TWI518100B - Method for producing methacrylic polymer - Google Patents

Description

Method for producing methacrylate polymer

The present invention relates to a process for producing a methacrylate polymer which can achieve high monomer conversion and productivity.

Among the industrial production methods of methacrylate resins, there are a method by suspension polymerization and a method by bulk polymerization. In the bulk polymerization method, it is known that a resin having excellent transparency can be produced without using an additive such as a dispersant used in the suspension polymerization method. Patent Document 1 and Patent Document 2 disclose a method for producing an acrylate resin in which polymerization is carried out in a completely mixed reactor in the production of an acrylate resin, followed by polymerization in a tubular reactor such as a plug flow reactor. In order to achieve a balance between productivity and physical properties.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2000-26507

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2003-2912

Patent Document 1 discloses a method for producing an acrylate resin in which, in the production of an acrylate resin, a balance between productivity and physical properties is obtained by using a tubular reactor after a tank reactor. Although an example in which the ultimate polymerization ratio of 72% is the highest value is described in this document, there is no description about a method of further increasing the polymerization rate.

Patent Document 2 describes a method of stopping polymerization by an equilibrium polymerization ratio, and determining a limit polymerization ratio from a final temperature of a polymer. Although an example of the maximum polymerization rate of 68% is described in this document, it is considered impossible. The ultimate polymerization rate is exceeded by the highest value. In addition, the factors determining the equilibrium polymerization rate are not explained at all.

An object of the present invention is to provide a process for producing a methacrylate polymer which can achieve high monomer conversion (limit polymerization ratio) and productivity in bulk polymerization of a methacrylate monomer.

From the viewpoint of the equilibrium polymerization rate, it is considered that even if the initial dose added to the tubular reactor is increased, the ultimate polymerization rate of the polymer cannot be increased. However, the inventors of the present invention conducted active research, and as a result, it was found that the monomer conversion rate can be improved by adding a predetermined amount of the initiator to the polymerization in the tubular reactor. Further, it has been found that by increasing the amount of methyl acrylate used as a copolymerization component of the methacrylate polymer, the monomer conversion rate can be improved even in the same amount of the initiator used as before. Based on these findings, the inventors of the present invention found that the concentration of the radical polymerization initiator in the second polymerization downstream of the fully mixed reactor and the (methyl group) after polymerization in the fully mixed reactor The concentration of the alkyl acrylate is adjusted to a predetermined range, and the monomer conversion rate can be improved, thereby completing the present invention.

That is, the present invention is a method for producing a methacrylate polymer, which comprises the steps of: (a), methyl methacrylate alone or in addition to methyl methacrylate and methyl methacrylate; The monomer of the alkyl (meth)acrylate is supplied to the completely mixed reactor (A), and the first radical polymerization initiator is used for polymerization to obtain a first slurry; and the step (b) is completely disposed. Downstream of the mixed reactor (A) a first slurry and a second radical polymerization initiator in the reactor (B) to carry out polymerization to obtain a second slurry; and a step (c), to devolatize the second slurry; and the above methacrylic acid The method for producing an ester polymer is characterized in that the content of the alkyl (meth)acrylate other than methyl methacrylate in the above monomer is x [wt%], and the above reactor (B) is used. When the weight ratio of the second radical polymerization initiator supply amount per unit time to the first slurry supply amount per unit time is y [ppm], x and y satisfy the following formula: 8.5x+ 123≧y≧-2.6x+45.

According to the present invention, it is possible to provide a method for producing a methacrylate polymer which can achieve high monomer conversion rate and productivity even in the case of bulk polymerization of a methacrylate monomer.

The above and other objects, features and advantages of the present invention will become more <RTIgt;

In the present invention, a methacrylate polymer is produced by polymerizing a methacrylate monomer. The "methacrylate polymer" means a homopolymer of methyl methacrylate or a copolymerization component such as methyl methacrylate or an alkyl (meth) acrylate other than methyl methacrylate (monomer). Total Polymer. In addition, "(meth)acrylate" means acrylate or methacrylate.

Examples of the polymerization method include a bulk polymerization method, a suspension polymerization method, and a solution polymerization method. In particular, in terms of monomer conversion rate and productivity, a bulk polymerization method is preferred. The polymerization method can be continuous or batchwise.

Specific examples of the (meth)acrylic acid alkyl ester other than methyl methacrylate as a copolymerization component include methyl acrylate and ethyl (meth) acrylate. N-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate (i-butyl(meth)) Acrylate), tert-butyl (meth)acrylate, sec-butyl(meth)acrylate, n-amyl (meth)acrylate N-pentyl(meth)acrylate), n-octyl(meth)acrylate, lauryl(meth)acrylate,stearyl (meth)acrylate (stearyl(meth)acrylate), tridecyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, (methyl) ) cyclohexyl (meth)acrylate. Among them, preferred are methyl acrylate, ethyl acrylate, and butyl acrylate. The alkyl (meth)acrylate which is a copolymerization component may be used alone or in combination of two or more.

Further, a monomer other than the alkyl (meth)acrylate may be used in combination as a copolymerization component. Specific examples of such a monomer include methacrylic acid. (methacrylic acid), acrylic acid, crotonic acid, vinyl benzoic acid, fumaric acid, itaconic acid, maleic acid (maleic) Acid), monobasic acid or dibasic acid vinyl monomer such as citraconic acid; dibasic acid anhydride vinyl monomer such as maleic anhydride; 2-hydroxyethyl (meth)acrylate (2) -hydroxyethyl(meth)acrylate), 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate a (meth) acrylate having a hydroxyalkyl group such as an ester or 6-hydroxyhexyl (meth)acrylate; and a β-butyrolactone ring-opening addition to 2-hydroxyethyl (meth)acrylate a ring-opening adduct of ε-caprolactone (ε-caprolactone) of 2-hydroxyethyl (meth)acrylate, and an open-loop addition of ethylene oxide of (meth)acrylic acid a compound, a ring-opening adduct of propylene oxide of (meth)acrylic acid, a 2-hydroxyethyl (meth)acrylate or a dimer of 2-hydroxypropyl (meth)acrylate or a (meth) acrylate having a hydroxyl group at a terminal such as a polymer; a 4-hydroxybutyl vinyl ether; a p-hydroxy styrene; and other hydroxyl group-containing vinyl monomer; Phenyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, styrene; O-methyl styrene, m-methyl styrene, p-methyl styrene, α-methyl styrene, pair B P-ethyl styrene, 2,4-dimethyl styrene (2,4-dimethyl styrene), styrene-based monomer such as pn-butyl styrene or p-tert-butyl styrene; acrylonitrile; Methacrylonitrile, vinyl acetate, glycidyl (meth)acrylate, methylglycidyl (meth)acrylate, An epoxy group-containing vinyl monomer such as allylglycidyl ether; dimethylaminoethyl (meth)acrylate; diethyl (meth)acrylate Diethylaminoethyl (meth)acrylate, N-methoxymethyl acrylamide, N-methoxymethyl methacrylamide, N- N-ethoxymethyl acrylamide, N-propoxymethyl acrylamide, N-butoxymethyl acrylamide; 2-hydroxyethyl methacrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxy (meth) acrylate Hydroxyalkyl esters having a (meth) acrylate.

Among the monomers used for the polymerization, the amount of the alkyl (meth)acrylate other than methyl methacrylate is preferably from 0.5% by weight to 20% by weight. Moreover, when a monomer other than the alkyl (meth)acrylate is used as a copolymerization component, the amount of the monomer other than the alkyl (meth)acrylate is preferably 20% by weight or less. Further, the monomer used for the polymerization is preferably an alkyl (meth)acrylate other than 80% by weight to 99.5% by weight of methyl methacrylate and 0.5% by weight to 20% by weight of methyl methacrylate. (meth)acrylic acid When the content of the alkyl ester is 0.5% by weight or more, the obtained methacrylate polymer is excellent in thermal stability, and it is difficult to carry out thermal decomposition of the resin during molding, and appearance defects such as generation of bubbles in the molded article are eliminated. In addition, when the content of the alkyl (meth)acrylate is 20% by weight or less, the heat resistance of the obtained methacrylate polymer becomes good, and the molded article is not deformed by heat, and can be suitably used for general use. the use of.

[Step (a)]

The step (a) in the present invention is a step of supplying the above monomer to the completely mixed reactor (A) and performing polymerization using the first radical polymerization initiator to obtain a first slurry.

The first radical polymerization initiator may be decomposed to generate a radical at the temperature of the reaction system in the step (a).

Specific examples of the above first radical polymerization initiator include tert-butyl peroxy-3,5,5-trimethylhexanate, and peroxidation. Tert-butyl peroxylaurate, tert-butyl peroxyisopropyl monocarbonate, tert-hexyl peroxyisopropyl monocarbonate , tert-butyl peroxyacetate, 1,1-bis(t-butylperoxy) 3,3,5-trimethylcyclohexane (1,1-bis(tert-butylperoxy) 3,3,5-trimethylcyclohexane), 1,1-bis(tert-butylperoxycyclohexane), third ethyl peroxyhexanoate Tert-butyl peroxy 2-ethylhexanate, peroxidation Tert-butyl peroxyisobutyrate, tert-hexyl-hexyl peroxy 2-ethylhexanate, di-tert-butyl peroxide (di-) Tert-butyl peroxide), 2,5-dimethyl-2,5-bis(tert-butyl peroxy)hexane, etc. Organic peroxide; 2-(carbamoyl azo)-isobutyronitrile, 1,1'-azobis(1-cyclohexanecarbonitrile) (1, 1'-azobis(1-cyclohexane carbonitrile), 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile) (2 , 2'-azobis(2-methylbutyronitrile), 2,2'-azobisisobutyrate, 2,2'-azobis (2,4,4 -2,2'-azobis(2,4,4-trimethylpentane), 2,2'-azobis(2-methylpropane) (2,2'-azobis(2- Methylpropane)) an azo compound; a persulfate such as potassium persulfate; a redox (redox) polymerization initiator. The first radical polymerization initiator may be used alone or in combination of two or more.

The radical polymerization initiator is preferably an initiator having a half-life of 10 seconds or more and 30 minutes or less with respect to the temperature used. If the half-life is moderately long, the radical polymerization initiator is uniformly diffused in the polymerization system and decomposed, and the generation of the oligomer which is easily thermally decomposed is suppressed. Further, when the half-life is moderately short, when the emergency operation is stopped, it is difficult to cause a problem such as difficulty in restarting due to the high viscosity of the reaction liquid.

The amount of the first radical polymerization initiator to be used may be appropriately determined depending on various conditions such as the polymerization temperature of the reaction system in the step (a), the average residence time of the reactants, and the target monomer conversion ratio. In particular, in terms of obtaining a methacrylate polymer having a small amount of terminal double bond and excellent heat decomposition resistance, the amount of the first radical polymerization initiator to be used is preferably 5.0 × 10 with respect to the monomer 1 molar. ^-5 mole or less, and in terms of productivity of industrial, preferably not less than 5.0 × 10 ^-6 mole.

A chain transfer agent can also be used in the polymerization of the step (a). It is particularly preferred to use a mercaptan compound. Specific examples of the thiol compound include n-butyl mercaptan, isobutyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, second butyl mercaptan, and second-dodecyl sulfide. a primary, secondary or tertiary thiol having an alkyl group or a substituted alkyl group such as an alcohol or a tert-butyl thiol; phenyl thiol, thiocresol, 4-tert-butyl-O- An aromatic thiol such as 4-tert-butyl-O-thiocresol; a thioglycolic acid and an ester thereof; and a thiol having a carbon number of 3 to 18 such as ethylene thioglycol. Among them, preferred are tert-butyl mercaptan, n-butyl mercaptan, n-octyl mercaptan, and n-dodecyl mercaptan. The chain transfer agent may be used alone or in combination of two or more.

Maintaining the strength of the product and obtaining a moderate degree of polymerization which can be subjected to a forming process (usually used as a molding material in the industrial range of the weight average molecular weight of the polymer after the final removal of the volatile component is 70,000 to 150,000), and heat resistance is produced. In terms of the methacrylate polymer excellent in decomposability, the amount of the chain transfer agent to be used is preferably 0.01 mol% to 1 mol%, more preferably 0.05 mol%, based on 100 mol% of the monomer. ~0.5 mol%.

In the case where step (a) is carried out by solution polymerization, an inert solvent is used. Specific examples of the inert solvent include methanol, ethanol, toluene, xylene, acetone, methyl isobutyl ketone, ethylbenzene, methyl ethyl ketone, and butyl acetate. Among them, preferred are methanol, toluene, ethylbenzene, and butyl acetate. The inert solvent may be used alone or in combination of two or more.

The inert solvent is preferably used in an amount of less than 5% by weight in the reaction liquid composition. More preferably, the bulk polymerization is carried out without using an inert solvent. However, if the amount of the inert solvent used is less than 5% by weight in the reaction liquid composition, the thermal decomposition resistance is not substantially impaired, and the gel is used in the same manner as the bulk polymerization. The effect is that the monomer conversion can be effectively increased by using a small amount of a radical polymerization initiator.

The completely mixed reactor (A) is a device that reacts the supplied raw materials in a state of being uniformly mixed by a stirring device or the like. The fully mixed reactor (A) may be a batch tank reactor or a continuous tubular reactor. As the tank type reactor, a tank type reaction apparatus having a supply port, an outlet, and a stirring device can be used. The stirring device preferably has a mixing property throughout the entire reaction zone. The tubular reactor is preferably a plug flow reactor, more preferably a jacketed tubular reactor equipped with a static mixer. If a static mixer is incorporated, the stirring effect can be utilized to stabilize the reaction and stabilize the flow of the reaction liquid. The static mixer is preferably a static mixer manufactured by Noritake Company, or a Through The Mixer manufactured by Sumitomo Heavy Industries Co., Ltd. The fully mixed reactor (A) may be used alone or in combination of two or more. Alternatively, one type of reactor may be connected in series.

In step (a), the inclusion of the single in the fully mixed reactor (A) The raw material composition of the body and the first radical polymerization initiator is heated under appropriate conditions to polymerize a part of the methacrylate monomer to obtain a first slurry. The polymerization temperature may be appropriately set within the range of obtaining the first slurry having the desired monomer conversion rate. The step (a) may be carried out by using a tank type reactor as the complete mixing type reactor (A), and for example, it may be selected from the range of 110 ° C to 180 ° C (preferably 120 ° C to 160 ° C). The step (a) is further carried out in the tubular reactor after the tank reactor, for example, from the inlet temperature of 110 ° C to 170 ° C (preferably 120 ° C to 140 ° C), and the outlet temperature of 120 ° C to 180 ° C. (preferably from 140 ° C to 160 ° C) and an average temperature of from 115 ° C to 175 ° C (preferably from 135 ° C to 155 ° C).

The monomer conversion rate in the first slurry obtained in the step (a) is preferably from 35 to 70% by weight, more preferably from 45 to 60% by weight. The upper limit of these ranges is meaningful in that the uniformity in the tank is maintained in the tank type reactor, and it is meaningful to sufficiently achieve mixing and heat transfer in the tank to perform stable operation. Further, the lower limit value is meaningful in terms of achieving sufficient monomer conversion rate and improving productivity.

The temperature of the first slurry obtained in the step (a) is preferably from 110 ° C to 180 ° C, more preferably from 120 ° C to 160 ° C. The lower limit of these ranges is significant in terms of suppressing the formation of a dimer and maintaining the transparency and mechanical strength of the polymer after removal of the volatile component. Further, the upper limit value is meaningful in terms of suppressing the acceleration phenomenon of the polymerization rate by the gel effect and stably operating at a high monomer conversion rate.

In the tank reactor, for example, the polymerization can be carried out as follows. By introducing an inert gas such as nitrogen into the raw material monomer or decompressing the raw material monomer The concentration is maintained for a certain period of time, and the dissolved oxygen concentration is 2 ppm by weight or less, more preferably 1 ppm by weight or less. When the dissolved oxygen concentration is lowered in the above manner, the polymerization reaction proceeds stably, and even if the temperature is maintained for a long period of time in the polymerization step, substantially no coloring component is generated to obtain a high-quality polymer.

Next, the first slurry is taken out from the complete mixing reactor (A) and supplied to the reactor (B) disposed in connection with the complete mixing reactor (A). The first slurry can also be cooled prior to delivery to the reactor (B).

[Step (b)]

The step (b) in the present invention is to supply the first slurry obtained in the above step (a) and the second radical polymerization initiator to the reactor disposed downstream of the fully mixed reactor (A) (B) The polymerization is carried out to obtain a second slurry.

In the step (b), when the content of the alkyl (meth)acrylate other than methyl methacrylate in the monomer is set to x [wt%], and the unit time in the reactor (B) is When the weight ratio of the second radical polymerization initiator supply amount to the first slurry supply amount is y [ppm], x and y satisfy the following formula.

8.5x+123≧y≧-2.6x+45

In the above formula, by satisfying the relationship of y≧-2.6x+45, the monomer conversion rate can be improved in a short time. Further, by satisfying the relationship of 8.5 x + 123 ≧ y, a methacrylate polymer excellent in thermal stability can be produced. If the thermal stability is excellent, thermal decomposition of the resin during molding is difficult, and in the molded article The appearance of bubbles, such as the appearance of defects, disappears.

As the second radical polymerization initiator, for example, the same initiator as the first radical polymerization initiator can be used. The amount of the second radical polymerization initiator to be used may be the same as that of the first radical polymerization initiator as long as the above formula is satisfied.

In the step (b), in order to increase the monomer conversion rate in a short time, it is preferred to carry out the polymerization at a higher temperature than the step (a). Therefore, the second radical polymerization initiator is also preferably a radical polymerization initiator which is more pyrolyzed than the first radical polymerization initiator. Specifically, the second radical polymerization initiator is preferably a radical polymerization initiator having a half life longer than the half life of the first radical polymerization initiator at the average temperature in the step (b). Further, the second radical polymerization initiator may also have a half-life radical polymerization initiator having a longer half-life than the first radical polymerization initiator at the average temperature in the step (b), and A radical polymerization initiator is used in combination with the same radical polymerization initiator. By using two kinds of radical polymerization initiators in combination, the amount of the polymerization initiator required to obtain the same monomer conversion rate can be reduced.

The second radical polymerization initiator can be divided into multiple additions. In this case, the total weight ratio [ppm] of the second radical polymerization initiator per unit time to the slurry supplied per unit time is set to y [ppm].

Specific examples of the reactor (B) include the same reactors as the specific examples of the completely mixed reactor (A) described above, and particularly preferred are tubular reactors. The reactor (B) may be used alone or in combination of two or more. Alternatively, one type of reactor may be connected in series.

In the step (b), the composition comprising the first slurry and the second radical polymerization initiator is heated in a reactor (B) under moderate conditions to polymerize a part of the monomers present in the first slurry. , obtaining a second slurry. The polymerization temperature may be appropriately set so that the second slurry becomes a desired monomer conversion ratio.

The monomer conversion rate in the second slurry obtained in the step (b) is preferably from 50% by weight to 90% by weight, more preferably from 70% by weight to 80% by weight. The upper limit of these ranges is meaningful in terms of moderately suppressing the viscosity of the slurry and reducing the pressure loss when flowing in the process. Further, the lower limit value is meaningful in terms of reducing the residual monomer and reducing the burden of the subsequent devolring step.

The temperature of the inner wall of the reactor (B) is preferably from 125 ° C to 210 ° C, more preferably from 150 ° C to 195 ° C. The lower limit of these ranges is significant in terms of the conversion ratio of the monomer to 70% or more. Further, the upper limit value is meaningful in that the polymer in the process maintains fluidity and performs stable operation.

[Step (c)]

The step (c) in the present invention is a step of deoxidizing the second slurry obtained in the above step (b) to take out the methacrylate polymer. By this step (c), the amount of residual monomers in the methacrylate polymer is reduced, and heat resistance is improved.

Step (c) can be carried out, for example, by feeding the second slurry into a devolverizing extruder. The second slurry may be at a temperature in the state obtained in the step (b), and may be further heated. In the case where the second slurry is further heated, it is preferably set to a temperature not exceeding 250 °C. In the devolverizing extruder, it is preferred to discharge the second slurry under a reduced pressure of 0.0001 MPa to 0.1 MPa, which will be a methacrylate. Most of the volatiles of the monomer as a host are continuously separated and removed.

The content of the monomer in the methacrylate polymer obtained by separating and removing the volatile matter is preferably 0.3% by weight or less, and the content of the dimer of the monomer as a by-product of the polymerization reaction is preferably 0.1% by weight or less. The content of the above thiol compound is preferably 50 ppm by weight or less.

In terms of economy, volatile matter such as unreacted methacrylate monomer is preferably condensed in a condenser and recovered, and then reused as a raw material of the step (a). In this case, it is more preferable to separate and remove high-boiling components such as a dimer of a methacrylate monomer contained in the volatile matter by distillation, and then reuse it as a raw material of the step (a).

The methacrylate polymer produced in the above manner can be used, for example, as a molding material. In this case, a lubricant such as a higher alcohol or a higher fatty acid ester, a UV absorber, a heat stabilizer, a colorant, an antistatic agent, or the like may be added as needed.

[Example]

Hereinafter, the present invention will be described in more detail by way of examples, but these examples are not intended to limit the invention. Further, the measurement of the molecular weight of the polymer was carried out by the following method.

<Molecular weight measurement by gel permeation chromatography (GPC)>

HLC-8020 was manufactured by Tosoh Corporation as a GPC apparatus, and two GMHXL manufactured by Tosoh Corporation was used as a column. The solvent was prepared by using tetrahydrofuran (THF) using TSK standard polystyrene manufactured by Tosoh Co., Ltd., and the sample was statically dissolved. Solution solution with a concentration of 0.1 g/dl. The weight average molecular weight Mw was determined by a GPC data processing apparatus (data apparatus SC-80.10 manufactured by Tosoh Corporation).

<Evaluation of Formability>

Using PS-60E (manufactured by Nissei Resin Industrial Co., Ltd.) as a molding machine, the molding temperature was set to 300 ° C, and a spiral-shaped molded body was produced, and the appearance was observed.

<Example 1>

The present invention is implemented in the manner described below using the apparatus shown in FIG.

[Step (a)]

Nitrogen gas was introduced into a monomer mixture containing 98% by weight of purified methyl methacrylate and 2% by weight of methyl acrylate to have a dissolved oxygen of 0.5 ppm. 0.157 mol% (0.23 wt%) of n-octyl mercaptan as a chain transfer agent, and 1,1-bis (t-butyl group) as a first radical initiator are mixed with respect to the monomer mixture. The raw material composition of oxidized 3,3,5-trimethylcyclohexane 2.67×10 ^-5 mol/monomer 1 mol (80 ppm) was continuously supplied to the polymerization temperature controlled at 135 ° C while stirring and mixing. In the first reactor 11, that is, the completely mixed reactor, the polymerization was carried out by setting the average residence time of the reaction zone of the raw material composition to 2.5 hours to obtain a first slurry. Further, the half life of 1,1-bis(t-butylperoxy) 3,3,5-trimethylcyclohexane at the polymerization temperature (135 ° C) was 230 seconds.

[Step (b)]

Then, the gear pump 31 is continuously taken out from the first reactor 11 A slurry was added to the starter feeder 21 (with piping of SMX Through The Mixer manufactured by Sumitomo Heavy Industries Co., Ltd.) to add 1,1-double as a second radical initiator. Tributyl peroxy) 3,3,5-trimethyloxane, so that the weight ratio of the slurry supply amount per unit time is 40 ppm, and then supplied to the second reactor 12, that is, the interior In a tubular reactor (plug flow type reactor) having a static mixer manufactured by Noritake Company, the inner wall temperature was 150 ° C, and the average residence time of the slurry was 20 minutes to carry out polymerization. Further, the half life of 1,1-bis(t-butylperoxy) 3,3,5-trimethyloxane at this temperature (150 ° C) was 54 seconds.

Next, the slurry polymerized in the second reactor 12 is introduced into the initiator input unit 22 of the same type as described above, and the di-tert-butyl peroxide as a further second radical initiator is added. The weight ratio of the slurry supply amount per unit time was 40 ppm, and it was supplied to the same third reactor 13 as the second reactor 12, that is, a static mixer manufactured by Noritake Company. In the tubular reactor (plug flow type reactor), the inner wall temperature was 170 ° C, the internal pressure was 25 kg/cm ² G, and the average residence time was 20 minutes to carry out polymerization to obtain a second slurry. Further, the half-life of the di-tert-butyl peroxide at this temperature (170 ° C) was 250 seconds.

[Step (c)]

Next, the second slurry is continuously supplied from the outlet of the third reactor 13 to the devolverizing extruder 14 (exhaust extruder type extruder) at 195 ° C, and will be unreacted at 270 ° C. The volatiles as a main component are separated and removed to obtain a methacrylate polymer.

The polymerization of methacrylate taken out from the devolverizing extruder 14 was measured. The amount of the substance and the cumulative amount of the raw material monomers charged were as a result, and the monomer conversion rate with respect to the input raw material was 78 wt%. In addition, in the continuous operation for 360 hours, there was no problem in the control of the polymerization, and the occurrence of attachment or foreign matter to the apparatus was not observed even in the observation in the reactor after the completion of the operation. In addition, the obtained methacrylate polymer was evaluated for the moldability described above, and as a result, the presence of bubbles was not confirmed, and the appearance of the molded article was good. The results are shown in Table 1.

<Example 2>

The initial dose added to the second reactor 12 [first reactor (B)] was changed to 60 ppm, and will be added to the third reactor 13 [second reactor (B)]. The same operation as in Example 1 was carried out except that the initial dose was changed to 60 ppm. The amount of the methacrylate polymer taken out from the devolatization extruder 14 and the cumulative amount of the raw material monomers charged were measured, and as a result, the monomer conversion rate with respect to the input raw material was 80 wt%. In addition, in the continuous operation for 360 hours, there was no problem in the control of the polymerization, and the occurrence of attachment or foreign matter to the apparatus was not observed even in the observation in the reactor after the completion of the operation. In addition, when the obtained methacrylate polymer was evaluated for the moldability described above, the presence of bubbles was not confirmed, and the appearance of the molded article was good. The results are shown in Table 1.

<Example 3>

In addition to changing the amount of methyl methacrylate in the monomer mixture to 85 wt%, the amount of methyl acrylate was changed to 15 wt%, which was added to the second reactor 12 [first reactor (B)]. The starting dose was changed to 20 ppm and will be added to the third reactor 13 [second reactor (B)] The same operation as in Example 1 was carried out except that the initial dose was changed to 15 ppm. The amount of the methacrylate polymer taken out from the devolatization extruder 14 and the cumulative amount of the raw material monomers charged were measured, and as a result, the monomer conversion rate with respect to the input raw material was 73 wt%. In addition, in the continuous operation for 360 hours, there was no problem in the control of the polymerization, and the occurrence of attachment or foreign matter to the apparatus was not observed even in the observation in the reactor after the completion of the operation. In addition, when the obtained methacrylate polymer was evaluated for the moldability described above, the presence of bubbles was not confirmed, and the appearance of the molded article was good. The results are shown in Table 1.

<Example 4>

The initial dose added to the second reactor 12 [first reactor (B)] was changed to 60 ppm, and will be added to the third reactor 13 [second reactor (B)]. The same operation as in Example 3 was carried out except that the initial dose was changed to 60 ppm. The amount of the methacrylate polymer taken out from the devolatization extruder 14 and the cumulative amount of the raw material monomers charged were measured, and as a result, the monomer conversion rate with respect to the input raw material was 77 wt%. In addition, in the continuous operation for 360 hours, there was no problem in the control of the polymerization, and the occurrence of attachment or foreign matter to the apparatus was not observed even in the observation in the reactor after the completion of the operation. In addition, when the obtained methacrylate polymer was evaluated for the moldability described above, the presence of bubbles was not confirmed, and the appearance of the molded article was good. The results are shown in Table 1.

<Example 5>

In addition to changing the initial dose added to the second reactor 12 [first reactor (B)] to 100 ppm, and adding to the third reactor 13 [ The same operation as in Example 3 was carried out except that the initial dose in the two reactors (B)] was changed to 100 ppm. The amount of the methacrylate polymer taken out from the devolatization extruder 14 and the cumulative amount of the raw material monomers charged were measured, and as a result, the monomer conversion rate with respect to the input raw material was 83 wt%. In addition, in the continuous operation for 360 hours, there was no problem in the control of the polymerization, and the occurrence of attachment or foreign matter to the apparatus was not observed even in the observation in the reactor after the completion of the operation. In addition, when the obtained methacrylate polymer was evaluated for the moldability described above, the presence of bubbles was not confirmed, and the appearance of the molded article was good. The results are shown in Table 1.

<Comparative Example 1>

The initial dose added to the second reactor 12 [first reactor (B)] was changed to 20 ppm, and will be added to the third reactor 13 [second reactor (B)]. The same operation as in Example 1 was carried out except that the initial dose was changed to 15 ppm. The amount of the methacrylate polymer taken out from the devolatization extruder 14 and the cumulative amount of the raw material monomers charged were measured, and as a result, the monomer conversion rate with respect to the input raw material was as low as 68 wt% per unit. The amount of resin obtained at the time is reduced. The results are shown in Table 1.

<Comparative Example 2>

Except that the initial dose added to the second reactor 12 [first reactor (B)] and the third reactor 13 [second reactor (B)] was changed to not added, proceeding with Example 3 The same operation. The amount of the methacrylate polymer taken out from the devolatization extruder 14 and the cumulative amount of the raw material monomers charged were measured, and as a result, the monomer conversion rate with respect to the input raw material was as low as 50 wt% per unit. The amount of resin obtained at the time is reduced. Will knot The results are shown in Table 1.

<Comparative Example 3>

The initial dose added to the second reactor 12 [first reactor (B)] was changed to 80 ppm, and added to the third reactor 13 [second reactor (B)] The same operation as in Example 1 was carried out except that the initial dose was changed to 80 ppm. The amount of the methacrylate polymer taken out from the devolatization extruder 14 and the cumulative amount of the raw material monomers charged were measured, and as a result, the monomer conversion rate with respect to the input raw material was 83 wt%. In addition, in the continuous operation for 360 hours, there was no problem in the control of the polymerization, and the occurrence of attachment or foreign matter to the apparatus was not observed even in the observation in the reactor after the completion of the operation. However, the obtained methacrylate polymer was evaluated for the moldability described above, and as a result, the presence of bubbles was confirmed, and the appearance of the molded article was caused by a white band called silver, and the molding was poor. The results are shown in Table 1.

<Comparative Example 4>

The initial dose added to the second reactor 21 [first reactor (B)] was changed to 150 ppm, and will be added to the third reactor 13 [second reactor (B)]. The same operation as in Example 3 was carried out except that the initial dose was changed to 150 ppm. The amount of the methacrylate polymer taken out from the devolatization extruder 14 and the cumulative amount of the raw material monomers charged were measured, and as a result, the monomer conversion rate with respect to the input raw material was 90 wt%. In addition, in the continuous operation for 360 hours, there was no problem in the control of the polymerization, and the occurrence of attachment or foreign matter to the apparatus was not observed even in the observation in the reactor after the completion of the operation. However, the resulting methacrylate When the polymer was evaluated for the moldability described above, the presence of bubbles was confirmed, and the appearance of the molded article caused a white band called a silver streak, resulting in poor molding. The results are shown in Table 1.

The conditions of the respective examples and the respective comparative examples and the properties of the obtained polymer are shown in Table 1.

The abbreviations in the table are as follows.

‧"MMA": Methyl methacrylate

‧"MA": Methyl acrylate

‧"I": 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane

‧"III": Di-tert-butyl peroxide

‧"F": n-octyl mercaptan

As indicated in the table, the monomer conversion was sufficient in each of the examples. However, the monomer conversion rate in each of the comparative examples was not sufficient.

While the present invention has been described in its preferred embodiments, the present invention is not intended to limit the invention, and the present invention may be modified and modified without departing from the spirit and scope of the invention. The scope of protection is subject to the definition of the scope of the patent application.

11‧‧‧First reactor

12‧‧‧Second reactor

13‧‧‧ Third reactor

14‧‧‧Devolution extruder

21‧‧‧Starting agent input device

22‧‧‧Starting agent input device

31‧‧‧ Gear pump

Fig. 1 is a schematic configuration diagram of an apparatus used in an example.

11‧‧‧First reactor

12‧‧‧Second reactor

13‧‧‧ Third reactor

14‧‧‧Devolution extruder

21‧‧‧Starting agent input device

22‧‧‧Starting agent input device

31‧‧‧ Gear pump

Claims (2)

A method for producing a methacrylate polymer, which comprises the steps of: producing a methacrylate polymer: step (a), methyl methacrylate alone or in combination with the above methyl methacrylate and methacrylic acid a monomer of an alkyl (meth)acrylate other than the ester is supplied to the fully mixed reactor (A), and polymerization is carried out using the first radical polymerization initiator to obtain a first slurry; and step (b), Supplying the first slurry and the second radical polymerization initiator to the reactor (B) disposed downstream of the above-described complete mixing reactor (A) and performing polymerization to obtain a second slurry; and the step (c) Desulphurizing the second slurry; and the method for producing the methacrylate polymer is characterized in that the (meth)acrylic acid alkyl ester other than the methyl methacrylate in the above monomer is used The content is set to x [wt%], and the amount of the second radical polymerization initiator supplied per unit time in the above reactor (B) is relative to the weight of the first slurry supply per unit time. When the ratio is set to y [ppm], x and y satisfy the following formula : 8.5x + 123 ≧ y ≧ -3.5x + 87. The method for producing a methacrylate polymer according to claim 1, wherein the monomer supplied to the above-mentioned fully mixed reactor (A) comprises 80% by weight to 99.5% by weight of the above methacrylic acid An ester, and 0.5% by weight to 20% by weight of the above alkyl (meth)acrylate other than the above methyl methacrylate.