JP3164668B2 - Method for producing granular polycarbonate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a granular polycarbonate. More specifically, a polycarbonate useful as an engineering resin or the like is efficiently granulated from an organic solvent solution thereof and has a high particle bulk density. The present invention relates to a method for producing a high-quality granular polycarbonate resin which is easy and has little residual solvent.

[0002] The method of the present invention is particularly useful in a post-treatment step following a polymerization step in a polycarbonate production process by various polymerization methods such as a phosgene method, in which a produced polymer, particularly a polymer after washing, is powdered to have an appropriate particle size. It can be suitably used as a step of collecting and obtaining.

[0003]

2. Description of the Related Art Polycarbonate is a tough thermoplastic resin having excellent mechanical strength, impact resistance, heat resistance, rigidity, transparency, etc., and is processed by various molding methods such as injection molding, extrusion molding, vacuum molding and the like. It is an engineering plastic that can be used in various fields as a resin material for various industrial materials.

There are a great variety of polycarbonates, and various synthetic methods are known, such as the phosgene method and the transesterification method. Among them, industrial production methods include a phosgene method (interfacial polycondensation method, pyridine reaction) in which various bisphenols such as bisphenol A and phosgene gas are reacted (polycondensation) in the presence of an alkali metal compound or an acid acceptor such as pyridine. Law) is the mainstream.

[0005] As with other polymers, such polycarbonates are once granulated into particulate products such as powders and pellets having an appropriate particle size from the viewpoint of handling properties such as molding, storage, and transportation. Is normal. Therefore, in the polycarbonate production process, it is an important issue to perform an appropriate granulation operation on the crude polymer and the washing polymer generated in the polymerization step, and to efficiently obtain a high-quality granular polycarbonate resin having good properties. I have.

Conventionally, various methods for granulating polycarbonate have been known as described below, but all of them have problems.

For example, there is a method in which a solvent is continuously evaporated from a polycarbonate solution, the obtained resin (desolvated polycarbonate) is continuously melt-extruded by an extruder, and the extrudate is cut and pelletized. is there. However, this method requires a special extruder specially designed, and in addition, the resin undergoes a heat history due to melting, thereby impairing the excellent properties of the polycarbonate resin. There is a problem that it is difficult to remove.

A high-temperature rapid granulation method for rapidly removing a solvent from a polycarbonate solution at a high temperature, a steam granulation method for passing a polycarbonate solution, water and steam together in a tube to separate a polymer, There are also a hot water granulation method and a spray drying granulation method to be introduced (Japanese Patent Application Laid-Open No. 63-35621, etc.). However, these granulation methods generally have problems such as low bulk density of the obtained polycarbonate particles. If the bulk density of the polymer particles is low, the extrusion of the polycarbonate particles into the extruder at the time of extrusion molding becomes insufficient, and it is easy to cause inconvenience such as scattering of the particles into the air. Tall ones are desirable. In general, granulated resins having a low bulk density often have non-uniform particle shapes and particle sizes.

In addition, the non-solvent or poor solvent for the polycarbonate such as alcohol or aliphatic hydrocarbon is added to the polycarbonate solution, or conversely, the polycarbonate solution is poured into the non-solvent or the poor solvent to convert the polymer. A precipitation method of depositing and collecting is also known. However, these methods have the advantage that the removal of low molecular weight components, unreacted raw materials and impurities is easy and the quality is easily improved, but on the other hand, it is difficult to avoid outflow of the polymer into the solvent liquid. This has the serious disadvantage that the yield is reduced. In addition, there is also a problem that the bulk density of the obtained polymer particles is reduced depending on the types of the poor solvent and the non-solvent used.

A powdering method utilizing crystallization of a polycarbonate having good crystallinity such as bisphenol A-based polycarbonate is also known. In this method, when a solution of such a polycarbonate (methylene chloride solution) is concentrated, a solid that is easily pulverized by crystallization is formed. However, in this method, since the polymer is crystallized directly from a solvent solution, impurities such as a solvent and ions remain with the polymer. Therefore, it is necessary to remove these by washing or the like. There is a problem that it is not easy to remove the solvent, ions and the like taken in between and that it takes time for drying. There is also a limitation that this method cannot be applied to polycarbonate having low crystallinity. Further, such a method of forming particles by pulverization has a disadvantage that the particle diameter and the particle shape are likely to be non-uniform.

[0011]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems observed in conventional methods for granulating polycarbonate, and to convert various polycarbonates from their solutions.
Efficiently granulate high-quality polycarbonate resin particles (granulated material) with high particle bulk density, good particle properties, and high purity with sufficient removal of impurities and residual solvents without giving heat history. Another object of the present invention is to provide a method for producing a granular polycarbonate by a novel granulation method, which has an advantage that it can be suitably applied to a polycarbonate having low crystallinity.

[0012]

Means for Solving the Problems In order to achieve the above object, the present inventors granulate a polycarbonate resin from an organic solvent solution by adding the solution to an aqueous medium mainly composed of water. As a result of a detailed study of the method at various points, a solution obtained by dissolving the polycarbonate in a low-boiling organic solvent having a boiling point sufficiently lower than the boiling point of water having a boiling point of 90 ° C. or less was used as a granulation raw material solution, A low-boiling organic solvent using a specific aqueous medium (aqueous mixed liquid) of a mixture of water and a water-soluble organic solvent as an aqueous medium to which is added, and using the polycarbonate solution (granulation raw material solution) as a solvent for the solution Is added to and dispersed in the aqueous mixture (a mixture of water and a water-soluble organic solvent) heated to a temperature higher than the boiling point of the solvent, and the low-boiling organic solvent is distilled off in the dispersed state (suspended state). Polica By specific granulation that particles of granulated resin Boneto, the found that the objects can be achieved, thereby completing the present invention based on this finding and the like.

That is, the present invention relates to a method of adding a solution of a polycarbonate dissolved in a low-boiling organic solvent having a boiling point of 90 ° C. or lower to a mixture of water and a water-soluble organic solvent, which is heated to a temperature higher than the boiling point of the organic solvent. The present invention provides a method for producing a granular polycarbonate, which comprises dispersing and distilling off the low-boiling organic solvent to obtain polycarbonate resin particles.

In the method for producing a granular polycarbonate according to the present invention, a solution of a polycarbonate dissolved (or dissolved) in a predetermined low-boiling organic solvent (organic solvent having a boiling point of 90 ° C. or lower) is prepared as described above. As it is added and dispersed in an aqueous medium to granulate polycarbonate,
It can be dissolved in such a low-boiling organic solvent to form a solution, and further, as long as it becomes a solid resinous state in the aqueous medium or in a dry state, it generally has any structure and composition for any polycarbonate. Is also applicable. That is, a wide variety of polycarbonates, such as aromatic polycarbonates produced by various known methods, can be selected as targets in the method of the present invention.
In addition, the present invention can be applied to not only polycarbonate having good crystallinity but also any polycarbonate such as a polycarbonate having poor crystallinity and a non-crystalline one.

[0015] Such polycarbonates include homopolymers composed of one kind of various repeating units, copolymers having various structures and compositions containing two or more kinds of different repeating units at various ratios. Those having a straight chain, those having a branched structure (for example, graft polymers and polymers having a crosslinked structure), those having a cyclic or cyclic structure, and those having a special structure introduced at the polymer terminal There are various structures such as
All of these can be applied as targets of the method of the present invention.

In the method of the present invention, each of these polycarbonates may be used alone or in combination of two or more polymers. It may be used as a composition of one or more kinds of polycarbonates and other components.

In the method of the present invention, polycarbonates having various structures and compositions can be selected as described above. Among them, usually, the following general formula [I] is generally used.

[0018]

Embedded image Wherein R ¹ and R ² in the formula [I] each independently represent an alkyl group having 1 to 6 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, or a substituted or unsubstituted 6 to 12 carbon atoms. A represents an aryl group or a halogen atom, and a and b each independently represent 0 to 4
X is a single bond, -O-, -S-, -SO
—, —SO ₂ —, —CR ³ R ⁴ — (where R ³ and R
⁴ is each independently a hydrogen atom, a trifluoromethyl group,
An alkyl group having 1 to 6 carbon atoms and a substituted or unsubstituted aryl group having 6 to 12 carbon atoms are shown. ), An unsubstituted or substituted 1,1-cycloalkylidene group having 5 to 11 carbon atoms, an α, ω-alkylene group having 2 to 10 carbon atoms or a polydimethylsiloxane group. Various polycarbonates comprising the repeating unit [I] represented by｝ are suitably used.

In the general formula [I], the numbers a and b of the substituents can each independently take an arbitrary value from 0 to 4. That is, as the repeating unit [I], an unsubstituted unit having no substituents R ¹ and R ² (a = b = 0), and a unit having only 1 to 4 of R ¹ and R ² ( a = 1 to 4 and b = 0), and only the latter is 1 to
There are four (a = 0 and b = 1 to 4) and both (a = 1 to 4 and b = 1 to 4),
Either may be used. When the total number of these substituents is 2 or more (a + b ≧ 2), the types of these substituents may be the same, all may be different, or only some may be different. Good. Further, the repeating unit [I] includes various units depending on the substitution positions of the substituents R ¹ and R ² , and any one may be used.

Specific examples of the substituents R ¹ and R ² include the following.

That is, for R ¹ and R ² , the alkyl group includes, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, isobutyl group Group, n-pentyl group, isopentyl group, sec-pentyl group, ter
t-pentyl group, neopentyl group, n-hexyl group, isohexyl group, sec-hexyl group, tert-hexyl group, neohexyl group, cyclopentylmethyl group, and the like.Examples of the cycloalkyl group include a cyclopentyl group. A cyclohexyl group, a methylcyclopentyl group, a cycloheptyl group, a methylcyclohexyl group, a dimethylcyclopentyl group, an ethylcyclopentyl group, and the like.Examples of the substituted or unsubstituted aryl group include a phenyl group, a methylphenyl group, Ethylphenyl group, propylphenyl group,
Butylphenyl group, dimethylphenyl group, trimethylphenyl group, cyclohexylphenyl group, 4-biphenyl group, 3-biphenyl group, 1-naphthyl group, 2-naphthyl group, methylnaphthyl group, dimethylnaphthyl group, ethylnaphthyl group, etc. And the halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.

R ³ and R ^{4 in} —CR ³ R ⁴ — are each independently a hydrogen atom, a trifluoromethyl group, an alkyl group having 1 to 6 carbon atoms, a substituted or unsubstituted group having 6 to 12 carbon atoms. Although an aryl group is shown, examples of the alkyl group include the various alkyl groups described above. Examples of the aryl group include various aryl groups described above, and further include, for example, a halogen atom, an alkoxy group, Examples thereof include those in which a substituent such as a cyano group is substituted. Note that R ³
And R ⁴ may be the same group or different from each other.

The substituted or unsubstituted 1, as X
As the 1-cycloalkylidene group, for example, 1,1-
Cyclopentylidene group, 1,1-cyclohexylidene group, 1,1-cycloheptylidene group and those in which substituents such as alkyl group, halogen atom, alkoxy group and cyano group are substituted. be able to.

X, α, ω- having 2 to 10 carbon atoms
Examples of the alkylene group include various polymethylene groups ranging from a dimethylene group to a decamethylene group.

The above-mentioned polydimethylsiloxane group as X
As-[O-Si (CH _Three)₂]_m-O- (here
And m represents an integer of 2 or more. )
You.

As described above, as the repeating unit [I], there are various types depending on the presence or absence of the substituents R ¹ and R ² , their type or combination, number (the number of substituents), substitution position, and the like. Yes, and there are various types depending on the type of X.

These various types of repeating units [I] can be formed from various types of monomers each having a corresponding structure. For example, a bisphenol (a dihydric phenol) having a corresponding structure is reacted with phosgene. Can be formed. Therefore, instead of directly showing specific examples of these various repeating units [I],
Specific examples of the corresponding bisphenols (dihydric phenols) will be given.

That is, specific examples of such bisphenols (dihydric phenols) include, for example, bis (4-hydroxyphenyl) methane, 1,1-bis (4
-Hydroxyphenyl) ethane, 1,2-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (3-methyl-
4-hydroxyphenyl) butane, 2,2-bis (4-
Hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) octane, 4,4-bis (4-hydroxyphenyl) heptane, 1,1-bis (4-hydroxyphenyl) -1,1-diphenylmethane, , 1-bis (4-hydroxyphenyl) -1-phenylethane,
1,1-bis (4-hydroxyphenyl) -1-phenylmethane, bis (4-hydroxyphenyl) ether,
Bis (4-hydroxyphenyl) sulfide, bis (4
-Hydroxyphenyl) sulfone, 1,1-bis (4-
Hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-
Bis (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3-phenyl-4-hydroxyphenyl) propane, 2- (3-methyl-4-hydroxyphenyl) -2- (4-hydroxyphenyl ) -1-phenylethane, bis (3-methyl-4-hydroxyphenyl) sulfide, bis (3-methyl-4-hydroxyphenyl) sulfone, bis (3-methyl-4-hydroxyphenyl) methane, 1,1- Bis (3-methyl-4-hydroxyphenyl) cyclohexane, 4,4'-dihydroxybiphenyl, 2,2-bis (2-methyl-4-hydroxyphenyl) propane, 1,1-bis (2-butyl-4- (Hydroxy-5-methylphenyl) butane,
1,1-bis (2-tert-butyl-4-hydroxy-3-methylphenyl) ethane, 1,1-bis (2-t
tert-butyl-4-hydroxy-5-methylphenyl) propane, 1,1-bis (2-tert-butyl-
4-hydroxy-5-methylphenyl) butane, 1,1
-Bis (2-tert-butyl-4-hydroxy-5-
Methylphenyl) isobutane, 1,1-bis (2-te
rt-butyl-4-hydroxy-5-methylphenyl)
Heptane, 1,1-bis (2-tert-butyl-4-
(Hydroxy-5-methylphenyl) -1-phenylmethane, 1,1-bis (2-tert-amyl-4-hydroxy-5-methylphenyl) butane, bis (3-chloro-4-hydroxyphenyl) methane, bis (3,5-dibromo-4-hydroxyphenyl) methane, 2,2-bis (3-chloro-4-hydroxyphenyl) propane,
2,2-bis (3-fluoro-4-hydroxyphenyl) propane, 2,2-bis (3-bromo-4-hydroxyphenyl) propane, 2,2-bis (3,5-difluoro-4-hydroxyphenyl) ) Propane, 2,2-
Bis (3,5-dichloro-4-hydroxyphenyl) propane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane, 2,2-bis (3-bromo-
4-hydroxy-5-chlorophenyl) propane, 2,
2-bis (3,5-dichloro-4-hydroxyphenyl) butane, 2,2-bis (3,5-dibromo-4-hydroxyphenyl) butane, 1-phenyl-1,1-bis (3-fluoro- 4-hydroxyphenyl) ethane,
Bis (3-fluoro-4-hydroxyphenyl) ether, 3,3'-difluoro-4,4'-dihydroxybiphenyl, 1,1-bis (3-cyclohexyl-4-hydroxyphenyl) cyclohexane, bis (4-hydroxy Phenyl) sulfoxide, 2,2-bis (4-hydroxyphenyl) hexafluoropropane, 1,1-bis (3-phenyl-4-hydroxyphenyl) cyclohexane, bis (3-phenyl-4-hydroxyphenyl) sulfone, , 4 '-(3,3,5-trimethylcyclohexylidene) diphenol, phenol polydimethylsiloxane at both ends, and the like.

Accordingly, examples of the polycarbonate comprising the repeating unit [I] include, for example, one or two of the above-mentioned various bisphenols (dihydric phenols).
Examples include various polycarbonates obtained by using the seed as a raw material monomer and homopolymerizing or copolymerizing by a phosgene method or the like. Among them, particularly, 2,2-bis (4
-Hydroxyphenyl) propane, 1,1-bis (4-
Hydroxyphenyl) -1,1-diphenylmethane,
1,1-bis (4-hydroxyphenyl) -1-phenylethane, bis (4-hydroxyphenyl) sulfone,
1,1-bis (4-hydroxyphenyl) cyclohexane, 2,2-bis (3-methyl-4-hydroxyphenyl) propane, 4,4′-dihydroxybiphenyl,
Various types obtained using 2,2-bis (3-phenyl-4-hydroxyphenyl) propane, 4,4 '-(3,3,5-trimethylcyclohexylidene) diphenol, phenol polydimethylsiloxane at both ends, etc. (Homopolymer or copolymer) is preferably applied.

Of course, a homopolymer of any one of the repeating units [I], a copolymer of two or more of the repeating units [I], and a homopolymer and a copolymer of these A polymer mixture containing two or more of
Furthermore, a resin composition containing at least one of these polycarbonates and other components such as other polymer components and additives can be appropriately selected as the object of the present invention. In addition, these polycarbonates also include those having a linear structure, a branched structure or a structure having a branched structure, a cyclic structure or a structure having a cyclic structure, and those having a special structure introduced at the polymer terminal. Those having various molecular structures can be used, and they can be used alone or as a mixture or composition at an arbitrary ratio. Further, these polycarbonates may contain a repeating unit other than the repeating unit [I] as long as the object of the present invention is not impaired.

The method for producing a polycarbonate comprising such a repeating unit [I] is not particularly limited. For example, an alkali metal compound, pyridine or the like using various bisphenols (dihydric phenols) as monomers described above as a monomer. Phosgene method (interfacial polycondensation method, pyridine method, etc.) in which phosgene gas is reacted in the presence of an acid acceptor (if necessary in an appropriate solvent), or a chloroformate method, a transesterification method (also a melt polymerization method) And those produced by various methods such as a known polymerization method. In the case of this phosgene method, the desired bisphenols and phosgene may be reacted at once to obtain a desired polycarbonate, or a portion of the bisphenols as a reaction raw material may be reacted with phosgene in advance to form a chloro group at the molecular end. A two-step method may be used in which an oligomer having a formate group is produced, and then the remaining reaction materials are added to complete the polycondensation to obtain a desired polycarbonate.

The above-mentioned polycarbonate, which is the object of the method of the present invention, has a reduced viscosity [η _{sp) in view of} its use as a molded article, the ease of molding and the ease of granulation in the method of the present invention. / C] (solution viscosity) is desirably in an appropriate range. Specifically, 20% of a solution having a polymer concentration of 0.5 g / dl using methylene chloride as a solvent is used.
The reduced viscosity [η _sp / c] measured at 0 ° C. is usually
Those in the range of 0.1 to 3.0 dl / g are preferred.
A resin having a reduced viscosity [η _sp / c] of less than 0.1 dl / g is not suitable for use as an engineering resin because the inherent mechanical strength of the resin is insufficient even if the granulation is successful. While the reduced viscosity [η _sp /
If c] is greater than 3.0 dl / g, the solution viscosity becomes too large, making it difficult to produce the polymer itself or to smoothly perform granulation in the method of the present invention, or to cause polymerization and granulation. Even if it goes well, it may be difficult to form the product later.

In the method of the present invention, a solution prepared by dissolving a polycarbonate as a raw material for granulation in a low-boiling organic solvent having a boiling point of 90 ° C. or lower is used as a raw material solution for granulation. Addition and dispersion in a mixture of water and a water-soluble organic solvent heated to a temperature higher than the boiling point (hereinafter, this may be referred to as an aqueous mixture) to distill off the low-boiling point organic solvent. Thereby, polycarbonate resin particles (granules) are obtained.

Here, the resin particles obtained by this granulation operation are in a state of being dispersed or precipitated in the aqueous mixed solution. Therefore, the resin particles are separated by filtration or the like, and then, if necessary, water, By washing with hot water or hot water to remove extra components adhering to the resin particles, and then drying as appropriate, desired high-quality polycarbonate resin particles (dry powder) can be obtained.

The low-boiling organic solvent used in the polycarbonate solution of the granulation raw material solution has at least sufficient solubility in the applied polycarbonate,
And an organic solvent that is immiscible with water and has a boiling point of 9
An organic solvent having a temperature of 0 ° C. or lower may be used.

There are a wide variety of such organic solvents, and typical examples thereof include, for example, 1,2
-Dichloroethane (bp 83 ° C), 1,1-dichloroethane (bp 57 ° C), methylene chloride (bp 90 ° C).
40 ° C.), halogenated hydrocarbons such as carbon tetrachloride (bp 76 ° C.), chloroform (bp 61 ° C.), and aromatic hydrocarbons such as benzene (bp 80 ° C.). be able to. Of these, methylene chloride is particularly preferably used. In addition, these organic solvents may be used as a single solvent alone or as a mixed solvent of two or more solvents. In addition, these low-boiling organic solvents include
Other solvent components and the like may be contained as long as the object of the present invention is not impaired.

As described above, in the method of the present invention, a low boiling organic solvent having a boiling point of 90 ° C. or less is used as the raw material solution for granulation because the polycarbonate solution is mixed with the aqueous mixture (water and water-soluble organic solvent). Mixed liquid) and dispersed.
When the low-boiling organic solvent is distilled off to proceed with granulation, as the boiling point of the organic solvent used in the polycarbonate solution is sufficiently lower than the boiling point of water, the polycarbonate solution particles dispersed in the aqueous mixed solution are used. It is based on the principle that the organic solvent can be efficiently and selectively distilled off to promote the granulation effectively, and thus the organic solvent at least 10 ° C. lower than the boiling point of water is used as a solvent for the polycarbonate solution. This is because the effect can be sufficiently achieved by using. In other words, when a granulated raw material polycarbonate solution dissolved in an organic solvent having a boiling point higher than 90 ° C. is used, when the organic solvent is distilled off, the water that constitutes the dispersion medium is also significantly distilled off. In addition, the organic solvent cannot be selectively distilled off, and it is difficult to perform the desired granulation properly.

In the method of the present invention, first, a solution in which a predetermined polycarbonate is dissolved in such an organic solvent (the above-mentioned low-boiling organic solvent) is prepared. Here, when undesired impurities are contained in the polycarbonate or the composition thereof dissolved in the low boiling point organic solvent, it is preferable to remove these impurities by washing or the like in advance. For example, a crude polymer produced by polymerization or a polymerization reaction solution may contain alkali metal components, unreacted raw materials, and the like. In such a case, these may be appropriately removed by a known washing method or the like. If this is the case, the washing operation after granulation can be further simplified. When an insoluble component is found in the polycarbonate solution dissolved in the low-boiling organic solvent, the insoluble component may be appropriately removed by filtration or the like before granulation, if necessary.

The polycarbonate concentration in the polycarbonate solution used as the granulation raw material solution is generally about 0.1 to 50% by weight, preferably 1 to 30% by weight, taking into account the solubility of the polycarbonate in the low-boiling organic solvent used. % Is preferably selected.
When the concentration of polycarbonate in this raw material solution is 0.1
When the amount is less than 50% by weight, the productivity is low. On the other hand, when the amount is more than 50% by weight, the solution viscosity becomes too high, and when added to an aqueous mixture, a suitable suspension state suitable for granulation (dispersion of polycarbonate solution particles). Gender etc.) may not be achieved. The particle size of the granulated resin particles can be controlled by appropriately changing the concentration in the above range. In general, the lower the polycarbonate concentration, the smaller the particle size of the resin particles.

The polycarbonate solution to be used as the raw material solution for granulation may be prepared by dissolving a polycarbonate resin in the solvent, or if such a solution is available in advance, it may be used as it is or as needed. The concentration may be adjusted accordingly and used. For example, in the case of a polycarbonate-containing solution (solution of a low-boiling organic solvent) obtained from a polymerization step such as a polymerization reaction solution obtained by polymerizing a predetermined low-boiling solvent such as methylene chloride as a solvent, the concentration is as described above. When appropriate, the granulation raw material solution may be used as it is, or after adjusting the concentration to the above range by dilution with the solvent or the like. Of course, the resin once recovered as a resin of various shapes from the solution after the polymerization reaction by various methods (for example, a precipitation method using a poor solvent or a solvent evaporation method) is used as a raw material polycarbonate solution as described above. Is also good. At this time, it is more preferable that the polycarbonate resin or a solution thereof is washed according to a conventional method before granulation as described above to remove unnecessary impurities such as alkali metal ions in advance.

The water used for preparing the aqueous mixture (mixture of water and a water-soluble organic solvent) is not particularly limited.
Pure water, distilled water, ion exchange water, tap water, industrial water, and the like can be used.

On the other hand, as the water-soluble organic solvent, various ones can be used. Usually, those which are uniformly dissolved in water at the granulation temperature are preferable.
Those in the range of 0 to 200 ° C are preferred. Representative examples of such water-soluble organic solvents include, for example, alcohols such as methanol, ethanol, 1-propanol and 2-propanol, diols such as ethylene glycol and polyhydric alcohols, ketones such as acetone and methyl ethyl ketone. And the like. Among these,
Particularly, 1-propanol and 2-propanol are preferable. These various water-soluble organic solvents may be used alone or in combination of two or more.

The ratio of water and water-soluble organic solvent in the aqueous mixture at which the above-mentioned granulated raw material polycarbonate solution is added is as follows:
Usually, 0.01 volume part or more, preferably 0.1 to 50
It is preferable that the volume ratio is mixed. Here, if water containing no water-soluble organic solvent is used in place of the aqueous mixture, the bulk density of the granulated resin particles remains low, and the shape of the resin particles may become non-uniform. You cannot achieve your goals. In addition, when the aqueous mixed solution has a mixing ratio of the water-soluble organic solvent of less than 0.01 part by volume with respect to 1 part by volume of water, the bulk density of the resin particles obtained by granulation is sufficiently large. On the other hand, even if the ratio exceeds 50 parts by volume with respect to 1 part by volume of water, the effect of improving the bulk density is generally not further obtained.

As described above, when the polycarbonate solution is added to a mixture of water and a water-soluble organic solvent to perform granulation, the polycarbonate solution is added to water to which no water-soluble organic solvent is added to perform granulation. Thus, the bulk density of the resin particles as the granulation product can be significantly increased. The exact mechanism by which the bulk density of the resulting polycarbonate resin particles is improved when the polycarbonate solution is added to a mixture of water and a water-soluble organic solvent than when the solution is added to water is not necessarily clear. When it is added to an aqueous mixed solution that is a mixed solution of water and a water-soluble organic solvent as in the method of the above, the organic solvent (low-boiling organic solvent) in the polycarbonate solution particles dispersed in the aqueous mixed solution is evaporated. In this case, it is considered that the evaporation rate is well controlled by the appropriate affinity between the organic solvent and the water-soluble organic solvent, and the pore diameter generated in the granulated resin particles becomes sufficiently small.
On the other hand, when the polycarbonate solution is simply added to water, the evaporation of the organic solvent from the polycarbonate solution particles becomes severe, the shape of the granulated resin particles collapses, the pore diameter increases, and the bulk density eventually increases. It becomes small resin particles.

In the method of the present invention, the above-mentioned polycarbonate solution is added to and dispersed in an aqueous mixture which is a mixture of water and a water-soluble organic solvent. Granulation is performed by adding and dispersing a polycarbonate solution under a condition where the organic solvent is heated to a temperature higher than the boiling point of the boiling organic solvent, and distilling off the low boiling organic solvent in the dispersed state.

That is, the granulation is carried out at a temperature higher than the boiling point of the low-boiling organic solvent used for the polycarbonate solution. Here, if the addition and dispersion of the polycarbonate solution is performed on the aqueous mixture at a temperature equal to or lower than the boiling point of the low-boiling organic solvent and the granulation is advanced at such a low temperature, the aqueous solution of the added polycarbonate solution particles The dispersibility (suspended state) in the mixed liquid is deteriorated, and the resin becomes large lumps during granulation, and in some cases, this adheres to the stirring blades and the like, causing problems such as difficulty in dispersion and stirring. Alternatively, problems such as a difficulty in efficiently performing granulation due to a remarkable decrease in the distillation rate of the low-boiling organic solvent, and the like, make it impossible to achieve the object of the present invention.
On the other hand, if the temperature of the aqueous mixture in which the polycarbonate solution is added and dispersed is too high, the organic solvent (low boiling point organic solvent) in the added polycarbonate solution evaporates so strongly that the bulk density cannot be sufficiently improved, or Evaporation of water and the water-soluble organic solvent from the aqueous mixture becomes remarkable, and it may be difficult to perform granulation suitably. Therefore, the preferred granulation temperature varies depending on other conditions such as the type of the water-soluble organic solvent used and the composition of the granulation system, but is usually 5 ° C. or more higher than the boiling point of the low-boiling organic solvent, and water Alternatively, the granulation is preferably performed in a temperature range not higher than the boiling point of the water-soluble organic solvent.

In the method of the present invention, at the time of performing the granulation at the above-mentioned granulation temperature, at least the added polycarbonate solution is sufficiently dispersed in the aqueous mixture in the form of particles, and the suspension is sufficiently dispersed in such a manner. The low-boiling organic solvent, which is the solvent of the polycarbonate solution, is distilled off in a suspended liquid state, and granulated into polycarbonate resin particles having desired properties.

When the polycarbonate solution is added and dispersed as described above and granulated, the polycarbonate solution may be added to and mixed with the aqueous mixed solution at once, may be added and mixed stepwise, or may be continuously added. It may be gradually added and mixed, may be added and mixed in any manner, but usually appropriately considering the dispersibility and uniformity of the dispersed particles in the aqueous mixture after the addition of the polycarbonate solution. A method of dropping over an appropriate time is preferably adopted. In this dropping method, it is not possible to uniformly determine how long it is preferable to drop the solution because it depends on various conditions such as the scale of the granulation system. Can be determined easily.

The ratio of the raw material polycarbonate solution (total amount) to be mixed in the granulation and the aqueous mixture (total amount) which is a mixture of water and a water-soluble organic solvent is usually as follows. About 0.01-1000 weight times,
Preferably, it is suitably selected to be 0.05 to 100 times by weight, more preferably 0.1 to 50 times by weight.

As a means for dispersing the polycarbonate solution in the aqueous mixed solution, any means (method and apparatus) may be used as long as the suspension state can be sufficiently maintained. Specifically, for example, a normal stirrer, a homomixer,
Homogenizer, disperser, static mixer,
A system using a dispersing machine such as a line mixer or an ultrasonic oscillator is preferably employed.

The type of the granulator is not particularly limited as long as it can sufficiently maintain the dispersed and suspended state, and various types of ordinary reactors or structures similar thereto can be applied. . That is, for example, a tank-type granulator such as a tank-type granulator with a baffle plate or a continuous tube-type granulator can be appropriately used.

Various methods such as a batch method, a continuous method, and a semi-continuous method can be adopted as the granulation method.

Usually, this granulation can be suitably carried out at around normal pressure, but as long as the object of the present invention is not hindered.
It may be performed under pressure or reduced pressure.

In the method of the present invention, it is important that the low-boiling organic solvent used in the polycarbonate solution is distilled off at least under the condition that the granulation system is in a suspended state during the granulation. The distillation of the solvent may be started from the start of the granulation operation (immediately after the addition of the polycarbonate) or may be started halfway, but usually, the solvent is gradually distilled off as the granulation proceeds. preferable. In any case, it is desirable that the predetermined solvent (the low-boiling organic solvent used for the polycarbonate solution) in the granulation system is finally sufficiently distilled off.
If necessary, after the granulation is completed, an operation of further increasing the temperature of the system or reducing the pressure to remove the remaining small amount of the solvent more sufficiently may be performed.

The distilled low-boiling organic solvent can be recovered using a cooler or the like.
This may be used repeatedly.

As described above, the raw material polycarbonate is made of resin particles having a high bulk density and a uniform particle diameter from which excess impurities have been sufficiently removed (usually having an average particle diameter of about several hundred μm to
It can be efficiently granulated into (several mm resin particles).
In this method, since the organic solvent that dissolves the polycarbonate during the granulation is removed by distillation, the polycarbonate having a desired high molecular weight does not flow out into the solvent,
Thus, there is virtually no loss of polycarbonate and the yield may be 100%.

In addition, at the stage after the granulation, excess impurities remaining in the raw material polycarbonate have already been removed due to the effective cleaning effect of the mixed solution of water and the water-soluble organic solvent during the preliminary cleaning and the granulation. (Alkali metal ions, unreacted polymerization raw materials, low molecular components such as oligomeric polycarbonate, solvent components, and the like) are also obtained, and resin particles from which they are sufficiently removed are obtained.

However, at the stage after the granulation, the resin particles are in an aqueous medium containing a water-soluble organic solvent.

In order to obtain desired high-quality polycarbonate resin particles (dry powder), the resin particles are separated and recovered from the aqueous medium system, and the water-soluble organic solvent adhering to the resin particles is washed and removed. Thereafter, it may be appropriately dried.

Separation and recovery of the resin particles from the aqueous medium may be performed by a conventional method such as filtration or centrifugation, and the filtration method is generally preferred.

The resin particles thus separated and recovered are washed with water, warm water, hot water or the like according to a conventional method, whereby the water-soluble organic solvent attached to the particles can be sufficiently removed. Since extra impurities other than the water-soluble organic solvent such as an organic solvent are sufficiently removed from the resin particles at the end of the granulation, the washing operation of the method of the present invention is significantly simpler than that of the conventional method. become.

Thereafter, by drying by a conventional drying technique such as drying under reduced pressure, air drying, and heat drying, desired resin particles can be obtained as a dry powder.

[0063]

Next, the present invention will be described more specifically with reference to examples of the present invention and comparative examples thereof, but the present invention is not limited to these examples.

Example 1 2,2-bis (4-hydroxyphenyl) propane 74
g in 550 ml of a 6% strength aqueous sodium hydroxide solution.
The dissolved solution and 250 ml of methylene chloride were mixed and stirred.
While stirring, 950 ml of phosgene gas was added to the liquid under cooling.
Per minute for 15 minutes. Then, the reaction solution
And the organic layer has a degree of polymerization of 2 to 4,
Methyl chloride of oligomers having a chloroformate group at the end
A ren solution was obtained.

Methylene chloride was added to the resulting oligomer solution to make a total volume of 450 ml.
A solution of 29 g of (hydroxyphenyl) propane in 150 ml of an 8% aqueous sodium hydroxide solution was mixed, and 3.0 g of p-tert-butylphenol as a molecular weight modifier was added thereto. Then, while vigorously stirring this mixture, a 7% aqueous solution of triethylamine was
l, and the mixture was reacted at 25 ° C. with stirring for 1.5 hours.

After completion of the reaction, the reaction product was treated with methylene chloride 1
Diluted with water and then twice with 1.5 liters of water,
It was washed twice with 1 liter of 0.01 N hydrochloric acid and 1 liter of water in this order to obtain a methylene chloride solution of polycarbonate.

Water heated to 65 ° C. and stirred
The resulting polycarbonate solution was added dropwise to a mixture of liter and 600 ml of 1-propanol over about 1 hour. As soon as the polycarbonate solution was mixed in the aqueous solution, distillation of methylene chloride started, and a granular solid was produced. The methylene chloride to be distilled off was collected by a condenser.
After completion of the dropping, the distillation of methylene chloride was stopped, followed by filtration to obtain a granular polymer. The granular polymer was washed with water and dried at 100 ° C.

The polymer thus obtained was prepared by adding a 0.5 g / dl solution of methylene chloride as a solvent at 20 ° C.
The reduced viscosity [η _sp / c] was 0.75 dl / g. ^{From 1} H-NMR spectrum analysis, it was confirmed to consist of the following repeating units. The crystallinity of the obtained polymer was 0.41%. The diameter of the polymer particles is about 3 mm to 6 mm, and the bulk density is 0.6 g
/ Ml.

[0069]

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Example 2 29 g of 2,2-bis (4-hydroxyphenyl) propane of Example 1 was added to 4,4'-dihydroxybiphenyl 24
g. In addition, the amount of water is changed from 1.2 liters to 60
0 ml, the amount of 1-propanol from 600 ml to 1.
Changed to 2 liters. Otherwise, the same operation as in Example 1 was carried out, and the amorphous polycarbonate polymer ([η _sp / c]) having the following repeating unit and composition was 0.78 dl /
g) was obtained.

The diameter of the obtained polymer particles is 3 mm to 6 mm.
mm and the bulk density was 0.6 g / ml.

[0072]

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Example 3 74 g of 2,2-bis (4-hydroxyphenyl) propane of Example 1 was changed to 83 g of 2,2-bis (3-methyl-4-hydroxyphenyl) propane, and 29 g of (4-hydroxyphenyl) propane is 2,2-
Bis (3-methyl-4-hydroxyphenyl) propane was changed to 33 g. In addition, 600 ml of 1-propanol
Was changed to 600 ml of 2-propanol. Otherwise, the same operation as in Example 1 was carried out, and an amorphous polycarbonate polymer ([η _sp / c]) comprising the following repeating units was 0.7
2 dl / g).

The particle size of the obtained polymer particles is from 3 mm to 6 mm.
mm, and the bulk density was 0.6 g / ml.

[0075]

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Comparative Example 1 A methylene chloride solution of the polycarbonate of Example 1 was added to 10 liters of methanol under stirring to obtain polycarbonate particles. The particle diameter of the particles is 5 mm to 10 mm
And the bulk density was 0.1 g / ml.

Comparative Example 2 1-propanol 6 was added to the polycarbonate solution of Example 2.
00 ml was added, and the mixed solution was dropped into 1.2 liters of water heated to about 65 ° C. After the start of the dropping, the precipitated polymer was entangled with the stirring blade and did not become granular, but became a rice cake-like polymer.

Comparative Example 3 400 ml of heptane was added to the polycarbonate solution of Example 3.
Was added dropwise to 3 liters of water heated to about 55 ° C. After the start of the dropping, the precipitated polymer was entangled with the stirring blade and became a large block polymer.

[0079]

According to the present invention, polycarbonates having various structures and compositions (homopolymers, copolymers, mixed polymers thereof, and compositions thereof) synthesized by various polymerization methods such as the phosgene method are described. , A high-quality polycarbonate resin that can be efficiently granulated from the solution, has a high particle bulk density, has a good particle size uniformity and particle shape, and has extremely few residual impurities such as solvents. Particles (particle powder) can be produced with high yield.

Further, in the method of the present invention, since high-temperature treatment is not required for granulation, the resin does not receive heat history, and therefore, resin particles having excellent characteristics inherent to polycarbonate resin are obtained. be able to.

Further, since the method of the present invention does not require a crystallization step in granulation, the method is similarly effective not only for crystalline ones but also for low crystalline polycarbonates.

The method of the present invention can be suitably used particularly as a post-treatment step of the polymerization step of the synthesis of polycarbonate, and the synthesized crude polycarbonate or the pre-washed polycarbonate has the above-mentioned excellent properties. It is extremely useful as an industrial process for collecting and acquiring high quality resin particles.

Claims (2)

(57) [Claims] 1. A solution of a polycarbonate dissolved in a low-boiling organic solvent having a boiling point of 90 ° C. or lower is added to and dispersed in a mixture of water and a water-soluble organic solvent, which is heated to a temperature higher than the boiling point of the low-boiling organic solvent. A process for producing a granular polycarbonate, wherein the low-boiling organic solvent is distilled off to obtain polycarbonate resin particles. 2. The water-soluble organic solvent used by mixing with water is uniformly dissolved in water at least at a granulation temperature,
The method for producing a granular polycarbonate according to claim 1, wherein the water-soluble organic solvent has a boiling point in the range of 50 to 200C.