JP2001031756A - Purification of polycarbonate resin solution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of continuously effectively purifying an organic solution of a polycarbonate with no induction period and reduced impurities and dust by removing water solution containing impurities from a polycarbonate resin emulsion. SOLUTION: The method of purifying a polycarbonate resin solution is conducted by passing an emulsion having a median value of 0.02 to 5 m2/g composed of an organic solution of a polycarbonate resin and water solution through a first metal filter of a filtration accuracy of 1 to 100 μm and the passing the emulsion through a second rougher metal filter having a filtration slope coefficient of 1.1 to 20 times that of the first filter. It is preferable that the second filter has a filtration slope coefficient of 2 to 10 times that of the first filter and the metal filter is 0.1 to 5 mm thick and contains 11 to 30 wt.% of Cr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for activating a metal filter medium suitable for regeneration which is effective for effectively separating droplets of a polycarbonate resin emulsion into an organic solvent solution and an aqueous solution, and a polycarbonate using the same. The present invention relates to a method for purifying a resin solution.

[0002]

2. Description of the Related Art As a method for producing a polycarbonate resin, an interfacial polymerization method or a solution polymerization method using a halogenated organic solvent such as methylene chloride, or a production method by transesterification is well known. Among them, when a polycarbonate resin is produced by an interfacial polymerization method, a mixture of an organic solvent solution containing the polycarbonate resin (hereinafter, abbreviated as an oil phase or O) and an aqueous solution (hereinafter, abbreviated as an aqueous phase or W) is obtained after the polymerization reaction. . Oil phase containing polycarbonate resin,
Since the emulsion is usually in an emulsion state, it is necessary to remove water-soluble impurities from the emulsion to purify the organic solvent solution of polycarbonate.

[0003] Further, since a small amount of impurities remain in the organic solvent solution of the polycarbonate resin after the reaction, an alkaline aqueous solution, an acidic aqueous solution,
The method of stirring and washing by adding pure water or the like is generally performed.In general, for the purpose of improving the washing efficiency, the mixture of the polycarbonate resin solution and the washing solution is vigorously stirred, emulsified again, and then dissolved in water again. Purification of the organic solvent solution of the polycarbonate is performed by removing the acidic impurities.

Conventionally, a liquid-liquid centrifuge or a stationary separation tank has been used to remove an aqueous solution containing impurities from the resin emulsion thus obtained. However, when an aqueous solution containing impurities is removed by a centrifuge, not only is the centrifuge used very expensive, but also a large expense is required for maintenance and operating power of the centrifuge. In addition, there is a drawback that the driving part and the rotating part are broken, and abnormal stoppage is caused due to abrasion and accumulation of resin due to volatilization of methylene chloride, and preparation of a spare machine is required.

On the other hand, in the case of removal by standing, even if a separation plate or a baffle plate is inserted into the separation tank, there is a problem that the separation tank becomes large and the hold-up becomes large in order to secure the settling time. Was. Also, when the phase is inverted to reduce the size of the separation tank, there is a problem that a new wastewater treatment is required depending on the added chemicals and water.

As a method for solving such a problem, Japanese Patent Publication No. 46-41622 discloses a method in which a polycarbonate resin liquid is passed through a filter layer having a contact angle with water of 40 ° or less. But with this method,
Since fine water droplets are relatively difficult to remove, it is necessary to repeatedly pass through the filter layer.After separation, contamination from the filter medium layer is remarkable, and it takes some time to separate after passing through the filter medium. A large stationary separation tank is required.

[0007] Japanese Patent Publication No. 59-22733 discloses a method in which a polycarbonate resin liquid is passed through a first hydrophobic or hydrophilic filtration layer, and then droplets of an aqueous layer are removed by a second hydrophobic filtration layer. It has been disclosed. This method uses a fine filter medium of 0.1 to 20 μm for the first filtration layer, and has a large filtration pressure loss because the thickness is preferably 0.5 mm or more, and the second filtration layer includes polytetrafluoroethylene and the like. There is a drawback that the pressure loss is further increased by the separated water because a hydrophobic filter medium is used. When filter materials of different materials are used, it is difficult to assemble them into a shape that is easy to handle, for example, a cartridge element or the like, due to problems such as the sealing properties of the joints, and it is difficult to use them repeatedly and repeatedly.

In Japanese Patent Application Laid-Open No. 55-104316, a polycarbonate resin solution is emulsified by using a hydrophilic cleaning solution having a pH in the range of 2 to 14, and is emulsified at a space velocity of 0.01 to 2 cm / sec. Thickness, 0.2-0.7
Disclosed is a method of separating two phases by passing through a fiber layer having an apparent density of g / ml. However, this method has the drawbacks that a large thickness of the filter medium layer causes a large pressure loss due to the packing material, and that not only does the filter medium flow out, but also a standing tank is required.

Further, in Japanese Patent Application Laid-Open No. 9-104747, after washing a crude polycarbonate solution with washing water under stirring, the crude polycarbonate solution containing the washing water is separated from the aqueous phase and the polycarbonate by standing separation or centrifugation. The organic phase containing polycarbonate is separated into an organic phase containing a polycarbonate and a filtration filter having a pore size of 20 to 180 μm.
A method of filtering at a filtration flow rate of 60 to 1000 mm / min is disclosed. However, in this method, an aqueous solution containing impurities cannot be sufficiently removed only by filtration using a filter medium, so that it is necessary to perform a combination of stationary separation and centrifugal separation. The merit of separation was small.

[0010] On the other hand, when a metal filter medium is used for such a filter, the price is high. Therefore, when the pressure loss increases and the separation / purification ability decreases, a regeneration treatment is generally performed. In the regeneration treatment, in order to decompose the adhering resin component and unreacted raw materials, the filter medium is heated in a 5-30% by weight aqueous solution of caustic soda. Passivated with sum or nitric acid, rinse the acid again with pure water, inspect and dry.

When these new or regenerated metal filter media are used, they are used as they are or after being degreased. In this case, although there is no problem with pressure loss even when the emulsion solution is passed, the water content is higher than in centrifugation, and the entrainment amount of the aqueous solution containing impurities is large. For this reason, the washing effect is low, and when used alone, the quality of the product including the hue is adversely affected. Therefore, as disclosed in JP-B-46-41622, the liquid is repeatedly passed, and
As disclosed in Japanese Unexamined Patent Publication No. 22733/1990, a hydrophobic filter medium is separately passed through to remove an aqueous solution.
As disclosed in Japanese Patent No. 04747, it was necessary to separately remove water containing impurities by combining other methods such as centrifugation, centrifugal extraction, and stationary separation.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional disadvantages and is suitable for regeneration when separating and purifying a polycarbonate resin emulsion into an organic solvent solution containing a polycarbonate resin and an aqueous solution containing impurities. And a method for activating a metal filter medium and a method for efficiently purifying a polycarbonate resin solution using the same.

[0013]

Means for Solving the Problems The present inventors comprise an organic solvent solution of a polycarbonate resin and an aqueous solution,
When purifying an emulsion having a median droplet surface area of 0.02 to ⁵ m ² / g, a metal filter medium suitable for liquid-liquid separation is treated with an acid before use, and the emulsion is washed without washing the acid. The present inventors have found that water-soluble impurities can be efficiently removed with a low pressure and a low pressure loss by passing the solution, and the present invention has been completed.

Specifically, when purifying an emulsion composed of an organic solvent solution of a polycarbonate resin and an aqueous solution and having a median value of the droplet surface area of 0.02 to ⁵ m ² / g, a metal filter medium suitable for regeneration is used. This is a method in which the resin is treated with an acid before use, and the acid is passed through the emulsion without washing, thereby effectively separating and purifying the polycarbonate resin solution.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The polycarbonate resin production method referred to in the present invention is a production method similar to a conventional production method of a polycarbonate resin using an organic solvent, that is, a production method by a solution method such as an interfacial polymerization method and a pyridine method. In these methods, a bisphenol compound is used as a main component, and is produced by reacting with a phosgene using a small amount of a molecular weight regulator and, if desired, a branching agent. An aromatic homo- or copolycarbonate resin using a normal bisphenol compound, a further branched one, a long chain alkyl group-introduced one, or the like, has a viscosity average molecular weight of 1,000.
Applicable to １００100,000. Moreover,
Manufacture of a polycarbonate resin having a carbon-carbon double bond or other graftable point as a terminal stopper or a comonomer, and grafting of styrene or the like to this, or phenolic hydroxyl group on polystyrene or the like, and start of graft polymerization of other polycarbonate resin It can be used for a solvent-soluble polycarbonate resin such as a copolymer of a compound having a point and a graft polymer of a polycarbonate resin. As a generally used aromatic polycarbonate resin, in particular, a polycarbonate containing 2,2-bis (4-hydroxyphenyl) propane [bisphenol A] as a main raw material is exemplified.
(4-hydroxyphenyl) cyclohexane [bisphenol Z] and 2,2-bis (4-hydroxy-3,5-
The present invention can also be applied to polycarbonate copolymers obtained by using dibromophenyl) propane [tetrabromobisphenol A] or the like, or branched products thereof or those modified with a terminal long-chain alkyl.

As the bisphenol compound used in the present invention, specifically, bis (4-hydroxyphenyl)
Methane, bis (3-methyl-4-hydroxyphenyl)
Methane, bis (3-chloro-4-hydroxyphenyl)
Methane, bis (3,5-dibromo-4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (2-t-butyl-4-hydroxy-3-methylphenyl) ) Ethane, 1,1-bis (2-t-butyl-4-hydroxy-5-methylphenyl) ethane, 1-phenyl-1,1-bis (3-fluoro-4-hydroxy-3-methylphenyl) ethane ,
2,2-bis (4-hydroxyphenyl) propane (bisphenol A; BPA), 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane (TB
A), 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (2-methyl-4-hydroxyphenyl) propane, 2,2-bis (4-hydroxy-3,5
-Dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5-difluorophenyl) propane,
2,2-bis (4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis (4-hydroxy-3-
Bromophenyl) propane, 2,2-bis (4-hydroxy-3-chlorophenyl) propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane,
2,2-bis (4-hydroxy-3-fluorophenyl) propane, 2,2-bis (4-hydroxy-1-methylphenyl) propane, 2,2-bis (3-bromo-
4-hydroxy-5-chlorophenyl) propane, 2,
2-bis (3-phenyl-4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 1,1-bis (2-t-butyl-4-hydroxy-
5-methylphenyl) butane, 1,1-bis (2-t-
Butyl-4-hydroxy-5-methylphenyl) isobutane, 1,1-bis (2-t-amyl-4-hydroxy-5-methylphenyl) butane, 1,1-bis (3,5
-Dichloro-4-hydroxyphenyl) butane, 1,1
-Bis (3,5-dibromo-4-hydroxyphenyl)
Butane, 4,4-bis (4-hydroxyphenyl) heptane, 1,1-bis (2-t-butyl-4-hydroxy-5-methylphenyl) heptane, 2,2-bis (4-
Bis (hydroxyaryl) alkanes such as hydroxyphenyl) octane; 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane (bisphenol Z; B
PZ), 1,1-bis (3-methyl-4-hydroxyphenyl) cyclohexane, 1,1-bis (3-cyclohexyl-4-hydroxyphenyl) cyclohexane,
Bis (4-hydroxyphenyl) cycloalkanes such as 1,1-bis (3-phenyl-4-hydroxyphenyl) cyclohexane and 1,1-bis (4-hydroxyphenyl) -3,5,5-trimethylcyclohexane;
4,4'-dihydroxybiphenyl, 4,4'-dihydroxy-2,2'-dimethylbiphenyl, 4,4'-dihydroxy-3,3'-dimethylbiphenyl, 4,4 '
Dihydroxybiphenyls such as -dihydroxy-3,3'-dicyclohexylbiphenyl; bis (4-hydroxyphenyl) ether, bis (4-hydroxy-3-
Bis (hydroxyaryl) ethers such as methylphenyl) ether; bis (4-hydroxyphenyl) sulfone, bis (3-methyl-4-hydroxyphenyl)
Bis (hydroxyaryl) sulfones such as sulfone; bis (hydroxyphenyl) sulfoxide, bis (3-methyl-4-hydroxyphenyl) sulfoxide, bis (hydroxyphenyl) sulfoxide and the like such as bis (3-phenyl-4-hydroxyphenyl) sulfoxide Aryl) sulfoxides; bis (hydroxyaryl) sulfides such as bis (4-hydroxyphenyl) sulfide and bis (3-methyl-4-hydroxyphenyl) sulfide; bis (4-hydroxyphenyl) ketone, and others
Examples thereof include phenol-modified siloxanes at both ends and phenol-modified silanes at both ends. These may be used in combination of two or more. Among them, bisphenol A,
Those selected from 1,1-bis (4-hydroxyphenyl) cyclohexane and 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane are desirable.

Examples of the terminal terminator or molecular weight regulator include compounds having a monovalent phenolic hydroxyl group.
Other than compounds having a monohydric phenolic hydroxyl group such as ordinary phenol, Pt-butylphenol, tribromophenol, long-chain alkylphenol, hydroxybenzoic acid alkyl ester, alkyl ether phenol, aliphatic carboxylic acid chloride, aliphatic carboxylic acid, aromatic Carboxylic acids such as aromatic carboxylic acids and aromatic acid chlorides and carboxylic acid halides. Further, a phenol having a reactive double bond may be used as a terminal terminator. In this case, acrylic acid, vinyl acetic acid,
-Pentenoic acid, 3-pentenoic acid, 5-hexenoic acid, 9-
Unsaturated carboxylic acids such as undecenoic acid; acid chlorides or chloroformates such as acrylic acid chloride, sorbic acid chloride, allyl alcohol chloroformate, isopropenylphenol chloroformate or hydroxystyrene chloroformate; isopropenylphenol, hydroxy Examples include phenols having an unsaturated group, such as styrene, hydroxyphenylmaleimide, allyl hydroxybenzoate or methylallyl hydroxybenzoate, phenol-modified siloxanes at one end, and silanes modified at one-end phenol.

These terminal terminators can be used in combination, and are usually used in the range of 1 to 25 mol%, preferably 1.5 to 10 mol%, per 1 mol of the above-mentioned bisphenol compound.

Organic solvents used in the reaction include chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, toluene, chlorobenzene, 1,1,1-trichloroethane, carbon tetrachloride; and aromatics such as benzene. Hydrocarbons; ether compounds such as diethyl ether can be mentioned, and these organic solvents can be used as a mixture of two or more kinds.

Further, a branching agent is used in an amount of 0.01 to 5 mol%, particularly 0.1 to 3 mol%, based on the above bisphenol compound.
A branched polycarbonate may be used in combination in the range of 0 mol%, and as a branching agent, phloroglucin,
2,6-dimethyl-2,4,6-tri (4-hydroxyphenyl) heptene-3,3,4,6-dimethyl-2,
4,6-tri (4-hydroxyphenyl) heptene-
2,1,3,5-tri (2-hydroxyphenyl) benzol, 1,1,1-tri (4-hydroxyphenyl)
Ethane, 2,6-bis (2-hydroxy-5-methylbenzyl) -4-methylphenol, α, α ′, α ″ -tri (4-hydroxyphenyl) -1,3,5-triisopropylbenzene, , 3-bis (4-hydroxyphenyl) oxindole (= isatin bisphenol), 5-chlorisatin bisphenol, 5,7-dichlorisatin bisphenol, 5-bromoisatin bisphenol and the like.

The polycarbonate resin to be produced has a viscosity average molecular weight of 1,000 to 100,
Although it is selected from the range of 000, it is preferably in the range of 5,000 to 50,000 in consideration of required physical properties such as impact resistance and abrasion resistance of the molded product and moldability.

Usually, in the interfacial polymerization reaction, the aromatic bisphenol compound is dissolved in a caustic aqueous solution, a phosgenation reaction is carried out in the presence of an organic solvent, and a polymerization catalyst is added if necessary and the polymerization reaction is carried out. . The concentration of the polycarbonate resin at the time of the polymerization reaction is preferably 5 to 30% by weight as an organic solvent solution. If the concentration of the polycarbonate resin is too high, the viscosity increases, which is not preferable.

When the polymerization reaction is completed, a mixture comprising an organic solvent solution of the polycarbonate (oil phase) and an aqueous solution (aqueous phase) containing impurities such as chlorides, carbonates and caustic by-products is obtained. Although this mixture may separate into an oil phase and an aqueous phase, the oil phase still contains some water, and the mixture after polymerization is in the form of an emulsion. The required oil phase is often W / O (water-in-oil dispersion type).

As a method for obtaining a high-purity polycarbonate resin solution by removing impurities from the organic solvent solution of the polycarbonate resin, washing water such as an alkaline aqueous solution, an acidic aqueous solution, and pure water is added to the organic solvent solution of the polycarbonate resin. Stirring extraction is performed. Such washing may be performed alone or in combination of two or more kinds of washing methods, but the present invention is applicable to liquid-liquid separation after any washing.

As a method for mixing the organic solvent solution of the polycarbonate resin and the washing water, any commercially available equipment for the purpose of liquid / liquid mixing can be used, but in order to obtain a desired stirring efficiency, In addition to a rotary stirrer, a reciprocating stirrer, an in-line mixer, a static mixer, an orifice mixer, a full zone (Shinko Pantic Co., Ltd.), a max blend (Sumitomo Heavy Industries, Ltd.), a homomixer (Special Kika Kogyo) Co., Ltd.), a through mixer (Sumitomo Heavy Industries, Ltd.), a static mixer, and the like.

The relationship between the oil phase and the aqueous phase constituting the emulsion may be O / W (oil-in-water type) or W / O (water-in-oil type). It is applied to W / O (water-in-oil) emulsions to raise and reduce wastewater. In addition, the surface area of the droplets in the oil phase constituting the emulsion varies depending on the concentration of the polycarbonate resin solution, the pH of the aqueous solution, the type of washing water, the volume ratio of the oil phase to the aqueous phase, etc. Median value of the droplet surface area is 0.02 to ⁵ m ² /
g are preferred. If the median value of the surface area of the droplets is less than 0.02 m ² / g, the cleaning effect is undesirably reduced. In addition, the median value of the surface area of the droplet is 5 m ² /
If it exceeds g, the volatilization of the solvent increases, which is not preferable.

In the present invention, since the organic solvent solution of the polycarbonate mixed with the washing water has the above-described surface area of the droplet, even if the stirring is stopped, the sedimentation gravity, the surface tension, and the molecular motion are antagonized, and the oil phase and the oil phase are separated. It usually exhibits an emulsion state without being separated into an aqueous phase.

Generally, the metal filter medium used in the present invention is:
To remove the oil adhering to the filter medium, it is degreased with an organic solvent such as methylene chloride before use, and when the filter medium is expensive, the pressure loss increases or the separation / purification capacity decreases, and the regeneration treatment is performed. The regeneration treatment generally decomposes the filter material by 5 to 3 in order to decompose the adhering resin and unreacted raw materials.
After heating in a 0% by weight aqueous solution of caustic soda to 50 ° C. or higher, rinse the decomposed product with pure water, neutralize with mineral acid or passivate with nitric acid at the same time, and rinse the acid again with pure water. And then dried and regenerated.

In the present invention, a new filter medium or a regenerated filter medium is preliminarily immersed in an acid before use. The method of immersion treatment may be such that the filter medium is immersed in an aqueous acid solution, and may be circulated and immersed or set in a housing to be used, and then passed through the aqueous acid solution. Need to be considered. Metal filter media is often passivated by nitric acid in the regeneration process, but if the filter media after a series of regeneration processes is not subjected to the acid treatment before use of the present invention, pressure loss and filtration accuracy can be recovered. However, the separation performance cannot be recovered.

The acid used for the immersion treatment in the present invention is p
H4 or less may be used, but mineral acids, phosphoric acid, nitric acid, sulfuric acid, and hydrochloric acid which do not cause deterioration in quality due to contamination with the product are preferable. In particular, when treating austenitic stainless steel, phosphoric acid which does not affect the material and polycarbonate product is optimal. If the timing of the acid treatment is too early, the concentration of the acid due to the evaporation of water and the acid corrosion of the filter medium during the immersion proceed undesirably, and it is generally preferable to use it one week before use.

In the neutralization of the polycarbonate resin solution, neutralization with a mineral acid such as phosphoric acid is carried out. Although the treatment can be replaced with an acid treatment, a treatment with an acid aqueous solution in advance can prevent the quality deterioration until the separation performance is improved.

The material of the filter medium used in the present invention has a surface energy of 2 which has good contact with oil and water of the emulsion.
A high energy material of at least 00 cal / cm ³ is preferable,
Preferred are metallic materials. Among them, a metal material containing 11 to 30% by weight of Cr is preferable. Specifically, as a material of the metal filter medium, stainless steel containing 11 to 30% by weight of Cr, particularly, from the viewpoint of solvent resistance, corrosion resistance, and the like, for example, SUS304, SUS316, SUS316L,
Austenitic stainless steels represented by SUS317 and SUS347 are preferred. Ni, C containing Cr including Hastelloy, Incoloy, Stellite, etc.
An o-based alloy can also be used effectively.

The thickness of the metal filter medium suitable for regeneration is
When the thickness is less than 0.1 mm, the strength is insufficient and separation failure due to breakage tends to occur.
If the thickness is larger than m, it is difficult to sufficiently perform cleaning and activation at the time of regeneration, and separation failure easily occurs. As the filter material, a metal nonwoven fabric or a filler for felt or demister can be used in addition to wire meshes of various weaves, but a nonwoven fabric is advantageous in terms of filtration accuracy and thickness.

[0034]

Next, the present invention will be described in detail with reference to examples, but the scope of the present invention is not limited thereby.

(Method of Measuring Viscosity of Resin Emulsion) The viscosity was measured with an E-type rotary viscometer manufactured by Tokyo Keiki, model number: Digital Viscometer DV LB. (Measurement method of droplet surface area of emulsion) Ultracentrifugal automatic particle size distribution analyzer manufactured by HORIBA, Ltd., model number CAPA-700
The median of the surface area of the droplet was measured by using. (Measurement method of viscosity average molecular weight: Mv) The intrinsic viscosity was measured with a Ubbelohde-type capillary viscometer and converted by Schnell's equation. (Measurement method of moisture content) It was measured with a Karl Fischer moisture meter (Kyoto Electronics: Model No. MKA-210).

(Synthesis of polycarbonate resin solution) 9%
25 kg of water and bisphenol A as dihydric phenol, 120 kg
And 0.6 g of hydrosulfite were dispersed and dissolved.
To this, 200 liters of methylene chloride (MC) was added and, while stirring, 2.6 kg of pt-butylphenol.
Then, 60 kg of liquid phosgene was gradually added thereto over 30 minutes, followed by stirring. After phosgene was charged, 166 liters of MC was added, and while stirring vigorously, 80 g of triethylamine was added, followed by stirring for about 1 hour to carry out polymerization. This mixture was allowed to stand for 30 minutes to separate into an aqueous solution (aqueous phase) and a polycarbonate resin liquid layer (oil phase). While repeating this operation, a part of the obtained oil phase was continuously extracted and used in Examples. Approximately 10 ml was sampled from the MC layer to evaporate the solvent to obtain a solid polycarbonate. The viscosity average molecular weight was measured, and the Mv was 28,000.

(Use and Regeneration of Filter Material) To regenerate the filter material, the filter was immersed in a 10% by weight aqueous solution of caustic soda, heated to 85 ° C., and the adhering resin component was decomposed in an alkali for 3 hours. Then, the washing water is pH adjusted with pure water.
After rinsing to 7.5, passivated in 10% nitric acid for 1 hour at room temperature. Then, after washing with pure water for 1 hour while applying ultrasonic waves until the pH becomes 6.5 to 7, 12
The filter was dried with a hot air dryer at 0 ° C.

Example 1 (Alkaline washing of polycarbonate resin solution) A polycarbonate resin solution (oil phase) obtained by the above-mentioned polycarbonate synthesis was withdrawn at 250 kg / h, and pure water 5
The mixture was added at 0 L / h, and stirred and mixed using a homomixer (Special Kika Kogyo) to prepare a W / O (water-in-oil dispersion) emulsion solution. The viscosity of the emulsion was 220 cp, and the droplet surface area of the sampled emulsion was 0.3 m ² / g in median value.

Metal filter medium (filtration accuracy 50 μm: thickness 0.
35 mm: size 52 mmφ × 254 mm: SUS304: non-woven fabric) was immersed in 2 w / v% phosphoric acid for 24 hours, attached to a filter housing, and a part of the emulsion resin solution washed with alkali from a stirring tank at 250 kg / h. It was withdrawn at a flow rate and pumped out of the filter using a gear pump. The pressure loss of the filter at this time is 0.3kg
/ cm ² . The resin solution was sampled from the housing outlet, and the water content was measured. As a result, it was 0.7 w / v%.
When the integrated flow rate reached 720 tons with this filter, the pressure loss reached 1.5 kg / cm ^2, and the filter was regenerated and used again after being immersed in 2 w / v% phosphoric acid for 24 hours. Recovered to 0.3 kg / cm ² and a water content of 0.8 w / v%.

Example 2 (Acid washing of polycarbonate resin solution) After washing the polycarbonate of Example 1 with alkali, 250 L of the polycarbonate resin solution (oil phase) obtained by liquid-liquid centrifugation was used.
/ H, 3% phosphoric acid is added at 30 L / h, and the mixture is stirred and mixed using a homomixer (Special Kika Kogyo Co., Ltd.).
A (water-in-oil dispersion type) emulsion solution was prepared. The viscosity of the emulsion was 220 cp, and the droplet surface area of the sampled emulsion was 1 m ² / g.

Metal filter medium (filtration accuracy 50 μm: thickness 0.
35 mm: size 52 mmφ x 254 mm: SUS316L: non-woven fabric) is immersed in 14 w / v% nitric acid for 1 hour, attached to the filter housing, and a part of the emulsion resin solution is extracted from the stirring tank at a flow rate of 250 kg / h. , And pumped in from outside the filter with a gear pump. At this time, the pressure loss of the filter was 0.3 kg / cm ² . The resin solution was sampled from the housing outlet, and the water content was measured to be 0.6 w / v%. When the integrated flow rate of this filter reaches 750 tons, the pressure loss is 1.2 kg / c.
m ² , it was subjected to a regeneration treatment, and was similarly immersed in 5% w / v hydrochloric acid for 1 hour. When the pressure loss was 0.3 kg / cm ² ,
The water content recovered to 0.8 w / v%.

Example 3 (Washing of polycarbonate resin solution with water) After the acid washing of the polycarbonate resin of Example 2, 250 kg / h of the polycarbonate resin solution (oil phase) obtained by liquid-liquid centrifugation was used.
And added with pure water at 50 L / h, and stirred and mixed using a homomixer (Special Kika Kogyo) to prepare a W / O (water-in-oil dispersion) emulsion solution. The viscosity of the emulsion was 220 cp, and the droplet surface area of the sampled emulsion had a median value of 1.2 m ² / g.

Metal filter medium (filtration accuracy 30 μm: thickness 0.
32 mm: size 52 mmφ × 254 mm: SUS316: non-woven fabric) was immersed in 5 w / v% sulfuric acid for 3 hours, attached to a filter housing, and a part of the emulsion resin solution washed with water from a stirring tank at a flow rate of 250 kg / h. And pumped out from inside the filter using a gear pump. At this time, the pressure loss of the filter was 0.2 kg / cm ² . The resin solution was sampled from the housing outlet, and the water content was measured. As a result, it was 0.7 w / v%. When the integrated flow rate reached 720 tons with this filter, the pressure loss reached 1.5 kg / cm ^2.
% loss of hydrochloric acid for 3 hours.
It recovered to 3 kg / cm ² and a water content of 0.8 w / v%.

Comparative Example 1 A metal filter medium (filtration accuracy 50 μm: thickness 0.35 mm: size 52 mmφ × 254 mm: SUS304: non-woven fabric) was directly attached to a filter housing, and one of the emulsion resin solutions of Example 1 was placed in a stirring tank. The part was withdrawn at a flow rate of 250 kg / h and pumped out of the filter using a gear pump. The pressure loss of the filter at this time is
It was 0.4 kg / cm ² . The resin solution was sampled from the housing outlet, and the water content was measured. As a result, it was 4.3 w / v%. Since the water content did not decrease even after passing the solution for 1 hour, the passing of the solution was stopped once, the element was taken out, the resin was dissolved and washed with methylene chloride, and then subjected to immersion treatment in 5% w / v phosphoric acid for 24 hours. After infiltration, the emulsion resin solution was again attached to the filter housing, a part of the alkali resin-washed emulsion resin solution was withdrawn from the stirring tank at a flow rate of 250 kg / h, and pumped out of the filter using a gear pump. The pressure loss of the filter at this time was 0.4 kg / cm ^2.
w / v%. When the integrated flow rate of this filter reached 720 tons, the pressure loss reached 1.6 kg / cm ² ,
After regenerating, it was immersed in 5 w / v% phosphoric acid for 24 hours and used. As a result, the pressure loss was 0.3 kg / cm ² and the water content was 0.8 w / v%.
Met.

Comparative Example 2 The metal filter medium used in Example 1 (filtration accuracy 50 μm: thickness 0.35 mm: size 52 mmφ × 254 mm: SUS316)
(L: non-woven fabric) was regenerated, attached to the filter housing as it was, a part of the emulsion resin solution of Example 2 was withdrawn at a flow rate of 250 kg / h from the stirring tank, and was pumped in from outside the filter by a gear pump. Although the pressure loss of the filter at this time was 0.4 kg / cm ² , the result of sampling the resin solution from the housing outlet and measuring the water content was 5.3 w / v%. Pass it through as it is 3
After a lapse of time, the water content dropped to 0.9 w / v%, and the process was continued. When the integrated flow rate reached 750 tons with the filter, the pressure loss reached 1.5 kg / cm ^2. Was. The regenerated filter medium was used after being immersed in 10 w / v% nitric acid for 1 hour. The initial pressure loss was 0.3 kg / cm ² and the water content was 0.1%.
It was 8% w / v.

Comparative Example 3 A new metal filter medium (filtration accuracy 30 μm: thickness 0.32 m)
m: size 52mmφ × 254mm: SUS316: non-woven fabric)
Was degreased with methylene chloride, attached directly to the filter housing, a part of the emulsion resin solution of Example 3 was withdrawn from the stirring tank at a flow rate of 250 kg / h, and pumped out of the filter using a gear pump. At this time, the pressure loss of the filter was 0.4 kg / cm ² . However, when the resin solution was sampled from the housing outlet and the water content was measured, it was 5.2 w / v%. When the accumulated flow rate reaches 200 tons with the filter,
The water content was 4.3 w / v%. The element was taken out once the liquid flow was stopped, the element was taken out, the element was regenerated, reattached, and the liquid was passed. The pressure loss was 0.3 kg / cm ² , but the water content was 5.5 w / v%.

Comparative Example 4 2 w / v% of a metal filter medium (filtration accuracy 50 μm: thickness 10 mm: size 52 mmφ × 254 mm: SUS316: nonwoven fabric)
Of phosphoric acid for 24 hours, attached to a filter housing, a part of the emulsion resin solution of Example 1 was withdrawn from the stirring tank at a flow rate of 250 kg / h, and pumped out of the filter using a gear pump. . At this time, the pressure loss of the filter was 2.3 kg / cm ² . The resin solution was sampled from the housing outlet, and the water content was measured. As a result, it was 0.4 w / v%. When the liquid was passed through the filter as it was, when the integrated flow rate reached 30 tons, the pressure loss reached 3.2 kg / cm ^2. Therefore, it was subjected to a regeneration treatment and was similarly immersed in 2 w / v% phosphoric acid for 24 hours. Although used, the pressure loss recovered only up to 2.8 kg / cm ² .

Comparative Example 5 A new filter medium made of glass fiber (filtration accuracy: 30 μm, thickness: 0.1 μm)
32 mm: size 52 mmφ × 254 mm) is 2 w / v%
Of phosphoric acid for 24 hours, attached to a filter housing, a part of the emulsion resin solution of Example 1 was withdrawn from the stirring tank at a flow rate of 250 kg / h, and pumped out of the filter using a gear pump. . At this time, the pressure loss of the filter was 0.3 kg / cm ² . However, when the resin solution was sampled from the housing outlet and the water content was measured, it was 3.0 w / v%. The flow was continued as it was, and when the integrated flow rate reached 500 tons with the filter, the pressure loss became 2.2 kg / cm ^2. Therefore, the flow was once stopped, the element was taken out, a regeneration process was performed, and the liquid was attached again and passed. However, the water content of the resin solution at the housing outlet was 3.2 w / v%.

[0049]

According to the method of the present invention, by activating a metal filter medium suitable for regeneration with an acid, an aqueous solution containing impurities is effectively removed from a polycarbonate resin emulsion immediately after use without an induction period. It can be purified.

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[Procedure amendment]

[Submission date] September 24, 1999 (1999.9.2)
4)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 4

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0032

[Correction method] Change

[Correction contents]

As a material of the filter medium used in the present invention, a high energy material having a surface free energy of 200 cal / cm ² or more, which is good in contact with the oil and water of the emulsion, is preferable, and a metal material is preferable. Among them, Cr
A metal material containing 0% by weight is desirable. Specifically, the material of the metal filter medium is stainless steel containing 11 to 30% by weight of Cr. Among them, from the viewpoint of solvent resistance, corrosion resistance, and the like, for example, SUS304, SUS316, SUS31
Austenitic stainless steel represented by 6L, SUS317 and SUS347 is preferred. Ni, Co-based alloys containing Cr , such as Hastelloy, Incoloy, and Stellite, can also be used effectively.

Claims (7)

[Claims] 1. A method comprising a polycarbonate resin in an organic solvent solution and an aqueous solution, wherein the median value of the surface area of the droplets is 0.1.
A method for purifying a polycarbonate resin solution, wherein an emulsion of 02 to ⁵ m ² / g is passed through a filter medium previously treated with an acid before use without washing the acid. 2. The method for purifying a polycarbonate resin solution according to claim 1, wherein the pH of the acid for treating the filter medium before use is 4 or less. 3. The acid for treating the filter medium before use is phosphoric acid,
2. The method according to claim 1, wherein the composition contains any one selected from sulfuric acid, nitric acid, and hydrochloric acid.
A method for purifying a polycarbonate resin solution according to the above. 4. The material having a surface free energy of 20
The method for purifying a polycarbonate resin solution according to claim 1, wherein the metal material is 0 cal / cm ³ or more. 5. The method for purifying a polycarbonate resin solution according to claim 1, wherein the thickness of the filter medium is 0.1 to 5 mm. 6. A metal filter medium comprising 11 to 30% by weight of Cr
The method for purifying a polycarbonate resin solution according to claim 1, which is a material containing: 7. The metal filter medium is SUS304, SUS3
04L, SUS316, SUS316L, SUS31
7. The method for purifying a polycarbonate resin solution according to claim 1, which is SUS317L or SUS347.