JPS5921326B2 - Continuous manufacturing method for methyl methacrylate syrup - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously and stably producing methyl methacrylate syrup with a high polymer content, and in particular to a method for producing a methyl methacrylate resin plate with an appropriate viscosity that provides good workability without deteriorating the quality of the methyl methacrylate resin plate. The present invention relates to a method for continuously and stably producing syrup with a high polymer content, which can simultaneously reduce the time required for plate making.

More specifically, the present invention provides a continuous syrup production method in which a methyl methacrylate monomer and a radical polymerization initiator are sequentially passed through specified reaction conditions to stably produce syrup with a high polymer content. In particular, the present invention relates to a continuous syrup production method for stably producing syrup with a narrow polymerization degree distribution, a low residual initiator concentration, and a high polymer content.

Methyl methacrylate resin plates are usually obtained by injecting a polymerizable liquid composition consisting of a polymerization initiator and methyl methacrylate syrup between two glass plates and polymerizing the composition under heating.

At this time, a syrup containing an appropriate amount of polymer is used as the injection liquid in order to improve the workability of injecting the polymerizable liquid composition, improve the quality of the resulting resin board, and shorten the board making time. ing. This syrup is added with a polymerization initiator and other necessary additives before injection, and
After being degassed under reduced pressure to remove any dissolved air contained therein, it is injected between two glass plates sealed with a gasket. If the viscosity of the syrup is too low during injection, it may cause leakage, and if it is too high, the injection time will be longer, both of which will reduce the workability of injection, so the viscosity of the syrup to be injected should be appropriate. must be selected within a certain range. In addition, by using syrup, the amount of heat generated during polymerization is reduced, and the shrinkage of the polymer during polymerization can be reduced, improving the surface condition of the resulting resin board and making it easier to control the board thickness. It is known that the content of the polymer in the syrup is higher for this purpose. Further, the higher the polymer content in the syrup, the greater the time required for plate making, so from this point of view as well, it is preferable that the polymer content is as high as possible. Note that the syrup used for this purpose must have high storage stability, and must not inhibit polymerization during board manufacturing nor reduce the quality of the resulting resin board.Methacrylic resin The production of plates has traditionally been carried out using the batch cell cast method, in which plates are produced by polymerizing between two glass plates, but in recent years, continuous gear casting has been used, in which plates are produced by continuous polymerization between two consecutive moving bands.・Conversion to strike law is underway.

This continuous casting method is used, for example, in Japanese Patent Publication No. 51-29916
As shown in the publication, two continuous moving bands in a vertical positional relationship are made to run in the same direction and at the same speed, and at least one continuous gasket is installed on each side of the moving bands. The space between the moving bands is sealed by running in contact with the moving band, the polymerizable liquid composition is supplied to the space between the moving bands, and the composition is run through the zone where the composition is polymerized to complete the polymerization. This is a continuous plate-making method in which a plate-shaped polymer is taken out from the other end between the moving bands. However, in this method, the equipment cost accounts for a large proportion of the manufacturing cost, so it is particularly required to shorten the plate manufacturing time compared to the cell casting method. Shortening the plate making time is achieved by increasing the polymer content in the syrup used as the injection liquid as high as possible within the viscosity range that ensures workability for injection. As a result, if the quality of the resulting resin board deteriorates, the value of the resin board as a product will decrease accordingly, and the effect of reducing manufacturing costs by shortening the board manufacturing time will be offset by that amount. should not reduce the quality of the resin plate as much as possible, but should preferably improve the quality. If the polymer content of the syrup is increased to shorten the board making time, the average degree of polymerization of the resulting resin board will usually decrease, resulting in a decrease in mechanical strength. Defects such as foaming during hot molding are more likely to occur.

The viscosity of syrup under constant temperature conditions is determined by the polymer content and the weight average degree of polymerization of the polymer, and the relationship is such that the higher the content in both of them, the higher the viscosity.

Therefore, in order to increase the polymer content as much as possible within the limited upper limit of viscosity from the viewpoint of workability such as injection, it is preferable that the weight average degree of polymerization is as low as possible. Also, the low degree of polymerization polymer produced by Shirozow is one of the reasons why foaming occurs easily during heat molding of resin plates, and its amount is determined by the number average degree of polymerization, and the higher the number average degree of polymerization, the higher the Since the amount of the low molecular weight polymer is in a decreasing relationship, it can be said that the higher the number average degree of polymerization is, the more preferable it is. In polymers with a degree of polymerization distribution, the weight average degree of polymerization is generally larger than the number average degree of polymerization, and the polydispersity expressed as the ratio of the two is used as a measure of the breadth of the distribution of degree of polymerization. It can be said that syrups with a smaller degree of dispersion are more preferable. In addition, if the concentration of residual initiator in the syrup is high, polymerization will proceed further during cooling during syrup production or during syrup storage, increasing the polymer content and viscosity of the syrup, making it difficult to obtain a product of constant quality. It has its drawbacks.

In addition, trace amounts of residual initiator such that the progress of polymerization is not substantially observed may cause deterioration of the syrup during storage, and residual monomers in resin plates obtained using such syrup may It is necessary to keep the residual initiator concentration as low as possible, since it may increase the content and cause quality deterioration, such as making the resin plate more likely to foam during heat molding. In addition, as a method of shortening the plate making time, it is possible to increase the concentration of the polymerization initiator used during plate making instead of increasing the polymer content of the syrup, but in this case, the average degree of polymerization of the resin plate will inevitably increase. It is difficult to say that this is an advantageous method because the quality decreases significantly. Various methods have been proposed for the production of syrup, but although all of them partially satisfy the above conditions, there is no known method that satisfies all of the above conditions. Shortening the board-making time leads to a decrease in quality, such as a decrease in the mechanical strength of the resulting resin board and the tendency to foam during heat forming, and shortening the board-making time does not necessarily lead to improved economic efficiency. Ta. Batch production of syrup usually involves using a stirred tank reactor, heating monomers to a high temperature and then adding a predetermined amount of polymerization initiator, or using a mixture of monomers and polymerization initiator. The syrup is heated to a high temperature, allowed to polymerize for a sufficient period of time to reduce the initiator concentration to a substantially negligible amount, and then cooled to remove the syrup.

In this method, the initiator concentration is high at the beginning of the reaction and decreases relatively rapidly as the reaction progresses, and the degree of polymerization of the resulting polymer varies from a fairly low degree at the beginning to a very high degree at the end. Even things change drastically. Therefore, the polymerization degree distribution of the polymer in the obtained syrup becomes extremely wide, with a high weight average degree of polymerization and a low number average degree of polymerization. The weight average degree of polymerization is directly related to the viscosity of the syrup, which means that the syrup has a higher viscosity when compared with the same polymer content, making it easier to pour into glass cells or between moving bands. Therefore, in order to make this easier, the polymer content of Shirozow must be kept to a low level, and we cannot expect much reduction in plate-making time. In addition, a low number average degree of polymerization means that it contains a relatively large amount of low polymerization degree polymers, which can cause quality deterioration. Alternatively, it may cause foaming during heat molding of the resin plate, resulting in quality deterioration, which is undesirable. Increasing the concentration of the polymerization initiator initially used in this method lowers the weight average degree of polymerization of the polymer in the syrup obtained, and the upper limit of the polymer content within the range of viscosity that is easy to pour is Although this increases the plate making time, the number average degree of polymerization also decreases correspondingly, which is not a good idea as it promotes deterioration in the quality of the resin plate. Note that the syrup obtained by this method usually has a sufficiently low concentration of residual initiator,
Storage stability is relatively good. On the other hand, in this batch production method, if polymerization is not carried out for a sufficient period of time, a syrup with a relatively narrow degree of polymerization distribution is produced, but due to the high residual initiator limit, further polymerization occurs during cooling and storage. This leads to the problem that the viscosity increases.

Additionally, polymerization inhibitors have been added for the purpose of increasing the storage stability of the syrup, but this has drawbacks such as delaying the polymerization time during plate manufacturing and causing discoloration. The method of adding a chain transfer agent during the batch production of syrup to suppress the formation of highly polymerized polymers has the disadvantage that if the chain transfer agent remains in the syrup, this will affect the plate making process and delay the polymerization time. It is difficult to say that this is a preferable method because it causes a decrease in the average degree of polymerization or coloration of the obtained resin plate.In contrast, several methods have been proposed in which syrup is produced by a continuous method. The method of continuously supplying monomers and polymerization initiator from the -4 end of the tubular reactor and continuously taking out the produced syrup from the other end essentially eliminates the disadvantages of the batch method mentioned above. cannot be overcome. In other words, if we look at the phenomenon that occurs when a reaction solution flows in the longitudinal direction through a long and narrow no-tube reactor from the perspective of the time course of the polymerization reaction, we can see that, excluding the influence of back mixing, it is a batch tank type reaction. It is equivalent to the time course of a polymerization reaction in the vessel, and the initiator concentration is high near the inlet, decreases relatively rapidly as the reaction liquid advances, and becomes a virtually negligible amount near the outlet. The degree of polymerization of the produced polymer varies widely from a fairly low degree of polymerization near the inlet to a very high degree of polymerization near the outlet, and the distribution of the degree of polymerization of the resulting polymer off the coast of Sirozov is extremely wide. Become.

On the other hand, if this method does not carry out polymerization at a sufficient temperature or residence time, a syrup with a relatively narrow degree of polymerization distribution is produced, but the storage stability of the syrup is poor, so a batch tank reactor is sufficient. It is the same as when you do not spend a lot of time doing it.

That is, even in a continuous tubular reactor, it is not expected that the plate making time will be reduced so much without degrading the quality of the resin plate obtained. A method has also been proposed in which monomers and polymerization initiators are continuously supplied from the inlet of a stirred tank reactor, and the produced syrup is continuously taken out from the outlet.

Japanese Patent Publication No. 38-4794 describes a method in which polymerization is carried out at a temperature and under conditions such that the polymerization initiator is just decomposed when the desired conversion is reached. In this method, in batch polymerization, if the reaction temperature is selected to be sufficiently high in °C and reaction temperature relative to the decomposition temperature of the polymerization initiator, the polymerization initiator will rapidly decompose and the polymerization will proceed to a certain conversion rate. If the polymerization initiator is completely decomposed after a certain period of time, the reaction will proceed only thermally and will be extremely slow. Also, carrying out the polymerization at temperatures and conditions just such that the polymerization initiator is decomposed makes it easier to control the reaction and keep the conversion within predetermined limits, i.e. This study focused on the fact that under high temperature conditions, the Tromsdorf effect appears to be significantly reduced, approaching dead-end polymerization. It states that it is perfectly suitable as a polymerization control method. However, the syrup obtained by polymerizing at such temperatures and conditions in a batch production method or a production method using a continuous tubular reactor has an extremely wide distribution of polymerization degree as described in detail above. It has the disadvantage that shortening does not necessarily lead to improved economic efficiency.

On the other hand, in the production method using a continuous tank reactor, a method in which polymerization is carried out at such temperatures and conditions allows stable steady operation and high polymer content due to the phenomenon of acceleration of polymerization rate based on the Tromsdorff effect. It has the disadvantage that it is difficult to obtain syrup, and the quality of the obtained syrup is also disadvantageous as will be described later.

That is, in this method, new polymerization initiator is constantly supplied into the reactor even under temperature conditions where rapid decomposition of the initiator occurs, and the concentration of polymerization initiator rapidly decreases as the reaction time increases. There is no such thing. The steady-state initiator concentration in a continuous tank reactor under conditions where complete mixing is achieved is equal to the residual initiator concentration at the outlet of this reactor -1
It is expressed as 0/(1+Kθ). Here, I is the residual initiator concentration (wt%), 10 is the supplied initiator concentration (wt%), and K
is the decomposition rate constant of the initiator (1/sec), and θ is the average residence time (sec). Now considering the temperature conditions under which rapid decomposition of the initiator occurs, K is sufficiently large, so Kθ>>1, and I+IO/Kθ holds true. In other words, as the reaction time increases, the residual initiator concentration shows a decrease that is at most inversely proportional to the reaction time, and there is no reaction time condition under which the polymerization initiator is just decomposed. It is impossible for the reaction to proceed very slowly over a period of time, and in this sense it is difficult to stop the polymerization at a desired level in the case of batch production methods or production methods using continuous tubular reactors. It is quite different from that, and it cannot necessarily be said that it is easy. Furthermore, in the bulk polymerization of methyl methacrylate monomers, a polymerization rate acceleration phenomenon called the Tromsdorff effect is known, and this is a phenomenon in which the polymerization rate constant increases as the polymer content increases. Now, if we consider the case of extending the reaction time in a continuous tank reactor, the polymer content will increase even if no acceleration phenomenon is observed, and the reaction time conditions must be strictly controlled to stop the polymerization at the desired level. As mentioned above, under conditions to obtain a syrup with a high polymer content, this acceleration phenomenon will promote the above relationship, and as the reaction time increases, the polymer content will increase. If the polymer content increases dramatically and exceeds a certain limit, stable operation becomes impossible even under isothermal conditions, resulting in a so-called concentration-unstable state. It has drawbacks that make it difficult or impossible to obtain. Furthermore, in a continuous tank reactor, as mentioned above, the residual initiator concentration only shows a slow decrease with reaction time even at temperatures at which rapid decomposition of the initiator occurs in batch reactions. Therefore, the concentration of residual initiator in the resulting syrup is higher than in the case of a batch reaction, and it is inevitable that polymerization will proceed further during cooling or storage, increasing the viscosity of the syrup. In order to obtain a syrup with good thermal stability that does not cause such polymerization to occur, it is necessary to reduce the residual initiator concentration to a lower level, which requires rapid decomposition in batch reactions. Although it is necessary to carry out the reaction at a temperature even higher than that at which it occurs, other disadvantages arise under such conditions. In other words, it takes a certain amount of time to uniformly mix the newly supplied monomer and polymerization initiator into the reaction mixture in the reactor, but under such temperature conditions, sufficient mixing is difficult. Before the polymerization is achieved, the decomposition of the polymerization initiator proceeds in a non-uniform state, and the resulting polymers produced in Shilotzhu have a wide range of polymerization levels, from very low polymerization degrees to very high polymerization degrees. It will have a degree distribution. Resin plates obtained using such syrups are of low quality because they contain low polymerization degree polymers, and also have high viscosity and high viscosity in relation to the polymer content ratio because the polymers produced in Syrup have a wide distribution of polymerization degrees. This is a drawback in that it is a constraint in increasing the polymer content, and it cannot be expected to shorten the plate making time very much. Further, Japanese Patent Publication No. 47-35307 describes a method in which two or more continuous tank reactors are arranged in series to carry out polymerization in order to improve the drawbacks of the above-mentioned method.

In this method, 40 to 95% by weight of the polymer in the syrup is produced in a first reactor, and then the remaining polymer is produced in second and subsequent reactors, and the polymer in the syrup is at least Because it is made in the presence of two concentrations of polymerization initiator, the polymer has at least two molecular weight moieties;
The weight average molecular weight of the high molecular weight fraction is at least twice the weight average molecular weight of the low molecular weight fraction, and the low molecular weight fraction is 40 to 95% by weight of the polymer in Silozow, and within this range, the low molecular weight fraction is It is stated that when containing at a high solids content, a syrup with a relatively low useful viscosity and a high solids content is obtained. This method reduces the weight average degree of polymerization, which is directly related to the viscosity of the syrup, by increasing the proportion of the low polymerization degree portion of the polymer in the syrup, thereby increasing the polymer content with a relatively low viscosity. It can be interpreted that the intention was to obtain a high syrup. However, a low polymerization degree polymer lowers the average degree of polymerization of the obtained resin plate and causes foaming to occur easily during heat molding of the resin plate, so by increasing the proportion of the low polymerization degree part, the polymer Although the method of obtaining syrup with a high content rate can shorten the board making time, it has the disadvantage that the quality of the resulting resin board is degraded.

Furthermore, from the relationship between the polymerization degree distribution of the polymer in the syrup obtained by this method and the residual initiator concentration, a relatively low proportion of low polymerization degree polymer within this range is produced in the first reactor. If the average residence time in the first reactor is relatively short relative to the initiator half-life, the number of reactors may be increased to sufficiently reduce the residual initiator concentration in the final syrup. At this time, the average degree of polymerization of the polymer produced in each reactor increases rapidly as it progresses to subsequent reactors, as in the case of continuous tubular reactors, and the average degree of polymerization in the final syrup increases. The polymer contains a large amount of a portion with a high degree of polymerization, resulting in a wide distribution of degree of polymerization and a disadvantage that the viscosity becomes high in proportion to the polymer content. on the other hand,
Within this range, a high percentage of low polymerization degree polymer is produced in the first reactor when the reaction time in the first reactor is sufficiently long compared to the half-life of the initiator; Although the initiator concentration can be reduced relatively easily by using two or more reactors, the residual initiator concentration in the first and second reactors is extremely different, resulting in a high degree of polymerization. The weight average degree of polymerization of the portion takes a very large value, more than twice the weight average degree of polymerization of the low polymerization degree portion. Therefore, even though the content of the high degree of polymerization portion is small, the distribution of the degree of polymerization of the polymer in the resulting syrup is relatively wide. In other words, even in this method, if the residual initiator concentration is sufficiently reduced, the polymerization degree distribution ends up becoming broader, which is still unsatisfactory from the point of view of shortening the plate-making time without degrading the quality of the resulting resin plate. It's hard to say it's something that should be done. In addition, Japanese Patent Publication No. 48-35357 uses a reactor in which at least one continuous stirred tank type reactor is arranged in series in the first stage and a tubular reactor in the second stage, so that the reaction mixture at the outlet of the first stage is conversion rate of 9-12%
A method for continuously producing a prepolymerized product of a methacrylic acid ester compound is described.

This method is related to the removal of the amount of heat generated during continuous production in a tank reactor, and due to the conditions for stably controlling the exothermic reaction, the conversion rate in one tank is at most 2. As a method of obtaining a prepolymer with a higher conversion rate, they used multiple tank reactors in series, and further improved the quality by combining them with a tubular reactor. The main purpose of this is to make it easy to adjust the production amount without changing it, and to prevent clogging in the tube, which is a drawback of tubular reactors. In this method, the conversion rate in the tank-type reactor in the first stage is within the range of 9 to 12% in order to stably control the reaction, so it is suitable for shortening the manufacturing time of resin plates. It has drawbacks that make it impossible to achieve the purpose of producing syrup.

Furthermore, since the polymerization is carried out at a temperature of 50 DEG to 100 DEG C., the concentration of residual initiator in the resulting syrup remains at a relatively high level, and from this point of view as well, it cannot be said that the method is satisfactory. The inventors of the present invention conducted intensive studies on methods to overcome these drawbacks, and found that a syrup produced by continuously supplying a methyl methacrylate monomer and a radical polymerization initiator to a reaction zone and partially polymerizing it was developed. In a method for continuous production of syrup to be taken out at a time, a reaction zone formed by arranging two or more continuous stirred tank reactors in series is used, and a monomer is continuously supplied to the first tank reactor, and continuously supplying the polymerization initiator to at least two tank reactors including the first tank reactor, and specifying the temperature and average residence time conditions for each tank reactor. It has been found that syrup with a high polymer content can be continuously and stably produced by the method, and more particularly, by mutually balancing the amount of initiator supplied to each tank reactor to produce syrup in the entire reaction zone. By controlling the polymerization degree distribution narrowly, and by arranging a tubular reactor in series after the reaction zone and regulating the temperature and average residence time conditions of the reactor, the polymerization degree distribution can be narrowed. The present invention was completed based on the discovery that the concentration of the residual initiator can be extremely effectively reduced while maintaining the concentration of the residual initiator. That is, the present invention continuously supplies a methyl methacrylate monomer to a first reaction zone of a reaction zone formed by arranging two or more reaction zones in series in which substantially complete mixing is achieved, and A radical polymerization initiator is continuously supplied to at least two reaction zones including the first reaction zone, and the residual initiator concentration in each reaction zone to which the polymerization initiator is supplied is at least 1 of the supplied initiator concentration. /2 to 1/1000 times the amount,
The conditions in each reaction zone are maintained so that the amount is preferably 1/5 to 1/1000 times, particularly preferably 1/10 to 1/500 times, and the reaction mixture is not overweight while passing through each reaction zone in turn. This is a continuous production method for methyl methacrylate syrup that causes coalescence to obtain syrup.

Further, the methyl methacrylate monomer is continuously supplied to a first reaction zone of a first reaction zone formed by arranging two or more reaction zones in series in which substantially complete mixing is achieved, and radical polymerization is carried out. At least two initiators containing the first reaction zone
The residual initiator concentration in each reaction zone to which the polymerization initiator is supplied is at least 1/2 to 1/1000 times, preferably 1/1/2, the concentration of the supplied initiator.
5 to 1/1000 times the amount, particularly preferably 1/10 to 1/
The conditions in each reaction zone are maintained to be 500 times the volume to produce the majority of the polymer in the final syrup in the reaction zone, and the resulting reaction mixture is then transferred to a second stage where substantially extrusion flow is achieved. temperature and average residence time conditions in the reaction zone such that a residual amount of polymer is produced during passage through the reaction zone and the residual initiator concentration is substantially negligible. The polydispersity of the degree of polymerization distribution expressed as the ratio of the weight average degree of polymerization to the number average degree of polymerization of the polymer in the final syrup is 3.0 or less, preferably 2.
5 or less, particularly preferably 2.2 or less.

As the methyl methacrylate monomer used in the production of syrup according to the method of the present invention, monomers or monomer mixtures normally used in the production of this type of syrup can be used as they are, but methyl methacrylate is the main component. Particularly preferred are monomers such as methyl methacrylate used alone, or alkyl acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, etc. within a range of 20% by weight or less based on the total amount of the monomer mixture; Alkyl methacrylates such as ethyl methacrylate and lauryl methacrylate; unsaturated nitrites such as acrylonitrile and methacrylonitrile;
A methyl methacrylate monomer mixture whose main constituent is a methyl methacrylate monomer containing one or more vinyl compounds such as styrene and α-methylstyrene is used.

These unsaturated vinyl compounds are generally used in amounts within this range for various quality improvements within the range that does not impair the characteristics of the resulting resin board as a methyl methacrylate resin board. The radical polymerization initiator used in the production of syrup by the method of the present invention is 90 to 200°C;
Preferably, an initiator that generates radicals relatively rapidly at 110 to 180°C is used, and a radical polymerization initiator whose half-life is 5 seconds or less at a temperature of 180°C or lower, preferably 140°C or lower is suitable, for example, Azo compounds such as azobisisobutyronitrile, asopisdimethylvaleronitrile, azobiscyclohexanenitrile, benzoyl peroxide, lauroyl peroxide, acetyl peroxide, cabryl peroxide, 2,4-
Dichlorobenzoyl peroxide, isobutyl peroxide, acetyl cyclohexyl sulfonyl peroxide, tert-butyl peroxy bivalate, tert-butyl peroxy-2-ethylhexanoate, isopropyl peroxy dicarbonate, isobutyl peroxy dicarbonate, secondary Butyl peroxydicarbonate, normal butyl peroxydicarbonate, 2-ethylhexyl peroxydicarbonate, bis(4-tert-butylcyclohexyl)
Examples include peroxides such as peroxydicarbonate, and one or more of these polymerization initiators are used.

In particular, when using a polymerization initiator whose half-life is 5 seconds or less and whose temperature is 140°C or lower, the reaction temperature is preferably carried out at a low temperature of 90 to 160°C, and the preheating of the monomers and the cooling of the syrup are preferably carried out. This is preferable because not only the load is reduced but also the pressure conditions are relaxed. The amount of polymerization initiator is usually 0.001 to 1% by weight, preferably 0.001 to 1% by weight based on the methyl methacrylate monomer.
．． When a high polymer content of 0.01 to 0.5% by weight is desired, the concentration of the initiator fed is adjusted to be high, and when a high number average degree of polymerization is desired, the concentration of the fed initiator is adjusted to be low.

In the production of syrup according to the method of the invention, without the use of chain transfer agents, by mutually adjusting the reaction temperature, the concentration of the initiator fed and the average residence time of the reaction mixture,
Chain transfer agents are not normally used because they have the advantage of easily adjusting the number-average degree of polymerization, weight-average degree of polymerization, or viscosity of the Silotov polymer to desired values, but they do not reduce the quality of the resulting syrup or resin plate. A chain transfer agent may be used as long as it does not interfere with the chain transfer.

The methyl methacrylate monomer and the radical polymerization initiator are first continuously introduced into a first reaction zone of a first reaction zone having one reaction zone arranged in series where substantially complete mixing is achieved. Supplied.

Under conditions where substantially complete mixing is achieved, the polymerization degree distribution of the resulting polymer is extremely narrow, and the polydispersity of the polymerization degree distribution expressed as the ratio of the weight average degree of polymerization to the number average degree of polymerization of the polymer is The polydispersity is extremely close to 2.0 in the most probable distribution, assuming that all polymerization chain terminations are due to disproportionation termination, and is substantially 2.2 or less. Next, a polymerization initiator is additionally supplied to at least one reaction zone among the second and subsequent reaction zones of the reaction zone.

In each reaction zone where additional polymerization initiator is fed, the reaction mixture obtained from the previous reaction zone and the newly added polymerization initiator are continuously fed, and each reaction zone is substantially completely fed. Since the conditions are maintained under which mixing is achieved, the degree of polymerization distribution of the newly formed polymer in each reaction zone is very narrow, with a respective polydispersity of substantially less than 2.2. The reaction zone can also include a reaction zone to which no additional polymerization initiator is supplied,
The number average degree of polymerization of the newly produced polymer in the reaction zone is generally higher than that in the reaction zone where the polymerization initiator is supplied, but the polydispersity of the polymerization degree distribution is substantially 2.2 or less. It is.

Particularly when the concentration of residual initiator in the reaction mixture fed from the previous reaction zone is relatively high, the polymer content can be increased without substantially broadening the degree of polymerization distribution of the polymer formed throughout the reaction zone. Polymerization initiator is preferably supplied to all reaction zones, which can contribute to increasing the yield, but generally to maintain a narrow degree of polymerization distribution of the polymer in the final syrup. The residual initiator concentration in the first reaction zone and each reaction zone to which polymerization initiator is additionally supplied is 1/2 to 1/1 of the initiator concentration supplied to the reaction zone.
000 times the amount, preferably 1/5 to 1/1000 times, particularly preferably 1/10 to 1/50
The conditions of reaction temperature and average residence time of the reaction mixture in the reaction zone are maintained so that the volume is 0 times.

In this range, when the proportion of the residual initiator concentration is small, the reaction zone can be operated in a particularly stable manner. When the concentration of residual initiator in the reaction zone is greater than this range, the reaction zone tends to become thermally unstable, and in order to achieve stable steady-state operation, the amount of polymer formed in the reaction zone must be minimized. This has the disadvantage of significantly increasing the number of reaction zones required to obtain a final syrup with a high polymer content, while residual initiator concentrations below this range have the disadvantage of (・The supplied initiator decomposes in a non-uniform state before it is sufficiently mixed with the reaction mixture, making it impossible to achieve substantially complete mixing, resulting in new polymer formation in the reaction zone. However, in the reaction zone where no additional polymerization initiator is supplied, the absolute value of the concentration of the initiator supplied to the reaction zone is small, so that Since the amount of newly produced polymer is small and stable steady operation can be performed relatively easily, there is no particular restriction on the ratio of the residual initiator concentration to the supplied initiator concentration in the reaction zone, but preferably selected within the above range.

In the method of the present invention, the reaction temperature of the first reaction zone is not particularly limited, but the reaction temperature of each reaction zone of the reaction zone is such that the ratio of the residual initiator concentration to the supplied initiator concentration is It is adjusted according to the decomposition temperature of the initiator so that it falls within the range of 90 to 200°C, preferably 110°C.
~180°C.

The sum of the average residence times of the reaction mixture in each reaction section of the reaction zone, as well as the feed initiator concentration, is adjusted depending on the desired polymer content and number average degree of polymerization in the final syrup. Usually 1 to 30 minutes, preferably 2 to 1 minute
It's 5 minutes. To maintain the temperature conditions of a tank reactor, a jacket is usually provided outside the reactor and a heat medium is circulated through the jacket to control the temperature of the heat medium, but the method of the present invention Because the reaction rate is extremely fast, it is difficult to maintain the reaction temperature at the desired conditions with this method, and it becomes thermally unstable, especially when scaled up, making stable steady operation impossible. becomes.
In the method of the present invention, the amount of heat generated by polymerization and the amount of sensible heat required to raise the temperature of the reaction mixture to the reaction temperature are approximately the same, and the amount of heat generated by the polymerization is approximately the same as the amount of sensible heat required to raise the temperature of the reaction mixture to the reaction temperature. The reaction temperature is maintained by heating or cooling, and the temperature of the first reaction zone is preferably controlled by varying the preheating temperature of the monomers fed to the first reaction zone of the reaction zone. be given It is more effective to use a method in which a jacket is provided outside each reaction zone of the reaction zone to circulate the heat medium. Any method may be used to preheat the supplied monomer as long as there is no substantial stagnation and the preheating temperature can be adjusted. This is suitably carried out by passing the monomer at a rate of several 5,000 or more, preferably 20,000 or more, circulating a heat medium through the jacket, and adjusting the temperature of the heat medium. Although the monomer and the polymerization initiator may be mixed in advance and supplied after being preheated, it is preferable that only the monomer is preheated and the polymerization initiator solution is supplied after being cooled.

The supplied methyl methacrylate monomer or polymerization initiator solution may optionally be pre-added with one or more of ultraviolet absorbers, antioxidants, pigments, dyes, and other additives used in the production of resin plates. It's okay. Each reaction zone of the first reaction zone must rapidly mix the supplied monomers and polymerization initiator into the reaction mixture so that concentration and temperature are maintained substantially uniform, but not substantially Any reactor and stirring method may be used as long as the method achieves complete mixing, and the stirring Reynolds number is 200.
A stirring method with a stirring rate of 0 or more, preferably 5000 or more is preferably used, for example a continuous stirred tank reactor equipped with a ribbon stirrer is used for this purpose.

Although it is preferable that the number of reaction zones in which substantially complete mixing is achieved in the reaction zone be as large as possible from the viewpoint of improving operational stability, unnecessarily increasing the number will complicate the operation.
Since it is expensive, it is not advisable to use 2 to 10 pieces, preferably 2 to 5 pieces. The amount of polymer to be produced in each reaction zone is controlled by the polymer content in the final batch and the number of reaction zones, but the proportion may be too large or too small in any reaction zone. Since it will impair the stability of operation in the reaction zone or reduce the meaning of installing the reaction zone, it is generally uniform, preferably from the first reaction zone to the last reaction zone. It is distributed in such a way that it becomes smaller and smaller.

The average residence time of the reaction mixture in each reaction zone is therefore usually selected to be approximately equal, preferably decreasing successively from the first reaction zone to the last reaction zone. Additionally, the residence time of the reaction mixture in the reaction zone where no initiator is supplied is usually selected to be shorter than in the reaction zone where additional initiator is supplied, and therefore the amount of polymer formed is relatively short. small. The amount of initiator supplied to each reaction zone is determined by the amount of polymer to be newly produced in that reaction zone, the number average degree of polymerization, the reaction temperature, and the concentration of residual initiator in the previous reaction zone. However, if a sufficiently high reaction temperature is chosen so that the residual initiator concentration is sufficiently small, the proportion will be equal to the proportion of the amount of new polymer to be produced in each reaction zone or the average retention of the reaction mixture. The proportions are adjusted in accordance with the time ratio, and are generally proportioned approximately equally, preferably gradually decreasing from the first reaction zone to the final reaction zone. In order to maintain a narrow polymerization degree distribution of the polymer at the end of Siroczów and to reduce the residual initiator concentration, it is necessary to maintain a narrow polymerization degree distribution of the polymer supplied from the previous reaction zone in the second reaction zone. ,
And it is necessary to maintain the condition of the residual initiator concentration leaving the first reaction zone so that the residual initiator concentration can be effectively reduced, and the residual initiator concentration in the last reaction zone of the reaction zone must be maintained. is 1/2 to 1/1000 times the concentration of initiator supplied to the reaction zone, preferably 1/5 to 1/1.
000 times the amount, particularly preferably 1/10 to 1/500 times the amount.

Within this range, it is possible to obtain a particularly narrow distribution of the degree of polymerization of the polymer in the dried syrup and a particularly low residual initiator concentration.
If the residual initiator concentration in the reaction zone is larger than this range, the residual initiator concentration off the final slope will be high, or the average residence time in the second reaction zone will be required to make the residual initiator concentration sufficiently small. During this time, a large amount of high polymerization degree polymer is generated, which results in a wide distribution of polymerization degree of the polymer at the final stage, which is not a good idea. When the above conditions regarding the residual initiator concentration in the last reaction zone of the first reaction zone are achieved, the proportion of polymer formed in the entire reaction zone to the polymer in the final syrup is usually between 60 and 99.5. % by weight, preferably 90-99.5% by weight, particularly preferably 95-99.5% by weight.

The amount of polymer produced in the first reaction zone and the number average degree of polymerization are determined by the type and concentration of the feed initiator, the reaction temperature and the average residence time of the reaction mixture in each reaction zone of the reaction zone; Depending on the desired final polymer content, number average degree of polymerization and number of reaction zones used, the preferred feed initiator concentration, reaction temperature and average residence time of the reaction mixture are selected. Although the number average degree of polymerization of the newly produced polymer in each of the reaction zones has different values, in order to narrow the distribution of the degree of polymerization of the polymer newly produced in the entire reaction zone,
It is desirable to match these with each other as much as possible;
The amount of polymerization initiator added to each reaction zone is mutually adjusted. The ratio of the maximum to minimum number average degree of polymerization of the polymer produced in each reaction zone is usually maintained at less than 3, preferably less than 2, so that the degree of polymerization distribution of the polymer exiting the reaction zone is The degree of dispersion is usually 2.5 or less, preferably 2.2 or less. In the method of the present invention, the amount of polymer produced in each reaction zone of the first reaction zone is selected to be relatively small, usually 3 to 35% by weight, preferably 5 to 25% by weight, so that the heat generation in each reaction zone is selected to be relatively small. The amounts are relatively small, and the temperature in each reaction zone is usually between 90 and 200°C, preferably between 1
The temperature is selected between 10 and 180°C.

Since the average residence time of the reaction mixture in each reaction zone is very short, usually 0.1 to 20 minutes, preferably 0.2 to 5 minutes, the reaction mixture is fed to the first reaction zone of the first reaction zone. Controlling the temperature throughout the reaction zone by varying the preheating temperature of the monomers can be carried out surprisingly effectively. In particular, the amount of polymer formed in the first reaction zone of the first reaction zone is selected to be relatively high within this range, and the amount of polymer formed in each subsequent reaction zone is selected to be relatively high within this range. When the temperature is selected to be low, controlling the reaction temperature in the first reaction zone allows each subsequent reaction zone to perform thermally stable steady-state operation even under substantially adiabatic conditions. In addition, since the amount of polymer produced in each reaction zone of the first reaction zone is selected to be relatively small, the polymerization rate constant in the reaction mixture supplied to the reaction zone and the reaction mixture discharged from the reaction zone are The difference in polymerization rate constants between the two components can be selected to be small, and the apparent acceleration of polymerization rate due to the Tromsdorff effect is significantly reduced, allowing syrup with extremely high polymer content to be obtained through stable steady operation. This is preferably carried out. The reaction mixture leaving the first reaction zone is then conducted to a second reaction zone where a substantially extrusion flow is achieved, and during passage through said reaction zone residual amounts of polymer are formed and residual Initiator concentration is reduced.

Since the reaction mixture led to the second reaction zone can no longer be supplied with a polymerization initiator while passing through the reaction zone, the polymerization initiator is constantly supplied and substantially complete mixing is achieved. The residual initiator concentration can be reduced very easily in the second reaction zone, unlike in the first reaction zone, and the amount of polymer formed during this time is small, making it relatively Despite the fact that a high polymerization degree polymer is produced, the distribution of polymerization degree of the polymer at the final stage remains surprisingly small. The temperature of the second reaction zone may be any temperature at which the residual initiator decomposes sufficiently rapidly, and is usually at a temperature at which the half-life is 20 seconds or less, preferably 5.
The temperature is selected such that the temperature is less than 2 seconds, but is preferably not lower than that of the previous reaction zone, especially when the temperature of the reaction mixture is substantially adiabatic due to the heat of polymerization etc. while passing through the second reaction zone. Preferably, conditions are maintained such that the temperature rises to . The reaction mixture supplied to the second reaction zone essentially does not require mixing in terms of concentration since there are no newly supplied components, and also in terms of temperature the amount of polymer produced in the reaction zone. is small and can be easily controlled without causing runaway even if the reaction is carried out adiabatically, so any reaction device and stirring method may be used as long as it achieves substantially extrusion flow; If this is not done, the polymer will adhere to the reactor wall, making it difficult to achieve a substantial extrusion flow, and if it progresses further, clogging will occur. Therefore, it is desirable to perform stirring, and the back mixing coefficient 0.2 or less, preferably 0.1 or less, using a stirring Reynolds number of 2000 or more, preferably 5000 or more, or a back mixing coefficient of 0.2 or less, preferably 0. A stirring method using a self-wiping type stirrer that achieves .1 or less is preferably used,
For example, a tubular reactor having a construction similar to a twin-screw extruder can be used for this purpose.

Mixing that occurs in the flow direction of the fluid is called back-mixing, and the back-mixing coefficient here refers to the degree to which the flow state of the reaction fluid in the tubular reactor differs from the ideal extrusion flow. It is expressed as 1/M, where M is the modified Péclet number, which is a dimensionless term that defines the relationship between the fluid passage speed and the back-mixing speed. This indicates that the extrusion flow approaches the ideal extrusion flow. Note that the modified Péclet number M applied in the present invention is 1968 10
Based on the M=UL/2E formula on the bottom line of page 191 of Kagaku Special Issue 36, "Reaction Engineering," published by Kagaku Doujin on May 20th. Although the reaction zone may be provided with an external jacket to control the temperature with a heat medium, it is preferable to maintain the reaction zone under substantially adiabatic conditions because the residual initiator is more rapidly reduced. Since the vapor pressure of the reaction mixture in both the first and second reaction zones is usually higher than atmospheric pressure, it is easy to control the residence time, temperature, etc. in both reaction zones, and therefore the polymer content in the final reactor, In order to maintain properties such as viscosity and residual initiator concentration substantially constant, it is desirable to apply a pressure equal to or higher than the vapor pressure so that the reaction mixture maintains a substantially liquid phase, and is usually 1 to 20 atmospheres, preferably. 2-10
Pressurized to atmospheric pressure.

the average residence time of the reaction mixture in the second reaction zone is 0.05 to 5 times the average residence time in the first reaction zone;
Preferably, 0.1 to 2 times is selected.

The average residence time only needs to be long enough so that the residual initiator concentration is essentially negligible; even if the average residence time is too long, the residual initiator concentration is no longer present in an essentially negligible amount, so that polymerization will not occur. There is no problem since the reaction progresses only thermally very slowly and therefore the increase in polymer content and viscosity is virtually negligible, but making it unnecessarily long would require a large reaction zone. There is no point in doing so;
Also, if the average residence time is shorter than 0.05 times,
This is not preferred because the concentration of residual initiator becomes high. Correspondingly, the residual initiator concentration in the reaction mixture passing through the reaction zone is essentially negligible, and the residual initiator concentration decreases rapidly from the inlet to the outlet of the reaction zone. The number average degree of polymerization of the newly produced polymer in the reaction zone increases rapidly from the inlet to the outlet, but the amount produced rapidly decreases from the inlet to the outlet of the reaction zone. , the polymer formed in the reaction zone will surprisingly have a number average degree of polymerization that is not very large compared to the number average degree of polymerization of the polymer formed in the first reaction zone, resulting in a lower number average degree of polymerization in the final syrup. It has been achieved to reduce the residual initiator concentration to a virtually negligible amount while at the same time maintaining a very narrow degree of polymerization distribution of the polymers in the syrup, with the weight-average and number-average degrees of polymerization of the polymers being kept very narrow. The polydispersity of the degree of polymerization distribution expressed as the ratio of is 3 or less, preferably 2.5 or less, particularly preferably 2.2 or less.
The residual initiator concentration in the reaction mixture leaving the second reaction zone is substantially negligible, below 1 ppm, preferably 0.
It is 1 ppm or less, particularly preferably 0.01 ppm or less.

Even when the final syrup obtained by the above method is left under the same temperature conditions, there is almost no increase in polymer content or viscosity, but until the final syrup is used for manufacturing resin plates, During this period, the syrup should be stored to minimize deterioration in quality, and during operations such as adding polymerization initiators and other additives and pouring syrup during the production of resin plates, the polymer content and viscosity should be controlled. The resin is cooled to an appropriate temperature, usually below 100°C, preferably below 80°C, in order to prevent the workability from decreasing due to an increase in temperature and the quality of the resulting resin plate. The syrup obtained by the method of the invention has a residual initiator concentration of 1 p.
a substantially negligible amount below pm, preferably 0.1 p
pm or less, particularly preferably 0.01 ppm or less, the increase in polymer content and viscosity is negligible even without rapid cooling after exiting the second reaction zone, so that the quality is constant. It has the advantage of being easy to obtain,
No increase in the polymer content or viscosity was observed during storage, and furthermore, the residual monomer content in the resin plates increased due to deterioration of the syrup during storage, and foaming occurred during heat molding of the resin plates. It has excellent storage stability, with no deterioration in quality such as oxidation.

Further, the polymerization degree distribution of the polymer in the syrup obtained by the method of the present invention is extremely narrow, and the polydispersity of the polymerization degree distribution expressed as the ratio of the weight average degree of polymerization to the number average degree of polymerization is 3 or less, preferably 2. 5 or less, particularly preferably 2.2 or less, the number average degree of polymerization, which affects the average degree of polymerization of the resin plate, should be relatively high, and the weight average degree of polymerization, which affects the viscosity of the syrup, should be selected to be relatively low. As a result, a syrup having a relatively low viscosity and a high polymer content can be obtained, and it has the extremely favorable advantage of shortening the board making time without degrading the quality of the resin board. Furthermore, when polymerization is carried out using this syrup under conditions that do not shorten the board-making time, the average degree of polymerization of the resin board can be improved, which has the advantage that resin boards of particularly excellent quality can be obtained. . Furthermore, when producing resin plates using syrup with a relatively low polymer content obtained by the method of the present invention, it is also possible to shorten the plate making time by increasing the concentration of the polymerization initiator used. This method also has the advantage that the quality of the resin plate obtained is relatively small. The polymer content in the final syrup produced by the method of the present invention is 15 to 80% by weight, and when it is lower than this range, the effect of shortening the plate making time is relatively small, and when it is higher than this range, it is extremely effective. Even under high reaction temperature conditions, the viscosity becomes high, making it impossible to achieve substantially complete mixing, which is not a good idea.

On the other hand, the viscosity of the final syrup at 25°C is 0.5-1
If the viscosity is lower than this range, it will cause liquid leakage during injection during the production of resin plates, and if the viscosity is 1000 poise or higher, which is on the high side of this range, it will be difficult to perform operations such as injection. Therefore, neither of these is a good idea, and within this range, those with 0.5 to 1000 poise are used as they are in the production of resin plates. The final syrup produced by the method of the invention has a polymer content of 20 to 40%.
% by weight and with a viscosity of 5 to 500 poise at 25°C, it has suitable workability for injection etc. during the production of resin plates, and the plate manufacturing time can be increased without deteriorating the quality of the resin plates obtained. This makes it particularly suitable for use in continuous sheet-making processes. The number average degree of polymerization of the polymers in the final syrup is selected to be between 300 and 6000, particularly in the case of syrups with high polymer content suitable for use in continuous plate making processes, but not limited to 300 to 2000, depending on the desired In order to improve the quality of the resulting resin plate, it is preferable to select a number average degree of polymerization as high as possible within a range where the viscosity is not too high relative to the polymer content. The syrup produced by the method of the present invention may be used in the production of resin plates as a syrup having the same polymer content and viscosity as obtained, but the syrup has a polymer content of 15 to 50% by weight.
, preferably 20 to 40% by weight, and the viscosity at 25°C is 0.5 to 1000 poise, preferably 5 to 500 poise.
It may be concentrated to the desired value within the poise range or diluted with monomeric or similar syrups.

Depending on the case, this can be used to advantageously improve the homogeneity or productivity of the syrup used in the production of resin plates. Since the syrup produced by the method of the present invention has a high polymer content, low viscosity, good strength and storage stability, its use is not limited only to the production of face oil plates. It is suitable for use in the production of molding materials, adhesives, paints, resin concrete compositions, and other applications in which syrups of this type are generally used.

EXAMPLES Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited thereto.

Note that % in the examples is % by weight. In addition, the viscosity of the syrup in the examples was measured at 25°C using a B-type viscometer, and the number average degree of polymerization and polydispersity of the polymerization degree distribution of the polymer in the syrup were measured using polystyrene gel as a filler and tetrahydrofuran. It was measured by gel permeation chromatography using an eluent. In addition, for polymerization foaming of the resin plate, the presence or absence of bubbles is semi-determined by visually observing the obtained resin plate, and for heating foaming, the obtained resin plate is placed in a circulating hot air oven and heated at 180°C for 30 minutes. The presence or absence of bubbles was determined by visual observation.

The reduced viscosity was determined by measuring a 0.1% chloroform solution of the obtained resin plate at 25°C, and the residual monomer concentration was measured by dissolving the obtained resin plate in methylene chloride and using gas chromatography. .

Example 1 Two stirred tank reactors each having a ribbon-shaped stirring blade installed at the front stage were arranged in series, and a stirring shaft was installed at the rear stage, and a pin installed on the stirring shaft in a direction perpendicular to the shaft was attached to the tube wall. The syrup was produced using a three-stage continuous reactor consisting of an array of tubular reactors arranged to wipe each other with fixing pins installed vertically toward the axis.

The volume ratio of the first tank reactor, second tank reactor, and tube reactor was 1:0.33:0.25. Methyl methacrylate monomer containing 0.047% of azobisisobutyronitrile as a polymerization initiator was continuously supplied so that the average residence time in the first tank reactor was 147 seconds, and polymerization was carried out. , plus 0.0% relative to the amount of reaction mixture.
2% of azobisisobutyronitrile to give 0.17%
The methyl methacrylate monomer solution was continuously added to the second tank reactor for polymerization, and then finally passed through the tubular reactor to complete the polymerization.

The temperature of each reactor, including the tubular reactor, was 160°C, and the pressure was 6.
．． The pressure was maintained at 0 atmospheres. The feed liquid to the first tank reactor was preheated to 80°C using a jacketed single tube, while the temperature of the initiator solution additionally fed to the second tank reactor was 2°C.
It was 5℃. The polymer content of the syrup leaving the tubular reactor was 33.5%, the viscosity at 25°C was 176 poise, and the proportion of polymer produced in each reactor was 70:
It was 25:5.

Further, the ratios of the residual initiator concentration to the supplied initiator concentration in the first and second tank reactors were 1/32 and 1/11 times the amount, respectively. The residual initiator concentration in the final batch was 0.01 ppm or less, and no change was observed in the polymer content or viscosity even after heating at 60°C for 5 hours. Furthermore, the polydispersity of the polymerization degree distribution off the coast of Shilotov was 2.02, but the residual initiator concentration was 15.
The amount was as high as 2 ppm, and when heated at 60°C, polymerization proceeded rapidly and did not lose fluidity at all within 1 hour.
The condition was such that it could not withstand long-term storage. Next, 0.04% of azobisdimethylvaleronitrile was added to this syrup, and polymerization was carried out using the continuous polymerization apparatus of Example 1 under the same conditions as in Example 1, except that the syrup was passed through the heated polymerization zone for 24 minutes. The process was completed to obtain a resin board.

The reduced viscosity of this product was 2.69 d1/7, and no polymerization foaming occurred, but the residual monomer concentration was as high as 4.2%, and thermal foaming occurred. When polymerization was carried out under the same conditions as above except that the resin was passed through the heating polymerization zone for 21 minutes, significant polymerization and foaming occurred, and the resulting resin plate had no value as a commercial product. Comparative Example 2 Two stirred tank reactors equipped with ribbon-shaped stirring blades were arranged in series, and the volume ratio of the first and second stage reactors was 1:
Using a two-stage continuous reactor with an azobisisobutyronitrile concentration of 0.25%, methyl methacrylate monomer containing 0.047% azobisisobutyronitrile was heated so that the average residence time in the first stage reactor was 147 seconds. Polymerization was carried out by continuously supplying the polymer while maintaining the temperature of each reactor at 160° C. and the pressure of each reactor at 6.0 atm.

The polymer content of the syrup leaving the second stage reactor is 28.
3%, viscosity is 80.9 poise, 88% of the total polymer
was produced in the first reactor. The residual initiator concentration off the coast of Shilotzow was 2.53 ppm, and at 60 °C
After heating for an hour, the polymer content increased to 28.7% and the viscosity increased to 780 poise. The number average degree of polymerization of the polymer in the syrup is 795, and the polydispersity of the degree of polymerization distribution is 2.
It was 55. 0.04% of azobisdimethylvaleronitrile was added to this syrup, and the polymerization was completed using the continuous polymerization apparatus of Example 1 under the same conditions as Example 1, except that the syrup was passed through the heated polymerization zone for 20 minutes. A resin plate was obtained. The reduced viscosity of this product was 2.65 d1/t, and no polymerization foaming occurred, but the residual monomer concentration was as high as 2.7%, and thermal foaming occurred. Comparative Example 3 The same reactor as Comparative Example 2 was used except that the volume ratio of the first and second reactors was 1:2, and the reaction was carried out under exactly the same conditions as Comparative Example 2. A syrup with a viscosity of 31.4% and a viscosity of 1100 poise was obtained.

80% of the polymer off Shilotzow was produced in the first reactor. Residual initiator concentration in syrup is 0.23 ppm
When the mixture was heated at 60° C. for 3 hours, the polymer content increased to 31.6% and the viscosity increased to 2500 poise. The number average degree of polymerization of the polymer in the syrup is 870.
The polydispersity of the polymerization degree distribution was 3.32. 0.04% of azobisdimethylvaleronitrile was added to this syrup, and the polymerization was completed using the continuous polymerization apparatus of Example 1 under the same conditions as Example 1, except that the syrup was passed through the heated polymerization zone for 17 minutes. A resin plate was obtained.

The high viscosity of this syrup made it difficult to inject between the moving bands, and the product exhibited polymeric foaming. In addition, this syrup was diluted with a monomer until the same viscosity as Comparative Example 2, 80.9 poise, and the polymer content was 25.0%.
syrup with azobisdimethylvaleronitrile 0.04
% was added and the polymerization was completed under the same conditions as above except that it passed through the heated polymerization zone for 23 minutes. The reduced viscosity of the product was 2.91 d1/V and the residual monomer concentration was 2.1%. Although polymerization foaming did not occur, heating foaming did occur.
In addition, when 0.07% of azobisdimethylvaleronitrile was added to the same diluted syrup and the polymerization was completed under the same conditions as above except that the syrup was passed through the heating polymerization zone for 18 minutes, the reduced viscosity of the product was At 2.20d1/7, the residual monomer concentration was 1.8% and no polymerization foaming occurred, but
Significant heat foaming occurred. When the syrup obtained by this method was diluted with a monomer until the polymer content reached 28.3%, the same as in Comparative Example 2, the viscosity was 280 poise.

Comparative Example 4 The general type continuous reaction apparatus of Comparative Example 1 was used.

Methyl methacrylate monomer containing 0.45% azobisisobutyronitrile was continuously fed so that the average residence time was 14.6 minutes, and the reactor pressure was normal pressure and the temperature was 85°C. I went to Further, the concentration of the residual initiator at the outlet of the reaction tank was about 90/100 times the concentration of the supplied initiator. At first, a syrup with a polymer content of about 25% and a viscosity of about 12 poise was obtained, but it became difficult to maintain a constant reaction temperature, and after about an hour, the temperature rose rapidly, and the polymerization reaction went out of control, causing the contents to drop. It solidified and it was impossible to continue the reaction. Example 2 Polymerization was carried out using the same apparatus as in Example 1, except that the volumes of the first tank reactor, second tank reactor, and tube reactor were all 51.

3. Preheat the methyl methacrylate monomer to 130°C.
The polymerization initiator, azobisisobutyronitrile, was continuously fed to the first tank reactor at a rate of 271/min.
An ethyl acrylate monomer solution at 20° C. containing 29% was continuously fed at 0.361/min to the first tank reactor, and a solution of ethyl acrylate monomer containing 3%
0.0351 methyl methacrylate monomer solution at 0°C
Polymerization was carried out by continuously adding the polymer to the second tank reactor at a rate of 1/min. The temperature of each tank reactor was maintained at 160°C, and the temperature of the tube reactor was raised adiabatically to 162°C. Further, the pressure in each reactor was maintained at 6.0 atmospheres. In addition, the residual initiator concentration in a tank reactor is 1 of the supplied initiator concentration.
/32 times the amount. The syrup leaving the tubular reactor had a polymer content of 32.0% and a viscosity of 159 poise at 25°C.

The number average degree of polymerization of the polymer in the syrup was 790, and the polydispersity of the degree of polymerization distribution was 2.18. Example
3 The same apparatus as in Example 1 was used except that the volume ratio of the first tank reactor, second tank reactor, and tube reactor was 1:0.5:0.5.

Methyl methacrylate monomer containing 0.046% azobisisobutyronitrile was continuously supplied to the first tank reactor so that the average residence time was 97.8 seconds, and the polymerization was carried out. 0.024% relative to the amount of mixture
A 2% methyl methacrylate monomer solution of azobisisobutyronitrile was additionally supplied to the second tank reactor so that the temperature of each reactor was maintained at 160°C and the pressure at 6.0 atm. Polymerization was carried out.

The polymer content of the syrup leaving the tubular reactor is 29.8%.
The viscosity at 25° C. was 23.0 poise, and the ratio of polymers produced in each reactor was 62:32:6. In addition, the ratio of the residual initiator concentration to the supplied initiator concentration in the first and second tank reactors is 1/1, respectively.
The amount was 21 and 1/11 times larger. The concentration of residual initiator in the final syrup was 0.01 ppm or less, the number average degree of polymerization of the polymer produced in Syropf was 605, and the polydispersity of the degree of polymerization distribution was 2.15. Example 4 Three stirred tank reactors each having a ribbon-shaped stirring blade installed at the front stage were arranged in series, and a stirring shaft was installed at the rear stage, and a pin installed on the stirring shaft in a direction perpendicular to the shaft was attached to the tube wall. A four-stage continuous reaction apparatus was used, which consisted of fixed pins installed vertically toward the axis and tubular reactors arranged so as to wipe each other.

The volume ratio of each reactor was 1:0.5:0.5:0.1. Polymerization was carried out by continuously feeding methyl methacrylate monomer containing 0.046% azobisisobutylonitrile so that the average residence time in the first tank reactor was 97.8 seconds. A 2% methyl methacrylate monomer solution of azobisisobutyronitrile was additionally supplied to the second and third tank reactors so that the amounts were 0.024% and 0.032% based on the amount, respectively, and polymerization was carried out. Ivy. The temperature in each reactor was 1601162, 164 and 165°C, and the pressure in each reactor was 6.3 atmospheres. The polymer content of the syrup leaving the tubular reactor is 45.
3%, the viscosity at 25°C is 1680 poise, and the ratio of polymer produced in each reactor is 43:22:3.
The ratio was 2:3.

In addition, the ratio of the residual initiator concentration to the supplied initiator concentration in the first, second, and third tank reactors is 1/1, respectively.
21, 1/13 and 1/15 times the amount. The concentration of residual initiator off the coast of the final Shilotov is less than 0.01 ppm,
The number average degree of polymerization of the polymer produced off the coast of Shilotzow was 615, and the polydispersity of the polymerization degree distribution was 2.12.

When this syrup was diluted with a monomer until the polymer content was 35.0%, a syrup with a viscosity of 95.5 poise at 25°C was obtained. Example 5 The same method as Example 4 was carried out except that the volume ratio of each reactor was changed to 1:0.5:0.33:0.2.

Methyl methacrylate monomer was continuously fed so that the average residence time in the first reactor was 106 seconds, and each tank reactor was supplied with 0.000 ml of methyl methacrylate monomer based on the amount of reaction mixture.
104, 0.054 and 0.054% azobisisobutyronitrile were fed continuously. The temperatures in each reactor were 1601163, 165 and 166°C, and the pressure in each reactor was 6.3 atm. The syrup leaving the tubular reactor had a polymer content of 62.5% and a viscosity of 8700 poise at 25°C.

In addition, the influence of the residual initiator concentration on the feed initiator concentration in the first, second, and third tank reactors is 1 and 1, respectively.
The amounts were 1/24, 1/15 and 1/12. The residual initiator concentration in the final syrup was 0.01 ppm or less, the number average degree of polymerization of the polymer in the syrup was 415, and the polydispersity of the polymerization degree distribution was 2.10. When this syrup was diluted with monomer until the polymer content was 40.3%, the viscosity at 25°C was 55.0 poise.
Examples 6 to 14 The volume ratio of the first tank reactor and the second tank reactor is set to the value shown in Table 1, and the volume of the tubular reactor is 0.5 of that of the first tank reactor. The same method as in Example 1 was carried out except that the amount was doubled.

Various radical polymerization initiators shown in Table 1 are used as polymerization initiators, and the first and second tank types are set so that the ratio of the amount of polymerization initiator to the amount of the reaction mixture becomes the value shown in Table 1. Using methyl methacrylate monomer as the monomer, the reaction was carried out at various temperatures and average residence times shown in Table 1 to produce the weights shown in Table 2. A syrup with coalesced content, viscosity and number average degree of polymerization was obtained. Furthermore, the ratios of the residual initiator concentration to the supplied initiator concentration in the first and second tank reactors were the values shown in Table 1, respectively. In all cases, the concentration of residual initiator in the syrup was 0.01 ppm or less, and no change was observed in the polymer content or viscosity even after heating at 60° C. for 3 hours. Furthermore, the polydispersity of the polymerization degree distribution of the polymer off the coast of Shilotzow was 2.2 or less. Example 15 Syrup was produced using a two-stage continuous reaction apparatus consisting of two stirred tank reactors equipped with ribbon-shaped stirring blades arranged in series.

The volume ratio of the first tank reactor and the second tank reactor is 3:1
It was hot. Methyl methacrylate monomer containing 0.047% of azobisisobutyronitrile as a polymerization initiator was continuously fed so that the average residence time in the first tank reactor was 147 seconds, and the reaction mixture A 2% methyl methacrylate monomer solution of azobisisobutyronitrile was continuously added to the second tank reactor so that the amount was 0.017% based on the amount of ℃
, the pressure was maintained at 6,0 atm. The feed liquid to the first tank reactor was preheated to 80°C using a single jacketed tube, while the temperature of the initiator solution additionally fed to the second tank reactor was 25°C. . The syrup leaving the second reactor has a polymer content of 31.8% and a viscosity of 90% at 25°C.
．． 8 poise, and the ratio of polymers produced in each reactor was 73:27.

Claims (1)

[Scope of Claims] 1. A monomer containing methyl methacrylate as a main component is continuously connected to the first reaction zone of a reaction zone formed by arranging two or more reaction zones in series in which substantially complete mixing is achieved. and continuously supplying the radical polymerization initiator to at least two reaction zones including the first reaction zone, such that at least the residual initiator concentration in each reaction zone to which the polymerization initiator is supplied is The method is characterized in that the conditions in each reaction zone are maintained so that the concentration of the initiator supplied is 1/2 to 1/1000 times, and a syrup is obtained by producing a polymer while the reaction mixture sequentially passes through each reaction zone. A continuous production method for methyl methacrylate syrup. 2. The method according to claim 1, which uses a radical polymerization initiator whose temperature at which its half-life is 5 seconds or less is 180° C. or less. 3 The number of reaction zones in which substantially complete mixing is achieved is from 2 to
10. The method according to claim 1, wherein the number is 10. 4. The method according to claim 1, wherein the stirring Reynolds number in each reaction zone is 2000 or more. 5 Residual initiator concentration is 1/5 to 1/1 of the supplied initiator concentration
The method according to claim 1, wherein the amount is 0.000 times. 6 The residual initiator concentration is 1/10 to 1/1/1 of the supplied initiator concentration.
500 times the amount. The method according to claim 1. 7. The method according to claim 1, wherein the syrup has a polymer content of 15 to 80% by weight and a viscosity of 0.5 to 10,000 poise at 25°C. 8. Continuously feeding a monomer mainly composed of methyl methacrylate to a first reaction zone of a first reaction zone formed by arranging two or more reaction zones in series in which substantially complete mixing is achieved. , and the radical polymerization initiator is continuously supplied to at least two reaction zones including the first reaction zone, and at least the residual initiator concentration in each reaction zone to which the polymerization initiator is supplied is equal to or less than the supplied initiator. Conditions in each reaction zone are maintained at 1/2 to 1/1000 times the concentration to produce the majority of the polymer in the final syrup in the reaction zone, and the resulting reaction mixture is then substantially The extrusion flow is directed to a second reaction zone in which a residual amount of polymer is produced during passage through the reaction zone, and the reaction zone is such that a residual initiator concentration is substantially negligible. Maintaining the temperature and average residence time conditions to obtain a syrup in which the polydispersity of the polymerization degree distribution expressed as the ratio of the weight average degree of polymerization to the number average degree of polymerization of the polymer in the final syrup is 3.0 or less. A continuous production method for methyl methacrylate syrup characterized by: 9. The method according to claim 8, which uses a radical polymerization initiator whose temperature at which its half-life is 5 seconds or less is 180° C. or less. 10 The number of reaction zones where substantially complete mixing is achieved is 2.
9. The method of claim 8, wherein the number is 10. 11. The method according to claim 8, wherein the stirring Reynolds number in each reaction zone of the first reaction zone is 2000 or more. 12 The proportion of the polymer produced in the first reaction zone in the final syrup is 60 to 99.5% by weight.
The method according to claim 8. 13 At least the residual initiator concentration in each reaction zone where the polymerization initiator is supplied is 1/5 to 1/1 of the supplied initiator concentration.
9. The method according to claim 8, wherein the polydispersity of the degree of polymerization distribution in the final syrup is 2.5 or less. 14 The residual initiator concentration in each reaction zone where the polymerization initiator is supplied is at least 1/10 to 1/1/1 of the supplied initiator concentration.
9. The method according to claim 8, wherein the polydispersity of the degree of polymerization distribution in the final syrup is 2.2 or less at 500 times the amount. 15. The method of claim 8, wherein the temperature of the second reaction zone is no lower than the temperature of the first reaction zone. 16 The average residence time of the reaction mixture in the second reaction zone is 0.1 to 2 of the average residence time in the first reaction zone.
9. The method according to claim 8, wherein the method is: 17. The method according to claim 8, which uses a stirring method in which the back mixing coefficient is 0.2 or less in the second reaction zone. 18. The method of claim 8, wherein the residual initiator concentration in the final syrup is 1 ppm or less. 19 Residual initiator concentration in final syrup is 0.01pp
9. The method according to claim 8, which is less than or equal to m. 20 The polymer content in the final syrup is 15-80% by weight, and the viscosity at 25°C is 0.5-1000.
9. The method according to claim 8, which has 0 poise. 21. The method according to claim 8, wherein the polymer content in the final syrup is 20-40% by weight and the viscosity at 25°C is 5-500 poise.