JP3719348B2 - Method for producing polycarbonate - Google Patents

Description

【００４０】
【発明の効果】
本発明のような溶融法によるポリカーボネート樹脂の製造法の場合、一定速度以上での昇温速度を要求され、一方で架橋反応を回避すべく加熱媒体の温度を上げられない、と云ったジレンマの関係にある。このジレンマを解決する手段として、本願の様な装置上の工夫をすることで両者を満足させることが可能となった。
【図面の簡単な説明】
【図１】実施例１に用いた重合缶の概念図。
【図２】実施例２に用いた重合缶の概念図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a polycarbonate, and more particularly to a production method for obtaining a polycarbonate with little thermal deterioration. In particular, the present invention relates to a production method for obtaining an optical polycarbonate resin.
[0002]
[Prior art]
Polycarbonate resins are excellent in mechanical strength, especially impact resistance and transparency, and are therefore widely used as optical materials in applications such as optical lenses, disks, and sheets. Under these circumstances, in recent years, a polycarbonate resin production method using a polycarbonate raw material (diaryl carbonate and diphenol) that does not use phosgene, methylene chloride, or the like is becoming mainstream. The degradation reaction (crosslinking reaction) of the polycarbonate oligomer or polymer on the wall surface in contact with the heating medium cannot be ignored, and many polymerization devices have been developed as means to avoid this, and as a horizontal polymerization device with a self-cleaning function Various devices have been devised such as SCR (trade name, manufactured by Mitsubishi Heavy Industries, Ltd.), Violac (trade name, manufactured by Sumitomo Heavy Industries, Ltd.) and lattice blades (manufactured by Hitachi, Ltd.).
[0003]
However, since these devices are also of a horizontal type, a certain liquid viscosity is required, and in the case of a melt that does not have a constant viscosity, there is a disadvantage that these models cannot be used. However, since the above degradation reaction (crosslinking reaction) occurs depending on the polymerization temperature, in the case of a polycarbonate oligomer in the previous stage entering the horizontal reactor, a vertical polymerization apparatus must be used, When the scale of this apparatus was increased, how to avoid the deterioration reaction was a very important proposition.
[0004]
Furthermore, in the method of increasing the molecular weight in such a molten state, it is also understood that the polycarbonate oligomer has a property of crystallizing when held for a certain period of time in a certain molecular weight range. Since it has been transformed into polycarbonate, it is necessary to raise the temperature to a temperature at which this crystallized product is melted, resulting in a dilemma that requires an operation to accelerate the thermal degradation. In particular, when the scale of the apparatus is increased, it is inevitable to maintain a temperature increase rate above a certain rate in order to avoid this crystallization behavior. However, whether to avoid the above deterioration reaction was an important issue.
[0005]
[Problems to be solved by the invention]
Under such a background, as a conventionally known technique, there was a technique of inserting a coil for introducing a heat medium in order to increase the heat transfer area in the polymerization can (JP-A-8-3309), Stirring in the polymerization canister is not necessarily performed uniformly, the oligomer of the poorly stirred part of the above-mentioned thermal degradation reaction is fast, and once the crosslinking reaction has started, it will move in a direction that is less likely to flow The difference between the well-stirred portion and the unsatisfactory portion is further enlarged. The melt between the coils corresponds to a typical example of the poorly stirred portion, and the development of a technique for allowing the inter-coil melt to flow skillfully and extending the molecular weight while maintaining a uniform molten state has been awaited.
In particular, when the obtained polycarbonate resin is used as an optical molded product, the microgel present in a very small amount is mainly generated from the above-mentioned cross-linking reaction or the residue of the crystallized product, which is a decisive damage to the product quality. .
[0006]
[Means for Solving the Problems]
In view of the above circumstances, the present invention has been intensively studied on the flow of the melt between the coils, and as a result, in order to improve the flow in the direction perpendicular to the coils, the flow between the coils in the direction perpendicular to the flow forcibly generated from the stirring blades. As a positioning speed and its linear velocity
[Equation 3]
log u ≧ −0.15 * logμa + 1.24 (1)
u: Linear velocity of melt (cm / sec), μa: Melt viscosity of melt (poise)
[0008]
The resin which stays by maintaining is suppressed, and it came to make this invention.
That is, in the present invention, when the polycarbonate raw material (diaryl carbonate and diphenol) is polycondensed in a molten state, the linear velocity of the wall surface in contact with the heating medium introduced for heating the portion that is a liquid phase is as follows:
[0009]
[Expression 4]
log u ≧ −0.15 * logμa + 1.24 (1)
u: Linear velocity of melt (cm / sec), μa: Melt viscosity of melt (poise)
[0010]
A method for producing a polycarbonate, comprising stirring in a polymerization can in a state where the linear velocity is maintained.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described in detail below.
The polycarbonate resin of the present invention is usually obtained by reacting diphenol with a carbonate raw material. The diphenol used in the present invention preferably corresponds to the general formula HO-Z-OH. Here, Z is one or more aromatic nuclei, and the hydrogen bonded to the carbon of the nucleus can be substituted with chlorine, bromine, an aliphatic group or an alicyclic group. The plurality of aromatic nuclei can also have different substituents. Further, the plurality of aromatic nuclei may be bonded by a crosslinking group. The bridging group includes an aliphatic group, an alicyclic group, a heteroatom, or a combination thereof.
[0012]
Specifically, hydroquinone, resorcin, dihydroxydiphenol, bis- (hydroxyphenyl) -alkane, bis- (hydroxyphenyl) -cycloalkane, bis- (hydroxyphenyl) -sulfide, bis- (hydroxyphenyl) -ether, bis -(Hydroxyphenyl) -ketones, bis- (hydroxyphenyl) -furphones, bis- (hydroxyphenyl) -sulfoxides, bis- (hydroxyphenyl) -dialkylbenzenes and their derivatives with alkyl or halogen substituents in the nucleus Is mentioned. Of course, two or more of these diphenols can be used in combination.
[0013]
These diphenols and other suitable diphenols are described, for example, in U.S. Pat. Nos. 4,982,014, 3,028,365, 2,999,835, and 3,148,172. 3,275,601, 2,991,273, 3,271,367, 3,062,781, 2,970,131, and 2,999. , 846, German Patent Publication Nos. 1,570,703, 2,063,050, 2,063,052, and 2,211,956, and It is described in the specification of French Patent No. 1,561,518.
[0014]
Particularly suitable diphenols include 2,2-bis- (4-hydroxyphenyl) -propane, 2,2-bis- (3,5-dimethyl-4-hydroxyphenyl) -propane, 1,1-bis- (4-hydroxyphenyl) -cyclohexane and 1,1-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane are included.
[0015]
The production method of diaryl carbonate, which is the other raw material, is roughly divided into two. One is dialkyl carbonate by reaction in the presence of a catalyst of carbon monoxide and monoalkyl alcohol, and then with aryl alcohol. There are ones that obtain diaryl carbonate by transesterification and the other one that uses phosgene as a raw material and obtains diaryl carbonate by reaction with aryl alcohol. Diphenyl carbonate is used.
[0016]
In addition, alkali metals, alkaline earth metals, their salt compounds, basic compounds, and the like are used as polymerization catalysts.
In the polymerization method of the present invention, first, polycarbonate raw materials (diaryl carbonate and diphenol) are charged in a molten state into a polymerization can equipped with a heating device and a stirring blade, and the molecular weight is extended while distilling off by-produced phenol under reduced pressure. However, as a method for improving the flow between the heat transfer coils, particularly the portion with poor flow, the coils are positioned in the vertical direction with respect to the flow forcibly generated from the stirring blades. It is possible to achieve this condition in any form such as a ribbon blade, a max blend blade, a full zone blade, and a turbine blade as a forced flow generated from the stirring blade. The linear velocity (u) of the melt needs to satisfy the formula (1). Especially when forced flow is generated in the circumferential direction, the support plate of the coil is positioned in a direction perpendicular to the flow to act as a baffle, and at the same time, the flow of the back surface of the support plate is taken into account, and the rotation direction of the stirring blade As the linear velocity between coils by having the same inclination as
[Equation 5]
log u ≧ −0.15 * logμa + 1.24 (1)
u: Linear velocity of melt (cm / sec), μa: Melt viscosity of melt (poise)
[0018]
Can be achieved. On the other hand, in the case of a ribbon blade in which a forced flow is generated in the vertical direction, the linear velocity between the coils can be obtained by arranging the coil at the position where the forced flow is strongest.
[Formula 6]
log u ≧ −0.15 * logμa + 1.24 (1)
u: Linear velocity of melt (cm / sec), μa: Melt viscosity of melt (poise)
[0020]
Can be achieved.
As the linear velocity of heat transfer walls such as coils,
[0021]
[Expression 7]
log u ≧ −0.15 * logμa + 1.24 (1)
u: Linear velocity of melt (cm / sec), μa: Melt viscosity of melt (poise)
[0022]
It is necessary, but preferably [0023]
[Equation 8]
log u ≧ −0.15 * logμa + 1.3 (1 ')
u: Linear velocity of melt (cm / sec), μa: Melt viscosity of melt (poise)
[0024]
More preferably, [0025]
[Equation 9]
log u ≧ −0.15 * logμa + 1.4 Equation (1 ”)
u: Linear velocity of melt (cm / sec), μa: Melt viscosity of melt (poise)
[0026]
Is desired. When this linear velocity is low, the melt stays between the coils, and as a result, a crosslinking reaction is unavoidable and a microgel is generated.
The molecular weight range to which the polymerization can of the present invention is applied is preferably up to about Mv = 10000 and the melt viscosity up to 1000 poise. When the molecular weight increases and enters a region exceeding 1,000 poise, the removal of unreacted monomer and by-product phenol that remains as a by-product beyond the molecular weight extension becomes a problem, and it has the self-cleaning property as described above. Since a model having a thin film evaporation function by a horizontal polymerization machine is selected, a vertical reaction machine is not very advantageous.
[0027]
In the polymerization temperature range, the range between 200 ° C. and 300 ° C. is the most important, and the temperature difference between the polymerization can internal temperature (internal temperature) and the heating medium is usually in the range of 10 ° C. to 80 ° C.
Since the temperature range in which crystallization is a problem is in the range of 200 ° C. to 250 ° C., the technique of the present invention is useful during this period.
[0028]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described according to examples. However, the present invention is not limited to these unless it exceeds the gist.
The measurement was performed by the following method.
(1) Viscosity average molecular weight (Mv)
From the specific viscosity (ηsp) measured at a temperature of 20 ° C. using an oligomer or polycarbonate concentration (C) 0.6 g / dl methylene chloride solution,
[Expression 10]
ηsp / C = [η] (1 + 0.28 ηsp)
[Η] = 1.23 × 10 ⁻⁴ Mv ^0.83
[0030]
It calculated using.
(2) Structural viscosity index (N)
Using Toyo Seiki Co., Ltd. CAPIROGRAPH-1B (Dice L / D = 10/1 (mm / mm))
The melt viscosity of the polymer at 250 ° C. was measured and determined by the following general formula. However, the larger N is, the more the crosslinking is progressing.
[0031]
[Expression 11]
logμa ₁ -logμa ₂ = {(1-N) / N} × (logγ ₁ -logγ ₂ )
(Wherein μa ₁ and μa ₂ (poise) indicate melt viscosities at shear rates γ ₁ and γ ₂ (sec ⁻¹ ), respectively, and γ ₁ and γ ₂ are two different points of 30 or less)
[0032]
(3) Estimation of fluid linear velocity around the coil:
As physical property values at the stage of changing from oligomer to polymer, specific gravity (791.9kg / m3) and viscosity (600poise) were used, and calculation analysis was performed by Star-CD (CD-adapco). The fluid linear velocity around the coil was estimated.
[0033]
<Manufacture of diphenyl carbonate>
In the presence of pyridine, which is a catalyst for phosgene and phenol, the reaction was carried out at 150 ° C., and crude diphenyl carbonate was obtained while removing hydrogen chloride gas. After washing with NaOH and H ₂ O, light boiling components (unreacted phenol, After distillation of pyridine), diphenyl carbonate could be distilled.
[0034]
Example 1
A reflux condenser in which 34.7 mol of the obtained diphenyl carbonate, 33.0 mol of bisphenol A (manufactured by Nippon Steel Chemical Co., Ltd.), an aqueous cesium carbonate solution (0.5 (μmol / bisphenol A-mol) as cesium carbonate) was controlled at 100 ° C. After being purged with nitrogen, the mixture was stirred at 300 rpm, heated through a heating medium at 230 ° C. and dissolved, and then the pressure was increased from 760 torr to 100 torr over 40 minutes. Subsequently, the oligomerization reaction was carried out for 80 minutes while the phenol was distilled off while maintaining the pressure at 100 torr.
[0035]
As shown in FIG. 1, this oligomer is fed to a 40 L polymerization tank equipped with a Max blend blade and a coil and a support plate (45 degrees in the same direction as the blade rotation method) around the blade at 38 rpm. While stirring, a heating medium of 300 ° C. was passed through the coil and the outer jacket, the pressure was adjusted to 0.5 torr over 120 minutes, and a condensation reaction was carried out for 90 minutes while maintaining this pressure. Ninety minutes after reaching the pressure of 0.5 torr, the stirring was stopped, and the operation of returning to 5 KG with nitrogen gas, extracting in a strand form, and forming into a pellet form was repeated four times. The results are shown in Table-1.
[0036]
Example 2
In Example 1, as shown in FIG. 2, the same operation as in Example 1 was performed except that the Max Blend wing was replaced with a helical ribbon wing and an apparatus excluding the coil support plate was used. The results are shown in Table-1.
[0037]
Example 3
In Example 2, the same operation as in Example 1 was performed except that an apparatus in which a coil was installed at the center of the helical ribbon blade was used. The results are shown in Table-1.
[0038]
Comparative Example 1
In Example 1, the same operation as in Example 1 was performed, except that a device in which only a coil was installed around the blade and no support plate was used was used. The results are shown in Table-1.
[0039]
[Table 1]

[0040]
【The invention's effect】
In the case of a method for producing a polycarbonate resin by a melting method such as the present invention, a dilemma that requires a temperature increase rate at a certain rate or more but cannot increase the temperature of the heating medium in order to avoid a crosslinking reaction. There is a relationship. As a means for solving this dilemma, it has become possible to satisfy both of them by devising the apparatus as in the present application.
[Brief description of the drawings]
1 is a conceptual diagram of a polymerization can used in Example 1. FIG.
2 is a conceptual diagram of a polymerization can used in Example 2. FIG.

Claims (4)

In the polycarbonate production method in which diaryl carbonate and diphenol are polycondensed in the molten state, the linear velocity of the wall surface in contact with the heating medium introduced for heating the liquid phase portion is as follows: A method for producing a polycarbonate, comprising stirring the polymerization can in a held state.

u: Linear velocity of melt (cm / sec), μa: Melt viscosity of melt (poise) In a polycarbonate production method in which diaryl carbonate and diphenol are polycondensed in a molten state, a heating medium introduced for heating a liquid phase portion is introduced as an internal coil, and the linear velocity (u) of the wall surface of the coil However, the inside of a superposition | polymerization can in the state by which the linear velocity of the following Formula was maintained is performed, The manufacturing method of the polycarbonate characterized by the above-mentioned.
log u ≧ −0.15 * log μa + 1.24 Formula (1)
u: linear velocity of melt (cm / sec) , μa: melt viscosity (poise) of melt A heating medium introduced for heating the liquid phase portion was introduced as an internal coil, and the linear velocity of the melt in the vertical direction of the coil was maintained at the linear velocity (u) of the above formula (1). The method for producing a polycarbonate according to claim 1 or 2, wherein stirring in the polymerization can in a state is performed in a continuous manner. The method for producing a polycarbonate according to claim 3, wherein the melt viscosity (µa) of the melt is in the range of the following formula in the formula (1).

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