KR20080007601A - Purification Method of Porous Polyamide Fine Powder - Google Patents

Abstract

Disclosed is a method for advantageously remove a solvent A remaining in a porous polyamide fine powder which has been obtained by bringing a polyamide solution prepared by dissolving a polyamide in the solvent A into contact with a nonsolvent B for polyamides. Specifically, the solvent A is extracted and removed from the porous polyamide fine powder by bringing a nonsolvent C for polyamides, which is compatible with the solvent A at least at a temperature not less than 40°C, into contact with the porous polyamide fine powder at a temperature not less than 40°C.

Description

Purification method of porous polyamide fine powder {METHOD FOR PURIFYING POROUS POLYAMIDE FINE POWDER}

The present invention relates to a method for purifying porous polyamide fine powder.

The porous polyamide fine powder is considered to be used as a cosmetic material such as a cleansing mask or a filler for chromatography. In addition, the use of various catalysts or an adsorbent has been studied.

As a method for producing the porous polyamide fine powder, a method of depositing polyamide particles by contacting a polyamide nonsolvent with a polyamide solution (hereinafter referred to as a solvent organic phase separation method) is known. Examples of the polyamide solvent (both solvents) include phenol compounds such as phenol, cresol, and chlorophenol, formic acid, sulfuric acid, acetic acid, trichloroacetic acid, ethylene carbonate, hexamethyl phosphate triamide (HMPT), and trifluoroethanol. Trichloroethanol, catcher chloral, hydrogen chloro fluoride, saturated alcohol solutions of alcohol soluble salts (e.g., calcium chloride, methanol containing magnesium chloride), hydrogen fluoride, hydrogen chloride, liquid sulfur dioxide and phosphoric acid are known.

Patent Document 1 discloses a method for obtaining porous polyamide spherical particles having a number average particle diameter of 1 to 30 µm and a BET specific surface area of 100 to 80000 m 2 / kg using the solvent organic phase separation method described above.

Patent Document 1: Japanese Unexamined Patent Publication No. 2002-80629

Disclosure of the Invention

Problems to be Solved by the Invention

The solvent organic phase separation method is an advantageous method for industrially producing porous polyamide fine powder having a uniform particle diameter. However, according to the investigation by the inventors, it was found that a large amount of the solvent of the polyamide used for the production remains in the porous polyamide fine powder produced by using the solvent organic phase separation method. In particular, phenolic compounds such as cresol and phenol, formic acid and sulfuric acid have a high affinity with polyamide, and it has been found to tend to remain in the porous polyamide fine powder. The porous polyamide fine powder in which the solvent of the polyamide remains is problematic in that it may adversely affect the human body when used as a cosmetic material in direct contact with the human body.

In addition, Patent Document 1 discloses that the porous polyamide spherical particles may be washed several times with methanol. According to the inventors' investigation, only the porous polyamide fine powder is washed with normal temperature (25 ° C.) methanol. As a result, it was difficult to significantly reduce the amount of the solvent remaining in the porous polyamide particles.

Accordingly, it is an object of the present invention to provide a high purity porous polyamide fine powder, and to provide an advantageous method for removing the solvent of the polyamide remaining in the porous polyamide particles produced by the solvent organic phase separation method. have.

Means to solve the problem

The present invention relates to a porous polyamide fine powder obtained by contacting a polyamide non-solvent B with a polyamide solution in which a polyamide is dissolved in a solvent A, which is compatible with the solvent A at a temperature of at least 40 ° C or higher. A method for purifying porous polyamide fine powder, characterized by extracting and removing solvent A of this polyamide from porous polyamide fine powder by contacting amide non-solvent C at a temperature of 40 ° C or higher.

This invention also exists in the porous polyamide fine powder obtained by the said refine | purification method of this invention.

This invention also exists in the porous polyamide fine powder which does not contain 100 mass ppm or more of any of a phenolic compound, a formic acid, and a sulfuric acid.

Preferable embodiments of the method for purifying the porous polyamide fine powder of the present invention are as follows.

(1) The solvent A is a compound selected from the group consisting of phenol compounds, formic acid and sulfuric acid.

(2) The polyamide nonsolvent B is a compound selected from the group consisting of water and a polyamide insoluble organic solvent.

(3) The polyamide nonsolvent C is a compound selected from the group consisting of aliphatic alcohols, aliphatic or aromatic ketones, aliphatic or aromatic hydrocarbons, and water.

(4) The polyamide is polyamide 6, and the non-solvent B contains water and a polyamide insoluble organic solvent.

(5) The polyamide is polyamide 12, and the non-solvent B contains a polyamide insoluble organic solvent other than alkylene glycol and alkylene glycol.

(6) Solvent A is a phenolic compound, and nonsolvent C is an aliphatic alcohol, aliphatic ketone, aromatic ketone or aromatic hydrocarbon.

(7) Solvent A is formic acid or sulfuric acid, and nonsolvent C is aliphatic alcohol, aliphatic ketone or water.

(8) The porous polyamide fine powder is contacted with an alkaline alcohol solution before contacting with the non-solvent C.

(9) The porous polyamide fine powder has a number average particle diameter in the range of 1 to 30 µm, and a BET specific surface area in the range of 100 to 80000 m 2 / kg.

Effects of the Invention

By using the method for purifying the porous polyamide fine powder of the present invention, the solvent of the polyamide remaining in the porous polyamide fine powder produced by the solvent organic phase separation method can be industrially advantageously reduced.

The porous polyamide fine powder obtained by using the method for purifying the porous polyamide fine powder of the present invention, in which the residual amount of the solvent of the polyamide is reduced, can be advantageously used as a material in direct contact with a human body such as a cosmetic material.

Implement the invention  Best form for

In the method for purifying the porous polyamide fine powder of the present invention, the porous polyamide fine powder to be treated is a porous polyamide obtained by contacting a polyamide non-solvent B with a polyamide solution in which polyamide is dissolved in solvent A. It is a fine powder. The porous polyamide fine powder is preferably formed of polyamide of any one of polyamide 6, polyamide 11, polyamide 12, and polyamide 66. It is preferable that the molecular weight of a polyamide exists in the range of 2000-100000 in a number average molecular weight, and it is especially preferable to exist in the range of 5000-400000.

Examples of the solvent A used to prepare the porous polyamide fine powder include phenol compounds such as phenol, cresol, and chlorophenol, formic acid, sulfuric acid, acetic acid, trichloroacetic acid, ethylene carbonate, hexamethylphosphate triamide (HMPT), tri Fluoroethanol, trichloroethanol, catcher chloral, hydrogen chloro fluoride, saturated alcohol solution of alcohol soluble salts, hydrogen fluoride, hydrogen chloride, liquid sulfur dioxide and phosphoric acid. The solvent A may be a mixture of two or more solvents.

The solvent A is preferably a phenol compound, formic acid and sulfuric acid, and particularly preferably a phenol compound. Phenol compounds are preferably phenol and cresol (particularly m-cresol).

A solidification point lowering agent may be added to the polyamide solution. As a solidification point lowering agent, as long as it is a range which does not precipitate polyamide in a polyamide solution, you may use the non-solvent of polyamide. Examples of solidification point lowering agents include water, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 1- Hexanol, ethylene glycol, triethylene glycol, propylene glycol, glycerin and diglycerin.

The polyamide concentration in the polyamide solution is preferably in the range of 0.1 to 30% by mass, more preferably in the range of 0.2 to 25% by mass.

Examples of the polyamide non-solvent B to be brought into contact with the polyamide solution include a compound selected from the group consisting of water and a polyamide insoluble organic solvent. The nonsolvent B may be a mixture of two or more solvents. It is preferable that non-solvent B does not melt | dissolve 0.01 mass% or more of polyamide in a polyamide solution at 25 degreeC of liquid temperature.

Examples of the polyamide insoluble organic solvent include alkylene glycols such as ethylene glycol and propylene glycol.

Other examples of polyamide insoluble organic solvents include monohydric alcohols and trihydric alcohols.

The monohydric alcohol is preferably a monohydric alcohol having 1 to 6 carbon atoms. The monohydric alcohol may be linear or may have a branch. Examples of monohydric alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 2-methyl-1-propanol, 2-methyl-2-propanol, 1-pentanol, 1-hexa You can play around.

Examples of trihydric alcohols include glycerin.

When the polyamide is polyamide 6, the non-solvent B is preferably a mixture containing water and a polyamide insoluble organic solvent (preferably monohydric alcohol).

When polyamide is polyamide 12, it is preferable that nonsolvent B is a mixture containing polyamide insoluble organic solvent (preferably trihydric alcohol) other than alkylene glycol and alkylene glycol.

In order to produce a porous polyamide fine powder, a method of temporarily mixing a polyamide solution and a non-solvent B to form a homogeneous mixed solution and then standing still can be used. The porous polyamide particles are precipitated by this operation. do. The liquid temperature of the mixed solution at the time of depositing porous polyamide particles is preferably in the range of 0 to 80 ° C, particularly preferably in the range of 25 to 40 ° C.

In the mixed solution of the polyamide solution and the non-solvent B, a thickener may be added to increase the viscosity of the mixed solution in order to prevent aggregation of the precipitated polyamide particles. As an example of a thickener, the polyalkylene glycol of the number average molecular weight 1000 or more (in particular, the range of 1100-5000) is mentioned. Examples of the polyalkylene glycols include polyethylene glycol and polypropylene glycol. As a method of adding a thickener, a method of adding to one or both of a polyamide solution and a non-solvent B, or a method of adding a thickener while mixing a polyamide solution and a non-solvent B, or a mixed solution immediately after preparation Any method of adding a thickener may be sufficient.

Porous polyamide particles precipitated in the mixed solution can be separated from the mixed solution using conventional methods such as filtration, decantation, centrifugation and the like.

In the method for purifying the porous polyamide fine powder of the present invention, the porous polyamide fine powder obtained as described above is brought into contact with the solvent A and the polyamide non-solvent C compatible at a temperature of at least 40 ° C or higher at a temperature of 40 ° C or higher. The solvent A is extracted and removed from the porous polyamide fine powder thereby.

Most of the solvent A remaining in the porous polyamide fine powder is present in the amorphous portion of the polyamide. For this reason, by contacting nonsolvent C at the temperature of 40 degreeC or more near the glass transition point of polyamide, the solvent A which remain | survives in the amorphous part of polyamide can be extracted and removed efficiently using nonsolvent C.

It is preferable that the contact temperature with the porous polyamide fine powder of non-solvent C exists in the range of 50 degreeC-140 degreeC.

Examples of the polyamide non-solvent C include a compound selected from the group consisting of aliphatic alcohols, aliphatic or aromatic ketones, aliphatic or aromatic hydrocarbons, and water. The non-solvent C may be a mixture of two or more solvents. It is preferable that non-solvent C does not melt | dissolve polyamide 0.01 mass% or more in 40 degreeC of liquid temperature.

Examples of the aliphatic alcohol include monovalent aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol, 1-propanol, and 2-propanol.

Examples of aliphatic ketones include acetone and methyl ethyl ketone.

Examples of aromatic ketones include acetophenone, propiophenone and butyrophenone.

Examples of aromatic hydrocarbons include toluene and xylene.

Examples of aliphatic hydrocarbons include heptane, hexane, octane and n-decane.

In consideration of the compatibility of the polyamide with the solvent A, when the solvent A is a phenol compound, the non-solvent C is preferably an aliphatic alcohol, an aliphatic ketone, an aromatic ketone or an aromatic hydrocarbon. Moreover, when solvent A is formic acid or sulfuric acid, it is preferable that nonsolvent C is aliphatic alcohol, aliphatic ketone, or water.

As a method for contacting the non-solvent C and the porous polyamide fine powder, a method of introducing the porous polyamide fine powder while stirring in the non-solvent C heated to 40 ° C. or higher, or a method using a thermally equipped soxhlet extractor, The method of contacting the non-solvent C heated at 40 degreeC or more, while rotating a porous polyamide fine powder at high speed using a centrifugal separator can be employ | adopted. The contact time of the non-solvent C and the porous polyamide fine powder is usually in the range of 10 minutes to 20 hours.

In the present invention, the porous polyamide fine powder may be contacted with an alkaline alcohol solution before being brought into contact with the non-solvent C to neutralize the porous polyamide fine powder.

As an example of alkaline alcohol, the methanol or ethanol solution which melt | dissolved hydroxide of alkali metals, such as potassium hydroxide and sodium hydroxide, is mentioned. It is preferable to exist in the range of 0.01-1N, and, as for the alkali concentration in alkaline alcohol, it is more preferable to exist in the range which is 0.05-0.5N.

Neutralization treatment by alkaline alcohol solution can be performed by disperse-suspending porous polyamide fine powder in alkaline alcohol. It is preferable to make the temperature of a neutralization process into the range of 10-40 degreeC.

In the porous polyamide fine powder treated by the purification method of the present invention, the residual amount of the solvent A of the polyamide used for the production of the porous polyamide fine powder is remarkably small. In particular, the phenolic compound, formic acid and sulfuric acid can be reduced so that the remaining amount thereof is less than 100 mass ppm (preferably less than 50 mass ppm, more preferably less than 10 mass ppm).

The porous polyamide fine powder of the present invention preferably has a number average particle diameter in the range of 1 to 30 µm and a BET specific surface area in the range of 100 to 80000 m 2 / kg. It is preferable that a number average particle diameter exists in the range of 0.3-25 micrometers. It is preferable that it is in the range of 1000-60000 m <2> / kg, and it is especially preferable that it exists in the range of 3000-50000 m <2> / kg.

The porous polyamide fine powder of the present invention can be advantageously used for the food industry or the medical field as a material for various cosmetics such as a cleansing mask, a filler for chromatography, a carrier or adsorbent for various catalysts. Moreover, a coloring agent is supported on the porous polyamide fine powder of this invention, and can also be used as electronic materials, such as an electrophotographic toner and a display apparatus.

In the following examples and comparative examples, the determination of the phenolic compound, formic acid and sulfuric acid in the porous polyamide fine powder, the determination of the particle shape of the porous polyamide fine powder, and the measurement of the particle diameter, specific surface area and crystallinity are as follows. It carried out by the method.

(1) Method of quantifying phenolic compound and formic acid

The phenolic compound and formic acid in the porous polyamide fine powder were thermally extracted using the gas chromatography mass spectrometer (GC-MS) under the following conditions, and the extract was separated by gas chromatography and identified and quantified by mass spectrometry. The detection limit was 1 mass ppm.

Sampling amount of porous polyamide fine powder: 1 mg

Heat extraction: 10 minutes at 230 ℃

Column: INNOWAX or FFAP, elevated to 50 ° C to 260 ° C

(2) Method of quantifying sulfuric acid amount

5 mg of the porous polyamide fine powder weighed on the filter paper was placed in a platinum basket, and sulfur oxide volatilized by oxygen flask combustion was absorbed into an ion chromatographic eluent, which was introduced into an ion chromatograph (column: IonPac or TSKgel). Sulfate ions (SO ₄ ^{2 −} ) were quantified. The detection limit was 1 mass ppm.

(3) Confirmation of particle shape and measuring method of particle diameter

Confirmation of the particle shape of the porous polyamide fine powder and measurement of the particle diameter were carried out using a scanning electron microscope (SEM). The particle diameter of polyamide particle | grains was measured by the SEM photograph, and the particle diameter of the particle | grains and other particle | grains measured the diameter of a corresponding circle | round | yen from the projection area.

The number average particle diameter (Dn) and the volume average particle diameter (Dv) were calculated according to equations (1) and (2) from 100 particle diameters.

Here, Xi: particle diameter of individual particles, n: number of measurements 100, Dn: number average particle diameter, Dv: volume average particle diameter.

(4) Measurement method of specific surface area

The specific surface area of the porous polyamide fine powder was measured by BET method three-point measurement by nitrogen adsorption.

(5) measuring method of crystallinity

Using a differential thermal analysis device (DSC), under a nitrogen stream with a flow rate of 40 mL / min, the temperature was raised from room temperature to a heating rate of 10 ° C / min, and the porous polyamide was obtained from the endothermic peak area in the temperature range of 180 to 235 ° C. The heat of fusion (Hf) of the fine powder was obtained, and the crystallinity was calculated by the following formula.

Crystallinity (%) = heat of fusion (Hf) / standard heat of fusion × 100

(However, the standard melting heat of polyamide 6 is 189J / g, the standard melting heat of polyamide 12 is 209J / g.)

Example 1

(1) 50 g of polyamide 6 (manufactured by Ube Heungsan Co., Ltd., 1013B, number average molecular weight 13000) was dissolved in 950 g of m-cresol to obtain an m-cresol solution of polyamide 6 having a concentration of 5% by mass. While stirring this solution, 6 kg of mixed liquids consisting of 5 kg of methanol and 1 kg of water were added. Stirring was continued and the stirring was stopped and it left still at the time when it became a uniform mixed solution. After a while, polyamide 6 particles were precipitated in the mixed solution. After standing still for 2 hours, the precipitated polyamide 6 particles were separated by filtration using a filter paper, and then washed three times with 10000 mL of 25 ° C. methanol on the filter paper. Subsequently, it dried at the temperature of 60 degreeC using the hot air dryer for 8 hours. Furthermore, it dried for 8 hours at the temperature of 60 degreeC using the vacuum dryer. As a result of observing the obtained polyamide 6 fine powder with a scanning electron microscope, the shape of the particle | grain was a substantially uniform porous spherical shape. The obtained porous polyamide 6 fine powder had a number average particle diameter of 8.6 micrometers, a volume average particle diameter of 9.3 micrometers, and the specific surface area was 10600 m <2> / kg. Moreover, heat of fusion (Hf) was 110 J / g, and crystallinity was 58%.

(2) 1 g of the porous polyamide 6 fine powder obtained in the above (1) was charged into a heat-insulating soxhlet extractor, and methanol was refluxed for 10 hours in contacting with the porous polyamide 6 fine powder. Subsequently, the porous polyamide 6 fine powder was taken out from the thermally equipped soxhlet extractor, dried at a temperature of 60 ° C. for 8 hours using a hot air dryer, and further dried at a temperature of 60 ° C. for 8 hours using a vacuum dryer. .

The residual solvent component was quantified about the porous polyamide 6 fine powder after drying. As a result, the amount of m-cresol in the fine powder was 4 mass ppm, and the amount of other phenol compounds, the amount of formic acid, and the amount of sulfuric acid were below the detection limit (<1 mass ppm) in all.

Comparative Example 1

The residual solvent component was quantified about the porous polyamide 6 fine powder obtained in Example 1 (1). As a result, the amount of m-cresol in the fine powder was 20000 ppm by mass, and the amounts of other phenol compounds, the amount of formic acid, and the amount of sulfuric acid were below the detection limit (<1 mass ppm) in all cases.

Example 2

The porous polyamide 6 fine powder obtained in Example 1 (1) was contacted with acetone in place of methanol by the method described in Example 1 (2) and dried. The residual solvent component was quantified about the porous polyamide 6 fine powder after drying. As a result, the amount of m-cresol in the fine powder was 2 mass ppm, and the amount of other phenol compounds, the amount of formic acid, and the amount of sulfuric acid were below the detection limit (<1 mass ppm) in all.

Example 3

10 g of the porous polyamide 6 fine powder obtained in Example 1 (1) was added to 200 ml of a methanol solution of potassium hydroxide at a concentration of 0.1 mol / L, and stirred for 1 hour to neutralize. Next, the porous polyamide 6 fine powder was taken out from the methanol solution, dried for 8 hours at a temperature of 60 ° C. using a hot air dryer, and then dried at a temperature of 60 ° C. for 8 hours using a vacuum dryer.

1 g of the neutralized porous polyamide 6 fine powder was brought into contact with methanol in the same manner as in Example 1 (2) and dried. The residual solvent component was quantified about the porous polyamide 6 fine powder after drying. As a result, the amount of m-cresol, the amount of other phenol compounds, the amount of formic acid, and the amount of sulfuric acid in the fine powder were below the detection limit (<1 mass ppm).

Example 4

In Example 3, it carried out similarly to Example 3 except having contacted and dried acetone instead of methanol to the porous polyamide 6 fine powder after neutralization treatment. The residual solvent component was quantified about the porous polyamide 6 fine powder after drying. As a result, the amount of m-cresol, the amount of other phenol compounds, the amount of formic acid, and the amount of sulfuric acid in the fine powder were below the detection limit (<1 mass ppm).

Example 5

In Example 3, it carried out similarly to Example 3 except having contacted and dried toluene for the porous polyamide 6 fine powder after neutralization process instead of methanol. The residual solvent component was quantified about the porous polyamide 6 fine powder after drying. As a result, the amount of m-cresol, the amount of other phenol compounds, the amount of formic acid and the amount of sulfuric acid in the fine powder were below the detection limit (<1 mass ppm).

Example 6

(1) Polyamide 6 fine powder was obtained like Example 1 (1) except having used the mixed solvent of 855g of phenols and 95g of methanol instead of m-cresol as a solvent of polyamide. As a result of observing the obtained polyamide 6 fine powder with a scanning electron microscope, the shape of the particle | grain was a substantially uniform porous spherical shape. The obtained porous polyamide 6 fine powder had a number average particle diameter of 8.4 micrometers, a volume average particle diameter of 9.0 micrometers, and the specific surface area was 9800 m <2> / kg. Moreover, heat of fusion (Hf) was 112 J / g and crystallinity was 59%.

(2) 1 g of the porous polyamide 6 fine powder obtained in the above (1) was carried out in the same manner as in Example 1 (2), and methanol was contacted and dried. The residual solvent component was quantified about the porous polyamide 6 fine powder after drying. As a result, the amount of phenols in the fine powder was 10 mass ppm, and the amount of other phenol compounds, the amount of formic acid and the amount of sulfuric acid were below the detection limit (<1 mass ppm) in all.

Comparative Example 2

The residual solvent component was quantified for the porous polyamide 6 fine powder obtained in Example 6 (1). As a result, the amount of phenols in the fine powder was 10000 ppm by mass, and the amount of phenol compounds, the amount of formic acid, and the amount of sulfuric acid other than that were below the detection limit (<1 mass ppm).

Example 7

1 g of porous polyamide 6 fine powder obtained in Example 6 (1) was charged into a sealed container containing 20 g of methanol heated to 50 ° C, and stirred for 1 hour, followed by filtration. After this contact treatment was repeated five times, the porous polyamide 6 fine powder was dried at a temperature of 60 ° C. for 8 hours using a hot air dryer, and then dried at a temperature of 60 ° C. for 8 hours using a vacuum dryer. The residual solvent component was quantified about the porous polyamide 6 fine powder after drying. As a result, the amount of phenols in the fine powder was 50 mass ppm, and the amount of other phenol compounds, the amount of formic acid and the amount of sulfuric acid were below the detection limit (<1 mass ppm) in all.

Example 8

30 g of the porous polyamide 6 fine powder obtained in Example 6 (1) was placed in a filter cloth, placed in a centrifuge and rotated at a rotational speed of 3000 rpm, while contacting the porous polyamide 6 fine powder with 300 g of methanol heated to 50 ° C. . After this contact treatment was repeated three times, the porous polyamide 6 fine powder was dried at a temperature of 60 ° C. for 8 hours using a hot air dryer, and then dried at a temperature of 60 ° C. for 8 hours using a vacuum dryer. The residual solvent component was quantified about the porous polyamide 6 fine powder after drying. As a result, the amount of phenols in the fine powder was 50 mass ppm, and the amount of other phenol compounds, the amount of formic acid and the amount of sulfuric acid were below the detection limit (<1 mass ppm) in all.

Example 9

(1) A polyamide 6 fine powder was obtained in the same manner as in Example 1 (1) except that 900 g of formic acid was used instead of m-cresol as the solvent of the polyamide. As a result of observing the obtained polyamide 6 fine powder with a scanning electron microscope, the shape of each particle was a relatively uniform porous spherical shape. The obtained porous polyamide 6 fine powder had a number average particle diameter of 10.4 micrometers, a volume average particle diameter of 11.0 micrometers, and the specific surface area was 11000 m <2> / kg.

(2) 1 g of the porous polyamide 6 fine powder obtained in the above (1) was brought into contact with methanol and dried in the same manner as in Example 1 (2). The residual solvent component was quantified about the porous polyamide 6 fine powder after drying. As a result, the amount of formic acid, the amount of sulfuric acid, and the amount of phenol compound were below the detection limit (<1 mass ppm) in all.

Comparative Example 3

The residual solvent component was quantified for the porous polyamide 6 fine powder obtained in Example 9 (1). As a result, the amount of formic acid in the fine powder was 5000 mass ppm, and the amount of the phenol compound and the amount of sulfuric acid were below the detection limit (<1 mass ppm) in all.

Example 10

(1) 10.0 g of ethylene glycol, 2.5 g of polyethylene glycol (number average molecular weight 1540), and 2.5 g of polypropylene glycol (number average molecular weight 3000) were added to 98.0 g of phenol having a liquid temperature of 70 ° C, and the mixture was stirred well to prepare a solvent mixture. . The solvent mixture was placed in an airtight container, and 2.0 g of polyamide 12 (manufactured by Ube Heungsan Co., Ltd., 3014U, number average molecular weight 14000) was added under a nitrogen gas atmosphere, and the mixture was stirred for 24 hours while adjusting the liquid temperature to 70 ° C. Amide 12 was completely dissolved, and a polymer alkylene glycol-containing polyamide 12 solution having a concentration of polyamide 12 of 1.74% by mass was prepared and stored at 30 ° C.

(2) 14 g of glycerin and 9.5 g of ethylene glycol were mixed to prepare a non-solvent mixture and stored at 30 ° C.

(3) The polyamide 12 solution (liquid temperature 30 ° C) prepared in (1) above and the non-solvent mixture (liquid temperature 30 ° C) prepared in (2) above were agitated using a stirrer (motor rotational speed 300 rpm). The mixture was stirred for 10 minutes to prepare a mixed solution. After completion of the stirring, the mixture was left standing at 30 ° C while maintaining the liquid temperature. As a result, 90 minutes after the end of the stirring, the mixed solution became cloudy by precipitation of the polyamide 12 particles. After the clouding, the liquid temperature was further allowed to stand for 24 hours with the temperature of 30 ° C. Precipitated polyamide 12 was separated by filtration using filter paper, and then washed three times with 1000 ml of 25 ° C methanol. Subsequently, the precipitated polyamide 12 particles were vacuum dried at a temperature of 60 ° C. for 12 hours. As a result of observing the obtained polyamide 12 fine powder with a scanning electron microscope, the shape of the particle was a substantially uniform porous spherical shape. The obtained porous polyamide 6 fine powder had a number average particle diameter of 15.1 µm, a volume average particle diameter of 15.4 µm, and a specific surface area of 5400 m 2 / kg. Moreover, heat of fusion (Hf) was 145 J / g and crystallinity was 69%.

(4) 0.5 g of the porous polyamide 12 fine powder obtained in the above (3) was charged into a thermally equipped soxhlet extractor, and methanol was refluxed in the extractor for 10 hours to come into contact with the porous polyamide 12 fine powder. Next, the porous polyamide 12 fine powder was taken out from the heat retention soxhlet extractor, and dried at a temperature of 60 ° C. for 8 hours using a hot air dryer.

The residual solvent component was quantified about the porous polyamide 12 fine powder after drying. As a result, the amount of phenol in the fine powder was 3 mass ppm, the amount of other phenol compounds, the amount of formic acid and the amount of sulfuric acid were below the detection limit (<1 mass ppm).

[Comparative Example 4]

The residual solvent component was quantified for the porous polyamide 12 fine powder obtained in Example 10 (3). As a result, the amount of phenol in the fine powder was 6000 mass ppm, the amount of other phenol compounds, the amount of formic acid, and the amount of sulfuric acid were below the detection limit (<1 mass ppm).

Claims (13)

The polyamide non-solvent C compatible with the porous polyamide fine powder obtained by contacting the polyamide non-solvent B with the polyamide solution in which the polyamide is dissolved in the solvent A at a temperature of at least 40 ° C or higher. The solvent A of this polyamide is extracted and removed from the porous polyamide fine powder by making it contact at the temperature of 40 degreeC or more, The refinement | purification method of the porous polyamide fine powder characterized by the above-mentioned. The method of claim 1, The purification method of the porous polyamide fine powder whose solvent A is a compound chosen from the group which consists of a phenol compound, formic acid, and a sulfuric acid. The method of claim 1, A method for purifying porous polyamide fine powder, wherein the polyamide non-solvent B is a compound selected from the group consisting of water and a polyamide insoluble organic solvent. The method of claim 1, A method for purifying porous polyamide fine powder, wherein the polyamide non-solvent C is a compound selected from the group consisting of aliphatic alcohols, aliphatic or aromatic ketones, aliphatic or aromatic hydrocarbons, and water. The method of claim 1, A method for purifying porous polyamide fine powder wherein polyamide is polyamide 6 and non-solvent B contains water and a polyamide insoluble organic solvent. The method of claim 1, A method for purifying porous polyamide fine powder wherein polyamide is polyamide 12 and non-solvent B contains a polyamide insoluble organic solvent other than alkylene glycol and alkylene glycol. The method of claim 1, The solvent A is a phenol compound, and the non-solvent C is an aliphatic alcohol, an aliphatic ketone, an aromatic ketone or an aromatic hydrocarbon. The method of claim 1, A method for purifying porous polyamide fine powder wherein solvent A is formic acid or sulfuric acid and nonsolvent C is aliphatic alcohol, aliphatic ketone or water. The method of claim 1, A process for purifying porous polyamide fine powder, wherein the porous polyamide fine powder is contacted with an alkaline alcohol solution before contacting with the non-solvent C. The method of claim 1, The porous polyamide fine powder has a number average particle diameter in the range of 1 to 30 µm, and has a BET specific surface area in the range of 100 to 80000 m 2 / kg. Porous polyamide fine powder obtained by the purification method of Claim 1. Porous polyamide fine powder containing no more than 100 mass ppm of any of phenolic compound, formic acid and sulfuric acid. The method of claim 12, Porous polyamide fine powder whose number average particle diameter is in the range of 1-30 micrometers, and whose BET specific surface area is in the range of 100-80000 m <2> / kg.