrylate and octyl acrylate; , ethylene-propylene-nonconjugated diene copolymer; sushirigone-based rubber polymer obtained by reacting dimethylsiloxane #4; and copolymers with monomers copolymerizable with these. Examples of copolymerizable monomers include aromatic vinyl compounds such as styrene and α-methylstyrene; methacrylic acid alkyl esters such as methyl methacrylate and ethyl methacrylate; and methacrylic acid alkyl esters such as methyl acrylate and ethyl acrylate, in which the number of carbon atoms in the alkyl group is 1 or more.
Acrylic acid alkyl ester of 3; acrylonitrile,
Examples include vinyl cyanide compounds such as methacrylonitrile. In addition, monomers forming hard polymers include:
Aromatic vinyl compounds such as styrene and α-methylstyrene; Methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate and butyl methacrylate; Vinyl cyanide compounds such as acrylonitrile and methacrylonitrile; Halogenated vinyl chloride, vinyl bromide, etc. Examples include vinyl. These monomers may be used alone or in combination of two or more.

There are no restrictions on the coagulant used in the method of the present invention, and ordinary coagulants can be used. For example, sodium chloride, calcium chloride, magnesium chloride,
Metal salts such as sodium sulfate, aluminum sulfate, zinc sulfate, magnesium sulfate, sodium carbonate, sodium bicarbonate, ammonium chloride, potassium alum, sulfuric acid,
Examples include acids such as hydrochloric acid, phosphoric acid, nitric acid, carbonic acid, and acetic acid, and alcohols such as methanol and ethanol, and these can be used alone or in combination. The amount added is not particularly limited, and is usually about 0.05 to 50% by weight based on the solid content of the polymer latex. Preferably about 0
．． It is 1 to 20% by weight.

When a coagulant is added to a polymer latex, the emulsified state of the polymer latex is destroyed, and the polymer particles that have been emulsified and dispersed in the polymer latex aggregate to form particles. These coagulated particles are dispersed in water, which was the dispersion medium for the polymer latex, to form a slurry (
(Hereinafter, this will be referred to as "polymer slurry.")

In the method of the present invention, coagulated particles are collected and granulated by a liquid crosslinking agent in a granulation step. Therefore, if coarse particles are mixed in the coagulated particles, the coarse particles are likely to be mixed in the granules obtained by granulation in the granulation step. In order to obtain granular powder with a sharp particle size distribution, it is necessary to obtain coagulated particles that do not contain coarse particles in the coagulation step. In particular, polymer latex containing a large amount of rubber components tends to produce coarse coagulated particles during coagulation.

In the present invention, the generation of coarse particles can be prevented by using a co-rotating twin-screw kneader as a coagulation device for polymer latex that tends to generate coarse coagulated particles. As a result, it became possible to obtain granular powder containing no coarse particles.

The time required for coagulation is very short, usually with an average residence time of 0.05 minutes to 1 hour. If the time is less than 0.05 minutes, coagulation will be incomplete and uncoagulated latex will flow into the next step, making granulation unstable, which is not preferable. 1
If the time is longer than that, the device becomes too large, which is not preferable.

In addition, when the coagulation process is carried out using a co-rotating two-shaft kneader, the average residence time in the two-wheel mixer is 0605
It is preferable to set the time to about 5 minutes to 5 minutes.

The production method of the present invention involves adding to the polymer slurry thus obtained an organic liquid that is sparingly soluble in water and that does not dissolve but wets the polymer (hereinafter referred to as "organic liquid"). , the polymer particles contained in this polymer slurry are granulated.

In the organic liquid that is sparingly soluble and does not dissolve the polymer but wets it, used in the present invention, "slightly soluble" means that the solubility in water at 20°C is 0.5% by weight or less, more preferably 0.1% by weight. It means that the following is true. Moreover, "wetting" means that the adhesion angle on the polymer surface is 30° or less. Organic liquids with solubility exceeding 0.5% by weight are
The interfacial tension with water is small, and therefore the cohesive force based on the "liquid bridging force" which is approximately proportional to the interfacial tension becomes small, which is not preferable because a larger amount of organic liquid is required to obtain a large cohesive force. Also, if the solubility is high,
The amount of organic liquid dissolved in the aqueous phase increases, the amount of organic liquid adsorbed on the coagulated particles and creates a "liquid bridging force" decreases, and in addition, larger facilities are used to process organic liquids dissolved in water. is required.

The ability of an organic liquid to dissolve a polymer cannot be quantitatively presented, or for convenience, an organic liquid can be selected by the following method. The target polymer is 1m in diameter.
Form into particles of about 111 mm or pellets of about 1 mm on a side, put into an organic liquid 10 times its weight, and stir for about 1 hour. At this point, if the polymer dissolves in the organic liquid and becomes a homogeneous phase, or if the polymer partially dissolves in the organic liquid,
If the viscosity of the organic liquid increases by more than 10% above its inherent viscosity, the organic liquid cannot be used as an organic liquid for practicing the invention for the polymer.

Furthermore, even if the viscosity does not increase by 10% or more, the granular or pellet-like polymer separated from the organic liquid and the solid-liquid may be
After centrifugal dehydration for 1 minute at 0G centrifugal force, if the granular or pellet-shaped polymer sticks to the surface or the weight of the polymer increases by 50% or more from the initial weight, Therefore, the organic liquid cannot be used as an organic liquid for practicing the present invention.

The organic liquid used in the present invention varies depending on the polymer used, but examples include paraffinic hydrocarbons such as pentane, hexane, and heptane, and alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane. and its alkyl substituted products. These organic liquids can be used alone or in combination of two or more.

The preferred amount of organic liquid used is in the range from 15 to 200 parts by weight, preferably from 20 parts to less than 60 parts by weight, based on 100 parts by weight of the polymer in the latex of the polymer. 15
If the amount is less than 1 part by weight, the effect of granulating the coagulated particles will be reduced, and fine powder will be easily generated, making it difficult to control the particle size distribution↑. In addition, if the amount exceeds 200 parts by weight, the dispersion of the granulated particles will become unstable due to the presence of a large amount of organic liquid.
Particle polymerization occurs, and coarse particles are likely to be produced.

Furthermore, a large amount of organic liquid must be treated, which is disadvantageous in terms of energy costs. The weight of the polymer in the polymer latex is determined by coagulating the polymer latex with a coagulant.
It can be determined by drying the polymer obtained by further raising the temperature and solidifying it and measuring the weight of one polymer.

The polymer weight obtained by such a method may also include polymerization aids such as emulsifiers and initiators added during emulsion polymerization.

In the present invention, since the polymer containing these emulsifiers and polymerization aids is granulated, the polymer weight determined by the above method is used as the polymer weight when calculating the weight ratio of the polymer in the organic liquid lid or the entire mixture. Use weight. Such polymer weight may be conventionally referred to as the solids content in the polymer.

In the present invention, the proportion of water in the total mixture after addition of the organic liquid in the granulation step is preferably in the range of 30 to 85% by weight, more preferably 50 to 75% by weight. Further, the proportion of the polymer in the entire mixture is preferably in the range of 10 to 50% by weight.

If the proportion of water in the total mixture is less than 30% by weight, the apparent viscosity of the total mixture increases and coarse particles are likely to be generated. on the other hand,
If the proportion of water in the total mixture exceeds 85% by weight, the bulk specific gravity of the resulting powdery polymer will decrease, and a larger amount of water will have to be treated, resulting in an increase in the size of the treatment equipment. be.

If the proportion of polymer in the total mixture is less than 10% by weight, the same disadvantages arise as if the proportion of water in the total mixture exceeds 85% by weight. Furthermore, if the proportion of the polymer in the total mixture exceeds 50% by weight, the same difficulties arise as when the proportion of water in the total mixture is less than 30% by weight.

The mixture of polymer slurry and organic liquid in the granulation step is desirably granulated by maintaining it at a temperature T ("C) of the following formula for an average of 5 seconds to 1 hour while mixing.

A-40≦T≦A Preferably A'-30≦T≦A More preferably A-25≦T≦A (In the formula, A represents the azeotropic temperature (“C”) of the mixture liquid.) When a co-rotating two-wheel mixer is used in the granulation process, it is preferable to hold the mixture in the twin-screw mixer within the temperature T (° C.) range of the above formula for an average of 5 seconds to 5 minutes.

Here, the azeotropic temperature is the lowest temperature at which a mixture boils, and is determined as follows. The volatile components in a mixture are mainly two components, water and an organic liquid, and since these two components are hardly soluble in each other, their total vapor pressure is expressed as the sum of the vapor pressures of each pure component. The temperature at which the total vapor pressure is equal to the total pressure on the liquid surface is the azeotropic temperature A of the mixture.

If the temperature T is less than A-40 ("C), the granulation rate will be significantly slow and ungranulated fine powder will be likely to be generated. On the other hand, if the temperature T exceeds the azeotropic point A ("C) of the mixture, Boiling occurs, making it impossible to perform a stable stirring operation, resulting in the formation of coarse particles, making it difficult to control the particle size distribution. In addition, if the average granulation time is less than 5 seconds, granulation is insufficient and fine powder is likely to be generated, and if it exceeds 1 hour, the granulation device becomes oversized.
This is disadvantageous in terms of productivity.

In the present invention, when the granulation process is carried out using a co-rotating twin-screw kneader, compared to the conventional method using a stirring tank etc.
Granular polymers with good powder properties can be produced.

In particular, when a stirring tank is used as a granulation device for copolymers and graft polymers containing large amounts of rubber components, granular polymers with high bulk specific gravity and good fluidity will be produced unless a large amount of organic liquid is used. There was a problem with not being able to get it. However, by using a co-rotating twin-screw kneader as a granulation device, even for copolymers and graft polymers containing a large amount of rubber components, a relatively small amount of organic liquid can be used to increase the bulk specific gravity. It becomes possible to obtain a polymer with a large flowability and good fluidity.

In the method of the present invention, when the granulation step is carried out using a co-rotating shaft mixer, in order to efficiently retain the mixture inside the co-rotating twin-screw mixer and promote granulation. In the section from where both the polymer slurry and the organic liquid are supplied to the discharge port, there is one section consisting of an element having a mixing function and one section consisting of an element having a conveying function in the opposite direction. It is preferable to provide at least a pair. As the element having a kneading function, (1) kneading or (2) progressive kneading can be used, and (3) kneading is preferred. Further, as the element having a conveying function in the reverse direction, (1) reverse conveyance or (2) reverse feed kneading can be used, and among these, (2) reverse feed kneading is preferable.

Additionally, the organic liquid may be added to the polymer slurry before being supplied to the axial kneader, but it is not possible to supply each of the organic liquids from a separate supply port and mix them for the first time in the two-wheeled mixer. preferable.

In the granulation process, the granulated particles are prevented from becoming coarse,
Additionally, a surfactant may be added to increase the flow stability of the slurry containing the granulated particles. Examples of surfactants include anionic surfactants containing sulfonic acid groups such as sodium alkylsulfonate, sodium alkylarylsulfonate, sodium amidosulfonate, sodium dialkylsulfosuccinate, sodium alkylbenzenesulfonate, and sodium alkylnaphthalenesulfonate; Preferably, the coagulant used does not lose its surfactant effect, such as partially saponified polyvinyl alcohol.

In addition, the amount of surfactant used is 0.05% based on the organic liquid.
-2% by weight, preferably 0.05-1.5% by weight. If the amount used exceeds 2% by weight, the purity of the resulting polymer will be reduced and the cost of the product will increase, which is not preferable. The method of adding the surfactant is not particularly limited, and the surfactant is added after being dissolved or dispersed in an organic liquid or water.

The polymer particles continuously granulated in this way are usually heated to a temperature of (Tg-lo)°C or higher (Tg represents the glass transition temperature of the polymer) in order to make them more dense. Raise and heat treat. Such processing is called solidification processing. Temperature of solidification treatment (hereinafter abbreviated as "solidification temperature")
depends on the glass transition temperature of the polymer, but is usually 60~
The treatment is carried out at 120°C, preferably 70 to 99°C, and the average residence time is about 1 to 60 minutes.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 10 parts by weight of methyl methacrylate and 10 parts by weight of styrene were graft-polymerized to 80 parts by weight of a rubber polymer having a copolymerization composition of 75% by weight of butadiene and 25% by weight of styrene, resulting in a graft polymer latex (solid content concentration of 34% by weight). %
) was obtained.

This polymer latex was treated using the apparatus shown in FIG. In the figure, 20 is a co-rotating twin-screw kneading machine with a diameter of 25 mm and L/D of 14, and its outline is shown in 1 to 1.
This is shown in Figure 3. Further, the configuration of the screw is shown in Table 4. Also, each element of the screw has a shape as shown in Figure 5, l is 15+sm, t is 7.5
It is mm. Reference numeral 21 denotes an aging tank having a volume of 2Il, and a six-blade fan turbine type stirrer 22 is disposed in the center. 23 is a co-rotating two-wheel mixer of the same type as 20, and the screw configuration is as shown in Table 5.

The polymer latex is supplied from the supply port 9 to the co-rotating two-wheel mixer 20 by a metering pump (not shown), and a predetermined amount of a 0.49% aqueous solution of coagulant is fed by the metering pump (not shown). Co-rotating twin-screw kneader 2 from supply port 8
The polymer latex was coagulated to obtain a polymer slurry. The polymer slurry discharged from the discharge port 12 is led to the aging tank 21, where coagulation is completed. The coagulated polymer slurry overflows from the aging tank 21 and is supplied to a co-rotating twin-screw kneader 23, which is a granulation device.

The organic liquid is supplied to the two-wheel mixer 2 using a metering pump (not shown).
3 and mixed with the polymer slurry. The polymer slurry granulated by cross-wire in the twin-screw kneader is discharged in a slurry state, heated to the solidification temperature (listed in Table 1) in a container not shown, and then dehydrated and dried to form a powder. A granular polymer was obtained. The operating conditions for each example are shown in Table 1. The organic liquid used was n-hebutane, and the azeotropic temperature A was 79°C.

The bulk specific gravity, average particle diameter, particle size distribution, and uniformity of the particles of the resulting powdery polymer were measured, and the results are shown in Table 3.

The bulk specific gravity is measured according to JIS-6721, and the fluidity is measured by putting the powder into a bulk specific gravity measuring machine used in JIS-6721, observing the flow state when the damper is removed, and measuring the fluidity as follows. Judgment was made using the following criteria.

Outflow condition ○: The sample naturally flows out when the damper is removed △ It flows out when a shock is applied X: It flows out when a shock is continuously applied
5o means the weight-based median diameter, and the uniformity N of the particles is expressed by the following formula % formula % (where D75 is the particle diameter (μl) at 75% of the integrated weight distribution curve, and I) zs is the particle diameter It represents the particle diameter (μm) at 25% of the integrated weight distribution curve of the group. ).

These measurement methods were also used in the following Examples and Comparative Examples.

Example 2 15 parts by weight of methyl methacrylate and 15 parts by weight of styrene were graft-polymerized to 70 parts by weight of a rubber polymer having a copolymerization composition of 75% by weight of butadiene and 25% by weight of styrene, resulting in a graft polymer latex (solid content concentration of 34% by weight). %
) was obtained.

This polymer latex was treated using the same equipment as in Example 1 to obtain a granular polymer. The operating conditions are shown in Table 1. The evaluation results of the obtained powdery polymer are shown in Table 3.

Example 3 The graft polymer latex used in Example 1 was treated using the apparatus shown in FIG. In the figure, 24 is Example 1
This is the same device as the co-rotating twin-screw kneader 20 used in Example 1, and the mixing tank 25 and the stirrer 2G are the same devices as 21 and 22 of Example 1. In addition, 27 is a maturing tank with a volume of 2 IL, and a homo mixer 28 (manufactured by Tokushu Kika ■,
Tabletop type M) is installed.

The polymer latex is supplied from the supply port 8 to the co-rotating twin-screw kneader 24 by a metering bomb (not shown), and a predetermined amount of a 0.49% aqueous solution of coagulant is fed by a metering pump (not shown). The polymer latex was supplied to the twin-screw kneader 24 from the supply port 9, and the polymer latex was coagulated to obtain a polymer slurry.

The polymer slurry discharged from the discharge port 12 is transferred to the mixing tank 25.
led to. An organic liquid as a liquid crosslinking agent and a surfactant dissolved in water were supplied to the mixing tank 25 by a metering pump (not shown). The slurry discharged from the mixing tank 25 was led to the aging tank 27, where granulation was completed. The slurry discharged from the aging 1fI27 was heated to a solidification temperature in a container not shown in the figure, and then dehydrated and dried to obtain a powdery polymer. The operating conditions are shown in Table 2. The evaluation results of the obtained powdery polymer are shown in Table 3.

Example 4 The graft polymer latex used in Example 2 was treated in the same manner as in Example 3 to obtain a granular polymer. The operating conditions and powder properties of the resulting granular polymer are shown in Tables 2 and 3, respectively.

Example 5 Copolymer latex with 85% by weight of methyl methacrylate and 15% by weight of butyl acrylate (solid content concentration 2
7.8% by weight) was produced by an emulsion polymerization method, and this latex was treated using the same equipment as in Example 1 to obtain a granular polymer. The operating conditions are shown in Table 1.

The evaluation results of the obtained powdery polymer are shown in Table 3. The azeotropic temperature A of the organic liquid hexane used was 61"C.
It is.

Examples 6 and 7 Polymer latex was processed using the same equipment as in Example 1, except that the screw rotation speeds of the co-rotating two-wheel mixer 20 in FIG. 7 were set to 350 rpm and 500 rpm, respectively. A granular polymer was obtained. The operating conditions are shown in Table 1. Further, the evaluation results of the obtained powdery polymer are shown in Table 3. The average particle diameter of the obtained powdery polymer increases as the screw rotation speed increases, and the particle size can be controlled by changing the screw rotation speed of the co-rotating two-wheel mixer 20. There was found.

Examples 8 and 9 The same equipment as in Example 1 was used, except that the screw configuration of the co-rotating twin-screw kneader 20 in FIG. 7 was changed as shown in Tables 6 and 7, respectively. The polymer latex was treated to obtain a powdery polymer. The operating conditions are shown in Table 1. Further, the evaluation results of the obtained powdery polymer are shown in Table 3.

The average particle diameters of the obtained powdery polymers were those of Example 1.
It was found that the particle size can also be controlled by changing the configuration of the screws of the co-rotating twin-screw kneader 20.

Example IO 15 parts by weight of methyl methacrylate and 25 parts by weight of styrene were graft-polymerized to 60 parts by weight of a rubber polymer having a copolymerization composition of 75% by weight of butadiene and 25% by weight of styrene, resulting in a graft polymer latex (solid content concentration of 40% by weight). %
) was obtained. This latex is transferred to the co-rotating two-wheel mixer 2.
Two-wheel mixer 20 that rotates in the same direction and is supplied from the supply port lO of 0.
The polymer latex was treated in the same apparatus as in Example 1 except that the screw configuration was changed as shown in Table 8 to obtain a granular polymer. The operating conditions are shown in Table 1. Moreover, the evaluation results of the obtained powdery polymer are shown in Table 3.

Example 11 The polymer latex used in Example 1 was treated using the apparatus shown in FIG. In the figure, 29 is the diameter 25+a
This is a co-rotating two-wheel hybrid machine with 14 +a and L/D, and its outline is shown in Figures 1-3. Further, the configuration of the screw is shown in Table 9.

A predetermined amount of a 1.8% aqueous solution of coagulant is supplied from the supply port 8 by a metering pump (not shown), and a polymer latex is supplied from the supply port 9 by a metering pump (not shown) by two wheels rotating in the same direction. The polymer latex was supplied to a machine 29, and the polymer latex was coagulated to form a polymer slurry. Further, the organic liquid was supplied to the co-rotating two-wheel mixer 29 from the supply port IO using a metering pump (not shown) and mixed with the polymer slurry.

The polymer slurry granulated by cross-wire in the twin-screw kneader is discharged from the discharge port 12 in a slurry state, and after being heated to the solidification temperature (listed in Table 10) in a container (not shown), A powdery polymer was obtained by dehydration and drying. The operating conditions are shown in Table 1O. Further, the evaluation results of the obtained powdery polymer are shown in Table 3.

Comparative Example 1 In place of the co-rotating twin-screw kneader 20 in FIG.
The polymer latex was treated under the same conditions as in Example 1, except that a container L was equipped with a six-blade fan turbine type stirrer in the center. The polymer slurry did not overflow stably, the outlet was blocked, and coagulation was unstable.

Examples 12 to 15 The graft polymer latex used in Example 10 was
The treatment was performed using the apparatus shown in Figure 0. In the diagram, mixing tank 30
, the stirrer 31 is the same device as 27.28 of Example 3, and the aging tank 32 and the stirrer 33 are the same as 21.2 of Example 1.
2 are the same devices. Moreover, 34 is the same device as the co-rotating twin-screw kneader 23 used in Example 1.

The polymer latex and coagulant were supplied to the mixing MI30 using a metering pump (not shown), and the polymer latex was coagulated to obtain a polymer slurry. The polymer slurry that overflowed the mixing tank 30 was led to the aging tank 32, where coagulation was completed. The coagulated polymer slurry is
It overflowed from the ripening N132 and was supplied from the supply port 8 to the co-rotating twin-screw kneader 34.

The organic liquid is supplied to the co-rotating twin-screw kneader from the supply port 9 using a metering pump (not shown), and the polymer slurry, which is mixed with the polymer slurry and granulated by kneading in the twin-screw kneader, is in a slurry state. The polymer was discharged and heated to the solidification temperature (listed in Table 1) in a container (not shown), and then dehydrated and dried to obtain a powdery polymer. The operating conditions are shown in Table 11.

The evaluation results of the obtained powdery polymer are shown in Table 12.

The bulk specific gravity of the resulting particulate polymer was higher than that of Comparative Example 2, and the fluidity was also improved. It can be seen that bulk specific gravity and fluidity can be improved by using a co-rotating twin-screw kneader as a granulation device.

Comparative Example 2 In place of the same direction rotating two-wheel mixer 34 in Figure 1O, a volume of 2
The polymer latex was treated under the same conditions as in Example 12, except that a container equipped with a six-blade fan turbine type stirrer in the center was used. The evaluation results of the obtained powdery polymer are shown in Table 12.

Compared to Example 12, the bulk specific gravity was lower and the fluidity was also worse.

Comparative Example 3 The treatment was carried out in exactly the same manner as in Example 12, except that the amount of organic liquid (n-hebutane) was 10 parts by weight.

The obtained polymer contained a large amount of fine powder and had poor fluidity.

Comparative Example 4 When the treatment was carried out in the same manner as in Example 12 except that the amount of organic liquid (n-hebutane) was changed to 300 parts by weight, the polymer was continuously agglomerated and a powdery polymer was formed. was not obtained.

Table 4 Table 6 Table 1 Table *l: The L/D of the section from the supply locus to the discharge port 12 is 2.3 Table *l: Cat per 100 parts by weight of polymer: Sulfuric acid 1.84 Aqueous solution $ 2: rpm Table 1 $ 1 = Umbrella 2 per 100 parts by weight of polymer: rpm Cat: 萄牝＾ σ) 0.4996 Swimsuit ￥樗 Table 12 [Effects of the invention] According to the production method, it is possible to produce a powdery granular polymer with few fine particles and a sharp particle size distribution using a relatively small amount of organic liquid. It became possible to manufacture continuously.

[Brief explanation of drawings]

Fig. 1 is a plan view of an example of a co-rotating twin-screw kneader used in the present invention, Fig. 2 is a front view of the mixer shown in Fig. 1, and Fig. 3 is a raw material for the kneader of Fig. 1. FIG. 3 is a sectional view taken along line XX at the supply port. FIG. 4 is a diagram showing a typical example of a screw element used in a co-rotating twin-screw kneader.
Figure 4(a) shows a double twist type, and Figure 4(b) shows a triple twist type. FIG. 5 (FIG. 5(a) to (e)) is
FIG. 6 is a diagram showing typical shapes when the screw elements of the double-threaded tie are functionally classified into five types, and FIG. 6 is a perspective view showing a combination of the screw elements. FIG. 7, FIG. 8, and FIG. 9 are schematic diagrams of the apparatus used in the embodiment of the present invention. 1: Barrel, 2 Niscrew shaft, 3: Rear seal plate, 4: Rear bearing, 5: Seal plate and flange, 6: Flange, 7: Gear box, 8.9,
10: Raw material supply port, 11: Barrel inner hole, 12: Discharge port, 14 Top of the flight of the varnish screw, 15 Groove of the varnish screw, 16: Hole for the screw shaft to pass through, 20.23.24.29.34: Same direction rotation two Axial kneader, 25.30: Mixing tank, 21.27.32: Aging tank, 22.26.28.31: Stirrer.

Claims (1)

[Claims] 1) Add and mix a coagulant to the polymer latex obtained by emulsion polymerization to form a polymer slurry, and then add to the polymer slurry an organic liquid that is sparingly soluble in water and does not dissolve but wets the polymer. In the method of granulating polymer particles contained in a polymer slurry by adding and mixing, at least one of the steps of mixing the polymer latex and the coagulant and the step of mixing the polymer slurry and the organic liquid are the same. A method for producing a particulate polymer, characterized in that the method is carried out using a directional rotating twin-screw kneader.