JP3224434B2 - Aromatic polycarbonate manufacturing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing an aromatic polycarbonate, and provides an aromatic polycarbonate having an excellent hue.

[0002]

2. Description of the Related Art Aromatic polycarbonates are widely used because they have excellent mechanical properties such as impact resistance, and also have excellent heat resistance and transparency. As a method for producing an aromatic polycarbonate, a method in which an aromatic dihydroxy compound such as bisphenol A is directly reacted with phosgene (interfacial method), or an ester exchange between an aromatic dihydroxy compound such as bisphenol A and a carbonic acid diester such as diphenyl carbonate is used. A method of performing a reaction (polycondensation reaction) and the like are known. The former method is currently generally practiced, but the latter method is considered to be promising because it does not use cumbersome compounds such as phosgene.

[0003] Generally, bisphenol A (melting point 156)
C.) and diphenyl carbonate (melting point 80 ° C.) separately or mixed and heated and melted. After adding a catalyst to a mixed solution of both compounds, the mixture is heated to the reaction temperature and polycondensed in a reactor.

However, there is a disadvantage that the product polycarbonate is colored because it is exposed to a high temperature for a long time due to the reaction in the molten state.

[0005] Aromatic polycarbonates are often used for optical applications. Therefore, it is desired that the polycarbonates have as good a hue as possible, that is, a low yellowish color and good transparency.
For that purpose, various catalyst systems have been proposed (JP-A-4-89824, JP-A-3-203928).
It is also known to attempt to reduce the coloring of the product polycarbonate by using a high-purity aromatic dihydroxy compound. In order to obtain a high-purity aromatic dihydroxy compound, a recrystallization method, a distillation method, and an adduct forming method are known.

It has also been suggested that the material of the reactor affects the hue of the aromatic polycarbonate produced. For example, as disclosed in U.S. Pat. No. 4,383,092, it has been proposed to prevent product coloring by using tantalum, nickel or chromium as a material for a reactor. However, these metals are expensive and impractical to use in such devices. Japanese Patent Application Laid-Open No. 4-7328 describes that a colorless and transparent aromatic polycarbonate can be produced by buffing the inner wall surface of a stainless steel reactor. The publication describes that a colorless and transparent aromatic polycarbonate can be produced by pickling a wetted portion of a stainless steel reactor. However, even when the above treatment is performed, there is a disadvantage that the aromatic polycarbonate produced is colored yellow or brown.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an apparatus for producing an aromatic polycarbonate having an excellent hue.

[0008]

SUMMARY OF THE INVENTION The present invention relates to an apparatus for producing an aromatic polycarbonate by melt-polycondensing an aromatic dihydroxy compound and a carbonic acid diester with at least one inner wall of a stainless steel pipe through which the molten polymer passes. The part is an apparatus characterized in that the surface roughness _Rmax is 5 μm or less.

That is, the inventors of the present invention cannot remove the disadvantage that the produced aromatic polycarbonate is colored only by treating the inner wall surface of the reactor as described above. It was found that it was caused by piping. However, it is not easy to perform the above-described processing on all inner wall surfaces of the pipe,
It is not economically advantageous. Then, the present inventors further investigated the cause, and found that the influence was particularly at a location where the melt viscosity of the polymer was high in the piping, and by performing surface treatment only on the location, the above-mentioned disadvantage was sufficiently solved. And found that the present invention can be removed.

[0010] In the apparatus of the present invention, the surface roughness R _max of stainless steel pipe wall and 5μm or less, preferably a 2μm or less, particularly preferably at 1μm or less. If the surface roughness R _max exceeds 5 μm, the produced aromatic polycarbonate is undesirably colored yellow or brown. Here, the surface roughness _Rmax is a value which is generally used as a unit indicating the smoothness of the inner wall surface of the pipe, and is defined by JIS.
B 0601-1970. Further, the value can be measured using a general surface roughness measuring device such as a stylus type, a light cutting type, and a light interference type.

As a method for providing such smoothness to the inner wall surface of the pipe, there are known mechanical polishing such as buff polishing specified in JIS H 0400-1961, or “Handbook of Metal Surface Techniques” (Revised New Edition, p. Chemical polishing or electrolytic polishing described in Surface Technology Association, Nikkan Kogyo Shimbun) is preferable.

The stainless steel pipe through which the polymer melted by the method of the present invention passes means, of course, a stainless steel pipe for connecting each reactor and a stainless steel pipe for taking out the generated aromatic polycarbonate. It also includes a pump for feeding the polymer, or a flow meter, a pressure gauge, and the like connected to the pipe. As the material of the stainless steel pipe, for example, SUS304, SUS30
4L, SUS316, SUS316L, and the like, but are not limited thereto.

In the method of the present invention, it is preferable that only the portion of the stainless steel pipe where the melt viscosity of the polymer is particularly high, for example, the downstream portion of the final reactor is polished to a predetermined surface roughness. . By performing the treatment, a colorless, transparent, and extremely excellent aromatic polycarbonate can be produced. Also, the entire inner wall surface of the pipe may be polished to a predetermined surface roughness.

Hereinafter, an example of the apparatus of the present invention will be described with reference to FIG.

In this apparatus, the surface roughness _{Rmax is set} to 5 μm or less for the inner wall surfaces of 10 and 14 of the stainless steel tubes 6, 10 and 14 through which the polymer passes.

The stirring tank 4 has stirring blades attached to a vertical rotating shaft, and the above-mentioned aromatic dihydroxy compound and carbonic acid diester are continuously supplied to the stirring tank via pipes 1 and 2, respectively. The stirring tank atmosphere is substantially free of oxygen, and the stirring tank is purged with, for example, nitrogen gas. A catalyst is supplied to the stirring tank through a pipe 3 and mixed with the reaction raw materials. Also, a plurality of agitation tanks can be provided in series to form a uniform solution.

The mixed raw materials are supplied to a pre-polymerization tank 8 through a pipe 6 by a pump 5. The prepolymerization tank is provided with a stirring blade having a vertical rotation axis. The inside of the tank is kept at a reduced pressure by a vent conduit 7 provided at the top. By-product phenol and some unreacted monomer sucked through the conduit 7 are respectively rectified, phenol is discharged out of the system, and unreacted monomer is returned to the polymerization tank. Further, a catalyst can be further supplied through the pipe 3 '.

One or more prepolymerization tanks 8 can be provided in series, and preferably two to four prepolymerization tanks are provided, and the more downstream, the more severe the reaction conditions. The reaction temperature in the first prepolymerization tank is usually 50 to 270 ° C, preferably 150 to 260 ° C.
° C, and the pressure can be reduced from normal pressure to 6 mmHg, and the lower limit is preferably 400 to 6 mmHg.
Hg, particularly preferably in the range of 300 to 6 mmHg.

The reaction temperature in the second and subsequent prepolymerization tanks is usually from 180 to 285 ° C, preferably from 200 to 270 ° C.
° C and the pressure is in the range of 1 to 50 mmHg, preferably 1 to 30 mmHg.

The aromatic polycarbonate having a certain degree of polymerization as described above has an intrinsic viscosity [η] measured in a methylene chloride solution at 20 ° C. of 0.1 to 0.5 dl /.
g, preferably 0.15 to 0.45 dl / g, and more preferably 0.15 to 0.4 dl / g.

Next, the polymer is supplied to a horizontal stirring polymerization tank 12. The horizontal stirring polymerization tank has one or more horizontal rotation axes, and one or more types of stirring blades such as a disk type, a wheel type, a paddle type, a rod type, and a window frame type are provided on the horizontal rotation axis. A horizontal high-viscosity liquid treatment apparatus in which two or more types are combined and installed at least two or more stages per rotation axis, and the stirring blade lifts or spreads the reaction solution to renew the surface of the reaction solution. The reaction temperature there is usually 240 to 3
The temperature is in the range of 20 ° C, preferably 250 to 310 ° C, and the pressure is 20 mmHg or less, preferably 10 mmHg or less.

At least one, preferably one or two, horizontal stirring polymerization tanks are provided in series. The viscous polymer is taken out from the bottom of the last horizontal stirring polymerization tank by the gear pump 13 and has an intrinsic viscosity [η] of 0.20 to 1.0 dl / g, preferably 0.1 to 0.1 dl / g, measured in a methylene chloride solution at 20 ° C. 25 to 0.9 dl / g, more preferably 0.2 to 0.9 dl / g.
A polycarbonate of 30 to 0.8 dl / g is obtained.
After the polycondensation reaction is carried out in a horizontal stirring polymerization tank, the reaction can be further carried out by a twin-screw vented extruder. In the case of using a twin-screw vented extruder, the polycondensation reaction has progressed considerably in the horizontal stirring polymerization tank in the preceding stage, so that the reaction conditions of the twin-screw vented extruder can be relaxed and the quality of polycarbonate is prevented from deteriorating. It is possible to do.

The above reactors and reaction conditions are merely examples and are not limiting.

In the present invention, the polymer refers to a polymer of an aromatic dihydroxy compound and a carbonic acid diester.

Here, the aromatic dihydroxy compound is represented by the following formula [I]

[0026]

Embedded image (Where X is

[0027]

Embedded image -O -, - S -, - SO- or -SO ₂ - and is, R
₁ and R ₂ are a hydrogen atom or a monovalent hydrocarbon group,
R ₃ is a divalent hydrocarbon group. The aromatic nucleus may have a monovalent hydrocarbon group. ).

As such an aromatic dihydroxy compound,
For example, bis (4-hydroxyphenyl) methane, 1,1
-Bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4
-Hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-bis (4-hydroxy-1-methylphenyl) propane, 1,1-bis (4-hydroxy-3-t-butylphenyl) Bis (hydroxyaryl) alkanes such as propane, 2,2-bis (4-hydroxy-3-bromophenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4- Bis (hydroxyaryl) cycloalkanes such as (hydroxyphenyl) cyclohexane, dihydroxyaryl ethers such as 4,4'-dihydroxydiphenylether and 4,4'-dihydroxy-3,3'-dimethylphenylether;
4,4'-dihydroxydiphenyl sulfide, 4,
Dihydroxydiaryl sulfides such as 4'-dihydroxy-3,3'-dimethyldiphenyl sulfide;
4,4'-dihydroxydiphenylsulfoxide, 4,
Dihydroxydiarylsulfoxides such as 4'-dihydroxy-3,3'-dimethylphenylsulfoxide;4,4'-dihydroxydiphenylsulfone;
Examples include dihydroxydiarylsulfones such as 4'-dihydroxy-3,3'-dimethyldiphenylsulfone and the like, and 2,2-bis (4-hydroxyphenyl) propane (so-called bisphenol A) is particularly preferred.

The carbonic diester may be, for example, diphenyl carbonate, ditolyl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, etc. And diphenyl carbonate is particularly preferred.

The above-mentioned carbonic acid diester may contain a dicarboxylic acid or a dicarboxylic acid ester in an amount of preferably 50 mol% or less, more preferably 30 mol% or less. Examples of the dicarboxylic acid or dicarboxylic acid ester include terephthalic acid, isophthalic acid, diphenyl terephthalate, and diphenyl isophthalate. When a dicarboxylic acid or a dicarboxylic acid ester is used in combination with a carbonic acid diester, a polyester polycarbonate is obtained.

The carbonic acid diester is preferably used in an amount of 1.01 to 1.30 mol, preferably 1.02 to 1.20 mol, per 1 mol of the aromatic dihydroxy compound. A compound having three or more functional groups (preferably a phenolic hydroxyl group or a carboxyl group) in one molecule can be further added, and preferably 0.001 to 0.03 mol, particularly 0 to 1 mol of the aromatic dihydroxy compound. It is used in an amount of 0.001 to 0.01 mol. Examples of such compounds are described in JP-A-4-89824.

The polymerization reaction proceeds in the presence of a catalyst. As the catalyst, any known catalyst can be used.
For example, a catalyst system comprising (a) a nitrogen-containing basic compound and (b) an alkali metal compound or an alkaline earth metal compound described in JP-A-2-124934, or (c) boric acid or boric acid Catalyst systems consisting of esters can be used. A catalyst system comprising an electron-donating amine compound and potassium borohydride or an alkali metal compound or an alkaline earth metal compound described in JP-A-4-46927 and JP-A-4-46928 can also be used. Also, Japanese Unexamined Patent Publication No. Sho.
A catalyst system comprising a nitrogen-containing basic compound and a boron compound described in Japanese Patent Application Laid-Open (JP-A) No. 6-284, can be used.

In the polymerization reaction, various phenols can be used as a terminal blocking agent.
No. 175723 can be mentioned.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

[0035]

EXAMPLES In Examples and Comparative Examples, intrinsic viscosity [IV] and hue [YI] of polymers were measured as follows.

Intrinsic viscosity [IV] Measured in methylene chloride at 20 ° C. using an Ubbelohde viscometer.

Hue [YI] A 3 mm thick injection molded plate is molded at a cylinder temperature of 290 ° C., an injection pressure of 1000 kg / cm, a cycle of 45 seconds, a mold temperature of 100 ° C., and the X, Y and Z values are determined by Nippon Denshoku Industries. (stock)
Made by Color and Color Differe
The yellowness [YI] was measured by a transmission method using Nonce Meter ND-1001 DP.

YI = 100 (1.277X−1.060Z) / Y

[0039]

Example 1 The polymerization reactor shown in FIG. 1 was used. Piping molten polymer passes is SUS316 steel tube, subjected to a surface treatment by mechanical polishing, pipe wall surface roughness R _max 3 the pipe 10 and 14 in FIG. 1
μm or less. There are two prepolymerization tanks and two horizontal stirring polymerization tanks, and the respective reaction conditions are as follows.

Pressure (torr) Temperature (° C.) Average residence time (hr) Stirring tank Nitrogen atmosphere 130 2.0 Pre-polymerization tank A 100 210 1.0 Pre-polymerization tank B 20 240 0.5 Horizontal stirring polymerization tank A 3 285 0.5 Horizontal stirring polymerization tank B 0.3 290 0.5 Bisphenol A (Nihon GE Plastics Co., Ltd.)
0.44 mmol, 0.46 mmol of diphenyl carbonate (manufactured by Any), and 0.11 mol (2.51 mol) of tetramethylammonium hydroxide as a catalyst.
× 10 ^-4 mol / mol-bisphenol A) and 0.00044 mol of sodium hydroxide (1 × 10 ^-6 mol / mol-
Bisphenol A) was continuously supplied to a stirring tank maintained at the above temperature to produce a homogeneous solution.

Subsequently, the solution was sequentially supplied to a pre-polymerization tank A, a pre-polymerization tank B, a horizontal stirring polymerization tank A, and a horizontal stirring polymerization tank B, and polymerization was performed under the above reaction conditions to produce a polycarbonate.

The limiting viscosity of the obtained polycarbonate is as follows:
0.50 dl / g in methylene chloride at 20 ° C.

The hue was 1.44.

[0044]

Example 2 Polycarbonate was manufactured using the same apparatus and conditions as in Example 1 except that the inner wall surfaces of the pipes 10 and 14 in FIG. 1 were mechanically polished so that the surface roughness _{Rmax was} 1 μm or less. did.

The intrinsic viscosity of the obtained polycarbonate is:
0.50 dl / g in methylene chloride at 20 ° C.

The hue was 1.35.

[0047]

Comparative Example 1 SUS316 through which a molten polymer passes
Polycarbonate was produced using the same apparatus and conditions as in Example 1 except that the inner wall surface of the steelmaking pipe was not subjected to surface treatment and an apparatus having a surface roughness _Rmax of 10 μm or more was used.

The intrinsic viscosity of the obtained polycarbonate is as follows:
0.50 dl / g in methylene chloride at 20 ° C.

The hue was 2.3.

As described above, the aromatic polycarbonate produced by using the apparatus of the present invention was remarkably excellent in hue as compared with the method of the comparative example.

[0051]

The aromatic polycarbonate produced by using the apparatus of the present invention is colorless and transparent and has a very excellent hue.

[Brief description of the drawings]

FIG. 1 is a flow sheet of the present invention.

[Explanation of symbols]

 1, 2 Raw material introduction pipe 3, 3 'Catalyst introduction pipe 4 Stirring tank 5, 9, 13 Pump 6, 10, 14 Pipe through which molten polymer passes 7, 11 Vent conduit 8 Prepolymerization tank 12 Horizontal stirring polymerization tank m ≧ 1, n ≧ 1

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kimiyoshi Miura 6-12-2 Waki, Waki-machi, Kuga-gun, Yamaguchi Japan Within GE Plastics Co., Ltd. (72) Tomoaki Shimoda Waki, Waki-cho, Kuga-gun, Yamaguchi 6-1-2 1-2 Japan GE Plastics Co., Ltd. (56) References JP-A-4-7328 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 64/00- 64/42

Claims (1)

(57) [Claims] In an apparatus for producing an aromatic polycarbonate by melt-polycondensing an aromatic dihydroxy compound and a carbonic acid diester, at least a part of the inner wall surface of a stainless steel pipe through which the molten polymer passes has a surface roughness R _max. An apparatus characterized in that the thickness is 5 μm or less.