EA037043B1 - Condensation polymer and manufacturing apparatus therefor - Google Patents

Abstract

Provided is a method for producing a polycondensation polymer capable of maintaining high quality of the polycondensation polymer. The method for producing the polycondensation polymer comprises a step of supplying a molten prepolymer into a polymerization reactor for producing the polycondensation polymer, the polymerization reactor comprising a casing, a guider provided in the casing and a polymer outlet connecting to the casing and provided at the lower part thereof; and a step of making the molten prepolymer to flow down the surface of the guider being in contact with the surface and polymerizing the molten prepolymer thus obtaining the polycondensation polymer, wherein controlling is such that the project area of a part in the taper-like lower part of the casing where the polycondensation polymer flows down is large, or such that the liquid surface of a retentate in the taper-like lower part of the casing contains a great deal of the part where the polycondensation polymer flows down.

Description

The present invention relates to a method for the production of a polycondensation polymer and a plant for its production.

Technology area

Polycondensation polymers are used in high demand engineering plastics. Typical examples are polycarbonate, polyamide and polyester resins, predominantly used in PET (PET) bottles. For example, aromatic polycarbonates are engineering plastics with excellent transparency, heat resistance, and mechanical strength such as impact resistance, and are widely used in optical discs and electrical / electronic applications, as well as in industrial applications such as automotive applications.

Various polymerization reactors for producing aromatic polycarbonates by cross-polymerization are generally known. However, the viscosity of the polycarbonate increases as polymerization proceeds. Thus, if a polymerization reactor requiring mechanical agitation is used, it becomes difficult to mechanically agitate the mixture when the viscosity increases with an increase in the degree of polymerization. As a consequence, the degree of polymerization of the polycarbonate produced by such a polymerization reactor is limited. Accordingly, it is difficult to produce a high molecular weight aromatic polycarbonate widely used in sheet materials.

As a polymerization equipment that does not require mechanical agitation, a guided wetting drop polymerization apparatus is known in which polymerization is carried out by allowing the molten prepolymer to fall along a guide such as a wire by its own weight. If such a polymerization unit is used, the problem that stirring becomes impossible as the polymerization proceeds can be overcome. In addition, a by-product, i.e. an aromatic monohydroxy compound (eg, phenol) can be effectively removed from the surface of the molten material, whereby a high molecular weight aromatic polycarbonate can be produced. For example, Patent Document 1 describes a method for producing a polycondensation resin using a polymerization reactor in which guide wires are arranged at predetermined intervals with respect to the width of a molten prepolymer mass. According to this production method, a high quality polycondensation polymer can be efficiently produced at a high polymerization rate.

Citation List

Patent documents.

Patent Document 1: International Publication No. WO 2012/056903.

The essence of the invention

Technical problem.

In a drop polymerization apparatus with guided wetting, the polymer freely falling from the guide wire remains at the bottom of the polymerization reactor (for example, see Patent Document 1; in Fig. 1, the region between the inert gas feed port and the polymer outlet 7) until it flows out of the outlet. The downward flowing amount of polymer is controlled so that it is approximately equal to its discharged amount; however, the amount flowing down slightly increases or decreases as the operation is repeated, with the result that the retentate liquid level sometimes rises and falls. When the liquid level rises, a portion of the polymer having a relatively high viscosity and in contact with the top wall surface of the bottom in the form of an inverse cone remains attached to the wall surface even after the liquid level drops. If the remaining polymer is present in the path of the downflow polymer, the remaining polymer is washed off by the downflow polymer and becomes part of the retentate. This case is not a problem.

However, if the remaining polymer does not adhere in the downward flow path of the polymer, but to the wall surface, the polymer is not washed off by the downward polymer and is readily exposed to the ambient atmosphere or various thermal influences. Therefore, when the liquid level of the retentate rises again, the remaining polymer must be mixed with the retentate. However, if the remaining polymer, which is often degraded by exposure to ambient atmosphere or heat, is mixed with the concentrate, the remaining polymer causes degradation of the resulting resin.

In the general case of a small polymerization reactor having a simple internal structure, the internal structure is easily made so as to avoid the occurrence of a residual portion. As a constructional idea, for example, vertical wires (vertically extending) simply spaced evenly can be mentioned. However, in the case where the polymer is industrially produced in practice, the polymerization reactor is large, and the internal structure of the polymerization reactor is complicated to overcome manufacturing and strength problems. For example, vertical wires, as required, are divided into several blocks and placed. As a result, the structure of the block of vertical wires has a large effect on the path of the polymer flowing downward.

- 1 037043 from wire. For this reason, it is necessary to design a structure that does not cause the remaining part of the polymer to appear.

The present invention has been made to solve the above problems identified by the applicants. An object of the present invention is to provide a process for the production of a polycondensation polymer capable of maintaining a high quality of the polycondensation polymer, as well as an installation for the production of the polymer.

The solution of the problem.

Applicants have carried out intensive research in order to achieve the above object and have implemented the invention. More specifically, the present invention is the invention described in claims 1-6 below.

1. A method of obtaining a polycondensation polymer, comprising the following stages (I) and (II):

(I) a step of supplying the molten prepolymer to a polymerization reactor for the production of a polycondensation polymer, the reactor having a housing, a guide formed in the housing, and a polymer outlet connected to the housing and formed in its lower part; and (ii) a step of allowing the molten prepolymer to flow downward along the surface of the guide while in contact with the surface, and polymerizing the molten prepolymer, resulting in a polycondensation polymer, wherein the body has a cylindrical upper portion that has a lower annular edge having a larger a diameter than the diameter of the upper annular face of the polymer outlet, and a tapered lower portion connecting the lower annular edge of the cylindrical upper portion and the upper annular face of the polymer outlet, and has a tapered wall extending from the lower annular face to the upper annular face;

the housing, the guide and the polymer outlet are disposed so that the polycondensation polymer falling from the guide remains in the tapered bottom portion and flows downward along the inner surface of the tapered wall to the polymer outlet; and in the circular portion that is formed by the liquid surface of the polycondensation polymer remaining on the tapered lower portion in contact with the inner surface of the tapered wall, the liquid level is maintained within the interval where the total circumference L0 of said circular portion and the length L1 of a portion of said circumference in contact with the portion where the polycondensation polymer flows downward, satisfy the condition represented by the following formula (2):

L1 / L0> 0.90 (2).

2. The production method according to claim 1, wherein the liquid level is maintained within a range where the total length L0 and the length L1 satisfy the condition represented by the following formula (2A):

L1 / L0 = 1.00 (2A).

3. The method of obtaining in accordance with claim 1 or 2, in which the tapered lower portion further includes a tapered upper portion, a tapered lower portion and a cylindrical middle portion inserted between the tapered upper and lower portions;

in the portion connecting the tapered upper portion and the cylindrical middle portion of the tapered lower portion, the portion where the polycondensation polymer does not flow downward is not present; and the control is carried out so that the liquid surface of the polycondensation polymer remaining on the tapered bottom portion is present on the cylindrical middle portion.

4. The production method according to any one of claims 1 to 3, in which the residence time of the polycondensation polymer remaining in the tapered lower portion is within 3 hours.

5. The method of producing a polycondensation polymer according to any one of claims 1 to 4, wherein the guide is a guide wire and the polycondensation polymer contacts each other between the various guide wires and is combined to form a flat fluid and flows downward along the guide wire.

6. A production method according to any one of claims 1 to 5, wherein the polycondensation polymer is an aromatic polycarbonate.

The positive effects of the invention.

According to the present invention, it is possible to provide a method for producing a polycondensation polymer that is capable of maintaining a high quality of the polycondensation polymer, and an apparatus for producing the polymer.

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Brief Description of Drawings

FIG. 1 is a schematic diagram showing an example of a polymerization plant used in an embodiment of the present invention.

FIG. 2 is a schematic view showing an example of a polymerization plant used in an embodiment of the present invention, in which (A) is a schematic view of a polymerization reactor; (B) is a schematic cross-sectional view of the polymerization reactor along line J-J; (C) is an enlarged view of the guide wires shown in image (B); and (D) is a schematic view showing a part of the guide wire shown in (C).

FIG. 3 is a schematic view of an example of a polymerization plant used in Comparative Examples 3 and 4, in which (A) is a schematic view of a polymerization reactor; (B) is a schematic cross-sectional view of the polymerization reactor along the K-K line; (C) is an enlarged view of the guide wires shown in image (B); and (D) is a schematic view showing a part of the guide wire shown in the image (C).

FIG. 4 is a schematic view showing another example of a polymerization plant used in an embodiment of the present invention.

FIG. 5 (A) and 5 (B) are schematic views each showing the order of the guide wires in the polymerization plant used in the examples of the present invention.

Description of embodiments

Hereinafter, an embodiment for carrying out the present invention (hereinafter referred to simply as an embodiment) will be more specifically described with reference to the drawings, if necessary; however, the present invention is not limited to the embodiment described below. The present invention can be modified in various ways as long as the modification is not outside the scope of the invention. It should be noted that in the drawings, like reference numbers are used to denote like structural elements and duplicate explanations are excluded. Relative position (eg, top, bottom, left, and right) are described based on the relative position shown in the drawings unless otherwise specifically indicated. Moreover, the aspect ratios in the drawings are not limited to those shown in the drawings. In the specification, the diameter, if it can be interpreted as either the inner diameter or the outer diameter, means the inner diameter, unless otherwise specified.

A method for producing a polycondensation polymer according to an embodiment comprises the following steps (I) and (II):

(I) a step of supplying the molten prepolymer to a polymerization reactor to produce a polycondensation polymer, the reactor having a housing, a guide formed in the housing, and a polymer outlet connected to the housing and formed in its lower part; and (ii) a step of allowing the molten prepolymer to flow downward along the surface of the guide while in contact with the surface, and polymerizing the molten prepolymer, resulting in a polycondensation polymer, wherein the body has a cylindrical upper portion that has a lower annular edge having a larger a diameter than the diameter of the upper annular face of the polymer outlet, and a tapered lower portion connecting the lower annular edge of the cylindrical upper portion and the upper annular face of the polymer outlet, and has a tapered wall extending from the lower annular face to the upper annular face; the housing, the guide and the polymer outlet are disposed so that the polycondensation polymer falling from the guide remains in the tapered bottom portion and flows downward along the inner surface of the tapered wall to the polymer outlet; and in the circular portion that is formed by the liquid surface of the polycondensation polymer remaining on the tapered lower portion in contact with the inner surface of the tapered wall, the liquid level fluctuates within an interval where the total circumference L0 and the circumferential length L1 are substantially in contact with the portion where the polycondensation polymer flows downward, satisfy the condition represented by the following formula (2):

L1 / L0> 0.90 (2).

In an embodiment, a polycondensation polymer refers to a polymer that is produced by reaction between functional groups of two molecules, with the loss of smaller molecules so that polymerization proceeds. Specific examples are polycarbonate resin, polyamide resin and polyester resin. Examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polytrimethylene terephthalate (PTT). As a typical example of the polycarbonate resin, there can be mentioned an aromatic polycarbonate obtained by reacting an aromatic hydroxy compound with a diaryl carbonate.

- 3 037043

In the embodiment, as a typical example of the polycarbonate resin, there can be mentioned an aromatic polycarbonate obtained by reacting an aromatic hydroxy compound with a diaryl carbonate.

Aromatic dihydroxy compounds can be used alone or in combination of two or more compounds. As a typical example of an aromatic dihydroxy compound, bisphenol A can be mentioned. When bisphenol A is used concurrently with another aromatic dihydroxy compound, bisphenol A is preferably used in a ratio of 85 mol% or more based on the total amount of aromatic dihydroxy compounds. In such aromatic dihydroxy compounds, the content of the chlorine atom and the alkali or alkaline earth metal is preferably low and, if possible, substantially zero (100 ppb or less).

As the diaryl carbonate, for example, a symmetric diaryl carbonate such as a lower alkyl substituted diphenyl carbonate including unsubstituted diphenyl carbonate, ditolyl carbonate and di-tert-butyl phenyl carbonate is preferable, and diphenyl carbonate is preferable. Such diaryl carbonates can be used alone or in combination of two or more of them. In such diaryl carbonates, the content of the chlorine atom and the alkali or alkaline earth metal is preferably low and, if possible, substantially zero, more precisely, their content is preferably 10 ppb or less.

The used ratio (initial ratio) of the aromatic dihydroxy compound and the diaryl carbonate varies depending on, for example, the type of aromatic dihydroxy compound and the type of diaryl carbonate used, the desired molecular weight, the ratio of hydroxyl terminations and polymerization conditions, and is not particularly limited. Diaryl carbonate is used in a ratio of preferably 0.9 to 2.5 mol relative to the aromatic dihydroxy compound (1 mol), more preferably 0.95 to 2.0 mol, and also preferably 0.98 to 1.5 mol. In an embodiment, for end-group conversion and molecular weight control, an aromatic monohydroxy compound such as phenol, t-butylphenol, or cumylphenol may be used in combination.

In an embodiment, a polyfunctional compound may be used in combination to introduce a branched structure into a polycondensation polymer, as long as this does not interfere with the object of the present invention. For example, when a branched aromatic polycarbonate polymer is produced, the amount of the polyfunctional compound such as a trivalent aromatic trihydroxy compound, relative to the aromatic dihydroxy compound (100 mol%), is preferably 0.2 to 1.0 mol%, more preferably 0.2 to 0.9 mol%, and particularly preferably 0.3 to 0.8 mol%.

The polycondensation polymer can be produced without adding a polymerization catalyst; however, to increase the rate of polymerization, production is carried out in the presence of a catalyst, if necessary. If a catalyst is used, one catalyst, or two or more catalysts in combination, can be used. The amount of the catalyst used, for example, in the production of an aromatic polycarbonate from an aromatic dihydroxy compound as a starting material, is selected from the range usually from 1.0 x 10 ^-8 to 1.0 parts by weight. with respect to the aromatic dihydroxy compound (100 parts by weight) used as a starting material, and preferably from 1.0x10 ^-7 to 1.0x10 ^-1 mass.

When the polycondensation polymer is an aromatic polycarbonate, the number average molecular weight preferably falls within the range from 500 to 100,000, and more preferably from 2,000 to 30,000. The number average molecular weight can be measured using gel permeation chromatography (GPC).

In an embodiment, molten prepolymer means molten material during polymerization. For example, when the polycondensation polymer is an aromatic polycarbonate, a molten prepolymer refers to a molten material during polymerization made from an aromatic dihydroxy compound and a diaryl carbonate and having a lower molecular weight than an aromatic polycarbonate having a desired number average molecular weight. More specifically, the molten prepolymer refers in some cases to the raw material (s) for the polymer that is (s) introduced into the polymerization reactor, and in other cases to the polymer with an increased molecular weight as a result of the polymerization reaction proceeding to some degree in the polymerization reactor. Alternatively, the molten prepolymer may be an oligomer. It should be noted that the mixture of an aromatic dihydroxy compound and a diaryl carbonate is essentially a molten prepolymer since their reaction is simply heat / melt. The number average molecular weight of the molten prepolymer used in the embodiment is not particularly limited as long as the prepolymer is melted at the polymerization temperature, and may vary depending on its chemical structure. The number average molecular weight generally falls within the range of 500 or more and less than 100,000, preferably 500 or more and less than 10,000, and more preferably 1,000 or less and less than 8,000. The molten prepolymer used as

- 4 037043 polymer raw material of an embodiment of the invention can be obtained by any method known in the art.

FIG. 1 is a schematic view showing an example of a polymerization plant of the embodiment. The polymerization unit includes a polymerization reactor 100. The polymerization reactor is a directed wetting drop polymerization reactor in which polymer raw materials are allowed to fall downward along a guide, such as guide wires, to produce polycondensation polymer (hereinafter referred to simply as guide wires) while in contact with the guides to effect free fall polymerization with guided wetting of the polymer raw material. The polymerization reactor 100 has a raw material inlet 1, a raw material feed zone 3 in communication with a raw material inlet 1, a free-fall guided wetting polymerization reaction zone 5 located below the raw material feeding zone 3 and in communication with zone 3 of the supply of raw material, and the outlet 7 of the polymer, located at the bottom of the zone 5 of the polymerization reaction in free fall with guided wetting. Such zones are surrounded by a housing 13. In the reaction zone 5, wire guides 4 are formed. Above the wire guides 4, there is a distribution plate 2 for distributing and feeding the molten prepolymer (raw materials for the polymer) to all the wire guides 4. On the distribution plate 2, feed holes for the polymer are formed for transferring the molten prepolymer on the distribution plate 2 to the guide wires 4. The housing 13 has a cylindrical upper portion 13a that has a lower annular edge 13e having a larger diameter than the diameter of the upper annular edge 7a of the polymer outlet 7; and a tapered bottom portion 13c that connects the bottom ring-shaped edge 13e of the top section 13a with the top ring-shaped edge 7a of the polymer outlet 7, and has a tapered wall extending from the bottom ring-shaped edge 13e towards the top ring-shaped edge 7a. The guide wires 4 are formed from a plurality of vertical wires 10 (vertically extending) and anchor wire (s) 11 (extending horizontally) in combination.

Anchoring wire (s) 11 structurally support (s) vertical wires 10; however, fixing wire (s) may (s) be omitted. When a plurality of fixing wires 11 are used, the spacing between adjacent fixing wires, which can be arbitrarily selected, is preferably 30 mm or more and 1000 mm or less, and also preferably 40 mm or more and 200 mm or less.

A directed wet dip polymerization reactor (hereinafter sometimes referred to simply as a polymerization reactor) and a manufacturing method using a polymerization reactor are more specifically described with reference to FIG. 1. In the following description, a case is considered in which the polycondensation polymer is an aromatic polycarbonate. However, the present invention is not limited to the case described below.

The molten prepolymer is fed from the raw material inlet 1 to the polymerization reactor 100. The supplied molten prepolymer is directed into the feed zone 3 of the raw material above the distribution plate 2 and then directed through the polymer feed holes 12 formed in the distribution plate 2 into the drop polymerization reaction zone 5 with guided wetting having the guide wires 4. The expanded prepolymer is fed to the upper end guide wires 4, and it falls down along the vertical wires 10 of the guide wires 4 by its own weight, while being in contact with the vertical wires 10. A monohydroxy compound (for example phenol), which is formed as a by-product of the polymerization reaction during the downward fall, taken out of the vacuum vent b. Thus, the polymerization reaction proceeds with the formation of an aromatic polycarbonate. The aromatic polycarbonate is discharged through the polymer outlet 7 located in the lower section using the discharge pump 8.

When the molten prepolymer and the aromatic polycarbonate produced from the molten prepolymer (hereinafter referred to as molten prepolymers) fall downward by their own weight, while being in contact with one guide wire 4, it is preferable that at least part of the molten prepolymers into contact with molten prepolymers falling down along the adjacent vertical wire 10, while in contact with it, and combined with the adjacent molten prepolymers into a single mass of molten prepolymers. Since contact / pooling of the molten prepolymers occurs among the plurality of vertical wires 10 and is distributed over substantially all of the guide wires 4, the mass of molten prepolymers no longer falls like lines along the individual vertical wires 10, but falls like a web (having a flat shape) relative to all wires. guides 4. In this case, the expression mass of molten prepolymers falls like a web (apparently flat) means that the mass of molten prepolymers is present on top of a plurality of vertical wires 10 and forms a vertical 5 037043 planar configuration parallel to the direction of placement of vertical wires 10. More precisely, the mass the molten prepolymers falls down along the guide wires 4, forming a planar fluid, and turns into an aromatic polycarbonate.

The use of a polymerization reactor having vertical wires that are positioned to form a planar fluid is particularly preferred in an embodiment of the invention. If an aromatic polycarbonate having the same molecular weight is produced at the same temperature and at the same degree of vacuum, it is better to use a polymerization reactor having a structure in which the mass of molten prepolymers does not fall linearly, but in the form of a plane, since the speed mass flow per unit cross-sectional area is high. As a result, the density of the aromatic polycarbonate falling on the tapered bottom portion 13c of the polymerization reactor increases. In addition, since the amount of aromatic polycarbonate falling on the tapered bottom portion 13c per unit time also increases in a plane-like falling shape, the cleaning effect of the tapered bottom portion 13c with the aromatic polycarbonate also increases.

The performance of aromatic polycarbonate i.e. stable productivity (kg / (h-100 mm)), preferably 3 kg / (h-100 mm) or more, more preferably 5 kg / (h-100 mm) or more, and also preferably 10 kg / (h-100 mm) or more. Stable productivity in this case refers to the production volume of the polycondensation polymer (aromatic polycarbonate) per unit of time and per 100 mm in the horizontal direction of a guide wire having a plurality of vertical wires; in other words, refers to the upper limit of the aromatic polycarbonate production volume produced stably. The unit of measurement is expressed in terms of kg / (h-100 mm). Whether or not the aromatic polycarbonate has been produced can be stably determined based on whether the number average molecular weight (Mn) of the produced aromatic polycarbonate falls within the range of ± 5% of the target value. If the Mn falls within the range of ± 5% of the target value, the aromatic polycarbonate can be said to have been produced successfully and stably.

In this case, if the streams of molten prepolymer present on the plurality of vertical wires 10 supplied through the polymer feed holes 12 come into contact and combine with each other, the falling state becomes uniform in the horizontal direction due to the interaction of the molten prepolymer streams in the horizontal direction. In other words, since all of the molten prepolymer falls at a uniform rate compared to the case where the molten polymer streams fall separately along the individual vertical wires 10, the residence time of the molten prepolymers in the polymerization reactor 100 can be more even. As a result, aromatic polycarbonates having the same number average molecular weight can be produced in high yields. Until now, it has been believed that if streams of molten prepolymer falling along vertical wires 10 adjacent to each other come into contact with each other and combine more and more, the surface area of the site from which the monohydroxy compound (e.g. phenol) is removed is produced side by side in the polymerization reaction becomes smaller, as a result of which the polymerization rate drops dramatically.

However, in accordance with the studies carried out by the applicants, it has been found that the polymerization rate itself decreases slightly; and that since the amount of molten prepolymer supplied to the guide wire 4 can be increased, the yield can be dramatically increased and the density of the molten prepolymer per unit cross-sectional area of the polymerization reactor can be increased, whereby the yield can be significantly increased compared to the case where streams of molten prepolymer are allowed to fall down separately along individual vertical wires 10, while being in contact with them.

The detailed structure of the guide wire 4 and details such as the relative position of the resin feed holes 12 and the guide wires 4 may be the same as those described in Patent Document 1. The contents of Patent Document 1 are incorporated herein by reference.

In order for the molten prepolymer to bubble during the polymerization to increase the surface area, it is preferred that the molten prepolymer is able to absorb the inert gas that is supplied from the inert gas inlet 9 prior to introduction into the polymerization reactor 100. As a specific method of allowing the molten prepolymer to absorb an inert gas, for example, the method described in International Publication No. WO 99/64492 can be used.

The aromatic polycarbonate produced on the guide wires 4 falls from the lower end of the guide wires 4; however, at least a portion of the aromatic polycarbonate falls on the tapered wall of the tapered bottom portion (hereinafter also referred to as the bottom of the housing) 13c of the housing 13. The aromatic polycarbonate that falls on the tapered wall falls down the inner surface of the tapered wall along a slope in the direction of the polymer outlet 7. The aromatic polycarbonate is discharged from the discharge pump 8 through the polymer outlet 7. In the tapered bottom portion 13c, a predetermined amount of aromatic polycarbonate is usually allowed to remain. If the remaining amount is low, that is, there is a tendency that it will be difficult to discharge a predetermined amount of aromatic polycarbonate using the discharge pump 8. If the amount of the remaining aromatic polycarbonate is further reduced, cavitation of the discharge pump may occur 8. The amount of aromatic polycarbonate which is allowed to remain on the cone-shaped bottom section 13c can be adjusted by changing the discharge amount using the discharge pump 8 and by adjusting a valve element (not shown) installed on the discharge line. At the same time, an aromatic polycarbonate remains in the bottom of the housing 13c (the remaining aromatic polycarbonate hereinafter will sometimes be referred to simply as retentate) and the liquid surface of the retentate is in contact with the tapered wall of the bottom of the housing 13c.

In an aspect of the embodiment, the cylindrical top portion (hereinafter also referred to as skin) 13a in the body 13 of the polymerization reactor 100 has a diameter (inner diameter) of 0.90 m or more and 10 m or less.

The diameter of the skin 13a is 0.90 m or more and 10 m or less. If the diameter is 0.90 m or more, the aromatic polycarbonate can be mass produced in good yield. For reliable production of an aromatic polycarbonate with a polymerization reactor, in practice, the diameter of the skin 13a is 10 m or less, and also preferably 8 m or less. The casing 13a is a cylinder, and the diameter of any portion thereof in the vertical direction (vertical direction) is preferably the same; however, the skin 13a can have different diameters in the direction of the height. If the skin 13a has different diameters in the direction of the height, their minimum value is determined as the diameter of the skin 13 a. It should be noted that the diameter of the skin 13a changes due to the presence of a vacuum vent 6 and an inert gas inlet 9 formed on its side wall; however, such a change is not taken into account when calculating the diameter of the skin 13a. An observation window can be additionally equipped on the casing 13a through which the bottom of the housing 13c can be checked.

The bottom 13c is tapered, tapering from top to bottom. Examples of the cone shape include pyramid (linear cone), exponential cone, parabolic cone, and hemispherical cone. In order to allow the aromatic polycarbonate to flow down more reliably and to prevent the aromatic polycarbonate from attaching to the wall surface as much as possible, an inverted pyramid configuration tapering from top to bottom is preferred, and an inverse cone configuration tapering from top to bottom is more preferred.

The expression “imaginary outermost peripheral region” refers to a region surrounded by a plurality of outermost points of a region (X) where the aromatic polycarbonate flows downward, and straight lines connecting the plurality of outermost points. The most distant points are determined as follows. In the perspective projection (top view) of the polymerization reactor 100 when viewed from above in the vertical direction, if a straight line is extended from the center of the polymer outlet 7 in arbitrary directions, the lines intersect with the projection of the guide wires 4 at many points. The farthest point refers to the farthest point; however, in this case, the point (s) that will not (s) contribute to the formation of a region having a convex configuration extending outward, which is surrounded by a straight line connecting the outermost points, are excluded. This will be more specifically described with reference to FIG. 2. FIG. 2 is a schematic view showing an example of a polymerization plant used in the embodiment. View (A) is a schematic representation of a polymerization reactor; view (B) is a schematic cross-sectional view of the polymerization reactor along line J-J; view (C) is an enlarged view of the guide wires shown in view (B); and view (D) is a schematic view showing a part of the guide wire shown in view (C). View (A) is the same view as shown in FIG. 1 except that the retentate, the retentate liquid level L, and the J-J section line are added, and therefore a detailed explanation is omitted. FIG. (B) a plurality of guide wires 4a and 4b (hereinafter collectively also referred to as guide wires 4) are formed from vertical wires 10 and fixing wire (s) 11 in combination. The polymer outlet 7 is shown in the center of the figure. FIG. (C), which is an enlarged view of (B), the outer edge is the outer edge of an imaginary outermost peripheral portion. More precisely, in a projection perspective, straight lines geometrically extended from the center Z of the polymer outlet 7 intersect with the lines of the guide wires 4a and 4b. The farthest point, which is the farthest intersection point, is denoted by W. The collection of the set of the farthest points is the section shown by the bold line. The straight line connecting the farthest points is the section indicated by a thin line. Points V in the given

7 037 043 also represent the farthest intersection points between a straight line geometrically extended from the center Z of the polymer outlet 7 and the lines of the guide wires 4a and 4b in the projection. However, if the V points are included as the outermost points, a region having a convex configuration extending outward cannot be obtained. For this reason, V points are excluded from the most distant points. In the case where the bottom of the housing 13c is a reverse cone (tapering from top to bottom), the shaded portion in view (C) is defined as a portion (Y) where the aromatic polycarbonate does not flow downward at an imaginary outermost peripheral portion.

FIG. 3 is a schematic view showing a polymerization plant outside the scope of the present invention. Similarly to FIG. 2, view (A) is a schematic representation of a polymerization reactor; view (B) is a schematic cross-sectional view of the polymerization reactor along the K-K line; view (C) is an enlarged view of the guide wires in view (B); and view (D) is a schematic view showing a part of the guide wires shown in view (C). FIG. 3, a triangular section that is surrounded by two straight lines geometrically extended from the center Z of the polymer outlet 7 to adjacent two outermost points W and a straight line connecting these adjacent outermost points W is defined as a section (Y) where the polymer is not flows down. In this case, as shown in FIG. 3, the outlet region located in the center is excluded from the region (Y) (where the polymer does not flow downward). As shown in FIG. 2 and FIG. 3, from polygons that are surrounded by a straight line connecting adjacent outermost points W, a straight line geometrically extended from the center Z of the polymer outlet 7 towards the outermost point W, and a line showing the guide wire in perspective, a polygon having a line ( in a projection view) showing a guide wire not represented in the inner region (excluding the periphery) is defined as a portion (Y) where the polymer does not flow downward. The line (in perspective) showing the guide wire refers to the line joining the vertical wires at the two ends of the guide wire when viewed from above.

In an embodiment, at the imaginary outermost peripheral region, the ratio of region (Y) (where the polymer does not flow downward) should be low.

The area (Y) where the aromatic polycarbonate falling from the guide wire 4 does not flow downward can be reduced by accurately determining the number, size, configuration and position of the guide wires 4 so as to satisfy such a condition, as compared to the case where such the condition is not met. As a consequence, even if the liquid level (represented by the symbol L in FIGS. 2 (A) and 2 (C)) of the retentate at the bottom 13s rises and then falls, the amount of aromatic polycarbonate remaining in the region (Y) (where the aromatic polycarbonate does not flow down) decreases. As a result, even if the remaining aromatic polycarbonate is exposed to the ambient atmosphere or is subject to a thermal history and degrades, the amount of destroyed aromatic polycarbonate that is mixed with the retentate when the retentate liquid level L rises again can be minimized. The flow path of the polymer flow at the bottom of the polymerization reactor often changes depending on the difference in the viscosity of the produced resin and the surface condition of the inner wall of the polymerization reactor. The difference in resin viscosity will be more specifically described below. In the case where a resin having a certain viscosity is produced in a polymerization reactor, and then a resin having a different viscosity is produced in the same polymerization reactor, the flow path of the polymer flow at the bottom of the polymerization reactor often changes between the produced resins. In this case, in the production of the second resin, if the flow path is changed, the portion of the remaining polymer (the remaining portion) is spread over the area used as the flow path in the production of the first resin. The remaining area appears to be exposed to the surrounding atmosphere or heat history. Therefore, when the first resin is produced again, the portion of the remaining degraded polymer is used as a flow path for the polymer (first resin) and the degraded polymer is washed off again. Simultaneously, a large amount of degraded polymer is mixed with the polymer, which is produced as a product. In the event that the flow path of the polymer rarely changes and the area where the polymer flows is limited, the area of the remaining polymer rarely expands and mixing of the degraded polymer with the retentate can be suppressed. Degradation of the aromatic polycarbonate means that the molecular weight of the aromatic polycarbonate increases when it undergoes a thermal history, or is exposed to the ambient atmosphere, or sometimes gel depending on conditions. Such degraded polycarbonate causes an increase in the molecular weight distribution of the aromatic polycarbonate ultimately obtained, or an increase in the amount of branched polymer, thereby deteriorating the physical properties, color and appearance of the product. However, in an embodiment, the amount of the mixed destroyed aromatic polycarbonate can be minimized as described above. Accordingly, high quality of the aromatic polycarbonate ultimately obtained can be maintained.

- 8 037043

In an aspect of the embodiment, in the annular portion that is formed by the liquid level L of the aromatic polycarbonate remaining at the bottom of the housing 13c in contact with the inner surface of the tapered wall, the liquid level L fluctuates within an interval where the total circumference L0 and the circumferential length L1 are substantially in contact with the portion where the polycondensation polymer flows downward, satisfies the condition represented by the following formula (2); and also preferably within a range satisfying the condition represented by formula (2A) below.

L1 / L0> 0.90 (2)

L1 / L0 = 1.00 (2A)

The annular portion here means a portion formed when the bottom of the body 13c has a reverse conical configuration (tapering from top to bottom), i.e. the area surrounded by the circle shown by the dashed line in FIG. 2 (C). When the L1 / L0 value exceeds 0.90, the retentate is in less contact with the portion where the aromatic polycarbonate does not flow downward as compared to the case where the L1 / L0 value is 0.90 or less. As a consequence, even if the level of the retentate liquid L rises and then falls, the amount of aromatic polycarbonate remaining in the portion where the aromatic polycarbonate does not flow down is reduced. Accordingly, the amount of destroyed aromatic polycarbonate mixed with the retentate can be further minimized, whereby the quality of the resulting aromatic polycarbonate can be kept even higher. Specifically, the case where the conditions represented by the above formula (2A) are satisfied means that the liquid level L may fluctuate so that the retentate is not in contact with the region where the aromatic polycarbonate does not flow down, and therefore the quality of the aromatic polycarbonate in particular can be kept high.

It is desirable to keep the position of the liquid level L as constant as possible. More specifically, the range of fluctuations in the liquid level is maintained to fall within the range of 10%, preferably 5% and also preferably 2%. The liquid level in this case means the position of the liquid surface in the vertical direction, expressed as a percentage, assuming that the position in the vertical direction of the upper annular edge of the polymer outlet at the bottom of the polymerization reactor is defined as 0%, and the vertical position of the upper annular edge (others in other words, the lower annular edge of the skin) of the hull bottom is defined as 100%. In the polymerization reactor 100, assuming that the vertical position of the upper annular face 7a of the polymer outlet 7 in the lower portion of the polymerization reactor 100 is determined to be 0%, and the vertical position of the upper annular face (more precisely, the lower annular face 13e of the skin 13a) of the bottom body 13c is defined as 100%, the vertical position of the liquid surface, expressed as a percentage, represents the liquid level.

In an embodiment, the residence time of a polycondensation polymer such as an aromatic polycarbonate remaining at the bottom of the housing 13c is preferably within 3 hours, more preferably within 2 hours and also preferably within one hour. If the residence time falls within the aforementioned range, it is possible to further protect the retentate at the bottom of the housing 13c from the effects of thermal history, whereby a deterioration in the quality of the obtained resin can be effectively prevented. The residence time in this case means the time during which the aromatic polycarbonate falling from the guide wire 4 is in contact with the tapered wall of the bottom of the housing 13c, or the average time from the time point (time 0) at which the aromatic polycarbonate falls directly onto the retentate, until the time point at which the aromatic polycarbonate passes through the discharge pump 8 located downstream of the polymer outlet 7. The residence time can be obtained based on the volume of retentate, which is calculated from the liquid level at the bottom of the housing 13c and the amount of retentate discharged according to the formula below:

Residence time T (time) = volume of retentate (L) / amount of retentate withdrawn (L / time).

The time from the time point at which the molten prepolymer passes through the inlet of the raw material 1 to the time point at which the produced polycondensation polymer passes through the discharge pump 8 (hereinafter referred to as the transit time of the polymerization reactor) is preferably within 5 hours, more preferably within 3 hours and also preferably within 2 hours.

In order for the above residence time and the polymerization reactor passage time to fall within the above range, the retentate liquid L level can be controlled as low as possible in the vertical direction. More specifically, if the liquid level is controlled to be preferably 50% or less, and more preferably 30% or less, the residence time can easily fall within the above range. If the length and volume (diameter) of the pipe connecting the polymer outlet 7 and the discharge pump 8 are increased, the control can be performed so that the surface of the retentate liquid is inside the pipe.

- 9 037043

In the case where the aromatic polycarbonate is produced in the polymerization unit of the embodiment, the polymerization unit may have one polymerization reactor 100, or two or more polymerization reactors 100 may be used in combination. In addition, an aromatic polycarbonate can be produced using the polymerization reactor 100 according to the embodiment and other polymerization reactors in combination. For example, it is preferable that the aromatic dihydroxy compound and the diaryl carbonate are first polymerized using a reactor equipped with a stirrer to obtain a molten prepolymer, and then the resulting molten prepolymer is polymerized using the polymerization reactor 100 according to the embodiment.

As equipment for the production of molten prepolymer, a reactor other than the aforementioned stirred reactor may be mentioned, for example, a thin film reactor, a film type centrifugal evaporator reactor, a surface renewing twin screw kneading reactor and a wetted wall reactor. In an embodiment, the desired molten prepolymer can be produced by a step polycondensation reaction using reactors in combination. With regard to such manufacturing methods, for example, US Pat. No. 5,589,564 can be referred to. Materials for the polymerization reactor according to the embodiment and for other reactors are not particularly limited. The material forming at least the surface of the inner wall of the polymerization reactor or the entire reactor may be stainless steel, nickel or glass.

In an embodiment where an aromatic polycarbonate is produced by reacting an aromatic dihydroxy compound and a diaryl carbonate, the reaction temperature is usually 50 to 350 ° C, and preferably 100 to 290 ° C. The aromatic monohydroxy compound that forms as the reaction proceeds is removed from the reaction system to increase the reaction rate. For this purpose, it is preferable to use a method of introducing an inert gas such as nitrogen, argon, helium, carbon dioxide or a lower hydrocarbon gas that does not adversely affect the reaction in the polymerization reactor 100 and in other reactors, whereby the resulting aromatic monohydroxy compound is removed together with these gases; or a method for carrying out the reaction under reduced pressure. An inert gas can be introduced into the polymerization reactor 100 from the inert gas inlet 9.

The preferred reaction temperature varies depending, for example, on the type and molecular weight of the aromatic polycarbonate to be produced and the polymerization temperature. For example, if the aromatic polycarbonate is produced from bisphenol A and diphenyl carbonate, the reaction temperature preferably falls within the range of 100 to 270 ° C for a number average molecular weight range of less than 1000, and preferably falls within the range of 200 to 290 ° C for a range of number average molecular weight masses 1000 or more.

The preferred reaction pressure varies depending, for example, on the type and molecular weight of the aromatic polycarbonate to be produced and the polymerization temperature. For example, if the aromatic polycarbonate is produced from bisphenol A and diphenyl carbonate, the reaction pressure is preferably in the range of 50 mm Hg. (6660 Pa) to normal pressure with a number average molecular weight range of less than 1000; preferably falls within the range of 3 to 50 mm Hg. (400-6600 Pa) with a number average molecular weight ranging from 1000 to 2000; and is preferably 20 mm Hg. (2670 Pa) or less, especially 10 mm Hg. (1330 Pa) or less; and also preferably 2 mm Hg. (267 Pa) or less in a number average molecular weight range of over 2000. Preferably, the above-mentioned reaction method is used by introducing an inert gas into the polymerization reactor 100 from an inert gas inlet 9 under reduced pressure. On the other hand, a polymerization method using a molten prepolymer pre-absorbing an inert gas is also preferable.

The polymerization reactor 100 according to the embodiment is preferably used as a main polymerization reactor for polymerizing a polycarbonate from a starting polycarbonate prepolymer having a number average molecular weight preferably 2000 or more, and also preferably 4000 or more. The main reactor for polymerization can be one, or two, or more reactors. The temperature of the main polymerization reactor is preferably 230 ° C or more and 300 ° C or less, and also preferably 240 ° C or more and 270 ° C or less. If the temperature is 230 ° C or more, it is possible to further prevent the temperature of the polymerization reactor and the negligible part of the pipe from falling within the range of 180 to 220 ° C due to insufficient heating or insufficient thermal inertia. Due to this, it is possible to further prevent clogging of the filter installed in the middle of the pipe or the polymer filter installed in the extruder due to crystallization of the prepolymer having a number average molecular weight of 1500 to 5000 in a short time. On the contrary, if the temperature of the main polymerization reactor is 270 ° C or less, the aromatic polycarbonate can be prevented from being brittle due to the increased branching degree in the aroma.

- 10 037043 polycarbonates when the residence time is extended. It should be noted that if the temperature of the main polymerization reactor is increased, the polymerization rate increases and the pressure increases during polymerization, as a result of which productivity can be increased. In particular, when the temperature is increased to 270 ° C. or more, the residence time in the main polymerization reactor falls within two hours in order to prevent an increase in the degree of branching in aromatic polycarbonates. The molecular weight of the desired polycarbonate product can be controlled based on the temperature and pressure of the polymerization reactor 100 and the production volume of the polycarbonate.

The polycarbonate productivity and polycarbonate molecular weight can be controlled by adjusting the temperature of the heating medium for the polymerization reactor 100 and / or the internal pressure of the polymerization reactor 100, for example, to suppress fluctuations in the molecular weight of the polycarbonate while maintaining the same productivity, the internal pressure of the polymerization reactor can be controlled. With this method, the polycarbonate product can be controlled to obtain the desired molecular weight. It is also possible to control the molecular weight and productivity of the desired polycarbonate product by adjusting the temperature and internal pressure of the polymerization reactor 100. When multiple polymerization reactors are used (at least one of which is polymerization reactor 100), the temperature of the pipe connecting the polymerization reactor together can be controlled by the temperature of each polymerization reactor and also controlled by the viscosity and flow rate of the polycarbonate. The viscosity of the molten prepolymer at the inlet of the raw material 1 can be reduced by using different heating systems for the inlet of the raw material 1 from it to the main body of the polymerization reactor 100 and / or by using a preheater. The outlet pipe for discharging polycarbonate from the polymerization reactor 100 may be branched into 2-4 pipes. After branching, the polycarbonate is fed via an outlet pipe, for example to an extruder, in which additives are mixed with the polycarbonate and granulated. On the other hand, the polycarbonate is fed via an outlet pipe to a polymerization reactor additionally installed downstream, in which the polycarbonate can be further polymerized. Moreover, it is preferable that, for example, a catalyst and a branching agent are added to the polycarbonate in the middle of the outlet pipe, and polymerization can be further carried out. In addition, in order to control the number of end groups of the polycarbonate, it is preferable to add an aromatic diaryl compound and an aromatic dihydroxy compound to the polycarbonate discharged from the polymerization reactor 100, and the mixture is further polymerized and then granulated with or without additives mixed therewith.

When many polymerization reactors are installed (at least one of which is polymerization reactor 100), the spread of foreign matter such as crystalline polycarbonate product and heat-treated polymer can be suppressed by controlling the temperature of the pipe connecting the polymerization reactor. The difference (inlet-outlet difference) between the outlet temperature of the heating medium and the inlet temperature of the heating medium of the equipment and the pipe is preferably -20 to 0.1 ° C, more preferably -15 to 0.1 ° C, also preferably -10 to 0.1 ° C, and particularly preferably -5 to 0.1 ° C.

The pipe connecting the outlet of the polymerization reactor upstream of the polymerization reactor 100 and the inlet of the raw material 1 of the polymerization reactor 100 is preferably equipped with a filter to prevent contamination of the polymerization reactor 100 with foreign materials. The shape of the filter, which is not particularly limited, is preferably in the shape of a cone, disc and cylinder. The filter is inserted into the tube or it can be a removable filter such as a distribution grid used in an extruder.

The aromatic polycarbonate obtained by the manufacturing method of the embodiment is usually granulated; however, the aromatic polycarbonate can be directly molded into a product such as a film, sheet and bottle by connecting the polymerization reactor to a molding machine. To make the fish-eye effect less or remove it, for example, a polymer filter having a filtration accuracy of about 1 to 50 microns can be equipped. In addition, additives such as a stabilizer, an antioxidant, dyes and pigments, ultraviolet absorbers and flame retardants, and an additive such as a reinforcing agent including glass fibers and filler can be added, and the resulting mixture is melt-kneaded and granulated using, for example, an extruder and mixer.

According to an embodiment, a high quality polycondensation polymer such as an aromatic polycarbonate having excellent molecular weight stability can be industrially produced in good yield. Thus, a polycondensation polymer having a narrow molecular weight distribution, a suitable degree of branching, an excellent color and excellent physical properties, and a reduced fish-eye effect attributed to a gel can be obtained. In particular, an aromatic polycarbonate having a molecular weight distribution (Mw / Mn) is preferably 1.0 or more and 3.0 or less, preferably

- 11 037043 but 2.0 or more and 2.8 or less, and also preferably 2.0 or more and 2.6 or less, can be obtained even if it has a number average molecular weight of preferably 10,000 mol / g or more, more preferably 12000 mol / g or more, also preferably 13000 mol / g or more, In addition, according to an embodiment, an aromatic polycarbonate with excellent physical properties and color and having a branched chain amount of preferably 0.3 mol% or less, more preferably 0.27 mol% or less, and also preferably 0.20 mol% or less.

An embodiment is described in detail below; however, the present invention is not limited to the above embodiment. For example, as the polymerization reactor according to the present invention, a polymerization reactor as shown in FIG. 4 instead of or in addition to the polymerization reactor 100 described above. FIG. 4 is a schematic view showing another example of a polymerization plant used in the present invention. The polymerization reactor 200 of the polymerization unit is the same as the polymerization reactor 100 mentioned above, except for the shape of the tapered lower body portion and the arrangement of the guide wires. In the polymerization reactor 200, the arrangement of the guide wires 4 is shown in a schematic cross-sectional view (B) showing the polymerization reactor 200 in section along line MM. Even if the guide wires are positioned as shown in view (B), the conditions represented by formula (1) can be met, and the retentate liquid level can fluctuate so as to satisfy the condition represented by formula (2) above.

In the polymerization reactor 200, the shape of the tapered lower portion 213c of the body 13 has the shape shown in view (A). The tapered bottom portion 213c has a tapered top portion 213f, a tapered bottom portion 213g, and a cylindrical middle portion 213h interposed therebetween. In this case, it is preferable that the polycondensation resin flows downward along the inner surface of the tapered wall of the tapered bottom portion 213g. The tapered top 213f and the tapered bottom 213g each have a tapered shape tapering from top to bottom. In order for the aromatic polycarbonate to flow down more reliably and rarely adhere to the wall surface, portions 213f and 213g are each preferably in the form of an inverted pyramid (tapering from top to bottom), and more preferably in the form of an inverted cone (tapering from top to bottom).

In the portion N joining the tapered bottom portion 213f and the cylindrical middle portion 213h, the portion where the polycondensation polymer does not flow downward is preferably not present in order to effectively reduce the area of the tapered bottom portion 213c where the polymer does not flow downwardly. In this case, it is also preferable to control the liquid level L of the polycondensation polymer (retentate) remaining in the tapered lower portion 213c to be in the cylindrical middle portion 213h. Thus, in the cylindrical middle portion 213h, the polycondensation resin flows downward. Therefore, even if the level of the retentate liquid L rises and then falls, the aromatic polycarbonate remaining on the wall surface higher than the level of the liquid L can be washed away by the polycondensation resin flowing downward (self-cleaning can be performed). In addition, since the aromatic polycarbonate rarely remains on the wall surface of the cylindrical middle portion 213h compared to the tapered portions, even if the liquid level L rises and falls in the cylindrical middle portion 213h, the aromatic polycarbonate falls easily without being attached to the wall surface.

Any guide can be used as long as it is a structure including at least a vertical wire and the guide is not limited to the aforementioned guide wire 4.

For example, in the method for manufacturing a polycondensation polymer of the present invention, a molten prepolymer with a low content of impurities is preferably used because a polymer having a higher quality can be obtained. In the production of the prepolymer, for example, a prepolymerization reactor equipped with a stirrer (not shown) can be used. In addition, a wire system of the nitrogen absorption unit can be used to allow the prepolymer to absorb nitrogen in advance to accelerate the evaporation of by-products such as an aromatic monohydroxy compound during polycondensation in the wire system of the polymerization reactor. Also, a final polymerization reactor wire system (not shown) can be used to produce a polymer having also a higher molecular weight from a polymer produced in the main polymerization reactor. A wire system here refers to a system in which a predetermined treatment is carried out while allowing the molten or liquid starting material or feed material (s) to fall along guides such as wires under its own weight.

For example, in the method for producing a polycondensation polymer of the present invention, in order to remove impurities in the prepolymer and polymer, it is preferable to install a filter (not shown) in at least one section of the outlet pipe that connects the bottom of the reactor to the

- 12 037043 polymerization, equipped with a stirrer, with installation for use in the next stage, and equipped with a transfer pump for the prepolymer, and an inlet or outlet for prepolymer and / or polymer in the wire system of the nitrogen absorption unit, the main polymerization reactor and the wire system final polymerization reactor. Examples of the filter type include a cone filter, a disc filter, and a distributor plate type filter mounted to the outlet of an extruder (not shown), and this is preferred.

Typically, the opening diameter of a filter element, such as a conical filter, is slightly smaller than the opening diameter of a distribution plate installed, for example, at the wire system of the polymerization reactor and nitrogen absorption unit. More specifically, the diameter of the filter opening is preferably 0.05-3 mm less than the diameter of the polymer distribution plate, more preferably 0.1-2 mm less, and also preferably 0.1-1 mm less.

When an outlet pipe directly connected to the transfer pump and provided with a filter is used, the outlet pipe is preferably an L-shaped (elbow) double pipe equipped with a discharge line pressure gauge (not shown) to easily replace the filter element. For replacement of the filter element, it is preferable that the outlet pipe can be flushed with a raw material (eg, an aromatic monohydroxy compound).

When using the oil heating medium supplied from the boiler to the heating medium of the heating source, if the pipe through which the oil heating medium flows has an L-shaped double-pipe portion, it is also preferable that the L-shaped double-pipe portion has a shape or structure that easily accelerates the removal of the oil heating medium. medium, for example a branch pipe, by means of which the flow of the heating oil medium is partially stopped. A discharge line pressure gauge is preferably installed upstream of the filter to determine the operating conditions of the transfer pump, the change in the number average molecular weight and viscosity of the prepolymer and / or polymer, and the clogging condition of the filter. In addition, an inverted L-shaped double-tube portion is preferably used as a pipe for feeding the prepolymer to a main polymerization reactor such as a wire mesh reactor. If a bent pipe section is used, the filter (filter element) can be replaced or checked more quickly.

Examples of

The content of the present invention is more specifically described below using examples and comparative examples.

Individual items are assessed using the measurement methods below.

(1) Number average molecular weight and molecular weight distribution.

Measurements were performed using gel permeation chromatography (instrument name HLC8320GPC from Tohso Corporation; two columns: product name TSK-GEL Super Multipore HZ-M from Tohso Corporation, IR detector) and tetrahydrofuran as eluent at 40 ° C. Molecular weight (number average molecular weight and weight average molecular weight) is obtained using the following conversion of a molecular weight calibration curve from a standard monodisperse polystyrene calibration curve (EasiVial manufactured by VARIAN):

Mpc = 0.3591xMps ¹ ' ⁰³⁸⁸ , where M _PC means the number average molecular weight or weight average molecular weight of the polymer and

M _PS is the number average molecular weight or weight average molecular weight of a standard monodisperse polystyrene.

(2) Fisheye effect.

A film having a thickness of 50 μm and a width of 30 cm was formed from the obtained polymer using a film forming machine (30 mm (φ) single screw extruder manufactured by TANABE PLASTICS MACHINERY CO., LTD .; screw rotation speed: 100 rpm; discharged quantity : 10 kg / h; cylinder temperature: 280 ° C; slit die temperature: 260 ° C; roll temperature: 120 ° C) and visually count the number of fish eyes having a size of 300 μm or more on an arbitrary area having a length of 1 m ...

(3) Viscosity.

After taking a sample from the starting prepolymer and the resulting polymer, the viscosity of the individual samples was measured at each of the temperatures corresponding to the examples and comparative examples. The measuring instrument used was a Capirograph (instrument name: CAPIROGRAPH 1B; model number: A-271902103) manufactured by TOYOSEIKI KOGYO CO., LTD.

The degree of branching is indicated by the total number of hetero-units (A) and hetero-units (B) described in WO 97/32916 and obtained according to the method described in WO 97/32916.

- 13 037043

Example 1.

The aromatic polycarbonate is produced using a guided wet dip drop polymerization reactor (FIG. 1) having guide wires 4 disposed as shown in FIG. 2. The body 13 has a cylindrical top of the body 13a and a reverse-tapered bottom of the body 13c. In the directed wetting drop polymerization reaction zone 5 shown in FIG. 2 (A), the cylindrical skin 13a has an inner diameter of 1,500 mm and a length of 10,000 mm. There are twelve guide wires 4 in which, as shown in FIG. 2 (D), a fixing wire 11 is provided on one side of the plurality of vertical wires 10 shown in FIG. 2 (B).

In the guide wires 4a 102, the vertical wires 10 are arranged at intervals of 10 mm as shown in FIG. 2 (D). The diameter of the vertical wires 10 is 3 mm, and the length (from one end to the other end) of the guide wire 4a in the horizontal direction is 1010 mm. Accordingly, in the 6 wire guides 4a, the total number of vertical wires 10 is 612.

Directly above the vertical wires 10 are a plurality of polymer feed holes 12 that allow the molten polymer to flow downward. The resin feed holes 12 are located at the level of the vertical wires 10 so that the distance between the centers of the resin feed holes 12 is 30 mm. Thirty-four polymer feed holes 12 are generally located on every second vertical wire starting from the top of the 2nd wire from the end of the vertical wires 10.

In the guide wires 4b 54, vertical wires 10 are arranged at intervals of 10 mm, as shown in FIG. 2 (D). The diameter of the vertical wires 10 is 3 mm, the length (from one end to the other end) of the guide wire in the horizontal direction is 530 mm. Accordingly, in the 6 guide wires 4b, the total number of vertical wires 10 is 324.

Directly above the vertical wires 10 are a plurality of polymer feed holes 12 that allow the molten polymer to flow downward. The resin feed holes 12 are located at the level of the vertical wires 10 so that the distance between the centers of the resin feed holes 12 is 30 mm. The polymer feed holes 12 are located on every second vertical wire, starting from the upper section of the 2nd wire from the end of the vertical wires 10.

The interval (pitch) of the plurality of fixing wires 11 (running horizontally) is 80 mm. The size and other data regarding the guide wire are presented in table. 1. The polymerization reactor is entirely made of SUS316 material. Outside the polymerization reactor, a jacket is equipped, heated with a heating medium up to 260 ° C.

Table 1

Example one Example 2 Example 3 Example 4 Example five Example 6 Molten prepolymer Number average molecular weight (Mp) 4500 4500 4500 4000 6000 2500 Viscosity, η (poise) 200 200 200 200 500 25 Wire guide Length (mm) 10000 10000 10000 10000 10000 10000 Inner sheathing diameter (mm) 1500 1500 4000 1500 4000 1500 Spacing between vertical wires (mm) ten ten ten fifteen ten 20 Wire diameter (mm) 3 2 2 3 2 3 Spacing between fixing wires (mm) 40 200 40 - 120 200 Layout of the polymerization reactor and wire guides FIG. 2 FIG. 2 FIG. 4, FIG. 5 (A) FIG. 4, FIG. 5 (A) FIG. 2 FIG. 2

- 14 037043

Number of vertical wire 936 936 10000 6500 936 936 Polymerization conditions Temperature (° C) 260 265 270 265 265 260 Pressure (Pa) thirty fifty fifty 100 fifty 600 Scented polycarbonate Molecular weight (Mp) 12800 13000 13000 10500 13500 6000 Molecular weight (Mw) 36000 36000 36000 26000 36500 12000 Molecular Weight Distribution (Mw / Mn) 2.8 2.8 2.8 2.5 2.7 2 Branching degree (mol%) 0.26 0.26 0.28 0.15 0.25 0.05 "Fish eye" 0 0 0 0 0 0 Stable productivity (kg / h-100 mm) 6 7 7.5 8 6 fifteen Example 7 Example 8 Example 9 Example ten Example eleven Example 12 Molten prepolymer Number average molecular weight (Mp) 4500 4500 4500 2500 4500 4500 Viscosity, η (poise) 200 200 200 25 200 200 Wire guide Polymerization conditions Scented polycarbonate Length (mm) 10000 10000 10000 10000 10000 10000 Inner sheathing diameter (mm) 1500 1500 1500 1500 1500 1500 Spacing between vertical wires (mm) ten ten ten 20 60 60 Wire diameter (mm) 2 2 2 3 3 3 Spacing between fixing wires (mm) Layout of polymerization reactor and guide wires Number of vertical wires Temperature (° C) Pressure (Pa) Molecular weight (Mp) Molecular weight (Mw) Molecular weight distribution (Mw / Mn) Degree of branching (mol%) Fisheye Stable performance (kg / h-100 mm) 200 FIG. 2 936 265 fifty 10000 26000 2, 6 0.15 0 14 200 FIG. 2 936 265 100 9500 24000 2.5 0.15 0 14 200 FIG. 2 936 265 170 8500 22000 2, 6 0.15 0 14 200 FIG. 2 936 250 300 6500 16000 2.5 0.05 0 thirteen 200 FIG. 3 320 265 fifty 12800 45000 3.5 0.45 4 1.5 200 FIG. 3 352 265 fifty 14000 45000 3.5 0.45 2 1.5

- 15 037043

Example 13 Comparative example 3 Comparative example 4 Molten prepolymer Number average molecular weight (Mp) Viscosity, η (poise) 4500 200 4500 200 4500 200 Length (mm) 10000 10000 10000 Inner diameter of casing (mm) 4000 2000 2000 Spacing between vertical wires (mm) ten 60 ten Wire guide Wire diameter (mm) Spacing between fixing wires (mm) 2 40 3 200 3 200 Layout of the polymerization reactor and wire guides FIG. 4, FIG. 5 (B) FIG. 3 FIG. 3 Number of vertical wires 11000 180 980 Terms Temperature (° C) 265 265 265 polymerization Pressure (Pa) fifty fifty fifty Aromatic Molecular weight (Mp) 14000 12800 12800 polycarbonate Molecular weight (Mw) 37000 45000 45000 Molecular Weight Distribution (Mw / Mn) 2.8 3.5 3.5 Branching degree (mol%) 0.28 0.45 0.45 "Fish eye" 0 ten 8 Stable performance (kg / h-100 mm) 7.5 1.5 6

Molten prepolymer (precursor of aromatic polycarbonate; number average molecular weight (Mn): 4500), which is produced from bisphenol A and diphenyl carbonate (molar ratio to bisphenol A: 1.08) and maintained at 260 ° C, is continuously fed by a feed pump from the inlet the openings of the raw material 1 into the feed zone 3 of the raw material. The molten prepolymer continuously supplied from the plurality of polymer feed holes 12 formed on the distribution plate 2 of the polymerization reactor 100 to the drop polymerization reaction zone 5 with controlled wetting flows along the guide wires 4. During this process, the polymerization reaction proceeds. The molten prepolymer discharged (fed) from the polymer feed holes 12 falls along the guide wires 4 located below the resin feed holes 12. The molten prepolymer streams come into contact with each other horizontally at a position 200 mm lower than the position of the upper end portion of the guide wires 4. Therefore, the falling mass (molten prepolymer) / (aromatic polycarbonate) looks like a plane. The resulting aromatic polycarbonate falls onto the inner surface of the tapered wall of the bottom of the housing 13 c.

The aromatic polycarbonate that has fallen on the inner surface of the cone-shaped wall flows downward under its own gravity towards the top of the reverse-conical bottom of the body 13c, passes through the polymer outlet 7 made in the bottom, and enters the pipe. From the perspective view of FIG. 2 (C), the shaded portion indicates a portion (Y) where the aromatic polycarbonate does not flow downward (the portion (Y) where the aromatic polycarbonate does not flow downward is shown in geometric projection as a top view in the vertical direction). The outermost boundary in FIG. 2 (C) represents the boundary of an imaginary outermost peripheral region. In the imaginary outermost peripheral portion, the portion except for portion (Y) (where the aromatic polycarbonate does not flow downward) is portion (X) (where the aromatic polycarbonate flows downward).

The aromatic polycarbonate that falls from the lower ends of the guide wires 4 to the tapered wall of the bottom of the casing 13c of the polymerization reactor 100 is continuously expelled from the polymer outlet 7 by means of the discharge pump 8 so that an almost constant amount of aromatic polycarbonate remains at the bottom of the casing 13c.

The liquid surface of the retentate is located at the bottom of the housing 13c as shown in FIG. 2 (A) and 2 (C), and the amount of retentate is controlled by adjusting the power of the discharge pump 8 so that the retentate liquid level varies within the range of 10 ± 2%.

At the same time, the fluctuation of the liquid level is controlled so that the liquid surface is present only in the region (X) where the aromatic polycarbonate flows downward. Therefore, the ratio L1 / L0 is 1.00, where L0 is the total circumference of the circular portion that is formed by the liquid surface of the aromatic polycarbonate remaining on the tapered portion in contact with the inner surface of the tapered wall, and L1 is the length of the circumferential portion in contact with the area where the aromatic polycarbonate flows down.

- 16 037043

The reduced pressure level in the wetting-guided drop polymerization reaction zone 5 is controlled by the vacuum vent 6 so that the number average molecular weight of the aromatic polycarbonate that is discharged through the polymer outlet 7 becomes 12800. The number average molecular weight of the aromatic polycarbonate produced is measured every hour. After confirming that the number average molecular weight falls within the range of 12800 ± 100 continuously for 10 hours, the amount of molten prepolymer supplied and the amount of aromatic polycarbonate withdrawn are increased in steps. As a result, an aromatic polycarbonate having a number average molecular weight of 12800 ± 100 is successfully and stably produced until the amount (stable productivity) of the aromatic polycarbonate withdrawn reaches 6 kg / (h-100 mm). The derived quantity in this case refers to the volume of production per unit length (100 mm) in the horizontal direction of the guide wire 4, consisting of a plurality of vertical wires 10, and expressed in units of measure: kg / (h-100 mm). The weight average molecular weight of the aromatic polycarbonate obtained is 36,000 and the molecular weight distribution is 2.8. The residence time of the retentate at the bottom of the building 13s is 50 minutes. The degree of branching is 0.26 mol% and the number of fish eyes is 0. The above results are summarized in table. 1. It should be noted that in table. 1, the viscosity value of the molten prepolymer is the value measured at 260 ° C. Fisheye eyes of 50 µm or more, which can be observed visually, were not detected. The aromatic polycarbonate is produced in an amount of up to 600 kg / h and this yield is sufficient.

Examples 2-13.

Aromatic polycarbonates are obtained in the same way as in example 1, except that the conditions are changed as shown in table. 1. Physical properties and evaluation of the results are summarized in table. 1. It should be noted that in Examples 3 and 4 the location of the guide wires is changed from the location shown in the cross section of FIG. 4 (B) to the location shown in the cross section of FIG. 5 (A). In Example 13, the location of the guide wires is changed from the location shown in the cross section of FIG. 4 (B) to the location shown in the cross section of FIG. 5 (B). Example 4 uses guide wires that do not have a fixed wire. In examples 2-10 and 13, the ratio L1 / L0 is 1.00.

In example 11, in addition to the changes shown in table. 1, the spacing between the wire guides is changed from 400 to 280 mm (respectively, 480 mm is changed to 540 mm) and from 720 to 240 mm (respectively, 320 mm is changed to 560 mm). Except for the above changes, the same polymerization reactor is used as shown in FIG. 3 (details will be described below). It should be noted that in example 11, the ratio L1 / L0 is 0.78.

In example 12, in addition to the changes shown in table. 1, the spacing between the wire guides is changed from 400 to 160 mm (respectively, 480 mm is changed to 600 mm) and from 720 to 240 mm (respectively, 320 mm is changed to 560 mm). Except for the above changes, the same polymerization reactor is used as shown in FIG. 3 (details will be described below). It should be noted that in example 12, the ratio L1 / L0 is 0.81.

Comparative example 1.

Polycarbonate is produced using a polymerization reactor (inner sheathing diameter 13a is 300 mm), in which 21 vertical wires are arranged in one line. The other conditions are the same as in example 1. A polycarbonate having a number average molecular weight (Mn) of 10300 was produced while the liquid level (L) was kept constant for 30 minutes. The number of fish eyes of the polymer obtained is two (relatively good); however, the productivity is extremely low (32 kg / h).

Comparative example 2.

A polymerization reactor was used (the inner diameter of the casing 13a was 2000 mm). An attempt to evenly place 400 vertical wires was unsuccessful due to production and load-bearing problems.

Comparative example 3.

The aromatic polycarbonate is produced using the guided wet drop polymerization reactor of FIG. 1 in which the guide wires 4 are positioned as shown in FIG. 3. The polymerization reactor is the same as in example 1 (for example, the shape of the housing 13 is the same), except for the arrangement of the guide wires 4. In the drop polymerization reaction zone 5 with directed wetting, as shown in FIG. 3 (A), the skin 13a is a cylinder having an inner diameter of 2000 mm and a length of 10000 mm. Twenty guide wires 4 having fixing wires 11 mounted on one side of a plurality of vertical wires 10 as shown in FIG. 3 (D) are arranged as shown in the schematic cross-sectional view (B) along the line K-K in FIG. 3 (A). It should be noted that FIG. 3 (A) -3 (E) correspond to FIG. 2 (A) -2 (D), respectively.

In this case, vertical wires 10 are placed in one guide wire 4,

- 17 037043 as shown in FIG. 3 (D); more precisely, 9 vertical wires 10 are placed at 60 mm intervals.

The diameter of the vertical wires 10 is 3 mm and the length of the guide wire 4 from one end to the other end in the horizontal direction is 480 mm. Since twenty guide wires 4 are used, the total number of vertical wires 10 is 180.

Above the vertical wires 10 are a plurality of polymer feed holes 12 that allow the molten prepolymer to flow downward. The polymer feed holes 12 are positioned exactly over all vertical wires.

The interval (pitch) of the plurality of fixing wires 11 (running horizontally) is 80 mm. The size and other parameters relative to the guide wire are shown in Table 1. The polymerization reactor is entirely made of SUS316 material. A jacket is mounted outside the polymerization reactor, which is heated by a heating medium to 265 ° C.

Molten prepolymer (precursor of aromatic polycarbonate; number average molecular weight (Mn): 4500), which is produced from bisphenol A and diphenyl carbonate (molar ratio to bisphenol A: 1.08) and kept at 265 ° C, is continuously supplied by means of a feed pump from the input openings of the raw material 1 to the feed zone of the raw material 3. The molten prepolymer supplied continuously from the plurality of polymer feed holes 12 formed in the distribution plate 2 of the polymerization reactor 100 to the drop polymerization reaction zone 5 with guided wetting flows down along the guide wires 4. During this process is a polymerization reaction. The molten prepolymer discharged (fed) from the polymer feed holes 12 falls along the guide wires 4 located under the resin feed holes 12. The molten prepolymer, while independently flowing downward from the upper end portion of the guide wires 4, turns into an aromatic polycarbonate and independently falls onto the inner surface of the tapered wall of the bottom of the housing 13c.

The aromatic polycarbonate falling on the inner surface of the cone-shaped wall flows under its own gravity towards the top of the reverse-conical bottom of the body 13c, passes through the polymer outlet 7, equipped in the bottom, and falls into the pipe. From the perspective view of FIG. 3 (C), the shaded portion indicates a portion (Y) where the aromatic polycarbonate does not flow downward (the portion (Y) where the aromatic polycarbonate does not flow downward is shown in geometric projection when viewed from above in the vertical direction). Since the aromatic polycarbonate falls independently downwardly from the vertical wires 10, there are also many regions (Y) (where the aromatic polycarbonate does not fall down) in the unshaded region shown in FIG. 3 (C).

The outermost boundary shown in FIG. 3 (C) is the boundary of an imaginary outermost peripheral region. In an imaginary outermost peripheral portion, a portion (X) where the aromatic polycarbonate flowing downward is observed in a portion except for a portion (Y) where the aromatic polycarbonate does not flow down.

The L1 / L0 ratio is 0.53.

The aromatic polycarbonate that falls from the lower end of the guide wire 4 towards the tapered wall of the bottom of the casing 13c of the polymerization reactor 100 is continuously withdrawn from the polymer outlet 7 by the discharge pump 8 so that an almost constant amount of aromatic polycarbonate remains at the bottom of the casing 13c.

The retentate liquid surface is located at the bottom of the housing 13c as shown in FIG. 3 (A) and 3 (C), and the amount of retentate is controlled by adjusting the power of the discharge pump 8 so that the level of the retentate liquid changes within the range of 30 ± 20%.

At the same time, fluctuations in the liquid level are controlled so that the liquid surface is present only in the area (Y) where the aromatic polycarbonate does not flow downwards. Thus, the aromatic polycarbonate that is attached to the area (Y) (where the aromatic polycarbonate does not flow downward) when the liquid surface rises, remains in the area (Y) (where the aromatic polycarbonate does not flow downwards) when the liquid surface descends, and is subject to thermal stories. As a result, the aromatic polycarbonate subjected to thermal history is mixed with the retentate when the liquid surface rises again and is discharged from the polymer outlet 7.

The reduced pressure level in the wetting-guided drop polymerization reaction zone 5 is controlled by the vacuum vent 6 so that the number average molecular weight of the aromatic polycarbonate that is discharged through the polymer outlet 7 becomes 12800. The number average molecular weight of the aromatic polycarbonate produced is measured every hour. After confirming that the number average molecular weight falls within the range of 12800 ± 100 continuously for 10 hours, the amount of molten prepolymer supplied and the amount of aromatic polycarbonate withdrawn are increased in steps. As a result, an aromatic polycarbonate having a number average molecular weight of 12800 ± 100 is successfully and stably produced until the amount (stable productivity) of the aromatic polycarbonate withdrawn reaches 1.5 kg / (h-100 mm). The derived quantity in this case refers to the volume of production per unit of length (100 mm) in the horizontal

- 18 037043 direction of the guide wire 4, consisting of a plurality of vertical wires 10 and expressed in units of measure: kg / (h-100 mm). The weight average molecular weight of the obtained aromatic polycarbonate is 45,000 and the molecular weight distribution is 3.5. The residence time of the retentate at the bottom of the housing 13s is 4 hours. The number of fish eyes is 10. The above results are presented in table. one.

Comparative example 4.

An aromatic polycarbonate was produced in the same manner as in Comparative Example 3, except that the spacing between the vertical wires 10 was defined as 10 mm (the total number of vertical wires 10 was 980. The L1 / L0 ratio was 0.55. The number of fish eyes was 8.

This patent application is based on Japanese Patent Publication No. 2014-057195, filed on March 19, 2014, the contents of which are incorporated herein by reference.

Industrial applicability

According to the present invention, a high quality polycondensation polymer, in particular an aromatic polycarbonate with excellent molecular weight stability, can be industrially produced in good yield. Consequently, the aromatic polycarbonate has a narrow molecular weight distribution, a suitable degree of branching, an excellent color, and excellent physical properties. In addition, the number of fish eyes attributed to the gel can be reduced. Thus, the present invention has industrial applicability in the production of a polycondensation polymer such as an aromatic polycarbonate.

List of reference positions

- raw material inlet;

- distribution plate;

- feed zone of raw material;

- wire guide;

- the reaction zone of polymerization falling with directional wetting;

- vacuum vent;

- polymer outlet;

- unloading pump;

- inert gas inlet;

- vertically extending wire (vertical wire);

- horizontally extending wire (fixing wire);

- polymer feeding hole;

- body;

100, 200 - drop polymerization reactor with directional wetting (polymerization reactor).

Claims (6)

1. A method of obtaining a polycondensation polymer, comprising the following stages (I) and (II): (I) a step of supplying the molten prepolymer to a polymerization reactor for the production of a polycondensation polymer, the reactor having a housing, a guide formed in the housing, and a polymer outlet connected to the housing and formed in its lower part; and (ii) a step of allowing the molten prepolymer to flow downward along the surface of the guide while in contact with the surface, and polymerizing the molten prepolymer, resulting in a polycondensation polymer, wherein the body has a cylindrical upper portion that has a lower annular edge having a larger a diameter than the diameter of the upper annular face of the polymer outlet and a tapered lower portion connecting the lower annular face of the cylindrical upper portion and the upper annular face of the polymer outlet has a tapered wall extending from the lower annular face to the upper annular face; the housing, the guide and the polymer outlet are disposed so that the polycondensation polymer falling from the guide remains in the tapered bottom portion and flows downward along the inner surface of the tapered wall to the polymer outlet; and in the circular portion that is formed by the liquid surface of the polycondensation polymer remaining on the tapered lower portion in contact with the inner surface of the tapered wall, the liquid level is maintained within the interval where the total circumference L0 of said circular portion and the length L1 of a portion of said circumference in contact with the portion where the polycondensation polymer flows downward, satisfy the condition represented by the following formula (2): L1 / L0> 0.90 (2). 2. A method according to claim 1, wherein the liquid level is maintained within a range where the total length L0 and the length L1 satisfy the condition represented by the following formula (2A): - 19 037043 L1 / L0 = 1.00 (2A). 3. The method according to claim 1 or 2, in which the tapered lower portion further includes a tapered upper portion, a tapered lower portion and a cylindrical middle portion inserted between the tapered upper and lower portions; in the portion connecting the tapered upper portion and the cylindrical middle portion of the tapered lower portion, the portion where the polycondensation polymer does not flow downward is not present; and the control is carried out so that the liquid surface of the polycondensation polymer remaining on the tapered bottom portion is present on the cylindrical middle portion. 4. The method according to any one of claims 1 to 3, in which the residence time of the polycondensation polymer remaining in the tapered lower section falls within 3 hours. 5. A method according to any one of claims 1 to 4, wherein the guide is a guide wire and the polycondensation polymer is in contact with each other between the various guide wires and is combined to form a flat fluid and flows downward along the guide wire. 6. A method according to any one of claims 1 to 5, wherein the polycondensation polymer is an aromatic polycarbonate.