JP5592226B2 - Method for removing and recovering porous forming agent from macroporous resin - Google Patents

Description

  The present invention relates to a method for removing and recovering a porous forming agent from a macroporous resin.

  In addition to ion exchange resins and adsorbents, macroporous resins are used in a wide range of fields as adsorption carriers for various substances, and generally contain monomers such as styrene, crosslinking agents such as divinylbenzene, and porous forming agents. It is produced by dispersing the oil phase in an aqueous phase to which a stabilizer such as gelatin or polyvinyl alcohol is added, and performing suspension polymerization.

  At this time, as the porous forming agent, a hydrophobic solvent that dissolves the monomer but hardly dissolves the polymer formed by polymerizing the monomer is used. Since such a porous forming agent remains in the gap of the polymer chain during suspension polymerization, desired pores can be formed by removing the porous forming agent after suspension polymerization from the produced resin. Can do.

  Here, if the porous forming agent is not removed and remains in the resin, pores are not formed, so the desired performance as a macroporous resin cannot be obtained, and the resin is used in an organic solvent or the like. In this case, the porous forming agent needs to be removed and recovered as much as possible from the resin after the production because it may be eluted as an impurity from the resin.

  Removal of the porous forming agent from the macroporous resin is usually performed by steam distillation. However, depending on the type of porous forming agent used, it is often difficult to remove the porous forming agent contained in the pores of the resin by steam distillation. Such a porous forming agent removal method includes, for example, a Soxhlet extraction method in which extraction and removal is performed with a solvent such as methanol, but the temperature of the extraction part cannot be increased in the Soxhlet extraction method. There is a problem that the porous forming agent is difficult to remove. Also, the Soxhlet extraction method is difficult to increase in size.

  Therefore, a method of removing the porous forming agent by putting a macroporous resin and a solvent such as methanol in the stirring tank and raising the temperature, and then performing solid-liquid separation by centrifugation or the like is also conceivable. However, the macroporous resin obtained by suspension polymerization usually contains a large amount of water, and it is necessary to remove this sufficiently before the extraction operation, and in order to increase the removal rate of the porous forming agent, It is necessary to repeat the operation, and it takes time to cool and raise the temperature and the energy consumption is large. Further, in this method, a large amount of solvent such as methanol is used, and enormous energy is required to recover the porous forming agent.

  As a method for solving these problems, for example, in Patent Document 1, a high-boiling organic solvent such as 2-methylhexanol (boiling point: 124 ° C.) or diethylene glycol monomethyl ether (boiling point: 194 ° C.) is added and distilled. A method for removing isooctane which is a porous forming agent is disclosed.

US Pat. No. 6,673,847

  However, in the method described in Patent Document 1, since the porous forming agent cannot be removed from the resin unless it is heated to the boiling point of the porous forming agent, further reduction in energy required for the removal is required. In order to form pores stably, it is preferable to use a porous forming agent having a lower solubility in water and a higher boiling point, but the boiling point of the porous forming agent is equal to the boiling point of the organic solvent. When the temperature is near or higher, the porous forming agent is not completely removed and remains on the macroporous resin side, so that there is a problem that the removal cannot be performed sufficiently and separation and recovery cannot be performed.

  Further, the method of Patent Document 1 also requires the use of a large amount of solvent for removing the porous forming agent, which is very expensive from the viewpoint of industrial macroporous resin production. There is also a problem that the load is large.

  In view of these problems, the present invention is a porous forming agent having a low water solubility and a high boiling point, particularly at room temperature, which has been difficult to remove and recover from the macroporous resin by conventional methods. It is an object of the present invention to provide an industrially applicable method for efficiently removing and recovering a porous forming agent having a water solubility of 0.1 g / 100 ml or less and a boiling point of 120 ° C. or more.

  As a result of intensive studies, the present inventors have found that a macroporous resin containing a porous forming agent having a solubility in water at room temperature of 0.1 g / 100 ml or less and a boiling point of 120 ° C. or higher and the above porous material An extraction process in which an organic solvent capable of dissolving the forming agent is placed in an extractor (stirring tank) and heated while stirring and mixing to extract the porous forming agent; porous from the stirring tank through a filter or the like Organic solvent refining process in which a part of the organic solvent containing the quality-forming agent and water is continuously extracted, and only the organic solvent is recovered using a distillation vessel, distillation tower, etc., and returned to the stirring tank; Then, the liquid remaining in the distillation vessel, distillation column, etc. is further concentrated to separate water and the porous forming agent, and according to the method comprising the recovery step of recovering the porous forming agent, the macroporous resin is used. Porous forming agent It found that allows the removal and recovery efficiently, and completed the present invention have.

  According to the method of the present invention, a porous forming agent having a low solubility in water and a high boiling point can be efficiently removed and recovered from the macroporous resin.

In Example 1, the conceptual diagram which shows the apparatus used in order to remove and collect | recover a porous formation agent from macroporous resin. In Example 1, the graph which shows the relationship between the liquid circulation cycle number and the removal rate of a dioctyl phthalate.

  The method for removing and recovering the porous forming agent from the resin according to the present invention includes a macro that includes a porous forming agent having a water solubility at room temperature of 0.1 g / 100 ml or less and a boiling point of 120 ° C. or higher. An extraction step of extracting a porous forming agent by putting a porous resin and an organic solvent capable of dissolving the porous forming agent in an extractor (stirring tank), and heating the mixture while stirring and mixing; Organic solvent purification by continuously extracting a part of the organic solvent containing the porous forming agent and water from the filter, etc., and recovering only the organic solvent using a distillation vessel, distillation tower, etc. and returning it to the stirring tank And a recovery step of concentrating the liquid remaining in the distillation vessel, the distillation tower, etc. to separate water and the porous forming agent, and recovering the porous forming agent.

  According to the method of the present invention, it is hydrophobic and has a boiling point higher than that of water so that it cannot be removed or recovered by the steam distillation or the method described in Patent Document 1 that has been conventionally performed industrially or is difficult to remove and recover. The porous forming agent possessed can be removed and recovered efficiently.

  In particular, the present invention is directed to a porous forming agent having a water solubility at room temperature of 0.1 g / 100 ml or less and a boiling point of 120 ° C. or more. Examples of such a porous forming agent include, but are not limited to, octane (boiling point: 125 ° C.), nonane (boiling point: 150.8 ° C.), decane (boiling point: 150.8 ° C.), undecane ( Boiling point: 196 ° C), dodecane (boiling point: 215 ° C), xylene (boiling point: 138-144 ° C), trimethylbenzene (boiling point: 165-169 ° C), dibutyl phthalate (boiling point: 187 ° C), dioctyl phthalate (boiling point: 386 ° C.), oligomers of styrene, and porous forming agents obtained by mixing these. In particular, a porous forming agent having a boiling point of 200 ° C. or higher such as dioctyl phthalate was almost impossible to separate by conventional steam distillation, but according to the present invention, it can be easily and efficiently removed from the macroporous resin. And can be recovered.

  The porous forming agent removal and recovery method of the present invention can be used in the production of any macroporous resin as long as it is a macroporous resin that uses these porous forming agents during production. . In the present invention, the macroporous resin is a porous resin obtained by polymerizing a monomer by adding a porous forming agent to form pores having an average diameter of 10 to 600 nm. Examples of such a resin include a styrene resin used as a base of a cation exchange resin, and a vinyl pyridine resin used as a carrier for a rhodium complex in the production of acetic acid.

  In the step of extracting the porous forming agent from the macroporous resin in the present invention, first, the resin containing the porous forming agent is heated together with the organic solvent, and the porous forming agent in the resin is extracted with the organic solvent.

  The organic solvent is not particularly limited as long as these porous forming agents can be dissolved, but it is preferable to use a lower alcohol having 1 to 6 carbon atoms. Of these, methanol is particularly preferable because it has a low boiling point and can be purchased at a low price.

  By heating the organic solvent at the time of extraction, the porous forming agent can be efficiently extracted and separated from within the fine pores of the macroporous resin. In the present invention, it is not necessary to heat to the boiling point of the porous forming agent as in the case of removing by the method described in Patent Document 1. In this case, the temperature of the organic solvent is preferably as high as possible below the boiling point of the organic solvent in order to extract the porous forming agent more efficiently. For example, in the case of methanol, 50 to 64 ° C. is preferably used. According to this method, the porous forming agent can be removed from the macroporous resin at a temperature lower than the boiling point of the porous forming agent.

  The mixing ratio of the organic solvent and the macroporous resin is preferably 20 to 50 vol%, more preferably 25 to 40 vol% in terms of resin concentration.

  In addition, since the macroporous resin produced by suspension polymerization is mixed and dispersed in a slurry containing water containing a surfactant or the like as a medium, it is dehydrated by a method such as centrifugation or filtration after polymerization. After washing, it is preferable to mix with an organic solvent. However, in the present invention, since extraction is performed while purifying a part of the organic solvent as described later, it is not necessary to dehydrate excessively, and the water content is sufficient to be 60 wt% or less, for example.

  In addition, in order to eliminate the unevenness of the product in order to extract the porous forming agent inside the macroporous resin more uniformly in the extraction container by increasing the chance of contact between the macroporous resin and the organic solvent, It is preferable to perform extraction while stirring the mixture of the macroporous resin and the organic solvent after adding the solvent. The rotational speed of stirring varies depending on the size of the extraction container used for extraction, the shape of the stirring blade, and the like, but is preferably set to a limit speed at which the macroporous resin floats. Excessive stirring speed can damage the macroporous resin.

  In this way, by heating and stirring the macroporous resin and the organic solvent as necessary, the penetration of the organic solvent into the pores of the macroporous resin and the liquid renewal on the surface of the resin particles are accelerated, thereby efficiently. The porous forming agent can be extracted and removed.

  In the present invention, a part of the extracted organic solvent containing the porous forming agent and water is separated into solid and liquid by a filter or the like and sent to the organic solvent purification step by a pump.

  In the organic solvent purification step, the porous forming agent and water are separated from the organic solvent. The separated organic solvent is returned to the extraction step again. The method for separating water and the organic solvent is not particularly limited. For example, the organic solvent can be separated by evaporating the organic solvent using an evaporation kettle or a distillation column. At this time, the vaporized organic solvent is cooled, liquefied, and returned to the extraction step. Moreover, you may isolate | separate by other methods, such as using an ion exchange resin and activated carbon, for example.

  Thus, the amount of organic solvent used can be reduced by continuously circulating the organic solvent between the extraction step and the recovery step. In addition, since the concentration of the porous forming agent in the organic solvent in the extraction process gradually decreases due to the purification of the organic solvent, the concentration difference between the porous forming agent in the pores and in the vicinity of the resin particle surface can be maintained. Efficient extraction and removal are possible. Furthermore, since it is not necessary to use a high purity organic solvent in the present invention, the cost of the extraction process can be reduced.

  In addition, since the organic solvent circulates through the organic solvent purification step and water entrained in the macroporous resin can be removed from the extraction step, it is necessary to dehydrate the resin after polymerization washing excessively by drying or the like. No simple dehydration is sufficient.

  By repeating the above steps continuously, the macroporous resin is eluted as an impurity when the resin is used in an organic solvent or the like until the pores necessary for exhibiting the desired properties are formed. The porous forming agent is extracted and removed from the macroporous resin to such an extent that does not affect the surface.

  The permissible residual amount of the porous forming agent varies depending on the use conditions of the porous forming agent and the resin, but is 5% by mass or less, preferably 2% by mass or less based on the resin.

  When the porous forming agent in the resin is less than the desired concentration by repeating the above steps, the circulation between the extraction step and the organic solvent recovery step is stopped, the temperature of the extractor is lowered, and then the resin / organic The macroporous resin can be separated from the organic solvent and recovered by extracting the solvent slurry and centrifuging, filtering, or the like.

  The recovered resin can be commercialized by subjecting it to washing, classification and the like according to the purpose of use.

  On the other hand, the separated organic solvent can be stored in a separate container and used for the initial filling of the organic solvent purification step when the porous forming agent is removed next time.

  Further, the liquid remaining in the distillation kettle or distillation column is concentrated to an organic solvent concentration at which water and the porous forming agent are separated, and then allowed to stand to separate the porous forming agent and water and recover them. The recovered porous forming agent and water can be reused as an oil phase and an aqueous phase, respectively, in the next suspension polymerization of the macroporous resin.

  Thus, according to the present invention, it is possible to efficiently and easily recover the high boiling point porous forming agent that has been difficult to recover. In addition, since the organic solvent can be repeatedly used with almost no damage, the porous forming agent can be removed from the macroporous resin that is economical and has a low environmental impact.

  The porous forming agent was removed from the macroporous resin using the apparatus shown in FIG.

  Using dioctyl phthalate as a porous forming agent, a styrene / divinylbenzene copolymer resin was prepared, and water was removed from the extractor (reaction vessel) through a filter. The moisture in the resin was about 50 wt%.

The same amount of methanol as the resin was placed in the extractor and the evaporation vessel.
While stirring, the liquid temperature of the extractor was raised to 50 ° C. and the liquid temperature of the evaporation vessel was raised to 65 ° C., and methanol was passed from the extractor through the filter to the evaporation vessel while performing extraction.

  The methanol vaporized in the evaporation vessel was liquefied by a condenser (about 5 ° C.) installed at the top of the extractor and returned to the extractor.

  From the volume of the extractor and the circulation speed, the time for all of the extractor liquid to be changed once was calculated, and this time was defined as one cycle. When the resin of the extractor was sampled for each cycle of liquid circulation and the remaining amount of dioctyl phthalate was analyzed, the relationship between the number of liquid circulation cycles and the removal rate of dioctyl phthalate was as shown in FIG.

  The removal rate reached 97% after 2 cycles, and dioctyl phthalate was not detected after 4 cycles.

  The residual amount of dioctyl phthalate in the resin was obtained by adding 100 g of methanol to 10 g of the dried resin, performing extraction at 65 ° C. for 3 hours, and analyzing the concentration of dioctyl phthalate in methanol by FID gas chromatography. .

Claims (6)

Organic solvent capable of dissolving the porous forming agent in a macroporous resin containing a porous forming agent having a water solubility at room temperature of 0.1 g / 100 ml or less and a boiling point of 120 ° C. or higher An extraction step of extracting a porous forming agent by adding a lower alcohol having 1 to 6 carbon atoms ,
Only organic solvent was separated from the organic solvent extracts the porous forming agent, an organic solvent purification step of returning to the extraction step, and a porous separating and water porous forming agent from the liquid remaining in the organic solvent purification step A method for removing and recovering a porous forming agent from a macroporous resin comprising a porous forming agent recovery step of recovering a forming agent.   The removal of the porous forming agent from the macroporous resin according to claim 1, wherein the extraction of the porous forming agent from the macroporous resin in the extraction step is performed at 50 ° C or higher and 64 ° C or lower. And recovery method.   The method for removing and recovering a porous forming agent from a macroporous resin according to claim 1 or 2, wherein the separation of the organic solvent in the organic solvent purification step is performed by distillation. The method for removing and recovering a porous forming agent from a macroporous resin according to any one of claims 1 to 3 , wherein the organic solvent is methanol. The porous forming agent is selected from the group consisting of octane, nonane, decane, undecane, dodecane, xylene, trimethylbenzene, dibutyl phthalate, dioctyl phthalate, styrene oligomer, and a porous forming agent obtained by mixing these 1 The method for removing and collecting the porous forming agent from the macroporous resin according to any one of claims 1 to 4 , wherein the porous forming agent is at least two porous forming agents. The method for removing and recovering a porous forming agent from a macroporous resin according to any one of claims 1 to 5 , wherein the boiling point of the porous forming agent is 200 ° C or higher.

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