JPH0260904A - Isolation of polymer - Google Patents

Abstract

PURPOSE:To obtain stably in a short time and efficiently a polymer with a uniform particle diameter and a high bulk density by mixing a soln. of a polymer in an org. solvent with an ag. solution contg. a water-soluble polymer dispersant, dispersing it therein and then, adding thereto a poor solvent for the polymer. CONSTITUTION:100 pts.wt. soln. of a polymer substantially imcompatible with water and soluble in an org. solvent (e.g., polycarbonate) in an org. solvent (e.g., methylene chloride) is dispersed in 10-1,000 pts.wt. ag. soln. contg. 0.001-3wt.% water-soluble polymer dispersant and the obtained dispersion is mixed with a poor solvent for the polymer.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to improvements in methods for isolating polymers.

More specifically, the present invention relates to a method for stably and efficiently isolating a homogeneous and high bulk density polymer from a solution containing the polymer.

[Prior Art 1] Conventionally, various methods have been known for isolating polymers from solutions containing them; one of them is, for example, adding a poor solvent directly to a polymer solution. A method for precipitating a polymer is disclosed (Japanese Patent Publication No. 37-5599
Publication No. 18399, Special Publication No. 18399, Special Publication No. 18399, Special Publication No. 18399-
1959, Special Publication No. 1477, etc.).

However, this method has problems such as a poor solvent remaining in the isolated polymer and a low bulk density of the polymer.

Other isolation methods include, for example, a method in which an organic solvent solution containing a polymer is brought into contact with hot water or hot steam, the organic solvent is distilled off together with the steam, and the polymer is obtained as a slurry in water; Known methods include heating and reducing the pressure of an organic solvent solution to distill off the organic solvent, and gelling and pulverizing the solution. However, all of these methods have drawbacks such as the isolated polymer having a low bulk density and requiring special equipment.

Therefore, as a method to improve these drawbacks, a method has been proposed in which, for example, an organic solvent solution containing a polymer is dispersed in an aqueous phase, and the organic solvent is distilled off from this dispersed mixture by heating or reduced pressure. (Japanese Unexamined Patent Publication No. 58-69225). However, this method has drawbacks such as requiring a relatively long time to isolate a polymer with a high bulk density and requiring temperature and pressure to be controlled within a narrow range. In other words, if the organic solvent distillation rate is too high or the temperature is too high, the polymer solution will foam and the bulk density of the resulting polymer will decrease, and if the stirring conditions and solvent distillation conditions do not match. If it is not present, there is a risk that undesirable situations such as polymers with low bulk density will coalesce with each other may occur.

[Problems to be Solved by the Invention] The present invention overcomes the drawbacks of such conventional polymer isolation methods and makes it possible to obtain a homogeneous and high bulk density polymer from an organic solvent solution containing the polymer. This was developed with the aim of providing a method for stable and efficient isolation in a short period of time.

[Means for Solving the Problems] As a result of intensive research to achieve the above object, the present inventors have discovered that an organic solvent solution containing a polymer is mixed with an aqueous solution containing a water-soluble polymer dispersant. After dispersing the
By mixing this with a poor solvent for the polymer,
We have found a way to achieve this objective, and based on this knowledge, we have completed the present invention.

That is, in the present invention, 100 parts by weight of a polymer solution prepared by dissolving a polymer in an organic solvent is mixed with 0.0 parts by weight of a water-soluble polymer dispersant.
Provided is a method for isolating a polymer, which comprises mixing and dispersing it with 10 to 1000 parts by weight of an aqueous solution containing 01 to 3% by weight, and then mixing this dispersion with a poor solvent for the polymer. It is.

The present invention will be explained in detail below.

The polymer to which the method of the present invention can be applied is not particularly limited as long as it can be dissolved in an organic solvent that is substantially incompatible with water, such as polycarbonate, polyester, polyamide, polyamide ester, polyester polycarbonate, Polysulfone, polyphenylene sulfide, polyphenylene ether, polystyrene, poly-α-methylstyrene, polymethyl methacrylate, polyvinyl chloride, polyacetal, etc. can be used.

Further, the organic solvent used in the method of the present invention is not particularly limited as long as it can dissolve the above-mentioned polymer and is substantially incompatible with water. The polymer concentration in the polymer solution is usually selected in the range of 1 to 80% by weight, preferably 5 to 40% by weight. If this concentration is less than 1% by weight, the amount of poor solvent used will increase and the burden for recovering it will increase, and if it exceeds 80% by weight, the viscosity of the polymer solution will increase, making it difficult to handle, which is undesirable. .

The water-soluble polymer dispersants used in the method of the present invention include conventionally known ones, such as polyvinyl alcohol and its derivatives, carboxymethyl cellulose, hydroxyethyl cellulose, styrene-maleic acid copolymer and its derivatives, polyvinylpyrrolidone, polyvinylpyridine- Examples include N-oxide, polyalkylene oxide and its derivatives, storium alginate and its derivatives, and lignin sulfonates. Among these, polyvinyl alcohol and its derivatives, polyvinylpyrrolidone, styrene-maleic acid copolymer and Its derivative is
This is preferred because a polymer with high bulk density can be obtained. One type of these water-soluble polymer dispersants may be used, or two or more types may be used in combination.

The concentration of these water-soluble polymer dispersants in the aqueous solution containing them is selected in the range of 0.001 to 3% by weight, preferably 0.005 to 1% by weight. This concentration is 0
．． If the amount is less than 0.001% by weight, the dispersion of the polymer solution will not be sufficient, and if it exceeds 3% by weight, the organic solvent may foam, which is not favorable for operation.

In the present invention, 10 parts by weight of the aqueous solution containing the water-soluble polymer dispersant is added to 100 parts by weight of the polymer solution.
~1000 parts by weight to form a so-called O/W phase emulsion in which the polymer solution forms the dispersed phase and the aqueous solution forms the continuous phase, but the amount of the aqueous solution used is within the above range. , it is better to have as few as possible. There are no particular restrictions on the method for producing the emulsion,
Methods conventionally used for making emulsions, such as simply vigorous stirring, circulation using a pump, static mixer, orifice, line mixer, ultrasonic mixer, etc. Any method can be selected and used.

Next, the emulsion thus prepared is poured into a poor solvent for the polymer as it is, or after some aqueous phase has been removed, or the poor solvent is poured into the emulsion and the emulsion is poured for several seconds or The mixture is stirred or allowed to stand for several tens of minutes, and then the precipitated polymer particles are separated.

The poor solvent for the polymer is appropriately selected depending on the type of polymer. For example, when the polymer is polycarbonate, alcohols such as methanol and ethanol, ketones such as acetone, etc. are used as poor solvents.
Moreover, in the case of polystyrene, alcohols such as methanol and ethanol are used. Furthermore, when the polymer is polyamide, alcohols, ethers, etc. are used as poor solvents.

The above operations may be carried out batchwise or continuously, or may be carried out in combination with a batchwise method and a continuous method in the operation of turning a polymer solution into an emulsion and the operation of using a poor solvent. Good too. Furthermore, in order to reduce the residual amount of solvent and shorten the operation time, a poor solvent of the same kind or different kind as the poor solvent used is added in advance to the polymer solution to the extent that the polymer does not precipitate. You can stay there.

The polymer particles precipitated by mixing a poor solvent are
After separation by commonly used means such as decantation, filtration, centrifugation, etc., if necessary, after washing, it may be dried by an appropriate method.

The polymer thus obtained has a uniform particle size,
Usually, the particle size is in the range from 0.1 to 2 mm and the bulk density is in the range from 0.3 to 0.7 g/cm3. Fillers, pigments,
Various additives such as stabilizers and mold release agents may be added, or different types of polymers may be blended.

The polymer obtained by the method of the present invention can be directly molded as it is, or can be molded through a chipping process. Furthermore, when a fine powder is obtained, it can be used for coating such as powder coating.

[Example] Next, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited in any way by these examples.

Example 1 Polycarbonate (manufactured by Idemitsu Petrochemical, Tough0n A300
0) was dissolved in methylene chloride to a concentration of 20% by weight to prepare a polymer solution, and on the other hand, an aqueous solution containing 0.015% by weight of polyvinyl alcohol (PVA) with a degree of polymerization of 500 was prepared.

Next, 33M parts of PVA aqueous solution was added to 100 parts by weight of the polymer solution, and using a separating funnel for 10 minutes,
After vigorous mixing, this polymer solution emulsion 10
Add 0 parts by weight to 400 parts by weight of methanol prepared in a beaker while stirring with a magnetic stirrer,
Stirring was continued for an additional 5 minutes to precipitate polymer particles. Next, the polymer particles were filtered, washed with water, and dried to obtain polycarbonate particles of extremely uniform particle size.

When this polymer particle was observed under an optical microscope, it was confirmed that it was obtained as semitransparent particles.

The particle size and bulk density are shown in Table 1.

Example 2 Polymer particles were obtained in the same manner as in Example 1, except that acetone was used instead of methanol.

This was somewhat opaque compared to Example I.

The particle size and bulk density of this product are shown in Table 1.

Example 3 Same as Example 1! Strain the polymer solution emulsion into MM
Thereafter, 100 parts by weight of this emulsion was placed in a beaker, and 400 parts by weight of methanol was added thereto while stirring with a magnetic stirrer. With this method,
Polymer particles substantially similar to those in Example 1 were obtained. The particle size and bulk density of this product are shown in Table 1.

Example 4 With respect to 100 parts by weight of the polymer solution of Example 1, 0.
100 parts by weight of a 15% by weight aqueous solution was added and an emulsion was prepared in the same manner. Next, this emulsion 10
When 0 parts by weight was added to 400 parts by weight of methanol prepared in a beaker while stirring with a magnetic stirrer, polymer particles were precipitated 10 minutes later.

Table 1 shows the particle diameter and bulk density of this polymer particle.

Example 5 Polymer particles were obtained in the same manner as in Example 4, except that 200 parts by weight of the PVA aqueous solution was used. The particle size and bulk density of this product are shown in Table 1.

Example 6 Polymer particles were obtained in the same manner as in Example 4, except that 400 parts by weight of the PVA aqueous solution was used. However, in this case, polymer particles precipitated 18 minutes after the emulsion was poured into methanol.

Table 1 shows the particle diameter and bulk density of the obtained polymer particles.

Example 7 0.0 parts of PVA was added to 100 parts by weight of the polymer solution of Example 1.
100 parts by weight of a 1% by weight aqueous solution was added and an emulsion was prepared in the same manner. Next, 100 parts by weight of this emulsion was added to 100 parts by weight of methanol prepared in a beaker with stirring, and polymer particles were precipitated 10 minutes later.

Table 1 shows the particle diameter and bulk density of this polymer particle.

Example 8 Polymer particles were obtained in the same manner as in Example 7, except that the concentration of the PVA aqueous solution was 0.5% by weight.

The particle size and bulk density of this product are shown in Table 1.

Comparative Example 1 After preparing a polymer solution emulsion in the same manner as in Example 1, 100 parts by weight of this emulsion was added to 1000 parts by weight of 42°C water prepared in a beaker while stirring with a magnetic stirrer. Then, the mixture was stirred for 60 minutes while maintaining the temperature at 42°C under atmospheric pressure to precipitate polymer particles.

Table 1 shows the particle diameter and bulk density of the polymer particles thus obtained.

Comparative Example 2 In Comparative Example 1, when the water temperature was set to 50° C., the polymer solution foamed and no particulate polymer was obtained. Moreover, the polymer precipitated after 15 minutes was a mass with many spaces.

Comparative Example 3 A polymer solution was prepared in the same manner as in Example 1, and this 100
To the weight part, 5 parts by weight of an aqueous solution containing 0.015% by weight of PVA was added, and an emulsion was prepared in the same manner. However, this emulsion was in the W2O phase. Next, 100 parts by weight of this emulsion was added to 4 parts of methanol prepared in a beaker.
When the emulsion was added to 0.00 parts by weight while stirring with a magnetic stirrer, the emulsion became string-like in methanol and did not form particles. Moreover, the precipitated polymer still contained the PVA aqueous solution.

Comparative Example 4 A polymer was obtained in the same manner as in Example 4, except that the concentration of the PVA aqueous solution was 5% by weight. However, the polymer precipitated 12 minutes after the emulsion was poured into methanol, and bubbling was observed when the polymer solution emulsion was prepared.

Table 1 shows the particle diameter and bulk density of this polymer particle.

(The following is a blank space) [Effects of the Invention] As explained above, according to the method for isolating a polymer of the present invention, particles having a uniform particle size,
Moreover, a polymer having a high bulk density can be isolated stably and efficiently in a short time.

In addition, the method of the present invention can be applied to, for example, an aromatic polyester obtained by an interfacial polymerization method in which aromatic dicarboxylic acid chloride dissolved in an organic solvent incompatible with water and bisphenols dissolved in an alkaline aqueous solution are mixed and polymerized. It can be suitably applied to isolate polymers from solutions.

Patent applicant: Idemitsu Petrochemical Co., Ltd.

Claims (1)

[Claims] 1 Polymer solution 100 made by dissolving a polymer in an organic solvent
parts by weight are mixed and dispersed with 10 to 1000 parts by weight of an aqueous solution containing 0.001 to 3% by weight of a water-soluble polymer dispersant, and then this dispersion is mixed with a poor solvent for the polymer. A method for isolating a polymer.