JP4469070B2 - Method and apparatus for producing aromatic polycarbonate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a polycarbonate by melt polymerization, and more specifically, relates to a method for producing a polycarbonate having a small amount of low molecular weight by devolatilizing a polycarbonate produced by melt polymerization using a vented biaxial ruder. .
[0002]
[Prior art]
When a polycarbonate produced by melt polymerization is subjected to a stabilizer addition process and a water addition devolatilization process using a vented biaxial rudder, a low pressure generated between the vent pipe and the vacuum generator while operating at a reduced pressure. It is common practice to collect molecular materials by evacuation.
[0003]
In the conventional collection, a plurality of heat exchangers or tanks having a cooling jacket and / or a coil are used. Under vacuum, a low molecular weight substance is cooled to a melting point or lower and condensed on a heat transfer surface. If the pressure difference at the entrance / exit of the device increases due to the adhesion of substances, after switching to the spare device, the method of recovering low molecular weight materials by heating cleaning or cleaning with a solvent, etc., or the generated low molecular weight materials can be dissolved A method has been used in which a solvent is used as a scrubber liquid, and the scrubber liquid and low molecular weight substance vapor are brought into contact with each other to be dissolved and collected.
[0004]
However, such a method requires switching of equipment and cleaning, so that complicated equipment is required, and in order to circulate and use the scrubber liquid, a large amount of solvent must be regenerated by distillation or the like. There has been a problem that a large amount of cost is required to carry out the collection continuously and stably.
[0005]
For this reason, the present invention is a method of separating and recovering insoluble matter of a scrubber liquid by solid-liquid separation using a scrubber condenser with cold water as a scrubber liquid, bringing the scrubber liquid into contact with a low molecular weight vapor, cooling and condensing it, and collecting it. Have been previously proposed by the authors.
[0006]
[Problems to be solved by the invention]
The improved method using chilled water as a scrubber liquid significantly improves operability compared with the method of collecting and condensing devolatilized low molecular substances below the melting point and condensing them on the heat transfer surface. The collection load is greatly reduced.
[0007]
However, in the method of using this cold water as a scrubber liquid, low molecular weight substances that are insoluble in the scrubber liquid gradually adhere to the apparatus, and in the long-term continuous operation, the capacity of the accessory equipment is reduced and the clogging in the cold water circulation system occurs. There was a problem of causing.
[0008]
An object of the present invention is to improve the long-term continuous operation of a cold water scrubber, and to provide a collection method that is inexpensive and excellent in operability.
[0009]
[Means for Solving the Problems]
That is, the present invention is as follows.
[0010]
1. A process for producing an aromatic polycarbonate in which a polycarbonate produced by transesterifying an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst is subjected to devolatilization treatment while adding water using a vented biaxial ruder. Because
The water vapor and devolatilized product generated by water addition devolatilization are led to a scrubber, and the water vapor is brought into contact with a scrubber liquid mainly containing water and having a temperature lower than the boiling point of water at the operation pressure of the scrubber. And a method for producing an aromatic polycarbonate in which the devolatilized product is condensed as part of the scrubber collection liquid.
[0011]
2. 1) adding a surfactant;
2) stirring and mixing the scrubber collection liquid;
3) a step of separating the solid devolatilized material from the scrubber collection liquid;
4) cooling the scrubber liquid entering the scrubber to a temperature below the boiling point of water at the operating pressure of the scrubber;
The manufacturing method of said 1 characterized by including.
[0012]
3. 3. The production method according to 1 or 2 above, wherein a scrubber solution having a contact angle with the carbonic acid diester compound of 45 ° or less is used.
[0013]
4). 4. The production method according to 3 above, wherein the contact angle is 15 ° or less.
[0014]
5). 5. The production method according to any one of 1 to 4 above, wherein the surfactant is a nonionic surfactant, an alkyldiamine type surfactant, or a mixture thereof.
[0015]
6). The production method according to any one of 1 to 5 above, wherein the scrubber liquid has a surfactant content of 1 ppm or more.
[0016]
7). The production method according to any one of 1 to 5 above, wherein the surfactant content of the scrubber liquid is 10 ppm or more.
[0017]
8). The manufacturing method according to any one of 1 to 7 above, wherein the scrubber is a spray scrubber.
[0018]
9. 9. The production method according to any one of 1 to 8 above, wherein the step of separating the solid devolatilized material from the scrubber collection liquid is performed by centrifugation and / or filtration using a filter.
[0019]
10. 10. The method according to 9 above, wherein the filter has a mesh opening of 10 μm or less.
[0020]
11. A vented biaxial ruder,
Scrubber,
Means for adding a surfactant;
Means for stirring and mixing the scrubber collection liquid collected by the scrubber;
Means for separating the solid devolatilization from the scrubber collection liquid;
Means for cooling the scrubber liquid entering the scrubber to a temperature below the boiling point of water at the operating pressure of the scrubber;
A liquid circulation means for circulating the scrubber collection liquid as a scrubber liquid;
An apparatus for producing an aromatic polycarbonate, comprising:
[0021]
12 12. The manufacturing apparatus as described in 11 above, wherein the scrubber is a spray scrubber.
[0022]
13. 13. The production apparatus as described in 11 or 12 above, wherein the means for separating the solid devolatilized product is a centrifuge and / or a filter.
[0023]
The meanings of the terms in the above are as follows.
[0024]
“The scrubber liquid mainly composed of water and containing a surfactant” usually uses normal water containing a surfactant at the beginning of operation, but this scrubber liquid is circulated and used. In the middle of the process, a part of the devolatilized polycarbonate collected by the scrubber is included.
[0025]
The step of adding the surfactant may be in any part of the scrubber circulation system, which will be described later, and the addition means is simply a connection of a pipe or a known pipe such as an addition pipe with a line mixer in order to ensure sufficient uniform mixing. Anything can be used as long as it meets the object of the present invention.
[0026]
The step of stirring and mixing the scrubber collection liquid serves to prevent precipitation of solids in the scrubber collection liquid and to ensure mixing of the added surfactant, which will be described later. It is good to carry out in the part where the scrubber collection liquid exists in the scrubber circulation system. Any known means such as a stirrer or a line mixer can be used as long as it meets the object of the present invention.
[0027]
The process of cooling the scrubber liquid entering the scrubber to a temperature below the boiling point of water at the scrubber operating pressure finally results in the temperature of the scrubber liquid supplied to the scrubber being below the boiling point of water at the scrubber operating pressure. As long as it can be cooled, the scrubber collection liquid before cooling the solid devolatilized material or the scrubber collection liquid from which the solid devolatilized material is separated can be used. It is conceivable to cool the two or combine them. It is more preferable to cool the scrubber collection liquid from which the solid devolatilized material is separated. Any known means can be used as long as it meets the purpose of the present invention.
[0028]
The contact angle between the scrubber liquid and the carbonic acid diester is that the carbonic acid diester melted at 90 ° C is placed in a stainless steel container with a mirror-finished bottom surface, cooled to 20 ° C, and brought into contact with the bottom surface of the solidified plate. It is possible to know the contact angle of the surface that has been measured by using a sessile drop method at room temperature.
[0029]
A plurality of surfactants may be used. This includes the case where a plurality of the same kind is included.
[0030]
The amount (ppm) of the surfactant is a value based on weight.
[0031]
The aromatic polycarbonate as referred to in the present invention is a transesterification catalyst comprising an aromatic dihydroxy compound and a carbonic acid diester as main components, for example, a basic nitrogen compound and an alkali metal compound and / or an alkaline earth metal compound. Polycarbonate melt-condensed in the presence.
[0032]
Examples of such aromatic diol compounds (aromatic dihydroxy compounds) include bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, and 2,2-bis (4-hydroxy-3). -Methylphenyl) propane, 4,4-bis (4-hydroxyphenyl) heptane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis (4-hydroxy-3,5) -Dibromophenyl) propane, bis (4-hydroxyphenyl) oxide, bis (3,5-dichloro-4-hydroxyphenyl) oxide, p, p'-dihydroxydiphenyl, 3,3'-dichloro-4,4'- Dihydroxydiphenyl, bis (hydroxyphenyl) sulfone, resorcinol, hydroquinone, 1,4-dihi Roxy-2,5-dichlorobenzene, 1,4-dihydroxy-3-methylbenzene, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) sulfoxide and the like can be mentioned. 4-hydroxyphenyl) propane is preferred.
[0033]
Examples of the carbonic acid diester compound used in the present invention include diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, Dicyclohexyl carbonate or the like is used. Of these, diphenyl carbonate is particularly preferred.
[0034]
The ratio of the two raw materials used in the present invention is 1.00 to 1.10 in the raw material molar ratio represented by the value obtained by dividing the number of moles of carbonic acid diester compound used by the number of moles of aromatic dihydroxy compound. It is preferable to select from the range.
[0035]
Furthermore, the aromatic polycarbonate of the present invention can be prepared by using, for example, ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,10-decanediol, etc. Examples of acids include succinic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, adipic acid, cyclohexanecarboxylic acid, terephthalic acid and the like; oxyacids such as lactic acid, P-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid Etc. may be contained.
[0036]
Although the catalyst used for this invention is not specifically limited, The transesterification catalyst which consists of a basic nitrogen compound, an alkali metal compound, and / or an alkaline-earth metal compound can be used.
[0037]
The alkali metal and / or alkaline earth metal compound used in the present invention is not particularly limited as long as it does not reduce the hue of the resulting aromatic polycarbonate, and various known compounds can be used.
[0038]
Examples of alkali metal compounds used as catalysts include alkali metal hydroxides, hydrogencarbonates, carbonates, acetates, nitrates, nitrites, sulfites, cyanates, thiocyanates, stearates, hydrogenates. Examples thereof include boron salts, benzoates, hydrogen phosphates, bisphenols, and phenol salts.
[0039]
Specific examples include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium bicarbonate, potassium bicarbonate, lithium bicarbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, potassium acetate, lithium acetate, sodium nitrate, Potassium nitrate, lithium nitrate, sodium nitrite, potassium nitrite, lithium nitrite, sodium sulfite, potassium sulfite, lithium sulfite, sodium cyanate, potassium cyanate, lithium cyanate, sodium thiocyanate, potassium thiocyanate, lithium thiocyanate, stearin Sodium phosphate, potassium stearate, lithium stearate, sodium borohydride, potassium borohydride, lithium borohydride, phenyl phenyl sodium borate, sodium benzoate, benzo Potassium acid, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium salt of bisphenol A, dipotassium salt, dilithium salt, sodium salt of phenol, potassium salt, lithium salt, etc. .
[0040]
Examples of the alkaline earth metal compound used as the catalyst include alkaline earth metal hydroxides, bicarbonates, carbonates, acetates, nitrates, nitrites, sulfites, cyanates, thiocyanates, stearic acids. Examples thereof include salts, benzoates, bisphenols, and phenol salts.
[0041]
Specific examples include calcium hydroxide, barium hydroxide, strontium hydroxide, calcium bicarbonate, barium bicarbonate, strontium bicarbonate, calcium carbonate, barium carbonate, strontium carbonate, calcium acetate, barium acetate, strontium acetate, calcium nitrate, Barium nitrate, strontium nitrate, calcium nitrite, barium nitrite, strontium nitrite, calcium sulfite, barium sulfite, strontium sulfite, calcium cyanate, barium cyanate, strontium cyanate, calcium thiocyanate, barium thiocyanate, strontium thiocyanate , Calcium stearate, barium stearate, strontium stearate, calcium borohydride, barium borohydride, boron borohydride Strontium, calcium benzoate, barium benzoate, strontium benzoate, calcium salts of bisphenol A, a barium salt, strontium salt, calcium salt of phenol, barium salt, etc. strontium salts.
[0042]
In the present invention, as desired, as an alkali metal compound of the catalyst, (a) an alkali metal salt of an ate complex of a group 14 element of the periodic table or (b) an alkali metal of an oxo acid of a group 14 element of the periodic table A salt can be used. Here, the element of Group 14 of the periodic table means silicon, germanium, and tin.
[0043]
(A) The alkali metal salt of the art complex of the group 14 element of the periodic rate table is the one described in JP-A-7-268091. Specifically, a germanium (Ge) compound; NaGe (OMe ) _Five , NaGe (OEt) _Three NaGe (OPr) _Five , NaGe (OBu) _Five NaGe (OPh) _Five , LiGe (OMe) _Five , LiGe (OBu) _Five , LiGe (OPh) _Five Can be mentioned.
[0044]
As a compound of tin (Sn), NaSn (OMe) _Three , NaSn (OMe) ₂ (OEt), NaSn (OPr) _Three NaSn (On-C ₆ H ₁₃ ) _Three , NaSn (OMe) _Five NaSn (OEt) _Five NaSn (OBu) _Five NaSn (On-C ₁₂ H _{twenty five} ) _Five , NaSn (OEt), NaSn (OPh) _Five , NaSnBu ₂ (OMe) _Three Can be mentioned.
[0045]
Further, (b) alkali metal salt of oxo acid of group 14 element of periodic table includes, for example, alkali metal salt of silicic acid, alkali metal salt of stannic acid, germanium (II) acid ( Preferred examples include alkali metal salts of germanous acid and alkali metal salts of germanium (IV) acid (germanic acid).
[0046]
The alkali metal salt of silicic acid is, for example, an acidic or neutral alkali metal salt of monosilicic acid or its condensate, and examples thereof include monosodium orthosilicate, disodium orthosilicate, trisodium orthosilicate, Mention may be made of tetrasodium orthosilicate.
[0047]
The alkali metal salt of stannic acid is, for example, an acid or neutral alkali metal salt of monostannic acid or a condensate thereof. Examples thereof include disodium monostannate (Na ₂ SnO _Three ・ XH ₂ O, X = 0 to 5), monostannic acid tetrasodium salt (Na _Four SnO _Four ).
[0048]
An alkali metal salt of germanium (II) acid is, for example, an acidic or neutral alkali metal salt of monogermanic acid or a condensate thereof, and examples thereof include germanium monosodium salt (NaHGeO). ₂ ).
[0049]
An alkali metal salt of germanium (IV) acid is, for example, an acid or neutral alkali metal salt of monogermanium (IV) acid or a condensate thereof, and examples thereof include orthogermanic acid monolithium acid (LiH). _Three GeO _Four ) Ortho-germanic acid disodium salt, ortho-germanic acid tetrasodium salt, digermanic acid disodium salt (Na ₂ Ge ₂ O _Five ), Tetragermanic acid disodium salt (Na ₂ Ge _Four O ₉ ), Pentagermanic acid disodium salt (Na ₂ Ge _Five O ₁₁ ).
[0050]
The alkali metal compound or alkaline earth metal compound as the catalyst is 1 × 10 5 per 1 mol of the aromatic diol compound by the alkali metal element or alkaline earth metal element in the catalyst. ^-8 ~ 5x10 ^-Five It is preferably used when the equivalent weight is reached. A more preferred ratio is 5 × 10 for the same criteria ^-7 ~ 1x10 ^-Five It is the ratio which becomes an equivalent.
[0051]
The amount of alkali metal element or alkaline earth metal element in the catalyst is 1 × 10 per mole of aromatic diol compound. ^-8 ~ 5x10 ^-Five Deviating from the equivalent range is not preferable because there are problems such as adversely affecting various physical properties of the resulting aromatic polycarbonate, and a problem that the transesterification reaction does not proceed sufficiently and a high molecular weight aromatic polycarbonate cannot be obtained.
[0052]
Examples of the nitrogen-containing basic compound as a catalyst include tetramethylammonium hydroxide (Me _Four NOH), tetraethylammonium hydroxide (Et _Four NOH), tetrabutylammonium hydroxide (Bu) _Four NOH), benzyltrimethylammonium hydroxide (φ-CH ₂ (Me) _Three NOH), ammonium hydroxides having alkyl, aryl, alkylaryl groups such as hexadecyltrimethylammonium hydroxide, tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, hexadecyldimethylamine, or tetramethylammonium Borohydride (Me _Four NBH _Four ), Tetrabutylammonium borohydride (Bu) _Four NBH _Four ), Tetrabutylammonium tetraphenylborate (Me _Four NBPh _Four ), Tetrabutylammonium tetraphenylborate (Bu) _Four NBPh _Four ) And other basic salts.
[0053]
In the nitrogen-containing basic compound, the ammonium nitrogen atom in the nitrogen-containing basic compound is 1 × 10 5 per mole of the aromatic diol compound. ^-Five ~ 5x10 ^-3 It is preferable to use it in the ratio which becomes equivalent. A more preferred ratio is 2 × 10 against the same criteria ^-Five ~ 5x10 ^-Four It is the ratio which becomes an equivalent. A particularly preferred ratio is 5 × 10 for the same criteria. ^-Five ~ 5x10 ^-Four It is the ratio which becomes an equivalent.
[0054]
In the present specification, the ratio of the alkali metal compound, alkaline earth metal compound, and nitrogen-containing basic compound to the charged aromatic diol compound (also referred to as aromatic dihydroxy compound) is expressed as “per mole of aromatic dihydroxy compound. It was expressed as “amount of Z (compound name) equivalent to W (numerical value) as a metal or basic nitrogen”. For example, Z represents sodium phenoxide or 2,2-bis (4-hydroxyphenyl) propane monosodium salt. Thus, if there is one sodium atom or one basic nitrogen such as triethylamine, it means that the amount of Z is an amount corresponding to W mole, and 2,2-bis (4- If it is two like hydroxyphenyl) propane disodium salt, it means an amount corresponding to W / 2 mol.
[0055]
In the polycondensation reaction of the present invention, together with the above catalyst, if necessary, at least one cocatalyst selected from the group consisting of an oxo acid of Group 14 element and an oxide of the same element is allowed to coexist. Can do.
[0056]
By using these cocatalysts at a specific ratio, end-blocking reaction, branching reaction that easily occurs during polycondensation reaction without impairing the polycondensation reaction rate, generation of foreign matter in the apparatus during molding, Undesirable side reactions such as burns can be more effectively suppressed.
[0057]
In the present invention, the polycarbonate obtained by the above method is subjected to a catalyst deactivator addition treatment and a devolatilization treatment by water addition using a vented biaxial ruder. Here, the “vented biaxial ruder” has a function of exhausting gas or the like in the biaxial ruder through a pipe provided on the upper surface of a predetermined place (called a vent portion) of the biaxial ruder. Means an axis ruder.
[0058]
At this time, the polycarbonate may be directly melted from the polymerization machine and supplied to the ruder, or may be once cooled and pelletized before being supplied to the ruder.
[0059]
In the present invention, prior to the devolatilization treatment, it is preferable to deactivate the polymerization catalyst contained in the polycarbonate obtained by polymerization in advance using a catalyst deactivator.
[0060]
When performing plural water addition devolatilization, deactivation and devolatilization can be performed simultaneously by adding water and a catalyst deactivator simultaneously in the first devolatilization. By doing in this way, deterioration of the polycarbonate in devolatilization operation can be suppressed.
[0061]
As the deactivator used in the present invention, known deactivators are effectively used. Among these, ammonium salts and phosphonium salts of sulfonic acid are preferable, and dodecylbenzene such as tetrabutylphosphonium salt of dodecylbenzene sulfonate. The salts of sulfonic acid and the salts of paratoluenesulfonic acid such as para-toluenesulfonic acid tetrabutylammonium salt are preferred. As esters of sulfonic acid, methyl benzenesulfonate, ethyl benzenesulfonate, butyl benzenesulfonate, octyl benzenesulfonate, phenyl benzenesulfonate, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, butyl paratoluenesulfonate, para Octyl toluenesulfonate, phenyl paratoluenesulfonate, and the like are preferably used, and among them, tetrabutylphosphonium dodecylbenzenesulfonate is most preferably used.
[0062]
The amount of these deactivators used is 0.5 to 50 moles, preferably 0.5 to 10 moles per mole of the polymerization catalyst selected from alkali metal compounds and / or alkaline earth metal compounds. More preferably, it can be used at a ratio of 0.8 to 5 mol.
[0063]
These deactivators are added or kneaded to the molten polycarbonate directly or after being dissolved or dispersed in a suitable solvent.
[0064]
Although there is no restriction | limiting in particular in such a solvent, It is most preferable to use the water which is the same solvent as the devolatilization aid used for a subsequent devolatilization process as a solvent. By doing in this way, it becomes possible to perform devolatilization operation simultaneously with deactivation operation as mentioned above.
[0065]
There are no particular restrictions on the equipment used for kneading the deactivator, but a biaxial ruder or the like is preferable. When the deactivator is dissolved or dispersed in a solvent, a vented biaxial ruder is particularly preferred. Is done.
[0066]
In the present invention, after adding and kneading water to the polycarbonate whose activity of the polymerization catalyst has been eliminated by the deactivator obtained as described above, impurities, particularly volatile impurities, etc. are obtained by devolatilization under reduced pressure. Thus, it is possible to produce a polycarbonate resin having an extremely low content of a low molecular weight substance and excellent in thermal stability, hue stability, and hydrolysis resistance.
[0067]
Here, the water added to perform the devolatilization treatment as described above is called a devolatilization aid, added to the melted polycarbonate, and accompanied by impurities contained in the polycarbonate when evaporated. Has the role of taking it out of the system.
[0068]
In the devolatilization process of the present invention, it is preferable to use a vented biaxial rudder having a unit treatment zone composed of a kneading part and a vent part with the material seal part sandwiched between the materials to be added and kneaded. The number of unit processing zones may be one, but a plurality may be owned.
[0069]
In the vent part, the pressure is reduced by a vacuum pump or the like, and water and low molecular weight volatiles used as a devolatilization aid are removed from the system. As the decompression treatment conditions, 760 mmHg (1.01 × 10 6 ² kPa) or less, preferably 500 mmHg (0.665 × 10 6 ² kPa) or less for 0.1 seconds or more.
[0070]
Vent pressure is 760mmHg (1.01x10 ² If it exceeds kPa), the added water and low molecular weight substances such as volatile impurities cannot be removed out of the system. The units of pressure used in the above description and in the text are all absolute pressures unless otherwise specified.
[0071]
The inventors of the present application have previously proposed scrubber collection using cold water as a method for collecting volatiles generated by water addition devolatilization.
[0072]
Cold water scrubbers can use water, which is the same material as the devolatilization aid, so that scrubber liquid treatment is simpler and operation is not necessary when compared with cooling / solidification type collection methods. It was characterized by being excellent. However, even if this water scrubber with excellent operability is operated for a long period of time exceeding one month, the scrubber liquid circulation system may become clogged due to devolatilized collection and may impair stable operation. I understand.
[0073]
The present invention has been achieved based on the continuous study by the present inventors in order to further improve the operability of the cold water scrubber.
[0074]
Embodiments of the present invention are illustrated below using the drawings. In addition, the figure illustrates one embodiment of the present invention, and does not limit the scope of the present invention.
[0075]
In FIG. 1, a vacuum generator 1 in the present invention refers to a device for generating a vacuum such as a vacuum pump or an ejector.
[0076]
A scrubber 3 is installed in the middle of a vent pipe 2 that connects the vent type biaxial ruder 8 and the vacuum generator 1.
[0077]
The scrubber used in the present invention is not particularly limited, and any scrubber having any structure that can satisfactorily contact the scrubber liquid and the vapor and has a small pressure loss can be used. For example, a spray type, a packed tower type, a retained water splash type, a water surface collision type, etc. can be considered. Among these, a spray scrubber is preferable in terms of operation efficiency. An example is shown in FIG.
[0078]
In FIG. 2, a plurality of spray nozzles 10 are installed at different positions inside the scrubber 3, which is a vertical vertical cylindrical tower, and a necessary amount of scrubber is provided from the spray nozzle 10. Liquid is sprayed.
[0079]
A scrubber inlet nozzle 5 is provided on the side surface of the scrubber 3 to guide the gas containing water vapor and devolatilized material generated from the biaxial rudder. The gas introduced into the tower comes into contact with the scrubber liquid. As a result, water vapor and devolatilized material are collected and removed.
[0080]
The gas from which the water vapor and the devolatilized material have been collected and removed in this manner is guided to the vacuum generator 1 from the scrubber outlet nozzle 4 provided at the top of the scrubber 3 and exhausted.
[0081]
It is important to consider that the scrubber liquid supplied by spraying is not directly applied to the scrubber inlet nozzle 5.
[0082]
A scrubber liquid containing the collected water vapor and devolatilized material (in the present invention, such a scrubber liquid is called a scrubber collection liquid) is discharged from a scrubber discharge liquid nozzle 6 installed at the lower part of the tower.
[0083]
In the present invention, since the scrubber liquid mainly uses the same water as the devolatilization aid, the scrubber collection liquid discharged from the scrubber becomes a water slurry containing the collected solid devolatilized material. The water slurry is guided to the pot 7 through the pipe 11 in FIG.
[0084]
In the present invention, the pot 7 is preferably provided with a stirrer for the purpose of preventing sedimentation of the slurry and keeping the concentration of the surfactant uniform.
[0085]
When the scrubber 3 is used in the present invention, a solid cone nozzle having spray droplets on the inner surface of the spray cone as shown in FIG. 3 or a hollow inner surface as shown in FIG. A hollow cone nozzle is preferable, and a solid cone nozzle is particularly preferable.
[0086]
In the present invention, the scrubber liquid flow rate is preferably 100 to 1000 times (by weight) the amount of water vapor and low molecular weight substance gas that volatilizes from the vented biaxial ruder.
[0087]
In the present invention, the temperature of the scrubber liquid entering the scrubber is preferably controlled to be equal to or lower than the boiling point of water at the collection operation pressure in the scrubber. When the liquid temperature is equal to or higher than the boiling point of water, it is difficult to maintain the degree of vacuum necessary for the devolatilization operation due to evaporation of the scrubber liquid, and volatile substances escape to the vacuum generator, which is not preferable. From the viewpoint of collection efficiency, it is desirable to control the liquid temperature by lowering it by 5 ° C. or more from the boiling point of water at the collection operation pressure.
[0088]
In the present invention, in order to prevent adhesion of low molecular weight volatiles to the portion of the pipe 2 connecting the vented biaxial rudder 8 and the scrubber 3 shown in FIG. 1 and the scrubber inlet nozzle 5 provided in the scrubber 3, It is desirable to keep traces with a heat medium such as steam or warming a jacket or the like, and always keep the nozzle and piping at 100 ° C. or higher.
[0089]
In the present invention, it is desirable that the scrubber inlet nozzle 5 has a downward slope toward the scrubber 3. Specifically, the installation angle α formed by the center line of the scrubber inlet nozzle 5 and the center line of the scrubber 3 is 45 to 45 °. 80 ° is desirable.
[0090]
In this invention, when a low molecular weight substance adheres in the scrubber 3, you may install the spray nozzle aiming at the washing | cleaning of an adhesion location, and may perform the forced washing by spray.
[0091]
In the pipe 11, it is desirable not to provide an abruptly different-diameter portion that becomes a resistance to the flow of the scrubber collecting liquid in order to prevent adhesion of solids. When it is unavoidable to provide a different diameter portion, it is desirable that the aperture angle be 10 ° or less.
[0092]
As shown in FIG. 1, the scrubber collection liquid in the pot 7 is led through a pump 13 to a solid-liquid separation device 14 for removing collected solids in the scrubber collection liquid.
[0093]
In the present invention, the method for separating the solid devolatilized material is not particularly limited, and any mechanism that can efficiently and sufficiently remove the solid material in the scrubber liquid may be used. Those to be carried out and those to be separated by filtration can be preferably used.
[0094]
There is no particular limitation on the apparatus for separating the solids by centrifugation, and a commercially available centrifugal apparatus can be used. For example, a horizontal continuous centrifugal apparatus or a semi-solid type having a bowl-shaped internal screen can be used. A continuous centrifugal separator can be mentioned.
[0095]
There are no particular limitations on the apparatus for separating the solid by filtration, and examples thereof include a continuous filter such as a belt filter and a drum filter, a cartridge filter, a basket filter, and a strainer. These facilities can be used in combination as needed.
[0096]
In the present invention, the accuracy of collecting the devolatilized solid content in the scrubber collection liquid is desirably 90% or more of 10 μm particles, more preferably 90% or more of 2 μm particles. desirable. When a device that does not perform sufficient solid-liquid separation is used, undissolved solid matter adheres to the inner surface of the pipe 16 and the attached device, which hinders continuous operation for a long time.
[0097]
Further, in the pipes 12 and 15 between the pot 7 and the solid-liquid separation device 14, in order to prevent solid matter from adhering to the inner surface of the pipe, the flow velocity in the pipe is set to 1 m / s or more, and an unnecessary bent portion or the like is formed. It is preferable to suppress piping resistance as much as possible.
[0098]
After passing through the solid-liquid separator 14, the excess water is appropriately discharged out of the system, and wastewater treatment is performed as necessary.
[0099]
In the present invention, since the liquid from which the solid devolatilized product has been removed is circulated and used as a scrubber liquid, it is cooled at the entrance to the scrubber so as to have a predetermined temperature below the boiling point of water at the scrubber operating pressure. The apparatus used for this purpose is not particularly limited. For example, a cooling jacket and / or a coil is installed in the pot 7 having the stirrer, a multi-tube heat exchanger, a plate heat exchanger, a scraping heat A heat exchanger such as an exchanger can be used.
[0100]
According to the study by the inventors of the present application, by using water containing a surfactant as the scrubber liquid, in the scrubber liquid circulation system that returns to the scrubber 3 from the scrubber 3 through the pot 7 solid-liquid separator 14 and the like, It has been found that the blockage generated by continuous operation is greatly improved. This blockage is particularly likely to occur at a site where the flow of liquid in the piping or device (reference numerals 11, 7, 12, 13, 15, 14, 18, 16) is stagnant.
[0101]
The surfactant used in the present invention is not particularly limited, and nonionic surfactants, anionic surfactants, and cationic surfactants can be used. Nonionic surfactants are preferably used.
[0102]
Examples of such nonionic surfactants include N, N ′, N′tris (2-hydroxyethyl) -N-alkyl (C14-18) 1,3-diaminopropane, N, N ′, N′—. Polyoxyethylene-N-alkyl (C14-18) -1,3-diaminopropane, polyoxyethylene nonylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid methyl, polyoxyalkylene alkyl ether, polyoxyethylene alkylamine , Alkylamine oxide, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monostearate, glycerin ester, sorbitan ester, sorbitan sesquioleate, sorbitan monooleate, sorbitan trioleate, etc. Kill diamine type N, N ′, N′tris (2-hydroxyethyl) -N-alkyl (C14-18) 1,3-diaminopropane is most preferred. In the present specification, (C14-18) means that the alkyl group has 14-18 carbon atoms.
[0103]
In the present invention, the concentration of these surfactants is preferably 1 ppm or more, and more preferably 10 ppm or more, when expressed by the concentration in the scrubber liquid. Further, the upper limit concentration of the surfactant to be used is not particularly limited, but is preferably 1% or less, more preferably 1000 PPM or less when considering the treatment of excess scrubber liquid discharged from the scrubber circulation system.
[0104]
In the present invention, the method for adding the surfactant is not particularly limited. For example, an amount corresponding to the surfactant contained in the extracted scrubber liquid is intermittently or continuously added to the pot 7. Is preferably implemented.
[0105]
In the present invention, the cause of the blockage of the scrubber fluid circulation system being suppressed by using a scrubber fluid containing a surfactant is not clear, but as a result of the study by the present inventors, substances adhering to the scrubber fluid circulation system are mainly It has been found that the interfacial tension between the scrubber liquid and the carbonic acid diester compound is reduced by the addition of the surfactant and the carbonic acid diester compound used in the reaction. It is thought that the adhesion of the carbonic acid diester compound contained in the scrubber liquid after collection to the device wall was suppressed because the affinity between the carbonic acid diester compound generated from the devolatilization process and the scrubber liquid was improved by It is done.
[0106]
In fact, the effect of preventing clogging of the scrubber fluid circulation system and the contact angle between the solid carbonic acid diester and the scrubber fluid show a good correlation, and the type and concentration of the surfactant used in the present invention For selection, it is possible to use as an effective index that the contact angle is 45 ° or less, preferably 15 ° or less.
[0107]
Moreover, in this invention, another additive can be added to a polycarbonate in the range which does not impair the objective of this invention.
[0108]
Examples of such additives include processing stabilizers, heat stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, metal deactivators, metal soaps, nucleating agents, antistatic agents, and slip agents. , Anti-blocking agent, lubricant, flame retardant, mold release agent, anti-mold agent, colorant, anti-fogging agent, natural oil, synthetic oil, wax, organic filler, inorganic filler, epoxy compound .
[0109]
Of these, heat stabilizers, ultraviolet absorbers, mold release agents, colorants and the like are particularly commonly used, and these can be used in combination of two or more.
[0110]
For purposes of processing stabilizers, heat stabilizers, antioxidants and the like used in the present invention, for example, phosphorus compounds, phenol stabilizers, organic thioether stabilizers, hindered amine stabilizers, and the like can be mentioned. .
[0111]
As the light stabilizer and the ultraviolet absorber, a general ultraviolet absorber is used. For example, a salicylic acid ultraviolet absorber, a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, a cyanoacrylate ultraviolet absorber, etc. Can be mentioned.
[0112]
As the release agent, generally known release agents can be used. For example, hydrocarbon release agents such as paraffins, fatty acid release agents such as stearic acid, and fatty acid amides such as stearic acid amide. Examples thereof include alcohol release agents such as stearyl alcohol and pentaerythritol, fatty acid ester release agents such as glycerin monostearate, silicone release agents such as silicone oil, and the like.
[0113]
Organic or inorganic pigments or dyes can be used as the colorant.
[0114]
Examples of metal deactivators include N, N ′-[3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine, and examples of metal soaps include calcium stearate and stearic acid. Nickel etc. are mentioned.
[0115]
Examples of the antistatic agent include quaternary ammonium salt compounds such as (β-lauramidopropyl) trimethylammonium methyl sulfate and alkyl phosphate compounds.
[0116]
Examples of the nucleating agent include sorbitol-based and phosphate-based compounds such as sodium di (4-t-butylphenyl) phosphonate, dibenzylidene sorbitol, and methylene bis (2,4-di-t-butylphenol) acid phosphate sodium salt. Is mentioned.
[0117]
Examples of the lubricant include erucic acid amide and stearic acid monoglyceride. Examples of the flame retardant include halogenated phosphates such as tris (2-chloroethyl) phosphate, halides such as hexabromocyclododecane and decabromophenyl oxide. And metal inorganic compounds such as antimony trioxide, antimony pentoxide, and aluminum hydroxide, and mixtures thereof.
[0118]
These additives are added or kneaded to the molten polycarbonate directly or dissolved or dispersed in a suitable solvent or polymer, or as master pellets. There are no particular restrictions on the equipment used to carry out such operations, but for example, a twin screw extruder or the like is preferable, and when supplying the additive in the form of a solution, a metering pump such as a plunger pump is used, When supplying an additive in the form of a master polymer, a side feeder or the like is generally used. When the additive is dissolved or dispersed in a solvent, a twin screw extruder with a vent is particularly preferably used.
[0119]
【Example】
Examples of the present invention will be shown below. In addition, this Example is for demonstrating this invention, This invention is not restrict | limited by this Example.
[0120]
The contact angle measurement method is as follows.
[0121]
[Contact angle measurement method]
Measurement was performed according to the measurement method described in JIS R 3257: 1999 “Method for testing wettability of substrate glass surface”.
[0122]
[Example 1]
Diphenyl carbonate is mixed and melted at a ratio of 1.01 mole to 1 mole of 2,2-bis (4-hydroxyphenyl) propane, and 1 mole of 2,2-bis (4-hydroxyphenyl) propane is added to the mixture. 1 × 10 against ^-6 1 x 10 equivalents of bisphenol A disodium salt ^-Four An equivalent amount of tetramethylammonium hydroxide was continuously added, and the resulting phenol was removed, and the reaction was carried out on the polymer [η] = 0.35 obtained using the equipment shown in FIG. did.
[0123]
The polymer obtained by polymerization was fed at 33 kg / hr to a vented biaxial rudder 8 having a four-stage treatment zone composed of two kneading parts and a vent part with a material seal part interposed therebetween.
[0124]
Next, a 0.01 wt% aqueous solution of tetrabutylphosphonium salt of dodecylbenzenesulfonic acid is added and kneaded from the addition nozzle 9a at a supply rate of 0.33 kg / hr in the vent type biaxial rudder 8, and a vent pressure of 15 mmHg (2. After vacuum suction at 0 kPa), pure water was further added and kneaded in three stages from the addition nozzles 9b, 9c and 9d at a supply rate of 0.33 kg / hr, and vacuum suction was performed at a vent pressure of 15 mmHg (2.0 kPa). . Here, the vent pressure was measured from the vent pipe 2 in the vicinity of the vent type biaxial ruder.
[0125]
When starting the operation of the scrubber according to the present invention, N, N ′, N′tris (2-hydroxyethyl) -N-alkyl (C14-18) 1,3-diaminopropane is previously added to the scrubber as a surfactant. A scrubber liquid having a liquid temperature of 10 ° C. mixed with pure water at a concentration of 75 ppm was used and supplied from two spray nozzles in an amount of 135 kg / hr / spray nozzle. A solid cone spray nozzle shown in FIG. 3 was used.
[0126]
The contact angle at room temperature between the scrubber liquid used and solid diphenyl carbonate was 15 ° at the beginning of the operation, and was kept below 15 ° during the operation.
[0127]
The vent pipe 2 was heated by performing a steam trace. The scrubber inlet nozzle 5 was provided with a steam jacket to prevent precipitation of low boiling point substances due to local cooling.
[0128]
Subsequently, the scrubber collection liquid discharged from the scrubber is dropped and supplied to the pot 7 connected by the pipe 11, and after complete mixing by the stirrer, the pipe 13 is passed through the pipe 12 connecting the pot 7 and the pump 13. Was continuously extracted at a rate of 270 kg / hr.
[0129]
In order to prevent a decrease in the concentration of the surfactant in the scrubber liquid due to the collection of water, which is a devolatilization aid generated from the biaxial ruder, the surfactant N, N ′, N ′ Tris ( 2-Hydroxyethyl) -N-alkyl (C14-18) 1,3-diaminopropane was added in 0.12 g portions every 4 hours.
[0130]
Further, after the scrubber collection liquid extracted by the pump is supplied to the cartridge type filter 14 having an opening of 1 μm and filtered, the heat transfer area is 0.35 m. ^Three The plate-type heat exchanger 18 was cooled so that the liquid temperature of the scrubber liquid supplied to the scrubber was 10 ° C., and was circulated and used in the scrubber.
[0131]
The solid devolatilized material filtered by the cartridge filter is recovered by switching the cartridge filter, and the increase in water as the devolatilization aid is continuously from the discharge pipe 17 at a rate of 1.32 kg / hr. I paid out.
[0132]
In this example, continuous operation was possible for 60 days without any problem, and volatiles devolatilized during this period were recovered by 98% with respect to the total amount of volatiles by a cartridge filter. Moreover, when the disassembly inspection of this apparatus was performed after 60 days continuous operation, the deposit | attachment inside an apparatus was not seen at all, but it has confirmed that smooth continuous operation could be performed.
[0133]
[Example 2]
Instead of N, N ′, N′tris (2-hydroxyethyl) -N-alkyl (C14-18) 1,3-diaminopropane, N, N ′, N′-polyoxy which is a nonionic surfactant The same operation as in Example 1 was performed except that ethylene-N-alkyl (C14-18) -1,3-diaminopropane was used, and the same result as in Example 1 was obtained.
[0134]
[Comparative Example 1]
The scrubber was operated in the same manner as in Example 1 except that no surfactant was added to the scrubber liquid used in the examples.
[0135]
As a result, in the continuous operation for about 40 days, the discharge pressure of the scrubber liquid circulation pump 13 fluctuated, and signs of blockage were observed in the suction line of the pump. For this reason, as a result of discontinuing the operation and inspecting the equipment, solids adhered to the inner surface of the pump suction pipe, pot 7 and pipe 11 to a thickness of 5 to 20 mm, and a solid mass of about 20 mm was also seen. .
[0136]
During the operation for 40 days, the amount of solid collected from the cartridge type filter was equivalent to 84% of the total amount of volatile matter.
[0137]
【The invention's effect】
According to the present invention, the affinity between the collected material and the scrubber liquid is improved, and blockage of the scrubber liquid circulation system is prevented. As a result, continuous operation for a long period of time becomes possible, and switching to a spare machine and cleaning work, which have been necessary in the past, are unnecessary or greatly reduced. As a result, labor and energy required during operation can be reduced, and operation costs can be reduced.
[Brief description of the drawings]
FIG. 1 shows an example of a manufacturing apparatus according to the present invention.
FIG. 2 shows an example of a scrubber according to the present invention.
FIG. 3 shows a cone spray shape (solid cone spray) whose inner surface is liquid-tight.
FIG. 4 shows a cone spray shape (hollow cone spray) with a hollow inner surface.
[Explanation of symbols]
1 Vacuum generator
2 Vent piping
3 Scrubber
4 Scrubber outlet nozzle
5 Scrubber entrance nozzle
6 Scrubber discharge nozzle
7 pots
8 Bent type 2-axis ruder
9a-9d Addition nozzle for stabilizers and devolatilization aids
10 Spray nozzle
11 Piping
12 Pipe connecting the pot 7 and the pump 13
13 Pump
14 Solid-liquid separator
15 Pipe connecting pump 13 and solid-liquid separator 14
16 Pipe connecting the solid-liquid separator 14 to the scrubber 3
17 Discharge piping
18 Scrubber liquid cooler

Claims (13)

A process for producing an aromatic polycarbonate in which a polycarbonate produced by transesterifying an aromatic dihydroxy compound and a carbonic acid diester in the presence / absence of a catalyst is subjected to devolatilization treatment while adding water using a vented biaxial ruder. Because
The water vapor and devolatilized product generated by water addition devolatilization are led to a scrubber, and the water vapor is brought into contact with a scrubber liquid mainly containing water and having a temperature lower than the boiling point of water at the operation pressure of the scrubber. And a method for producing an aromatic polycarbonate in which the devolatilized product is condensed as part of the scrubber collection liquid. 1) a step of adding a surfactant, 2) a step of stirring and mixing the scrubber collection liquid, 3) a step of separating solid devolatilized material from the scrubber collection liquid, and 4) a scrubber liquid entering the scrubber. And a step of cooling to a temperature not higher than the boiling point of water at the operating pressure. The production method according to claim 1 or 2, wherein a scrubber liquid having a contact angle with the carbonic acid diester compound of 45 ° or less is used. The manufacturing method according to claim 3, wherein the contact angle is 15 ° or less. The production method according to claim 1, wherein the surfactant is a nonionic surfactant, an alkyldiamine type surfactant, or a mixture thereof. The production method according to any one of claims 1 to 5, wherein the content of the surfactant in the scrubber liquid is 1 ppm or more. The production method according to any one of claims 1 to 5, wherein the scrubber liquid has a surfactant content of 10 ppm or more. The manufacturing method according to claim 1, wherein the scrubber is a spray scrubber. The method according to any one of claims 1 to 8, wherein the step of separating the solid devolatilized product from the scrubber collection liquid is performed by centrifugation and / or filtration using a filter. The manufacturing method according to claim 9, wherein the opening of the filter is 10 μm or less. A vented biaxial ruder,
Scrubber,
Means for adding a surfactant;
Means for stirring and mixing the scrubber collection liquid collected by the scrubber;
Means for separating the solid devolatilization from the scrubber collection liquid;
Means for cooling the scrubber liquid entering the scrubber to a temperature below the boiling point of water at the operating pressure of the scrubber;
A liquid circulation means for circulating the scrubber collection liquid as a scrubber liquid;
An apparatus for producing an aromatic polycarbonate, comprising: The manufacturing apparatus according to claim 11, wherein the scrubber is a spray scrubber. The manufacturing apparatus according to claim 11 or 12, wherein the means for separating the solid devolatilized material is a centrifuge and / or a filter.

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