JP2012016886A - Devolatilizing extruder, and devolatilizing extrusion method of polymer composition using the same and method of producing methacryl based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a devolatilizing extruder capable of suppressing the contamination of a polymer composition or a methacrylic polymer to be produced.SOLUTION: The devolatilizing extruder for producing the methacrylic polymer is provided with: a cylinder 10 having a polymer composition supply port 12, a gas discharge port 14, a polymer outlet 16 and a through-hole 18; a rotatable screw 20 penetrating the through-hole 18 and inserted into the cylinder 10; and a shaft seal bearing 30 extended to the outside of the cylinder 10 from the through-hole 18 of the screw 20 and supporting a shaft 20a. In the devolatilizing extruder for producing the methacrylic polymer, the shaft seal section 32 of the shaft seal bearing 30 is formed of a mechanical seal using at least one kind selected from a group composed adipic acid ester, phthalic acid ester, di-isobutyric ester and acetylated glyceride as a mechanical seal liquid.

Description

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

  As a method for producing a methacrylic polymer, after obtaining a polymer composition containing a methacrylic polymer and a volatile component by a solution polymerization method or a bulk polymerization method, this is supplied to a screw-type devolatilizing extruder to remove the volatile component. A method for removing the methacrylic polymer is known (see, for example, Patent Documents 1 and 2).

  The screw inserted into the devolatilizing extruder used in the above method is supported by the shaft seal bearing part of the devolatilizing extruder, and a shaft seal part is provided around the screw in the shaft seal bearing part. It has been. Various types of seal structures that form the shaft seal portion are known, and mechanical seals are known as one of typical seal structures.

JP-A-3-49925 JP 2003-96105 A

  The mechanical seal uses a mechanical seal liquid as a lubricating liquid for the seal surface. Therefore, in a conventional devolatilizing extruder using a mechanical seal, when a continuous operation is performed for a long period of time, a part of the mechanical seal liquid leaks from the shaft seal part, and the polymer composition or the methacrylic product to be produced It had the problem that it could contaminate the polymer. When the polymer composition or the methacrylic polymer to be produced is contaminated, there arises a problem that the transparency of the methacrylic polymer is lowered or it is easily colored during molding.

  The present invention has been made in view of the above-described problems of the prior art. A devolatilizing extruder capable of suppressing contamination of a polymer composition and a methacrylic polymer to be produced, and a heavy weight using the same. It aims at providing the devolatilization extrusion method of a unification composition, and the manufacturing method of a methacrylic polymer.

  In order to achieve the above object, the present invention includes a polymer composition supply port, a gas discharge port, a polymer outlet, a cylinder having a through hole, and a through hole inserted into the cylinder. A devolatilizing extruder for producing a methacrylic polymer, comprising: a rotatable screw; and a shaft seal bearing portion that supports a shaft portion extending from the through hole of the screw to the outside of the cylinder. The shaft seal portion of the shaft seal bearing portion is formed by a mechanical seal using at least one selected from the group consisting of adipic acid ester, phthalic acid ester, diisobutyric acid ester and acetylated glyceride as a mechanical seal liquid. Provide a devolatilizing extruder.

  Even if at least one selected from the group consisting of adipic acid ester, phthalic acid ester, diisobutyric acid ester and acetylated glyceride used as the mechanical seal liquid is mixed in the polymer composition, It has the property that the transparency of the polymer is less likely to be adversely affected, such that the transparency of the polymer is reduced, and the polymer is easily colored during molding. Therefore, in the devolatilizing extruder, the shaft seal portion is formed by a mechanical seal, and at least selected from the group consisting of adipic acid ester, phthalic acid ester, diisobutyric acid ester and acetylated glyceride as the mechanical seal liquid. By using 1 type, even if a mechanical seal liquid leaks in a cylinder by a long-term continuous operation, contamination of a polymer composition or the methacrylic polymer to manufacture can be suppressed. Therefore, according to the devolatilizing extruder, a methacrylic polymer in which contamination is suppressed can be efficiently produced even when a long-term operation is continuously performed.

  The present invention also supplies a polymer composition containing a methacrylic polymer and a volatile component into the cylinder from the polymer composition supply port in the devolatilizing extruder of the present invention, and the volatile component is exhausted from the gas. A method for devolatilizing and extruding a polymer composition, in which a methacrylic polymer after devolatilization is discharged from the polymer outlet from an outlet, respectively.

  According to this devolatilization extrusion method, since the devolatilization extruder of the present invention is used, contamination of the polymer composition and the methacrylic polymer to be produced can be suppressed. Therefore, according to the devolatilization extrusion method, a methacrylic polymer in which contamination is suppressed can be efficiently produced even when a long-term operation is continuously performed.

  The present invention further includes a step of continuously supplying a raw material containing a monomer component mainly composed of a methacrylic monomer, a radical polymerization initiator, and a chain transfer agent to the polymerization reaction tank, The step of polymerizing the monomer component to obtain a polymer composition containing a methacrylic polymer and a volatile component containing an unreacted monomer, and the polymer composition as claimed in claim 1. Supplying the inside of the cylinder from the polymer composition supply port in the devolatilization extruder, and discharging the volatile component from the gas discharge port and the methacrylic polymer after devolatilization from the polymer outlet, respectively. A method for producing a methacrylic polymer is provided.

  According to this method for producing a methacrylic polymer, since the devolatilizing extruder of the present invention is used, contamination of the polymer composition and the methacrylic polymer to be produced can be suppressed. Therefore, according to the devolatilization extrusion method, a methacrylic polymer in which contamination is suppressed can be efficiently produced even when a long-term operation is continuously performed.

  ADVANTAGE OF THE INVENTION According to this invention, the devolatilization extruder which can suppress contamination of a polymer composition and the methacrylic polymer to manufacture, the devolatilization extrusion method of a polymer composition using the same, and a methacrylic polymer The manufacturing method of can be provided.

It is the schematic which shows the internal structure of the devolatilization extruder which concerns on suitable embodiment of this invention. It is a fragmentary sectional view of the shaft seal bearing part of the devolatilization extruder concerning the suitable embodiment of the present invention. It is a schematic block diagram which shows the manufacturing system of a methacrylic polymer using the devolatilization extruder of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant description is omitted. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

  FIG. 1 is a schematic view showing the internal structure of a devolatilizing extruder according to a preferred embodiment of the present invention. As shown in FIG. 1, a devolatilizing extruder 100 includes a polymer composition supply port 12 for supplying a polymer composition containing a methacrylic polymer and a volatile component, and a gas discharge port for discharging a volatile component. 14, a polymer outlet 16 for discharging the methacrylic polymer after devolatilization, a cylinder 10 having a through hole 18, and a rotatable screw 20 inserted into the cylinder 10 through the through hole 18. And a shaft seal bearing portion 30 that supports a shaft portion 20a extending from the through hole 18 of the screw 20 to the outside of the cylinder 10. The cylinder 10 is provided with four gas discharge ports 14, and one gas discharge port (back vent) 14 a is provided on the shaft seal bearing portion 30 side as viewed from the polymer composition supply port 12, and the polymer outlet 16. Three gas discharge ports (fore vents) 14b, 14c, and 14d are provided on the side. Further, the shaft seal bearing portion 30 has a shaft seal portion 32.

  FIG. 2 is a partial cross-sectional view of a shaft seal bearing portion of a devolatilizing extruder according to a preferred embodiment of the present invention. As shown in FIG. 2, the shaft seal portion 32 is formed by a mechanical seal. A drive device (not shown) for rotating the screw 20 is provided on the opposite side of the shaft seal portion 32 from the cylinder 10.

  The type of the mechanical seal that forms the shaft seal portion 32 is not particularly limited, and a known type of mechanical seal can be used. For example, as shown in FIG. 2, the mechanical seal has a rotary ring 32a fixed to the screw 20 side and a fixed ring 32b fixed to the shaft seal bearing body (casing) side, and a spring (not shown). The rotating ring 32a and the stationary ring 32b are pressed against each other with a constant force so as to be in close contact with each other. Further, in order to reduce the friction on the contact surface between the rotating ring 32a and the stationary ring 32b, the inside of the mechanical seal 32 is filled with a mechanical seal liquid 32c. In FIG. 2, the structure by the mechanical seal which has two combinations of the rotating ring 32a and the fixed ring 32b, ie, a double mechanical seal, is shown. The mechanical seal liquid 32c is normally continuously supplied from a mechanical seal liquid inlet (not shown) using a pump or the like, and continuously discharged from a mechanical seal liquid outlet (not shown). The mechanical seal liquid is preferably circulated and supplied. The filling pressure is appropriately set depending on the size of the devolatilizing extruder, the extrusion conditions, and the like, but is set higher than the pressure of the gas outlet 14a of the devolatilizing extruder 100. Further, since the devolatilizing extruder is provided with a pressure gauge and a safety valve according to the maximum operating pressure, the filling pressure is adjusted within a range in which the safety valve does not operate.

  As the mechanical seal liquid 32c, at least one selected from the group consisting of adipic acid ester, phthalic acid ester, diisobutyric acid ester, and acetylated glyceride is used. Examples of adipic acid esters include bis (2-ethylhexyl) adipate, diisononyl adipate, diisodecyl adipate, and the like. Examples of the phthalic acid ester include bis (2-ethylhexyl) phthalate, diisononyl phthalate, diisodecyl phthalate, and the like. Examples of the diisobutyric acid ester include 2,2,4-trimethyl-1,3-pentanediol diisobutyrate. Examples of the acetylated glyceride include glycerin diacetomonolaurate, glycerin diacetomonostearate, glycerin diacetomonooleate, glycerin diacetomonolinoleate, glycerin diacetomono12-hydroxystearate, glycerin diacetomonomyristate, glycerin diacetomonopalmi Tate, glycerol diacetomonolaurate, glycerol monoacetomonostearate, glycerol monoacetomonomyristate, glycerol monoacetomonopalinate, glycerol monoacetomonolysinolate, glycerol monoacetomono 12-hydroxystearate, glycerol monoacetomonobe Henate, glycerol monoacetomonooleate, glycerol monoacetomonolaurate, glycerol monoacetate Oleate, glycerol mono acetic Jiri ricinoleate, glycerol mono-acetoacetate dicaprylate, glycerol mono-acetoacetate dilaurate, glycerin mono- acetonate distearate and the like. Among these, adipic acid esters and diisobutyric acid esters are preferable, and adipic acid esters are particularly preferable. Adipic acid ester, phthalic acid ester, diisobutyric acid ester, and acetylated glyceride do not promote the polymerization reaction of monomers based on unreacted methacrylic monomers even when mixed in the polymer composition. Also, there is an advantage that adverse effects such as causing coloring of the obtained methacrylic polymer are hardly generated.

  The material of the rotating ring 32a and the fixed ring 32b is not particularly limited as long as it is made of a known material. Examples of the material of the rotating ring 32a and the stationary ring 32b include carbon, silicone carbide, cemented carbide, and chromium oxide coating.

  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 atomized 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 discharges | emits from near gas discharge port 14a, 14b. Further, the polymer composition advances to the polymer outlet 16 side by the rotation of the screw 20, and by the time it reaches the polymer outlet 16, most of the volatile components contained in the polymer composition are vaporized, and the gas discharge port 14b. , 14c, 14d. Further, the volatile components discharged from the gas outlet 14 include, in addition to unreacted monomers, solvents and additives used as necessary, volatile by-products generated in the polymerization process, and the like. As described above, a methacrylic polymer after devolatilization from which most of the volatile components have been removed can be obtained from the polymer outlet 16. The methacrylic polymer can be obtained, for example, in the form of pellets.

  The devolatilizing extruder 100 described above can be suitably used for producing a methacrylic polymer obtained by polymerizing a monomer mixture mainly composed of methyl methacrylate among methacrylic polymers.

  In the devolatilizing extruder 100, the number of gas discharge ports 14 formed in the cylinder 10 is not particularly limited. Although FIG. 1 shows a configuration in which four gas discharge ports 14 are provided, the number of gas discharge ports 14 may be 1 to 3, or 5 or more. In terms of efficiently discharging volatile components in the polymer composition, the cylinder 10 includes a gas discharge port (back vent) provided between the polymer composition supply port 12 and the shaft seal bearing portion 30; It is preferable to have one or more gas outlets (fore vents) provided between the polymer composition supply port 12 and the polymer outlet 16, respectively. More preferably, it has forevent.

  The number of screws 20 used in the devolatilizing extruder 100 is not particularly limited, but is preferably 1 or 2 and more preferably 2. A twin screw devolatilizing extruder having two screws 20 is preferable because it can efficiently produce a methacrylic polymer. The diameter of the screw 20 is not particularly limited, but is usually φ100 to 450 mm.

  Next, the devolatilization extrusion method for the polymer composition of the present invention and the production method for the methacrylic polymer will be described.

  The method for producing a methacrylic polymer of the present invention comprises a step of continuously supplying a raw material containing a monomer component mainly composed of a methacrylic monomer, a radical polymerization initiator, and a chain transfer agent to a polymerization reaction tank. And a step of polymerizing a monomer component in a polymerization reaction tank to obtain a polymer composition containing a methacrylic polymer and a volatile component containing an unreacted monomer, and a polymer composition, Supplying the polymer composition from the polymer composition supply port in the devolatilizing extruder of the present invention into the cylinder, discharging the volatile component from the gas outlet, and discharging the methacrylic polymer after devolatilization from the polymer outlet, respectively. It is a method to have. Hereinafter, each step will be described in detail.

  FIG. 3 is a schematic configuration diagram showing a methacrylic polymer production system. As shown in FIG. 3, first, an initiator composition and a monomer composition are respectively prepared in an initiator preparation tank 101 and a monomer preparation tank 102. The initiator composition is a mixture of a radical polymerization initiator, a monomer component mainly composed of a methacrylic monomer, and a chain transfer agent. The monomer composition is a mixture of a monomer component mainly composed of a methacrylic monomer and a chain transfer agent. And the prepared initiator composition and monomer composition are continuously supplied to the polymerization reaction tank 103, and a polymerization reaction is performed.

  Here, the monomer component mainly composed of a methacrylic monomer, the radical polymerization initiator and the chain transfer agent are selected according to the methacrylic polymer to be produced. Hereinafter, each component will be described in detail. In the present specification, “(meth) acryl” means “acryl” and “methacryl” corresponding to it.

  The monomer component mainly composed of a methacrylic monomer may be a methacrylic monomer alone or a mixture of a methacrylic monomer and another monomer copolymerizable with the methacrylic monomer. is there. When mixing monomers other than a methacrylic monomer, content of a methacrylic monomer is 50 mass% or more on the basis of the whole monomer quantity, and it is preferable that it is 75 mass% or more.

  Although it does not specifically limit as a methacrylic monomer, For example, the alkyl methacrylate (thing whose carbon number of an alkyl group is 1-4) is mentioned. Examples of the alkyl of the alkyl methacrylate (the alkyl group having 1 to 4 carbon atoms) include methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, etc. Of these, methyl methacrylate is preferable. These methacrylic monomers can be used alone or in combination of two or more. When two or more types are used in combination, the monomer component mainly composed of the methacrylic monomer is a mixture of two or more methacrylic monomers, or two or more methacrylic monomers and It is a mixture of other monomers copolymerizable with the methacrylic monomer. When mixing two or more methacrylic monomers with other monomers copolymerizable with the methacrylic monomers, the total content of the two or more methacrylic monomers is the total amount of monomers. Based on the above, it is 50% by mass or more, and preferably 75% by mass or more.

  Other monomers that can be used in combination with methacrylic monomers include other vinyl monomers copolymerizable with methacrylic monomers. Other vinyl monomers include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, dodecyl acrylate, stearyl acrylate, etc. Acrylic acid alkyl ester having 18 alkyl groups: unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, maleic anhydride, itaconic anhydride, its acid anhydride: 2-hydroxyethyl acrylate, acrylic Hydroxyl group-containing monomers such as 2-hydroxypropyl acid, monoglycerol acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, monoglycerol methacrylate: acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, diacetate Nitrogen-containing monomers such as acrylamide and dimethylaminoethyl methacrylate: Epoxy group-containing monomers such as allyl glycidyl ether, glycidyl acrylate and glycidyl methacrylate: Styrene monomers such as styrene and α-methylstyrene: Can be mentioned.

  In the present invention, examples of the polymerization initiator supplied to the reaction vessel include a radical polymerization initiator. Examples of the radical polymerization initiator include azobisisobutyronitrile, azobisdimethylvaleronitrile, azobiscyclohexanenitrile, 1,1′-azobis (1-acetoxy-1-phenylethane), dimethyl 2,2 ′. -Azo compounds such as azobisisobutyrate and 4,4'-azobis-4-cyanovaleric acid; benzoyl peroxide, lauroyl peroxide, acetyl peroxide, capryel peroxide, 2,4-dichlorobenzoyl peroxide, Isobutyl peroxide, acetylcyclohexylsulfonyl peroxide, t-butyl peroxybiparate, t-butyl peroxy-2-ethylhexanoate, 1,1-di-t-butylperoxycyclohexane, 1,1-di- t-butyl peroxy -3,3,5-trimethylcyclohexane, 1,1-di-t-hexylperoxy-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-ethylhexaenoate, 1,1,3 3-tetramethylbutylperoxy-ethylhexanoate, 1,1,2-trimethylpropylperoxy-2-ethylhexanoate, t-butylperoxyisopropylmonocarbonate, t-amylperoxyisopropylmonocarbonate, t -Butyl par Xyl-2-ethylhexyl carbonate, t-butyl peroxyallyl carbonate, t-butyl peroxyisopropyl carbonate, 1,1,3,3-tetramethylbutyl peroxyisopropyl monocarbonate, 1,1,2-trimethylpropyl peroxy Examples thereof include organic peroxides such as isopropyl monocarbonate, 1,1,3,3-tetramethylbutylperoxyisononate, 1,1,2-trimethylpropylperoxy-isononate, and t-butylperoxybenzoate. These polymerization initiators may be used alone or in a combination of two or more.

  Although it does not specifically limit as a compounding quantity of a radical polymerization initiator, Usually, it is 0.001-1 mass part with respect to 100 mass parts of monomer components of a raw material. When two or more kinds of radical polymerization initiators are mixed and used, the total amount used may be within this range. The polymerization initiator supplied to the reaction vessel is selected according to the type of methacrylic polymer to be produced and the raw material monomer component to be used, and is not particularly limited in the present invention. The radical polymerization initiator is preferably one having a half-life at the polymerization temperature of 1 minute or less. If the half-life at the polymerization temperature exceeds 1 minute, the reaction rate becomes slow, which may make it unsuitable for a polymerization reaction in a continuous polymerization apparatus. The relationship between the temperature and the half-life of the radical polymerization initiator is described in various documents and technical data of the manufacturer for each type of radical polymerization initiator. In the present invention, values described in known product catalogs such as Wako Pure Chemical Industries, Ltd. or Kayaku Akzo Corporation were used.

  In the present invention, a chain transfer agent can be blended in the reaction vessel in order to adjust the molecular weight of the methacrylic polymer produced. The chain transfer agent may be any of monofunctional and polyfunctional chain transfer agents. Specifically, for example, propyl mercaptan, butyl mercaptan, hexyl mercaptan, octyl mercaptan, 2-ethylhexyl mercaptan, dodecyl mercaptan Alkyl mercaptans such as phenyl mercaptan and thiocresol; mercaptans having 18 or less carbon atoms such as ethylene thioglycol; ethylene glycol, neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, tripenta Polyhydric alcohols such as erythritol and sorbitol; hydroxyl group esterified with thioglycolic acid or 3-mercaptopropionic acid, 1,4-dihydronaphthalene , 1,4,5,8-tetrahydronaphthalene, beta-terpinene, terpinolene, 1,4-cyclohexadiene, 1,4-cyclohexadiene, and the like hydrogen sulfide. These may be used alone or in combination of two or more.

  The amount of the chain transfer agent is not particularly limited because it varies depending on the type of chain transfer agent to be used. For example, when a mercaptan is used, the monomer component 100 of the raw material is used. It is preferable that it is 0.01-3 mass parts with respect to a mass part, and it is more preferable that it is 0.05-1 mass part. The amount used in this range is preferable because it does not impair the mechanical properties of the methacrylic polymer and maintains good thermal stability. When two or more kinds of chain transfer agents are used in combination, the total amount used may be within this range.

  The polymerization reaction tank 103 used in the present embodiment is a tank reactor equipped with a stirrer. And this stirring apparatus makes the solution in a tank substantially complete mixing state. As the shape of the stirring blade, there are used Sumitomo Heavy Industries, Ltd. Max blend blade, paddle blade, double helical ribbon blade, MIG blade, Shinko Pantech Co., Ltd. full zone blade, etc. . In order to enhance the stirring effect, it is desirable to attach a baffle.

Needless to say, the higher the stirring efficiency is, the more preferable it is. However, an excessive stirring power is not preferable because it only adds an extra amount of heat to the reaction vessel. Therefore, the stirring power is 0.5 to 20 kW / m ³ , preferably 1 to 15 kW / m ³ . The stirring power needs to be increased as the viscosity of the content liquid, that is, the polymer content increases.

  It is preferable that the inside of the polymerization reaction tank 103 is in a fully filled state with substantially no gas phase. By making the liquid full, adhesion and generation of the polymer on the inner wall surface of the gas phase portion and the gas-liquid interface can be suppressed, and deterioration in quality due to mixing into these products can be suppressed. In addition, since the entire volume of the polymerization reaction tank 103 can be effectively used, productivity can be improved.

In order to fill the inside of the polymerization reaction tank 103, it is easiest to install the outlet of the solution in the tank at the top of the reaction tank. In this case, it is preferable to provide the feed port for the raw materials (initiator composition and monomer composition) at the bottom of the polymerization reaction tank 103. It is desirable to prevent the monomer gas from being generated in the polymerization reaction tank 103. For this purpose, the pressure in the tank is preferably set to a pressure equal to or higher than the vapor pressure at the temperature of the content liquid. This pressure is about 10 to ²⁰ kg / cm ² .

  Moreover, it is preferable to make the inside of the polymerization reaction tank 103 into an adiabatic state in which heat does not substantially enter and exit from the outside. That is, it is preferable that the temperature in the reaction tank and the temperature on the outer wall surface side of the reaction tank are substantially the same. Specifically, for example, by installing a jacket on the outer wall surface side of the reaction tank and using the steam or other heat medium etc., the reaction tank outer wall temperature is made to follow the temperature in the reaction tank to be approximately the same temperature. it can.

  The reason why the polymerization reaction tank 103 is in an adiabatic state is that the formation of a polymer on the inner wall surface of the reaction tank can be prevented, and the self-controllability that stabilizes the polymerization reaction and suppresses the runaway reaction is brought about. In addition, it is not preferable to make the temperature of the inner wall of the reaction tank too higher than the temperature of the inner solution because extra heat is applied to the reaction tank. Although it is preferable that the temperature difference between the inside of the reaction tank and the outer wall of the reaction tank is small, it may be adjusted within a range of a swing width of about ± 5 ° C.

  In this embodiment, it is preferable to balance the heat generated in the polymerization reaction vessel 103, that is, the polymerization heat and the stirring heat, with the amount of heat taken away by the liquid (syrup-like) polymer composition exiting the polymerization reaction vessel 103. . The amount of heat carried away by the polymer composition is determined by the amount of the polymer composition, specific heat, and temperature (polymerization temperature).

  Although superposition | polymerization temperature is based also on the kind of radical polymerization initiator to be used, Preferably it is about 120-180 degreeC, More preferably, it is 130-180 degreeC. If this temperature is too high, the syndiotactic properties of the resulting methacrylic polymer will be low, the amount of oligomer produced will increase, and the heat resistance of the resin will tend to be low.

  The average residence time in the polymerization reaction tank 103 is preferably 15 minutes or more and 2 hours or less, more preferably 20 minutes or more and 1.5 hours or less. If this time is longer than necessary, the amount of oligomers such as dimers and trimers increases, and the heat resistance of the product tends to decrease. The average residence time can be adjusted by changing the amount of monomer supplied per unit time.

  As the initiator compounding tank 101 and the monomer compounding tank 102 used in the present embodiment, a compounding tank equipped with a stirring device similar to the polymerization reaction tank 103 described above can be used. In the initiator preparation tank 101, the radical polymerization initiator is completely dissolved in the monomer to obtain an initiator liquid. Moreover, the temperature in the initiator preparation tank 101 is maintained at a temperature at which the polymerization reaction does not proceed, and is preferably maintained at −20 to 10 ° C. On the other hand, the temperature in the monomer preparation tank 102 is maintained at a temperature at which the monomer does not volatilize, and is preferably maintained at −20 to 10 ° C. From these initiator preparation tank 101 and monomer preparation tank 102, an initiator composition and a monomer composition, which are raw materials for the methacrylic polymer, are continuously supplied to the polymerization reaction tank 103 by a pump or the like.

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

  In addition, as a monomer prepared in the polymerization reaction tank 103, not only a fresh monomer but also a monomer separated and recovered without being reacted as shown in FIG. 3 may be used. In addition, in order to prevent the influence of dissolved oxygen during monomer preparation, it is common to remove the dissolved oxygen by bubbling an inert gas in the monomer preparation tank 102 or by degassing under reduced pressure. However, in the method of this embodiment, it is not always necessary to remove it strictly, and the polymerization reaction can be carried out stably even if it is present at about 1.5 to 3 ppm. When the prepared monomer composition is supplied to the polymerization reaction vessel 103, the resulting methacrylic polymer can be used as a material for optical equipment by filtering with a filter having a size suitable for the purpose in order to remove foreign matters. Particularly desirable.

  In the method for producing a methacrylic polymer according to the present embodiment, as described above, the initiator composition and the monomer composition, which are raw materials for the methacrylic polymer, are prepared from the initiator preparation tank 101 and the monomer preparation tank 102. It supplies continuously to the polymerization reaction tank 103, and at least one part of a monomer is polymerized in the polymerization reaction tank 103, The polymer composition containing a methacrylic polymer and an unreacted monomer is obtained. In the polymerization reaction vessel 103, the polymerization method of the methacrylic polymer may be bulk polymerization without using a solvent or solution polymerization using a solvent, but bulk polymerization is particularly preferable.

  When the polymerization is carried out by the continuous solution polymerization method, it is carried out in the same manner as the continuous bulk polymerization method described above except that a solvent is used for the polymerization reaction. The solvent used for the polymerization reaction is appropriately set according to the raw material monomer component of the continuous solution polymerization reaction and is not particularly limited. For example, toluene, xylene, ethylbenzene, methyl Examples include isobutyl ketone, methyl alcohol, ethyl alcohol, octane, decane, cyclohexane, decalin, butyl acetate, and pentyl acetate. Of these, toluene, methanol, ethylbenzene, and butyl acetate are preferable. The solvent can be used by adding to one or both of the initiator composition and the monomer composition. Although the ratio of a solvent is not specifically limited, 5-30 mass% of the whole polymer composition is preferable, and 1-20 mass% is more preferable.

  The polymer content of the polymer composition is preferably 40 to 70% by mass. If the polymer content is too high, the efficiency of mixing and heat transfer tends to decrease and the stability tends to deteriorate. When the polymer content is too low, it tends to be difficult to separate a volatile component containing an unreacted monomer as a main component.

  The polymer composition produced in the polymerization reaction tank 103 is continuously withdrawn from the polymerization reaction tank 103 and guided to the heater 104 as necessary. In the heater 104, the liquid polymer composition is preheated for the purpose of increasing the devolatilization efficiency in the subsequent devolatilization extruder 100. The preheating temperature at this time is preferably 180 to 220 ° C. If the preheating temperature is higher than the above range, the volatile component may be gasified and liquid feeding at a constant flow rate may be difficult.

  Next, the polymer composition is supplied to the devolatilizing extruder 100. As the devolatilizing extruder 100, the devolatilizing extruder 100 of the present invention described above is used. In the devolatilization extrusion, the polymer composition is continuously supplied from the polymer composition supply port 12 in the devolatilization extruder 100 into the cylinder 10, and the volatile components mainly composed of unreacted monomers are gas discharge ports. The methacrylic polymer after devolatilization is discharged from the polymer outlet 16 from 14.

  In devolatilization, the polymer composition that is continuously supplied is heated to 200 to 290 ° C., so that most of the volatile components mainly composed of unreacted monomers are continuously separated and removed. Can be implemented. As pressure conditions at the time of devolatilization extrusion, for example, the pressure of the gas discharge port (back vent) 14a is set to about −0.05 to 0.15 MPaG (gauge pressure notation), and the gas discharge ports (fore vent) 14b, 14c, The pressure of 14d is adjusted to approximately -0.09 to -0.02 MPaG (gauge pressure notation). The gasified volatile component and the methacrylic polymer enter the devolatilizing extruder 100 from the polymer composition supply port 12, and at this time, when the back vent pressure is in a reduced pressure state from -0.05 MPaG, Since the entrainment phenomenon (entrainment) occurs in the back vent, the pressure is preferably in the above range. On the other hand, in order to remove volatile components, it is preferable that the pressure of the forevent be in the above range. Usually, a pressure control valve is installed between the heater 104 and the devolatilizing extruder 100 to adjust the pressure during devolatilizing extrusion.

  Simultaneously with or after the above devolatilization extrusion, if necessary, a lubricant such as higher alcohols and higher fatty acid esters, an ultraviolet absorber, a heat stabilizer, a colorant, an antistatic agent, etc. Can be added.

  Volatile components mainly composed of unreacted monomers discharged from the gas outlet 14 are sent to the monomer recovery tower 105. Volatile components mainly composed of unreacted monomers contain impurities originally contained in the monomers, oligomers such as dimers and trimers, and impurities such as radical polymerization initiator residues. Moreover, when superposition | polymerization is performed by the continuous solution polymerization method, in addition to these impurities, a solvent may also be contained. As impurities accumulate, the resulting methacrylic polymer is colored. Therefore, the monomer recovery tower 105 removes impurities from unreacted monomers by means such as distillation or adsorption, and polymerizes the monomer. Reused as a mass. For example, in the monomer recovery tower 105, the monomer is recovered as a distillate from the top of the monomer recovery tower 105 by continuous distillation and recycled to the monomer preparation tank 102. Impurities removed by the monomer recovery tower 105 are discarded as waste. In addition, the volatile component which has an unreacted monomer as a main component usually means what contains 30 mass% or more of unreacted monomers in a volatile component.

  According to the devolatilization extrusion method of a polymer composition and the method for producing a methacrylic polymer described above, a methacrylic polymer in which contamination is suppressed even when continuously operated for a long time. It can be manufactured efficiently.

  A methacrylic polymer obtained by polymerizing a monomer mixture mainly composed of methyl methacrylate among methacrylic polymers is a devolatilization extrusion method for a polymer composition and a method for producing a methacrylic polymer. It can use suitably for manufacture of.

  The methacrylic polymer obtained by the above method can be suitably used in many fields such as lighting, signboards, vehicles and the like because excellent transparency and weather resistance are obtained. In addition, methacrylic polymers are materials for optical equipment such as optical disk base materials, Fresnel lenses, lenticular lenses, light guide plates used in backlight systems for liquid crystal displays, diffusion plates, and protective front plates for liquid crystal displays. , Tail lamp covers, head lamp covers, visors, meter panels and other vehicle members.

  DESCRIPTION OF SYMBOLS 10 ... Cylinder, 12 ... Polymer composition supply port, 14 ... Gas discharge port, 16 ... Polymer outlet, 18 ... Through-hole, 20 ... Screw, 20a ... Shaft part, 30 ... Shaft seal bearing part, 32 ... Shaft seal Part, 100 ... devolatilizing extruder.

Claims (3)

A cylinder having a polymer composition supply port, a gas discharge port, a polymer outlet, and a through hole;
A rotatable screw inserted through the through hole and into the cylinder;
A shaft-seal bearing portion for supporting a shaft portion extending from the through hole of the screw to the outside of the cylinder;
A devolatilizing extruder for producing a methacrylic polymer,
The shaft seal portion of the shaft seal bearing portion is formed by a mechanical seal using at least one selected from the group consisting of adipic acid ester, phthalic acid ester, diisobutyric acid ester and acetylated glyceride as a mechanical seal liquid. Devolatilizing extruder.   A polymer composition containing a methacrylic polymer and a volatile component is supplied into the cylinder from the polymer composition supply port in the devolatilizing extruder according to claim 1, and the volatile component is removed from the gas discharge port. A devolatilizing extrusion method for a polymer composition, wherein the methacrylic polymer after volatilization is discharged from the polymer outlet. A step of continuously supplying a raw material containing a monomer component mainly composed of a methacrylic monomer, a radical polymerization initiator, and a chain transfer agent to the polymerization reaction tank;
Polymerizing the monomer component in the polymerization reaction tank to obtain a polymer composition containing a methacrylic polymer and a volatile component containing an unreacted monomer;
The methacrylic polymer after devolatilization is supplied from the polymer composition supply port in the devolatilization extruder according to claim 1 into the cylinder, and the volatile component is supplied from the gas discharge port. Discharging each from the polymer outlet;
A process for producing a methacrylic polymer.

Images