JPH0367524B2 - - Google Patents

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a method for removing emulsifiers and impurities from powdered or granular polymers recovered from polymer latex obtained by emulsion polymerization or suspension polymerization. "Prior Art and Problems" Conventionally, emulsion polymerization and suspension polymerization, which are methods of polymerizing monomers to obtain polymers, have been used because of the ease of controlling the polymerization system, the realization of high polymerization rates, and the high degree of polymerization. It is widely used industrially as an excellent polymerization method for obtaining polymers. However, in such a method, the polymer is recovered as an aggregate of latex particles and further heat-fused to form powder, so the emulsifier (surfactant) used in polymerization, oil-soluble substances, etc. In addition, impurities produced as by-products during polymerization are embedded inside the polymer aggregate, and their removal is extremely difficult. In this way, contamination with emulsifiers and other impurities induces quality deterioration such as discoloration of molded products, decrease in heat resistance, and occurrence of burns, and this is the biggest weakness. Regarding the removal of impurities such as the above-mentioned emulsifier, the recovered polymer is generally dried and pulverized, and then extracted using an organic liquid. However, no matter how fine the powder is, this method only removes impurities that exist on the surface.
If the powder is too fine, it will be difficult to collect it after extraction, and the removal will be incomplete.In addition, by extracting the product after it has been dried, double operations will be required after the drying process, which will complicate the process. This method cannot necessarily be said to be industrially advantageous since it causes an increase in production and costs. "Means for Solving the Problems" The present invention relates to a method for efficiently and inexpensively removing emulsifiers and impurities remaining in polymers, which are the essential drawbacks of emulsion polymerization. That is, the first aspect of the present invention is to (A) coagulate a polymer latex obtained by emulsion polymerization or suspension polymerization to form a water-containing aggregate in which latex particles are not fused together; B) treating the aggregates with an organic liquid that wets the aggregate polymers but does not dissolve or swell them and dissolves contaminants in the aggregates at a temperature lower than the temperature at which the latex particles constituting the aggregates are fused together; By contacting the aggregate, water in the aggregate is replaced with the organic liquid, and impurities in the aggregate are dissolved and extracted into the organic liquid. The second aspect of the present invention is a method for removing the latex by coagulating a polymer latex obtained by emulsion polymerization or suspension polymerization, and forming a water-containing aggregate in which latex particles are not fused together. None, (B) by contacting the aggregate with a first organic liquid that wets the aggregate polymer but does not dissolve or swell the aggregate at a temperature lower than the temperature at which the latex particles constituting the aggregate coalesce;
After replacing the moisture in the aggregate with the organic liquid, or dissolving and extracting a portion of the impurities in the aggregate at the same time as the replacement, (C) without dissolving or swelling the polymer; By bringing the aggregate into contact with a second organic liquid that dissolves impurities in the aggregate, the second
Each content includes a method for removing impurities from polymer aggregates, which is characterized by dissolving and extracting impurities in the pre-aggregates in an organic liquid. First, a latex obtained by emulsion polymerization or suspension polymerization is made into a polymer aggregate by contacting it with a substance (coagulant) having coagulability such as salt or acid. This aggregate is a collection of latex particles, and has a porous structure with gaps between the particles, which contain water. In order to obtain an aggregate with such a structure, it is necessary to maintain the temperature lower than the temperature at which the latex particles fuse together to form a continuous layer of polymer (referred to as the fusion temperature).
Aggregates in which latex particles are not fused together are weak and easy to break apart because they are aggregates of latex particles gathered together, and when they are dehydrated and dried to obtain a powder, they become brittle and crumble into fine particles, making them difficult to use industrially. becomes extremely difficult to handle. Conventionally, it has been common practice to heat this aggregate to a temperature higher than the fusion temperature of the latex particles to form solid particles that can be easily handled as a single fused body. Here, the aggregate is placed as it is without being fused into a first organic liquid that does not dissolve or swell the polymer and is compatible with the polymer, preferably an organic liquid that is insoluble or sparingly soluble in water. By soaking, the water present inside the aggregate can be expelled out of the aggregate and replaced by the organic liquid. When the organic liquid is a mixed liquid of two or more types, it is sufficient that the mixed liquid wets the polymer and does not dissolve or swell the polymer. For example, even an organic liquid that is difficult to wet the polymer can dissolve the polymer. If it does not cause swelling and is insoluble or poorly soluble in water, it can be used as the main component, mixed with a small amount of an organic liquid that dissolves the polymer but has the ability to wet it. When the aggregate is immersed in the above-mentioned organic liquid, the surface of the aggregate particles is immediately wetted, the water penetrates into the surface and the gaps inside the particles, and the water existing there is expelled and replaced. At this time, aqueous impurities contained in the polymerization system are also carried out of the particles.
The speed of this replacement is fast, and even if the aggregate particles are large particles with a diameter exceeding 10 mm, the replacement is almost completed within about 10 minutes. However, when the aggregate swells or dissolves, the latex particles on the surface of the aggregate particles and inside the particles fuse together to form a continuous layer with no interparticle gaps, making it impossible to replace water. Not only that, but the subsequent drying speed becomes extremely slow, making it impossible to handle it industrially. The method of immersing the aggregate particles in an organic liquid can be as simple as leaving the aggregate particles still in the organic liquid and immersing them, but it is more effective to place the aggregate particles in the flow of the organic liquid by stirring or passing the liquid through. be. However, it is necessary to prevent the aggregate particles from breaking and becoming finer due to stirring or severe turbulence, so the immersion conditions are selected depending on the strength of the particles. The amount of organic liquid required to replace water is determined by replacing the water inside the aggregate with the organic liquid after the aggregate particles are immersed in the organic liquid, and then combining the expelled water with the organic liquid in which the aggregate particles are immersed. forms two phases, and the liquid height at which the aggregate particles are immersed in the organic liquid phase is the required amount of the organic liquid. In addition, the required soaking time is determined by the properties of the aggregates, the type of organic liquid, the degree of filling of aggregate particles, etc., and cannot be unambiguously determined, but it is possible to achieve a rejection rate of 80% or more of the contained water within 10 minutes. It is best to use this as an indicator when selecting types and conditions. In addition, since the organic liquid phase containing the aggregate particles and the water expelled from the particles form two phases, the aqueous phase can be easily taken out of the system, and the aggregate particles can be recovered from the organic liquid phase. You just have to target it. In this way, water and water-soluble impurities are removed from the interior of the aggregate particles, and the aggregates that have become compatible with the organic liquid are immersed in a second organic liquid that dissolves oil-soluble impurities for subsequent extraction. At this time, the first organic liquid used to replace water and the second organic liquid used for extraction do not need to be the same. The first liquid used to replace water is
From an economic standpoint, it is desirable to recover and reuse the solvent, and the solvent dissolved in the aqueous phase is recovered by steaming, distillation, or the like. In this sense, it is more advantageous if the liquid is insoluble in water, since the liquid can be easily recovered by a simple oil-water separation operation. Since emulsifiers and oil-soluble substances to be removed during extraction need to be dissolved in the extraction liquid, it is necessary to select an optimal liquid. It no longer matters whether the extraction liquid is soluble or insoluble in water, but when extraction operations are performed continuously or simultaneously, it becomes necessary to separate the extraction liquid from the liquid used to replace the water contained in the aggregates. Therefore, it is advantageous to choose to use the same liquid. If the first organic liquid dissolves oil-soluble contaminants, extraction of the oil-soluble contaminants also starts at the same time as the phenomenon in which the organic liquid replaces the water inside the aggregate particles. Therefore, in this case, it is not necessary to perform extraction again, but extraction may be performed subsequently by changing the type of organic liquid. Also,
If the emulsifier is not easily soluble in the liquid, it can be made soluble before replacing the water with the organic liquid. For example, the emulsifier is fatty acid soda,
When an inorganic salt is used as a coagulant, since the emulsifier exists in the form of a metal salt of a fatty acid, it is poorly soluble in an organic liquid regardless of the type of metal salt. In this case, the emulsifier can be easily extracted and removed by adding acid to the aggregates in advance to convert them into free fatty acids. General solid-liquid extraction operations can be applied to this extraction. That is, a method is adopted in which the extract in the aggregate is extracted with a liquid, the extract in the extracted liquid is removed by a purification process such as distillation or adsorption, and the liquid is recovered and reused. Extraction proceeds rapidly through the surface of the aggregate particles and through the interstices of the latex particles inside. After extraction, the aggregates are deliquified, washed, and dried to become powder. If it is necessary to prevent the aggregates from breaking apart and becoming fine powder, the polymer may be It is sufficient to heat it to a temperature higher than the fusion temperature. As described above, the polymer targeted by the present invention is an aggregate of latex obtained by emulsion polymerization or suspension polymerization, and this aggregate is a packed aggregate of constituent latex particles. It is a porous aggregate with voids between the particles. Normally, such aggregates contain a large amount of water and require a large amount of drying energy to dry them, but by replacing them with an organic liquid, the latent heat of vaporization is drastically reduced, resulting in a significant energy saving. reduction can be achieved. In addition, since the liquid to replace water is insoluble or hardly soluble in water, the liquid can be easily recovered and reused at a low cost. Since the aggregate is porous, it is possible to quickly and easily replace the liquid with water, extract the extract, and dry the liquid remaining after extraction.
From the above, it becomes possible to industrially produce high-purity polymers by removing emulsifiers and impurities from latex obtained by emulsion polymerization or suspension polymerization. The polymer latex that can be the object of the present invention is almost all polymer latexes that can be recovered in resin form obtained by emulsion polymerization or suspension polymerization. The object may be a single or mixed latex of a polymer obtained by polymerizing, copolymerizing, or graft polymerizing a monomer composition mainly containing one or more monomers selected from the following monomer groups. However, it is natural to exclude those that cannot be polymerized. Vinyl aromatics such as styrene, monochlorostyrene, dichlorostyrene, α-methylstyrene; vinyl cyanides such as acrylonitrile, methacrylonitrile; acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate; methyl methacrylate, ethyl methacrylate, butyl methacrylate Methacrylic esters such as; vinyl halides such as vinyl chloride, vinyl bromide, and vinyl fluoride; vinylidene halides such as vinylidene chloride and vinylidene bromide; acrylic acid, methacrylic acid, itaconic acid, maleic acid, vinyl acetate, ethylene, Propylene, butylene, butadiene, isoprene, chloroprene; crosslinking monomers such as allyl methacrylate, diallyl phthalate, triallyl cyanurate, monoethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, divinylbenzene, glycidyl methacrylate. Further, in the present invention, the following polymer latexes can be particularly preferably used. (1) A monomer consisting of 20 to 80 parts of an acrylonitrile monomer, 20 to 80 parts of a mixture of one or more of vinyl chloride, vinylidene chloride, vinyl bromide, and vinylidene bromide, and 0 to 10 parts of an easily dyeable monomer. A polymer latex obtained by polymerizing polymers. (2) Styrene 0-50wt% (weight%, below other types%)
(% is wt% unless otherwise noted), butadiene
Butadiene polymer latex consisting of 50-100%. (2′) Butadiene-based polymer latex 20 of (2)
0 to 50 acrylic ester in the presence of ~80 parts
%, methacrylic esters 0-100%, vinyl aromatics 0-90%, vinyl cyanide 0-90%
A polymer latex obtained by polymerizing 20 to 80 parts of a monomer containing 0 to 20% of other copolymerizable monomers. (3) Styrene 0-50%, butadiene 50-100%,
In the presence of 0 to 20 parts of a rubbery polymer latex consisting of 0 to 30% of acrylic esters, 0 to 100% of methyl methacrylate, 0 to 60% of other methacrylic esters or acrylic esters other than methyl methacrylate, and 0 to 60% of vinyl aromatics. 90%, vinyl cyanide 0-90% monomer 80-100
Polymer latex obtained by polymerizing parts. (4) One type selected from vinyl aromatics, methacrylic esters, acrylic esters, and vinyl cyanides in the presence of 10 to 90 parts of a butadiene polymer consisting of 0 to 50% styrene and 50 to 100% butadiene. Or a graft copolymer (A) obtained by polymerizing 10 to 90 parts of two or more types of monomers, containing 0 to 50 parts of α-methylstyrene and 0 to 70 mol%, vinyl aromatic, methacrylic ester, acrylic ester ,
30 to 100 mol% of one or more monomers selected from acrylic acid and vinyl cyanide
A mixed latex with 50 to 100 parts of a polymer (B) obtained by polymerizing monomers. (5) 40 to 100% of acrylic ester and one or more monomers selected from vinyl aromatics, vinyl cyanide, vinyl chloride, vinylidene chloride, vinyl acetate, or conjugated diolefins.
60% and 0 to 10% of a crosslinking agent in the presence of 5 to 85 parts of a rubber polymer obtained by polymerizing methacrylic esters, vinyl cyanides, acrylic esters, vinyl aromatics, and copolymerizable therewith. One or more monomers selected from monomers
Polymer latex obtained by polymerizing 15 to 95 parts. (6) 40 to 100 parts of vinylidene chloride and vinyl aromatic,
A polymer obtained by polymerizing 0 to 60 parts of one or more monomers selected from vinyl cyanide, acrylic ester, methacrylic ester, acrylic acid, methacrylic acid, itaconic acid, maleic acid, and crosslinking monomers. Molecular latex. (7) 40 to 100 parts of vinyl chloride, 0 vinyl cyanide
~20 parts and one or more monomers selected from vinylidene chloride, vinyl bromide, vinylidene bromide, acrylic ester, methacrylic ester, acrylic acid, methacrylic acid, itaconic acid, maleic acid, and crosslinking monomers A polymer latex obtained by polymerizing 0 to 60 parts of the body. The coagulant used to coagulate the polymer latex to form an aggregate may be any coagulant as long as it can coagulate the polymer latex. Generally, it is selected based on the intended use of the polymer, operability, cost, etc. For example, sodium chloride, potassium chloride, lithium chloride, sodium bromide, potassium bromide, lithium bromide, potassium iodide, potassium sulfate, ammonium sulfate, sodium sulfate, ammonium chloride, sodium nitrate, potassium nitrate, calcium chloride, ferrous sulfate. , magnesium sulfate,
Zinc sulfate, copper sulfate, barium chloride, ferrous chloride,
Inorganic salts such as magnesium chloride, ferric chloride, ferric sulfate, aluminum sulfate, potassium alum, iron alum, inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, caustic soda, caustic potash, calcium hydroxide, magnesium hydroxide Inorganic alkalis such as
Organic acids such as acetic acid and formic acid, and salts of organic acids such as sodium acetate, calcium acetate, sodium formate, and calcium formate, including solid, liquid, aqueous solutions, or solutions in water-soluble organic solvents, either alone or as a mixture. The first is used to replace the water inside the aggregate.
It is essential that the organic liquid (1) wets (familiarizes) aggregate polymers, (2) does not dissolve or swell the aggregated polymer, and (3) is sparingly soluble in water to achieve sufficient water replacement. Or, it needs to be insoluble, and furthermore, it is most advantageous to be insoluble in water in order to separate and recover it from the water expelled from the aggregate and reuse it. the above
Regarding (1) and (2), the difference in surface tension and solubility parameter for the polymer is considered to be an indicator. In order to wet a polymer, it is said that the surface tension of the liquid should be lower than the critical surface tension of the polymer, but the wetting referred to here corresponds to immersion wetting that penetrates into the aggregate particles. This wetting is determined by interfacial tension, and it is thought that wetting occurs due to a decrease in the interfacial tension between solid and liquid. Specifically, the condition is that the free energy of the interface between the aggregate particles and the organic liquid is smaller than the free energy of the interface between the aggregate particles and water. However, although it naturally varies depending on the type of polymer, in most cases it can be considered that water replacement is possible if it is 30 dyne/cm or less. In addition, in order to prevent the polymer from dissolving or swelling, the difference in solubility parameter (SP value) should be set at 1.5 to 2.0.
It is said that a certain degree is sufficient, but in reality it varies depending on the operating temperature, the polymerization degree and copolymerization structure, and especially in the case of a solution or a mixture of two or more types of polymers. In this case, selection based on SP value becomes practically impossible. In any case, the presence or absence of dissolution or swelling can be easily and quickly examined by mixing them together, so selection based on SP value has the meaning of preliminary selection. Examples of such liquids include hydrocarbons, halogenated hydrocarbons, alcohols, ethers, acetals, ketones, esters, polyhydric alcohols, polyhydric alcohol derivatives, phenols, nitrogen compounds,
There are organic liquids containing sulfur compounds and phosphorus compounds. When selecting a liquid, the range of selection is narrowed down to those that do not dissolve or swell the polymer at operating temperatures. From this point of view, hydrocarbons and alcohols are often suitable.
In order to satisfy the above requirements (1), (2), and (3), a mixture of two or more types of liquids may be used. Generally, paraffins, alicyclic hydrocarbons, and their alkyl substituted products are insoluble in water, but if their molecular weight becomes large, they cause the polymer to swell. Furthermore, as the molecular weight of alcohol increases, it becomes less soluble in water, but at the same time it swells the polymer.
Therefore, as a single liquid, hydrocarbons having 4 to 7 carbon atoms and alcohols having 4 to 5 carbon atoms are often selected. In addition, when using a mixed solvent, C is 4
Alcohols containing 1 to 5 carbon atoms and mainly composed of 7 to 7 hydrocarbons are often selected. From the viewpoint of operability, it is convenient for the second organic liquid for extracting impurities to be the same as the first organic liquid for replacing water. At this time, the ability to dissolve the extract is added to the liquid selection conditions.
In general, most organic liquids dissolve organic substances such as emulsifiers and oily substances, so this condition does not need to be taken into consideration much. However, if the organic liquid dissolves a considerable amount of water, care must be taken since the ability to dissolve organic substances will also decrease. On the other hand, when using a liquid other than the liquid for water replacement as the extraction liquid, it is sufficient to first drain the previous liquid and then bring it into contact with the extraction liquid.
At this time, since the aggregate does not already contain water, it does not matter whether it is soluble or insoluble in water, and the selection is easy because it only needs to dissolve the extract and not dissolve or swell the aggregate polymer. Become. Furthermore, after extraction, the aggregates are dried to obtain polymer powder, which is optimal in terms of drying properties of the solvent (boiling point, latent heat of vaporization), safety during work, and cost. organic liquid should be chosen. The emulsifiers to be removed in the present invention are those used in emulsion polymerization and suspension polymerization, and generally two or more types of emulsifiers are used in combination, but typical ones include the following: Things can be mentioned. That is, sodium and potassium salts of fatty acids are typical anionic surfactants and are used in most polymerization systems. These include saturated fatty acids such as palmitic acid and stearic acid, unsaturated fatty acids such as oleic acid and lauric acid, or salts of natural products such as rosin, castor oil, coconut oil and tallow.
In addition to fatty acids, higher alcohol sulfate ester salts,
Examples include sodium alkylbenzene sulfonate, alkyl diphenyl ether disulfonate, and polyoxyethylene alkyl ether sulfate.
On the other hand, nonionic surfactants are sometimes used, such as polyethylene glycol ethers and polyoxyethylene sorbitan esters. Anionic surfactants, such as carboxylic acid and sulfonic acid salts, are difficult to dissolve in organic liquids as they are, so they can be extracted and removed more efficiently if they are in the form of their respective acids. In other words, if a polymer latex is coagulated using an acid, it becomes an acid state, but when coagulating using a salt, the acid can be added after coagulation. Normally, fatty acid soda has an extraction rate of 1/1 compared to dilute fatty acid.
It will be 5 to 1/10th. There is no problem with the nonionic surfactant as it is. In addition, oil-soluble impurities include various monomers, polymerization initiators, chain transfer agents, crosslinking agents, polymerization regulators such as polymerization inhibitors, surfactants, and aids for improving dispersion stability used in polymerization. A wide variety of substances can be considered, such as impurities contained in the main sub-materials, impurities, unreacted residues, decomposition products by-produced in the polymerization reaction system, and low molecular weight reactants such as dimers and trimers. Therefore, the extraction liquid should be selected depending on the objects to be removed. The fusion temperature refers to the temperature at which latex particles fuse and coalesce, and can generally be considered as the melting point of the substance.
However, since there is no clear melting point for polymers, it is difficult to define them, and even if they are the same polymer, it is determined not only by the degree of polymerization and its distribution, but also by its crystallinity and residual substances that give a plasticizing effect. greatly affected. However, in practice, the glass transition point is Tg
(°C), it can be considered to be in the range of Tg+273/0.8-273 to Tg+273/0.6-273(°C). When implementing the present invention specifically, if you know the approximate value of Tg of the polymer, you can also get the approximate value of softening, so you can easily find the optimal temperature range by trying 2 to 3 temperatures. I can do it. The validity of the above equation was confirmed by using a scanning electron microscope to observe the presence or absence of fusion of latex particles inside the particles obtained by operating them at various temperatures using various polymer latexes with different softening temperatures. Confirmed by. "Function/Effect" The present invention is characterized in that the latex particles are porous aggregate particles that are not fused together, and that the moisture contained in the aggregate particles is absorbed into the organic liquid by immersing the latex particles in a first organic liquid. After forming two phases of the displaced water and the organic liquid in which the aggregate particles are immersed, the particles are dissolved in a first or second organic liquid that dissolves impurities in the aggregate. By extraction, impurities in the polymerization system can be efficiently removed regardless of whether they are water-soluble or oil-soluble, and highly pure polymers can be obtained inexpensively and advantageously. "Examples" The present invention will be described below with reference to Examples and Comparative Examples, but the present invention is not limited in any way by these. Example 1 A polymer latex is prepared by graft copolymerizing a mixture of styrene, acrylonitrile, and methyl methacrylate onto a butadiene polymer emulsion-polymerized using potassium rosinate.
60% methyl methacrylate, 10% acrylonitrile and 20% styrene (33%) and sodium palmitate (A) consisting of 20% α-methylstyrene, 25% acrylonitrile and 55% styrene as an emulsifier. It is a polymer latex mixed with 67% homocopolymer polymer latex (B), and the solid content concentration in the latex is 30%.
%, carboxyl group consisting of potassium rosinate and sodium palmitate per 1g of polymer solid content
Contains 0.097 mmol, and α-
A polymer latex at a temperature of 30°C with residual monomers of 2.8% methylstyrene monomer and 1.7% styrene monomer was placed in a 1 liter beaker.
Using 3-blade propeller blades with d/D=0.5,
Stirred at 300 rpm at room temperature. As a coagulant (1)10
% hydrochloric acid aqueous solution and (2) 30% calcium chloride aqueous solution were added and dispersed, and after about 10 seconds, the rotation speed was decreased.
The temperature was set to 100 rpm, and the treatment was performed for 10 minutes with gentle stirring. Then, coagulated particles were separated from the polymer latex through a 32 mesh sieve. These coagulated particles are sharp spherical particles with a particle size distribution of more than 90% in 4 to 10 meshes, and the solid content concentration of the coagulated particles is 35 to 10.
It was 38%. These coagulated particles are further dispersed in water,
The temperature was raised to 85°C and held for 15 minutes, and then dehydrated using a 32-mesh sieve to obtain samples (1) and (2) for extraction. In addition, while the coagulated particles obtained by the same operation as (1) were heated to 85℃ and kept at 85℃, the pH was
The particles adjusted to pH 10.5 and dehydrated are used as sample (3), and when the coagulated particles are dispersed in water by the same operation as in (2), the pH is adjusted to 2.0 with an aqueous hydrochloric acid solution, then heated and dehydrated. The resulting particles were used as sample (4) for extraction. When samples (1) to (4) were heated at 85°C, the particles contracted and the solid content concentration increased to 50 to 55%. Take 50g of the above water-containing particles, put them in a 10-mesh wire mesh container, immerse them in 150ml of the organic liquid shown in Table 1 at a constant temperature, take them out after 30 minutes, and check the amount of carboxyl groups contained in the particles and the monomer. The amount was measured. Table 2 also shows the SP values and surface tensions (at 20°C) of the organic liquids used. The fusion temperature of the polymer was 92°C, the estimated SP value was 9.3±2, and the estimated critical interfacial tension was 33±2 dyne/cm.

[Table] Based on tograph.
The equilibrium concentration in the extraction of carboxyl groups is approximately
Since the amount was 0.027 mmol/g, the removal rate was high in all cases, especially in cases A and G, which appear to have been almost completely removed. In addition, the equilibrium concentration of monomers is approximately 0.79% for α-methylstyrene and approximately 0.48% for styrene.
%, so all tests show a high extraction rate. In all of the above tests, after the particles were immersed in the first organic liquid, the water within the particles was expelled and collected at the bottom of the extraction vessel within a few minutes. In steps A, E, and H above, take out the particles 10 minutes after soaking them, drain the liquid, and soak them in 150 ml of ethanol, methanol, and propanol at 40°C, respectively.
After 20 minutes, it was taken out and the carboxyl group content and residual monomer amount were measured. As a result, the extraction rates were all the same as in A. In this operation, the particles were able to maintain their spherical shape without breaking or coalescing.

【table】

[Table] Comparative Example 1 Particles obtained in the same manner as in Example 1 but heated to 95°C instead of 85°C were obtained in the same manner and tested with the same organic liquid as in Example 1. I went to Even when the particles were immersed in an organic liquid, only a small amount of water, which was thought to have adhered to the particle surface, was found at the bottom of the container, and the water inside the particles was clearly not able to be drained. This is because the drying properties of the particles after extraction are extremely poor, and it is presumed that by raising the temperature to 95°C, the particles become fused particles in which the surface and inside of the particles are fused. In both tests, the carboxyl group content decreased by 10-15% and the residual monomer content decreased by 10-20% from the initial content, and the extraction time was increased for another 1 hour.
Even when the time was extended to 2 hours, almost no decrease was observed. Comparative Example 2 Particles obtained in the same manner as in Example 1 were extracted in the same manner as in Example 1 using the liquid and temperature shown in Table 3.

[Table] No fusion was observed in the particles after extraction in tests A and F, but the other test particles swelled and became fused. In B, C, D, and H, 20 to 25% of the water in the particles was discharged and accumulated at the bottom of the container. The water phase did not separate between A and F. The above extractive removal did not proceed any further even when the extraction time was extended to 1 hour. As described above, extraction efficiency is extremely low, and drying is extremely difficult after deliquing in B, C, D, and E, and a phenomenon in which the particles swell when the drying temperature is increased to 70°C or higher was observed. Example 2 A polymer latex is obtained by graft polymerizing a mixture of styrene and methyl methacrylate to a copolymer of styrene and butadiene with potassium rosinate and semi-hardened beef fatty acid soda.
%, methyl methacrylate 20%, butadiene 45%
The solid content concentration is 30% at a fusion temperature of 67℃.
Polymer latex at 30°C was sprayed into a cylindrical coagulation chamber using an empty conical nozzle, which is a type of pressurized nozzle.
The sprayed latex droplets have an average droplet diameter of 220
It was micron. On the other hand, this coagulation chamber has a side spray nozzle attached to the upper part of the inner wall that collects 45°C hot water and flows down the inner wall surface.
Hydrochloric acid aqueous solution is dispersed into fine droplets of 100 microns or less with water vapor of 0.6 kg/cm ² using an internal mixing type two-fluid nozzle with a pore size of 2.0 mm, and a coagulating atmosphere with a temperature of 42 to 45 °C and a pressure of atmospheric pressure is created. formed inside it. The dispersed latex droplets came into contact with the coagulant while falling in the coagulation chamber, were coagulated, were collected by the recovery liquid, and were taken out from the coagulation chamber as a slurry. The coagulated particles of latex in the slurry taken out from the coagulation chamber were almost perfectly spherical independent particles with almost no breakage or coalescence. This slurry is stirred
After heating to 60°C and holding for 10 minutes, the coagulated particles were taken out using a centrifugal dehydrator using a filter cloth. The coagulated particles had an average particle size of 200 microns, an almost perfectly spherical shape, and a solid content concentration of 53%. In addition, the coagulated particles contained 0.058 mmol/g carboxylic acid compound per solid content as carboxyl groups brought in from potassium rosinate as an emulsifier and semi-hardened beef tallow fatty acid, and also contained 8900 ppm of residual styrene monomer. Take 50g of this water-containing coagulated particle and put it in a beaker with 150ml of the following organic liquid to keep the temperature constant. After keeping it for 30 minutes with gentle stirring, remove the liquid by draining it with a Nutsutie and remove the amount of carboxyl group. was quantitatively measured by conductivity titration, and the amount of styrene was quantitatively measured by gas chromatography. Furthermore, the estimated SP of this polymer
Value is 8.8±2, estimated critical interfacial tension is 34±2dyne/cm
It is.

[Table] From the results in Table 4, the equilibrium concentrations in the extraction of carboxyl groups and styrene are 0.0164 mmol/g and 2520 ppm, respectively, so all of the above tests show a large removal rate. In all of the above tests, water was expelled from the particles within a few minutes after being immersed in the organic liquid and collected at the bottom of the beaker, forming two phases. The particles were present at the bottom of the upper phase organic liquid. Incidentally, the stirring was performed at a gentle enough level to prevent the water accumulated at the bottom from dispersing into the liquid. Through this extraction procedure, the particles remained spherical without breaking or coalescing. We also test the residue inside the particles,
By fluorescent X-ray analysis, K, Cl, S, P, Si, Mg,
When the concentration of each element of Na was investigated, Table 5 was obtained, indicating that impurities were almost completely removed.

【table】

[Table] Comparative Example 3 A slurry obtained in the same manner as in Example 2 was heated to 82°C instead of 60°C to obtain particles, and the same test was conducted with an organic liquid as in Example 2. did. In both tests, the carboxyl group is 15-20%,
The residual styrene monomer content was only reduced by 20 to 25% from the initial content, and even if the extraction time was further extended to 1 or 2 hours, there was almost no reduction. Furthermore, even when the particles were immersed in liquid, only a small amount of water, which was thought to have adhered to the particle surface, was found at the bottom of the beaker, and the water inside the particles was clearly not removed. Because of this phenomenon and the extremely poor drying properties of the particles after extraction, it seems that the surface and interior of the particles were fused by raising the temperature to 82°C. Comparative Example 4 Particles obtained in the same manner as in Example 2 were extracted in the same manner as in Example 2 using the organic liquid and temperature shown in Table 6. The results are shown in Table 6.

[Table] No fusion was observed in the particles after extraction in tests, G, and C. Moreover, no separated phase of water appeared at the bottom of the beaker. In addition, in the tests, the particles swelled and became softened and fused. In particular, the particles of Ri and Nu coalesced into a lump inside the beaker. It seems that a very small amount of water was expelled, and a small amount of water collected at the bottom of the beaker. It was confirmed that the results of the extraction and removal described above did not change much even if the extraction time was extended to 1 hour. In this way, extraction is extremely inefficient and results in
It was very difficult to dry the particles after removing the liquid, and when the temperature was raised, the inside of the particles swelled. Example 3 Take 50 g of water-containing particles obtained in the same manner as in Example 1, place them in a 10-mesh wire mesh container, and add n-hexane.
When 50 ml of the particles was added and immersed at 60°C for 5 minutes, the water inside the particles was expelled and accumulated at the bottom of the container. Next, dehydrate the particles and add 60 ml of ethanol to 150 ml of ethanol.
Soaked at ℃ for 30 minutes. Deliquify and remove the particles,
When the amount of carboxyl groups contained in the particles was measured, it was found to have decreased from 0.097 mmol/g of polymer solid content to 0.030 mmol/g. The equilibrium concentration in the extraction of carboxyl groups is approximately
Since it was 0.027 mmol/g, it can be said that it was almost completely removed.

Claims (1)

[Claims] 1 (A) A polymer latex obtained by emulsion polymerization or suspension polymerization is coagulated to form a water-containing aggregate in which latex particles are not fused together; (B) By immersing the aggregate in an organic liquid that is insoluble or poorly soluble in water, which wets the aggregate polymer but does not dissolve or swell it, at a temperature lower than the temperature at which the latex particles constituting the aggregate are fused together. (C) forming two phases of the rejected water and the organic liquid in which the aggregate is immersed, and removing impurities from the aggregate into the organic liquid; A method for removing impurities from polymer aggregates, characterized by dissolution and extraction. 2 (A) coagulating a polymer latex obtained by emulsion polymerization or suspension polymerization to form a water-containing aggregate in which latex particles are not fused together; (B) coagulating the aggregate to an aggregate height; Water in the aggregate is removed by immersing it in an organic liquid that is insoluble or poorly soluble in water and that wets the molecules but does not dissolve or swell them at a temperature lower than the temperature at which the latex particles constituting the aggregate fuse and coalesce. (C) forming two phases of the expelled water and the organic liquid in which the aggregates are immersed, and (D) not dissolving or swelling the polymer and removing the aggregates. A polymer aggregate characterized in that impurities in the aggregate are dissolved and extracted in the second organic liquid by immersing the aggregate in a second organic liquid that dissolves impurities therein. A method of removing contaminants from agglomerates.