KR20120005408A - Devolatilizing extruder, and devolatilizing extrusion method of polymer composition using the same and method of producing polymer - Google Patents

Abstract

PURPOSE: A devolatilizing extruder is provided to prevent the attaching of non-reacted monomer and polymer to shaft seal bearing part. CONSTITUTION: A devolatilizing extruder(100) comprises: a cylinder(10) consisting of a polymer composition supply port(12), gas discharge ports(14), a polymer exit(16) and a through hole(18); a rotatable screw(20) which is inserted into the cylinder through the through hole; and a shaft seal bearing part(30) supplying the shaft part(20a) of the screw, which is reached from the through hole to the outside of the cylinder. The shaft seal bearing part comprises a first shaft seal part(32), a second shaft seal part(34) between the first shaft seal part and the cylinder, and a gas inlet part(36) flowing gas into the second shaft seal part. The shaft seal bearing part has a gap as a flowing path, between the inner wall of the through hole, and the surface of the shaft part of the screw. Gas, which is inserted into the second shaft seal part through the gas inlet part, is discharged to the inside of the cylinder through the gap of the shaft bearing part.

Description

DEVOLATILIZING EXTRUDER, AND DEVOLATILIZING EXTRUSION METHOD OF POLYMER COMPOSITION USING THE SAME AND METHOD OF PRODUCING POLYMER}

The present invention relates to a devolatilizing extruder used in the production of a polymer, a devolatilizing extrusion method of a polymer composition using the same, and a process for producing the polymer.

As a method for producing a polymer such as a (meth) acrylic polymer, a polymer composition containing the polymer and the volatile component is obtained by a solution polymerization method or a bulk polymerization method, and the obtained polymer composition is then screwed to remove the volatile component. It is fed to a type devolatilizing extruder, and therefore a method of obtaining a polymer is known (see, for example, patent documents 1 and 2).

Patent Document 1: JP-A-3-49925 Patent Document 2: JP-A-2003-96105

In the screw inserted into the devolatilizing extruder, the shaft portion is supported by the shaft seal bearing portion of the devolatilizing extruder and the shaft seal portion is provided around the shaft portion of the screw of the shaft seal bearing portion. The devolatilizing extrusion method using a conventional devolatilizing extruder is characterized in that, when the operation is carried out continuously for a long time, unreacted monomer of the polymer composition or a polymer thereof is attached to such a shaft seal bearing portion, and poor rotation of the screw occurs, thus The problem was that it became difficult to operate the devolatilizing extruder.

In view of the problems of the prior art, the present invention has been made and its object is a devolatilizing extruder capable of preventing the unreacted monomer and its polymer from adhering to the shaft seal bearing portion during operation, and devolatilizing extrusion of the polymer composition using the same. To provide a method for producing a polymer and a method for producing a polymer.

In order to achieve the above-mentioned object, the present invention provides a cylinder comprising a polymer composition supply port, a gas discharge port, a polymer outlet and a through hole; A rotatable screw inserted into the cylinder through the through hole; And a shaft seal bearing portion for supporting a shaft portion of the screw extending from the through hole to the outside of the cylinder, wherein the shaft seal bearing portion includes a first shaft seal portion, a first shaft seal portion, and a cylinder. A second shaft seal portion interposed therebetween, and a gas introduction port for allowing gas to be introduced into the second shaft seal portion, wherein the shaft seal bearing portion is disposed between the inner wall surface of the through hole and the surface of the shaft portion of the screw; And a gap serving as the flow path, through which the gas introduced through the gas introduction port into the second shaft seal portion is discharged into the cylinder.

Conventional devolatilizing extruders, when the polymer is continuously produced over a long period of time, unreacted monomers, polymers, and the like contained in the volatile components adhere to the shaft seal bearing portion of the devolatilizing extruder, thus causing poor rotation of the screw. I had a problem. Unreacted monomers contained in the volatile components are considered to be attached in the vicinity of the shaft seal bearings and thus the monomers are converted to polymers as a result of thermal polymerization. In the devolatilizing extruder of the present invention, since a gas introduction port for introducing gas into the second shaft seal portion of the shaft seal bearing portion is provided, the introduced gas passes through the second shaft seal portion and the through hole and the shaft of the screw are provided. Passing the gap between the parts, the gas is then introduced into the cylinder. Thus, a flow of gas from the shaft seal bearing portion toward the cylinder is formed, thus making it difficult for the unreacted monomer to reach near the shaft seal bearing portion. As a result, adhesion of the unreacted monomer and its polymer in the vicinity of the shaft seal bearing portion can be sufficiently suppressed and it is possible to sufficiently suppress the poor rotation of the screw even when the operation is carried out continuously for a long time.

In the devolatilizing extruder of the present invention, the second shaft seal portion is preferably formed of a labyrinth seal. Thereby, the abrasion of the shaft seal portion is suppressed as large as possible, and thus continuous operation can be stably executed for a long time.

In the devolatilizing extruder of the present invention, the first shaft seal portion is preferably formed of a Wilson seal since it is possible to easily absorb the axial runout of the rotating shaft.

The present invention also provides a method for devolatilizing extrusion of the polymer composition, which method comprises: feeding a polymer composition containing the polymer and the volatile components into the cylinder through the polymer composition supply port of the devolatilizing extruder of the present invention and respectively supplying a gas discharge port. Supplying the gas through the gas introduction port to the second shaft seal portion to evacuate the gas and volatile components therethrough and to evacuate the polymer after devolatilization through the polymer outlet.

According to this devolatilizing extrusion method, since the devolatilizing extruder of the present invention is used, the unreacted monomers, polymers, and the like contained in the volatile components are sufficiently suppressed from adhering to the shaft seal bearing portion of the devolatilizing extruder, and the screw is poor. It is possible to continuously carry out the devolatilization extrusion process of the polymer composition over a long period without causing problems such as rotation.

The present invention also provides a method of making a polymer, the method comprising the steps of: continuously feeding a raw material containing a monomer, a radical polymerization initiator and a chain transfer agent to a polymerization reaction vessel; Polymerizing the monomers in a polymerization reaction vessel to obtain a polymer composition containing a volatile component containing the polymer and unreacted monomers; And gas introduction to feed the polymer composition into the cylinder through the polymer composition supply port into the devolatilizing extruder of the present invention, and to discharge the gas and volatile components through the gas outlet port, respectively, and to discharge the polymer after devolatilization through the polymer outlet. Supplying to the second shaft seal portion through the port.

According to the method for producing a polymer, since the devolatilizing extruder of the present invention is used, unreacted monomers, polymers, and the like contained in the volatile component are attached to the shaft seal bearing portion of the devolatilizing extruder in the step of performing the devolatilizing extrusion process. It is possible to sufficiently suppress this and to continuously prepare the polymer composition over a long period without causing problems such as poor rotation of the screw.

In the method for devolatilizing extrusion of the polymer composition of the present invention and the method for producing the polymer, the gas supplied through the gas introduction port is preferably an inert gas or a mixed gas consisting of oxygen gas and inert gas, and the content of oxygen gas is 10 volume% or less. The use of this gas makes it possible to inhibit unreacted monomers from polymerizing near the shaft seal bearing portion and to more reliably prevent the polymer of unreacted monomers from adhering near the shaft seal bearing portion. It can also prevent oxidative degradation of the polymer.

According to the present invention, there is provided a devolatilizing extruder capable of inhibiting unreacted monomers and polymers thereof from adhering to the shaft seal bearing portion during operation, and capable of continuously operating for a long time without causing poor rotation of the screw; And a method for devolatilizing extrusion of a polymer composition using the same, and a method for producing a polymer.

1 is a schematic view showing an internal structure of a devolatilizing extruder according to a preferred embodiment of the present invention.
2 is a partial cross-sectional view of the shaft seal bearing portion of the devolatilizing extruder according to the preferred embodiment of the present invention.
3 is a schematic block diagram showing a system for preparing a polymer using the devolatilizing extruder of the present invention.

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. Like numbers have been used for the same or like parts in the drawings, and repeated descriptions are omitted. In addition, the dimension ratio of drawing is not restrict | limited to the ratio shown.

1 is a schematic view showing an internal structure of a devolatilizing extruder according to a preferred embodiment of the present invention. As shown in FIG. 1, the devolatilizing extruder 100 includes a polymer composition supply port 12 for supplying a polymer composition containing volatile components and a polymer, a gas discharge port 14 for exhausting gas and volatile components, and devolatilization A cylinder 10 comprising a polymer outlet 16 for discharging the polymer, and a through hole 18; A rotatable screw 20 inserted into the cylinder 10 through the through hole 18; And the shaft seal bearing part 30 which supports the shaft part 20a of the screw 20 extended from the through-hole 18 to the outer side of the cylinder 10 is provided. The cylinder 10 is provided with four gas discharge ports 14, and one gas discharge port (rear vent) 14a is the side of the shaft seal bearing portion 30 when viewed from the polymer composition supply port 12. Three gas discharge ports (front vents) 14a, 14b, 14c are provided on the side of the polymer outlet 16, respectively. The shaft seal bearing portion 30 removes the first shaft seal portion 32, the second shaft seal portion 34 placed between the first shaft seal portion 32 and the cylinder 10, and the gas. A gas introduction port 36 for introduction into the two shaft seal portion 34.

2 is a partial cross-sectional view of the shaft seal bearing portion of the devolatilizing extruder according to the preferred embodiment of the present invention. As shown in FIG. 2, the first shaft seal portion 32 is formed of a Wilson seal in this embodiment. The second shaft seal portion 34 is formed of a labyrinth seal in this embodiment. The inside of the shaft seal bearing portion 30 and the inside of the cylinder 10 are connected through the through hole 18, and the shaft portion 20a of the screw 20 passes through the through hole 18. A drive device (not shown) for rotationally driving the screw 20 is provided on the side opposite to the second shaft seal portion 34 of the first shaft seal portion 32. As shown in FIG. 2, at the boundary between the shaft seal bearing portion 30 and the cylinder 10, a gap is formed between the inner wall surface of the through hole 18 and the surface of the shaft portion 20a of the screw 20. Gas, which is introduced into the second shaft seal portion 34 through the gas introduction port 36, is discharged into the cylinder through this gap as the flow path FP. The gas discharged to the cylinder 10 is discharged out of the cylinder 10 through the gas discharge port 14 together with the volatile component of the polymer composition.

The first shaft seal portion 32 can have a known shaft seal structure. Examples of this structure include Wilson seals, gland packing, mechanical seals, oil seals, labyrinth seals, o-ring seals, bellows seals and the like. Among them, Wilson seals are preferred in view of easy absorption of the axial shaking of the rotating shaft. In the first shaft seal portion 32 shown in FIG. 2, the form of a Wilson seal with a plurality of lip seals 32a is shown. In use the direction of the lip seal 32a can be varied and all lip seals can be used in the direction shown in FIG. As long as at least one direction is the direction shown in Fig. 2, the rest can be used in a state facing in the inverted direction. Since the second shaft seal portion 34 is pressurized as a result of the introduction of the gas, the lip seal 32a is preferably used in the direction shown in FIG. Examples of the material of the lip seal 32a include polytetrafluoroethylene (PTFE) and fluorine-containing rubber. As grease 32b used for Wilson seal, it is possible to use silicon grease or the like. The oil seal 32c is provided on the same side as the cylinder 10 of the Wilson seal to prevent leakage of the grease 32b. The distance between the Wilson seal and the surface of the shaft portion 20a of the screw 20 is usually 0.01 to 0.1 mm, preferably 0.01 to 0.05 mm. When this distance is larger than 0.1 mm, it may be difficult to obtain a sufficient shaft sealing effect.

The second shaft seal portion 34 may be formed in the form of a known shaft seal and examples of the form include shaft seals such as labyrinth seals, gland packings and ABC seals. It is preferable that the second shaft seal portion is formed of a labyrinth seal because the effect of introducing gas into the second shaft seal portion 34 through the gas introduction port 36 can be effectively obtained. Labyrinth seals may be formed in known forms. In the second shaft seal portion 34 shown in Fig. 2, the shape of the labyrinth seal using two labyrinth passages 34a and 34b each having a different size is shown. Examples of the material of the labyrinth passages 34a and 34b include polytetrafluoroethylene (PTFE), fluorine-containing rubber, stainless steel such as SUS304 or SUS316, and the like. PTFE and fluorine-containing rubber can narrow the distance between the seal and the surface of the shaft portion 20a of the screw 20, thus making it possible to increase the sealing effect. However, there is a problem that deterioration may occur from the viewpoint of low chemical resistance to monomers at high temperatures during continuous operation over a long period of time. In contrast, stainless steel has a high resistance to degradation. However, when axial shaking occurs, it may contact the shaft portion 20a of the screw 20, which causes damage to both materials. Therefore, the labyrinth passage 34a is preferably formed of stainless steel and the labyrinth passage 34b can suppress damage of the shaft portion 20a of the screw 20 during axial shaking while increasing the sealing effect. And from the viewpoint of being able to make a continuous production of the polymer over a long period of time, preferably formed of PTFE. When the labyrinth passage 34a is formed of stainless steel and the labyrinth passage 34b is formed of PTFE, in the labyrinth passage 34a, between the seal and the surface of the shaft portion 20a of the screw 20 The distance is usually 0.1 to 2 mm, preferably 0.1 to 1.5 mm. In contrast, in the labyrinth passage 34b, the distance between the seal and the surface of the shaft portion 20a of the screw 20 is usually 0.01 to 0.1 mm, preferably 0.01 to 0.05 mm.

There is no particular limitation on the gas introduced into the second shaft seal portion 34 through the gas introduction port 36. Preferably, an inert gas or a mixed gas of an inert gas and an oxygen gas whose content of oxygen gas is 10 vol% or less is used. Examples of inert gases include nitrogen gas, helium gas, and argon gas. Among these inert gases, nitrogen gas is preferable. In particular, oxygen gas can function as a polymerization inhibitor with respect to the monomer of a (meth) acrylic-type polymer, and can suppress the polymerization reaction of an unreacted monomer. As the oxygen source of the mixed gas, it is possible to use air and pure oxygen. When using a mixed gas, the polymer can cause oxidative degradation when the concentration of oxygen gas is too high. Therefore, the concentration is preferably in the above-mentioned range, more preferably 8% by volume or less. The use of this gas makes it possible to inhibit unreacted monomers from polymerizing in the vicinity of the shaft seal bearing portion 30 and to more reliably prevent the polymer from adhering in the vicinity of the shaft seal bearing portion 30. The position of the gas introduction port 36 is not particularly limited as long as the gas is introduced into the second shaft seal portion 34 and the introduced gas is discharged to the side of the cylinder 10.

The flow rate of the gas to be introduced is appropriately set according to the size of the devolatilizing extruder, the extrusion conditions, and the like by the speed of the vessel (rate through the labyrinth), which is usually 0.5 to 50 L / min, preferably 6 to 45 L / min. When the flow rate of the gas is larger than the above-mentioned range, the pressure of the devolatilizing extruder increases and thus it becomes impossible to carry out a stable operation. In contrast, when the flow rate of the gas is smaller than the above-mentioned range, the effect of preventing the unreacted monomer and the polymer from infiltrating into the shaft seal bearing portion 30 can be reduced.

In the devolatilizing extruder 100, the gas introduction port 36 is provided with a second shaft seal portion 34, and the introduction of the gas causes the interior of the second shaft seal portion 34 to remain pressurized and pressurized. It can be made higher than the pressure of the gas discharge port 14 of this devolatilizing extruder 100. Thus, it is possible to sufficiently prevent unreacted monomers and polymers from entering the shaft seal bearing portion 30 through the flow path FP. It is also possible to protect the first shaft seal portion 32, which is formed of the Wilson seal by the second shaft seal portion 34. In addition, since the inside of the second shaft seal portion 34 is kept in a pressurized state, leakage of grease from the Wilson seal can be prevented and mixing of impurities of the obtained polymer can be prevented. The preferred range of pressure is appropriately set according to the size of the devolatilizing extruder, the extrusion conditions and the like. Since pressure gauges and safety valves are provided to the devolatilizing extruder according to the maximum working pressure, the pressure is set within a range in which the safety valve is not operated.

The distance between the inner wall surface of the through hole 18 and the surface of the shaft portion 20a of the screw 20 is appropriately set according to the size of the devolatilizing extruder, the extrusion conditions, and the like, and usually 0.1 to 2.0 mm, preferably 0.1 to 1.5 mm. When this distance is greater than the above-mentioned range, unreacted monomers and polymers can easily enter the flow path (FP). In contrast, when the distance is smaller than the above-mentioned range, it may be difficult to discharge the gas introduced into the second shaft seal portion 34 into the cylinder 10 so that the polymer of the unreacted monomer is the shaft seal. The effect of suppressing attachment to the vicinity of the bearing portion 30 can be reduced.

In the devolatilizing extruder 100, the polymer composition is supplied from the polymer composition supply port 12. At this time, the liquid polymer composition is converted into vapor mist by adjusting the pressure in the vicinity of the polymer composition supply port 12, and at least a part of the volatile components contained in the polymer composition is supplied to the polymer composition supply port 12. It is discharged through the gas discharge ports 14a and 14b adjacent to it. The gas introduced through the gas introduction port 36 and passing through the second shaft seal portion 34 and then discharged to the cylinder 10 via the flow path FP is mainly gas discharged along with some of the volatile components. Discharge is carried out through the port (rear vent) 14a. The polymer composition is sent to the side of the polymer outlet 16 by the rotation of the screw 20 and most of the volatile components contained in the polymer composition are vaporized until the polymer composition reaches the polymer outlet 16 and then the gas outlet port. Discharge through 14b, 14c, 14d. In addition to the unreacted monomers, additives and solvents optionally used and volatile by-products produced during the polymerization process are contained in the volatile components discharged through the gas discharge port 14. Thus, it is possible to obtain a polymer devolatilized through the polymer outlet 16, where most of the volatile components are to be removed. The polymer can be obtained, for example, in the form of pellets.

The above-mentioned devolatilizing extruder 100 can be suitably used to prepare a (meth) acrylic polymer obtained by polymerizing a monomer mixture containing methyl (meth) acrylate as a main component in the polymer.

In the devolatilizing extruder 100, there is no particular limitation on the number of gas discharge ports 14 formed in the cylinder 10. Although a configuration in which four gas discharge ports 14 are provided is illustrated in FIG. 1, the number of gas discharge ports 14 may be 1 to 3, or 5 or more. From the point of view of effectively evacuating the gas introduced through the gas introduction port 36 and the volatile components of the polymer composition, the cylinder 10 is preferably provided between the polymer composition supply port 12 and the shaft seal bearing portion 30. At least one gas exhaust port (rear vent) provided, and at least one gas exhaust port (front vent) provided between the polymer composition supply port 12 and the polymer outlet 16, and more preferably one rear vent and It includes one to three front vents.

There is no particular limitation on the number of screws 20 used in the devolatilizing extruder 100. The number of screws is preferably 1 to 2, more preferably 2. A twin-screw devolatilizing extruder comprising two screws 20 is preferred because (meth) acrylic polymers can be produced effectively. The diameter of the screw 20 is not particularly limited and is usually φ100 to 450 mm.

The devolatilization extrusion method of the polymer composition of the present invention and the production method of the polymer will be described below.

The process for producing the polymer of the present invention comprises the steps of: continuously feeding a raw material containing a monomer, a radical polymerization initiator and a chain transfer agent into a polymerization reaction vessel; Polymerizing the monomers in a polymerization reaction vessel to obtain a polymer composition containing the polymer and the volatile component containing unreacted monomers; And supplying the polymer composition into the cylinder through the polymer composition supply port of the devolatilizing extruder of the present invention, and also exhausting gas and volatile components through the gas outlet port and exhausting the polymer after devolatilization through the polymer outlet, respectively. Feeding the second shaft seal portion through the introduction port. Each step will be described in detail below.

3 is a schematic block diagram showing a system for preparing a polymer. As shown in FIG. 3, first, an initiator composition and a monomer composition are mix | blended in the initiator mix container 101 and the monomer mix container 102, respectively. An initiator composition is prepared by mixing a radical polymerization initiator, a monomer and a chain transfer agent. The monomer composition is prepared by mixing a monomer and a chain transfer agent. Thereafter, the blended initiator composition and the monomer composition are continuously supplied to the polymerization reaction vessel 103 in which the polymerization reaction is performed.

Here, the monomers, radical polymerization initiators and chain transfer agents are selected according to the polymer to be produced. The case where a (meth) acrylic polymer such as polymethyl methacrylate is produced will be described below as a preferred embodiment. In this description, "(meth) acryl" means "acryl" and the corresponding "methacryl".

There is no particular limitation on the monomer used as a raw material of the (meth) acrylic polymer. Examples of monomers include at least 80% by mass of alkyl (meth) acrylate alone (alkyl group having 1 to 4 carbon atoms) alone or alkyl (meth) acrylate (alkyl group having 1 to 4 carbon atoms) and alkyl ( 20 mass% of other vinyl monomers copolymerizable with meth) acrylate. Examples of alkyl of alkyl (meth) acrylates (alkyl groups having 1 to 4 carbon atoms) include methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, and the like, and these alkyl (meth) Of the acrylates, methyl (meth) acrylates are preferred.

Examples of copolymerizable vinyl monomers include (meth) acrylates other than alkyl (meth) acrylates (alkyl groups having from 1 to 4 carbon atoms) such as benzyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; Unsaturated carboxylic acids or acid anhydrides thereof such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride and itaconic anhydride; Hydroxyl group-containing monomers such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, monoglycerol acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate and mono glycerol methacrylate; Nitrogen-containing monomers such as acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, diacetone acrylamide and dimethylaminoethyl methacrylate; Epoxy group-containing monomers such as allyl glycidyl ether, glycidyl acrylate and glycidyl methacrylate; And styrene-based monomers such as styrene and α-methylstyrene.

When the present invention is applied to the preparation of the (meth) acrylic acid polymer, examples of the polymerization initiator supplied to the reaction vessel include radical polymerization initiators. Examples of radical polymerization initiators include azobisisobutyronitrile, azobisdimethylvaleronitrile, azobiscyclohexanenitrile, 1,1'-azobis (1-acetoxy-1-phenylethane), dimethyl 2,2 Azo compounds such as' -azobisisobutylate and 4,4'-azobis-4-cyanovaleric acid; Benzoyl peroxide, lauroyl peroxide, acetyl peroxide, capryl peroxide, 2,4-dichlorobenzoyl peroxide, isobutyl peroxide, acetylcyclohexylsulfonyl peroxide, t-butyl peroxypivalate, t -Butyl peroxy-2-ethyl hexanoate, 1,1-di-t-butylperoxycyclohexane, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1, 1-di-t-hexyl peroxy-3,3,5-trimethylcyclohexane, isopropyl peroxydicarbonate, isobutyl peroxydicarbonate, s-butyl peroxydicarbonate, n-butyl peroxydicarbonate, 2-ethylhexyl Peroxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, t-amylperoxy-2-ethyl hexanoate, 1,1,3,3-tetramethylbutyl peroxy-ethyl hexanoate, 1,1,2-trimethylpropyl peroxy-2-ethylhexanoate, t-butyl peroxyisopropyl monocarbo T-amyl peroxyisopropyl monocarbonate, t-butyl peroxy-2-ethylhexyl carbonate, t-butyl peroxyallyl carbonate, t-butyl peroxyisopropyl carbonate, 1,1,3,3-tetra Methylbutyl peroxyisopropyl monocarbonate, 1,1,2-trimethylpropyl peroxyisopropyl monocarbonate, 1,1,3,3-tetramethylbutyl peroxyisononanoate, 1,1,2-trimethylpropyl peroxide Organic peroxides such as oxyisononanoate and t-buty peroxybenzoate. These polymerization initiators may be used alone or in a mixture of two or more kinds.

There is no restriction | limiting in particular about the compounding quantity of a radical polymerization initiator, The compounding quantity is normally 0.001-1 mass part based on 100 mass parts of monomers as a raw material. When a mixture of two or more kinds of radical polymerization initiators is used, the total amount used may be within this range. The polymerization initiator fed into the reaction vessel is selected depending on the polymer to be produced and the type of raw monomers used and is not particularly limited in the present invention. For example, the radical polymerization initiator is preferably a radical polymerization initiator having a half-life of 1 minute or less at the polymerization temperature. When the half-life at the polymerization temperature exceeds 1 minute, the reaction rate is lowered, so the radical polymerization initiator may not be suitable for the polymerization reaction of the continuous polymerization apparatus. The relationship between the half-life and the temperature of the radical polymerization initiator is described in the technical data of the manufacturer for each kind of radical polymerization initiator and in various documents. In the present invention, the values described in known product catalogs such as Wako Pure Chemical Industries, Ltd., KAYAKU AKZO CO., LTD.

When the present invention is applied to the preparation of a (meth) acrylic acid polymer, a chain transfer agent may be formulated in the reaction vessel to adjust the molecular weight of the polymer to be produced. The chain transfer agent may be a monofunctional or polyfunctional chain transfer agent. Specific examples of chain transfer agents include alkyl mercaptans such as propyl mercaptan, butyl mercaptan, hexyl mercaptan, octyl mercaptan, 2-ethylhexyl mercaptan and dodecyl mercaptan; Aromatic mercaptans such as phenylmercaptan and thiocresol; Mercaptans having up to 18 carbon atoms, such as ethylene thioglycol; Polyhydric alcohols such as ethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripentaerythritol and sorbitol; Obtained by esterifying a hydroxyl group with thioglycolic acid or 3-mercaptopropionic acid, 1,4-dihydronaphthalene, 1,4,5,8-tetrahydronaphthalene, β-terpinene, terpinolene, 1,4 -Cyclohexadiene, 1,4-cyclohexadiene, hydrogen sulfide and the like. Such chain transfer agents may be used alone, or two or more kinds thereof may be used in combination.

Since the blending amount of the chain transfer agent varies depending on the kind of the chain transfer agent used and the like, there is no particular limitation on the blending amount. For example, when mercaptan is used, the compounding amount is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 1 part by mass based on 100 parts by mass of the monomer as a raw material. Usage within these ranges is preferred because thermal stability is maintained satisfactorily without compromising the mechanical properties of the polymer. When two or more kinds of chain transfer agents are used in combination, the total amount of use can be adjusted within this range.

The polymerization reaction vessel 103 used in the present embodiment is a vessel type reactor equipped with a stirrer. The stirrer makes it possible to convert the solution in the vessel into a substantially completely mixed state. As stirring blade, Maxblend wings, paddle wings, double helical ribbon wings, MIG wings, manufactured by Sumitomo Heavy Industries, Ltd., Shinko Pantech Co Ltd. It is possible to use a full zone blade or the like manufactured by, but there is no particular limitation. It is desirable to attach a buffle to increase the stirring effect.

Needless to say, it is preferable that the stirring efficiency is as high as possible. More than necessary stirring force is undesirable because only extra heat is applied to the reaction vessel. Therefore, the stirring force is 0.5 to 20 kPa / m 3, preferably 1 to 15 kPa / m 3. This agitation force needs to be increased as the viscosity of the content liquid, ie the content of the polymer, increases.

The polymerization reaction vessel 103 is preferably in a state filled with a liquid substantially free of a vapor state. When the polymerization reaction vessel is filled with the liquid, the production and adhesion of the polymer inside the vessel inner wall and the vapor gas phase portion as the gas liquid interface can be suppressed, and thus the deterioration in quality due to their mixing in the product can be suppressed. In addition, the total volume of the polymerization reaction vessel 103 can be effectively used, and the productivity can be improved.

In order to fill the polymerization reaction vessel 103 with liquid, it is simplest to locate the outlet of the solution of the vessel on top of the reaction vessel. In this case, the supply port of the raw materials (initiator composition and monomer composition) is preferably provided at the bottom of the polymerization reaction vessel 103. It is preferable to prevent the gas of the monomer from being generated in the polymerization reaction vessel 103. For this purpose, it is desirable to adjust the pressure of the vessel above the vapor pressure at the temperature of the contents liquid. This pressure is generally about 10-20 kg / cm 2.

The interior of the polymerization reaction vessel 103 is preferably in an adiabatic state with substantially no inflow / outflow of heat from the outside. That is, it is preferable to adjust the temperature of the reaction vessel and the temperature on the side of the reaction vessel outer wall surface to approximately the same temperature. Specifically, it is possible for a jacket to be placed on the side of the reaction vessel outer wall, for example, and the temperature of the reaction vessel outer wall can be made to follow the temperature of the reaction vessel using steam, other thermal media, etc., so that approximately the same temperature is achieved. Can be.

The polymerization reaction vessel 103 is kept adiabatic because the formation of polymers on the inner wall of the reaction vessel can be prevented and self-controllability is provided which can suppress runaway reactions by stabilizing the polymerization reaction. It is not desirable to adjust the temperature of the reaction vessel inner wall to an excessively higher temperature than the content liquid because extra heat is applied inside the reaction vessel. The temperature difference between the inside of the reaction vessel and the reaction vessel outer wall is preferably as small as possible. However, the temperature can actually be adjusted with deviations in the range of about ± 5 ° C.

In the present embodiment, the heat generated in the polymerization reaction vessel 103, that is, the heat of polymerization and the stirring heat, is preferably balanced with the amount of heat taken by the liquid (syrup-type) polymer composition discharged from the polymerization reaction vessel 103. Achieve. The amount of heat taken up by the polymer composition is determined by the amount, specific heat and temperature (polymerization temperature) of the polymer composition.

The polymerization temperature varies depending on the kind of radical polymerization initiator used, and is preferably about 120 to 180 ° C, more preferably 130 to 180 ° C. When this temperature is too high, the resulting polymer exhibits low syndiotacticity, so the amount of oligomers produced can increase and the heat resistance of the resin can be lowered.

The average residence time of the polymerization reaction vessel 103 is preferably 15 minutes or more and 2 hours or less, more preferably 20 minutes or more and 1.5 hours or less. When the average residence time is longer than necessary, the amount produced of the oligomers, such as dimers or trimers, is increased and thus the heat resistance of the product may be lowered. The average residence time can be adjusted by changing the feed amount of monomer per unit time.

As the initiator compounding vessel 101 and the monomer compounding vessel 102 used in the present embodiment, it is possible to use a compounding vessel equipped with the same stirrer as the stirrer of the polymerization reaction vessel 103 mentioned above. In the initiator compounding vessel 101, the radical polymerization initiator is completely dissolved in the monomer to obtain an initiator solution. The temperature of the initiator compounding vessel 101 is maintained at a temperature at which the polymerization reaction does not proceed, and is preferably maintained at -20 to 10 ° C. In contrast, the temperature of the monomer compounding vessel 102 is maintained at a temperature at which the monomer does not volatilize, and is preferably maintained at -20 to 10 ° C. As the raw material of the polymer, the initiator composition and the monomer composition are continuously supplied from the initiator compounding vessel 101 and the monomer compounding vessel 102 into the polymerization reaction vessel 103 by a pump or the like.

The amount of the initiator composition supplied from the initiator compounding vessel 101 to the polymerization reaction vessel 103 varies depending on the capacity of the polymerization reaction vessel 103 and the like, and this amount is preferably, for example, when the capacity of the polymerization reaction vessel 103 is 10L. Is 0.1 to 10 kg / hr, more preferably 0.5 to 5 kg / hr. The amount of the monomer composition supplied from the monomer compounding vessel 102 to the polymerization reaction vessel 103 varies depending on the capacity of the polymerization reaction vessel 103 and the like, and the amount is preferably, for example, when the capacity of the polymerization reaction vessel 103 is 10L. Is 4 to 40 kg / hr, more preferably 10 to 30 kg / hr.

As the monomer to be blended in the monomer compounding vessel 102, not only fresh monomers, but also monomers separated and recovered in an unreacted state, as shown in FIG. 3, may also be used. When the monomers are blended, it is common for the inert gas to be bubbled into the monomer blending vessel 102 or dissolved oxygen to be removed by vacuum degassing to prevent the effects of dissolved oxygen. In the process of this embodiment, it is not necessary to strictly remove the dissolved oxygen, and the polymerization reaction can be stably performed even in the presence of about 1.5 to 3 ppm of dissolved oxygen. When the blended monomer composition is fed into the polymerization reaction vessel 103, it is particularly preferable to filter with a filter having a suitable size selected according to the purpose in order to remove foreign substances when using a polymer obtained from a material for optical equipment. .

In the method for producing the polymer of the present embodiment, as described above, the initiator composition and the monomer composition are continuously supplied from the initiator compounding vessel 101 and the monomer compounding vessel 102 into the polymerization reaction vessel 103 as raw materials of the polymer. Then, at least a portion of the monomers are polymerized in the polymerization reaction vessel 103 to obtain a polymer composition containing the polymer and the unreacted monomers. In the polymerization reaction vessel 103, the polymerization method of the polymer may be either bulk polymerization without using a solvent or solution polymerization using a solvent, and a bulk polymerization method is particularly preferable.

The polymerization is carried out by the continuous solution polymerization method in the same manner as in the above-mentioned continuous bulk polymerization method, except that a solvent is used for the polymerization reaction. The solvent used for the polymerization reaction can be appropriately set according to the raw material monomer of the continuous solution polymerization reaction and the like, and is not particularly limited. Examples of this solvent are toluene, xylene, ethylbenzene, methyl isobutyl ketone, methyl alcohol, ethyl alcohol , Octane, decane, cyclohexane, decalin, butyl acetate, pentyl acetate and the like. Of these solvents, toluene, methanol, ethylbenzene and butyl acetate are preferred. The solvent may be added to one or both of the initiator composition and the monomer composition. There is no restriction | limiting in particular about the ratio of a solvent, The ratio is based on the whole polymer composition, Preferably it is 5-30 mass%, More preferably, it is 1-20 mass%.

The content of the polymer of the polymer composition is preferably 40 to 70 mass%. When the content of the polymer is too high, the efficiency of heat transfer and mixing may decrease and thus the stability may deteriorate. In contrast, when the content of the polymer is too low, it may be difficult to separate volatile components containing unreacted monomers as main components.

The polymer composition produced in the polymerization reaction vessel 103 is continuously extracted from the polymerization reaction vessel 103 and then optionally introduced to the heater 104. In the heater 104, the liquid polymer composition is preheated to increase the efficiency of devolatilization in the subsequent devolatilizing extruder 100. At this time, the preheating temperature is preferably adjusted within 180 to 220 ° C. When the preheating temperature is higher than the above-mentioned range, the volatile components may be gasified and thus it may be difficult to deliver the liquid at a given flow rate.

Next, the polymer composition is fed to the devolatilizing extruder 100. As the devolatilizing extruder 100, the above-mentioned devolatilizing extruder 100 is used. The devolatilization extrusion continuously supplies the polymer composition to the cylinder 10 through the polymer composition supply port 12 of the devolatilizing extruder 100, and also contains the gas and the unreacted monomer as main components through the gas discharge port 14, respectively. Is carried out by supplying a gas through the gas introduction port 36 to the second shaft seal portion 34 to discharge the volatile components and to discharge the polymer after devolatilization through the polymer outlet 16. The flow rate and type of gas to be supplied are as described previously.

The devolatilization extrusion is carried out by heating the polymer composition fed continuously at 200 to 290 ° C, thereby continuously separating and removing most of the volatile components containing the unreacted monomer as a main component. With respect to the pressure conditions during devolatilization extrusion, the pressure of the gas discharge port (rear vent) 14a is adjusted to within about -0.05 to 0.15 MPaG (gauge pressure) and the gas discharge port (front vent) 14b, 14c, 14d Pressures are adjusted to within about -0.09 to -0.02 MPaG (gauge pressure). The gasified volatile components and the polymer are introduced into the devolatilizing extruder 100 through the polymer composition supply port 12. At this time, when the pressure of the rear vent is reduced below -0.05 MPaG, an intake phenomenon occurs in the rear vent, and therefore, it is preferable to adjust the pressure within the above-mentioned range. In order to remove volatile components, the pressure of the four vents is preferably adjusted within the above-mentioned range. Usually, a pressure regulating valve is placed between the heater 104 and the devolatilizing extruder 100, thereby adjusting the pressure during devolatilizing extrusion.

During or after the above mentioned devolatilization extrusion, lubricants such as higher alcohols and higher fatty acid esters, ultraviolet absorbers, heat stabilizers, colorants, antistatic agents and the like can be added to the polymer.

The volatile component containing the unreacted monomer discharged through the gas discharge port 14 as a main component is sent to the monomer recovery tower 105. Volatile components containing unreacted monomers as main components contain impurities originally contained in the monomers, oligomers such as dimers and trimers, and impurities such as radical polymerization initiator residues. When the polymerization is carried out by a continuous solution polymerization method, a solvent may be contained in addition to these impurities. When impurities accumulate, the polymer obtained is colored. Therefore, impurities are removed from the unreacted monomers by absorption or distillation of the monomer recovery tower 105 or the like, and the monomers obtained thereafter are reused as monomers for polymerization. For example, in the monomer recovery tower 105, the monomer is recovered as distillate from the tower top of the monomer recovery tower 105 by continuous distillation, and then reused in the monomer compounding vessel 102. Impurities removed in the monomer recovery tower 105 are discarded as waste. The volatile component containing an unreacted monomer as a main component usually indicates that at least 30% by mass of the unreacted monomer is contained in the volatile component.

In the above-mentioned devolatilizing extrusion method of the polymer composition and the manufacturing method of the polymer, it is possible to sufficiently inhibit the unreacted monomer, the polymer thereof, and the like from adhering to the shaft seal bearing portion of the devolatilizing extruder, so that the polymer is poor in the screw. It can be produced continuously over a long period without causing problems such as rotation.

The above-mentioned devolatilization extrusion method of the polymer composition and the method for producing the polymer can be suitably used for the preparation of the (meth) acrylic polymer in the polymer, and are obtained by polymerizing a monomer mixture containing methyl (meth) acrylate as a main component ( It can be used particularly suitably for the preparation of the meth) acrylic polymer.

Polymers such as (meth) acrylic polymers obtained by the above-mentioned methods can be suitably used in various fields such as lighting, signboards, and vehicles because excellent transparency and weatherability can be obtained. The (meth) acrylic polymer may be a material for an optical disk substrate; Materials for optical instruments such as Fresnel lenses, lenticular lenses, diffuser panels and light guide plates used in backlight systems of liquid crystal displays, and protective front panels of liquid crystal displays; It may be particularly suitably used for a vehicle member such as a tail lamp cover, a head lamp cover, a visor and a meter panel.

10 cylinder 12 polymer composition supply port
14 gas discharge port 16 polymer outlet
18: through hole 20: screw
20a: shaft portion 30: shaft seal bearing portion
32: first shaft seal portion 34: second shaft seal portion
36 gas introduction port 100 devolatilizing extruder

Claims (7)

A cylinder having a polymer composition supply port, a gas discharge port, a polymer outlet, and a through hole;
A rotatable screw inserted into the cylinder through the through hole; And
A devolatilizing extruder comprising a shaft seal bearing portion for supporting a shaft portion of a screw extending out of a cylinder from a through hole,
The shaft seal bearing portion comprises a first shaft seal portion, a second shaft seal portion lying between the first shaft seal portion and the cylinder, and a gas introduction port for introducing gas into the second shaft seal portion; ,
The shaft seal bearing portion has a gap serving as a flow path between the inner wall surface of the through hole and the surface of the shaft portion of the screw, through which the gas introduced through the gas introduction port into the second shaft seal portion is introduced. A devolatilizing extruder discharged into the cylinder. The devolatilizing extruder according to claim 1, wherein the second shaft seal portion is formed of a labyrinth seal. The devolatilizing extruder according to claim 1 or 2, wherein the first shaft seal portion is formed of a Wilson seal. As a method for devolatilization extrusion of the polymer composition;
The polymer composition containing the polymer and the volatile components is fed into the cylinder through the polymer composition supply port of the devolatilizing extruder according to any one of claims 1 to 3, and the gas and volatile components are discharged through the gas discharge ports respectively. A method for devolatilization extrusion of a polymer composition comprising feeding gas through a gas introduction port to a second shaft seal portion for discharging the polymer after devolatilization through a polymer outlet. The method for devolatilizing extrusion of a polymer composition according to claim 4, wherein the gas is an inert gas or a mixed gas containing an oxygen gas and an inert gas whose content of oxygen gas is 10% by volume or less. As a method of producing a polymer;
Continuously supplying a raw material containing the monomer, the radical polymerization initiator and the chain transfer agent to the polymerization reaction vessel;
Polymerizing the monomers in a polymerization reaction vessel to obtain a polymer composition containing a volatile component containing the polymer and unreacted monomers; And
The polymer composition is fed into the cylinder through the polymer composition supply port into the devolatilizing extruder according to any one of claims 1 to 3, and the gas and volatile components are respectively discharged through the gas discharge port and after devolatilization through the polymer outlet. Supplying a gas to the second shaft seal through a gas introduction port to discharge the polymer. The method for producing a polymer according to claim 6, wherein the gas is an inert gas or a mixed gas containing an inert gas and an oxygen gas having a content of 10 vol% or less.

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