JP2000159816A - Preparation of methacrylic polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a continuous polymerization method of a methacrylic polymer excellent in operational stability of polymerization and reduced in spots of the copolymerization composition ratio of the formed polymer. SOLUTION: In continuously feeding a monomer mixture having methyl methacrylate as the major component and a polymerization initiator into a complete mixing-type reactor to effect bulk or solution polymerization, the average retention time of the reaction liquid is rendered constant and, the polymerization initiator and the mixing time in the reactor are selected in such a manner that the highest peak temperature at which the polymer conversion comes to a maximum is present in the range of 110-160 deg.C to effect the polymerization in the range of the peak temperature ±10 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an improved method for producing a methacrylic polymer. More specifically, the present invention relates to a production method which employs specific reaction conditions and is extremely excellent in operation stability when continuously polymerizing methyl methacrylate or a monomer mixture containing methyl methacrylate as a main component using a complete mixing type reactor. .

[0002]

2. Description of the Related Art Conventional polymethyl methacrylate (PM)
The industrial production method of MA) was mainly a batch polymerization method using a suspension polymerization method. This method is a production method suitable for high-mix low-volume production, but because of the use of an auxiliary agent such as a dispersant, these remain in the molding material and deteriorate the quality.
Further, the post-treatment required washing with a large amount of water and subsequent drying. Furthermore, since the polymerization operation is of a batch type, the operation operation is inefficient and complicated, and at the same time, the required costs such as equipment costs and operation costs are high. Furthermore, at the time when pollution regulations are becoming stricter, it is not preferable to discharge a large amount of water or washing water used for polymerization containing auxiliary agents such as dispersants and unreacted monomers. If a processing apparatus is newly installed, the required cost is further increased, and this is inevitably an industrially disadvantageous manufacturing method. In order to solve such problems of the suspension polymerization method, a method of continuously producing MMA by bulk polymerization has been proposed.

For example, Japanese Patent Publication No. 52-32665 specifies the half life and the amount of a radical polymerization initiator added at a polymerization temperature, and increases the polymer conversion rate from 50% by weight to 78% at a polymerization reaction temperature of 130 ° C. to 160 ° C. % Is disclosed. According to this method, a methacrylic polymer molding material having excellent heat resistance and excellent thermal decomposability during molding and having a wide molding temperature range could be produced. However, in this method, since the conversion of the polymer greatly fluctuates due to the fluctuation of the polymerization temperature, it is necessary to strictly control the polymerization conditions, and it is difficult to manage the operation, and improvement has been demanded.

Japanese Patent Application Laid-Open No. 3-111408 discloses that a monomer mixture containing methyl methacrylate as a main component can be used as a radical initiator in a half-life at a polymerization temperature of 0.5 to 0.5 with a single complete mixing reactor. The average residence time was 1/200 to 1/10000 in terms of the ratio to the half-life of the radical initiator while stirring with a stirrer having a stirring power of 0.5 to 20 kW per 1 m ^{3 of} the reaction solution using a 120-second solution. A method for producing a methacrylic polymer which is set so as to obtain a polymer conversion rate of 45 to 70% by weight at a temperature of 130 to 160 ° C is disclosed.

This method is advantageous in that a runaway reaction can be suppressed by finding a phenomenon different from the common sense of the conventional reaction kinetics that the polymer conversion rate becomes lower as the polymerization temperature becomes higher. Also, if the reaction temperature rises for some reason, the amount of heat generated will decrease because the conversion rate of the polymer will decrease, and the self-controllability will automatically lower the polymerization temperature and restore the original temperature, which is advantageous for stable operation. It is said that there is. However, the polymerization temperature in a complete mixing reactor is actually controlled to maintain a constant temperature by adjusting the monomer supply temperature and the jacket temperature of the reactor. There is a problem that the conversion of the polymer is not stable due to the fluctuation of the polymerization temperature.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has a very excellent operation stability in controlling the polymerization temperature and the conversion of the polymer. The aim is to provide a method.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that the object can be achieved by adopting specific reaction conditions. Was completed.

That is, according to the present invention, a raw material containing methyl methacrylate or a monomer mixture containing methyl methacrylate as a main component and a polymerization initiator or a raw material further containing a solvent is continuously supplied to a complete mixing type reactor to carry out bulk polymerization or In the solution polymerization method, the average residence time of the reaction solution in the reactor is constant, and the peak temperature at which the polymer conversion rate is highest in the relationship between the polymerization temperature and the polymer conversion rate is between 110 and 160 ° C. A method for producing a methacrylic polymer, characterized in that a mixing time of a polymerization initiator and a reactor is selected so as to be present, and polymerization is carried out at a constant temperature within a range of ± 10 ° C. around the peak temperature.

In this method, the polymerization is preferably performed at a temperature lower than the peak temperature.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The production method of the present invention is applied to the production of a methacrylic polymer, that is, a homopolymer or a copolymer of methyl methacrylate. In the case of producing a copolymer, a monomer mixture containing methyl methacrylate as a main component, that is, 80% by weight or more of methyl methacrylate and 20% by weight copolymerizable with methyl methacrylate.
It is preferable to use a monomer mixture containing the following other monomers.

Other monomers to be subjected to copolymerization include:
Although not particularly limited, (meth) acrylates such as methyl acrylate, ethyl acrylate, n-butyl acrylate, fluoroalkyl methacrylate and benzyl methacrylate are preferably used. Hereinafter, methyl methacrylate or a monomer mixture is referred to as “raw material monomer”.

In the present invention, the dissolved oxygen is reduced to 2 ppm or less by introducing an inert gas such as nitrogen into the raw material monomer or the reaction raw material containing the raw material monomer and the solvent, or by maintaining the same under reduced pressure for a certain time. Is preferred.
If the dissolved oxygen is more than 2 ppm, not only the polymerization reaction is not stable, but also the coloring is easily performed by keeping the high temperature for a long time in the polymerization step. More preferably, it is 1 ppm or less.

The raw material monomer or reaction raw material from which dissolved oxygen has been removed as described above is mixed with a polymerization initiator and, if necessary, a mercaptan compound as a chain transfer agent.
Feed continuously to a complete mixing reactor. Then, the polymerization reaction starts in the reactor, and the raw material becomes a reaction solution.

The mercaptan compound used in the present invention is not particularly limited, but n-butyl, n-octyl, n-dodecyl, tert-butyl mercaptan and the like are preferably used.

A polymer terminated by a mercaptan chain transfer reaction is excellent in thermal decomposition resistance, and the higher the ratio of the number of mercaptan terminated terminals to the total number of terminals in the polymer, the more excellent the polymer is in thermal decomposition resistance. can get. However, if the amount is too large, the degree of polymerization of the polymer is lowered and the strength of the polymer is reduced. Therefore, an appropriate degree of polymerization capable of forming and processing while maintaining the strength (in the present invention, after removing volatile components finally, In order to obtain a polymer having a weight average molecular weight in the range of 70,000 to 150,000) and to produce a polymer having excellent thermal decomposition resistance, the amount of mercaptan used should be 1.0 to 1 mol of monomer. The amount is from × 10 ^{−4 to} 1.0 × 10 ⁻² mol, preferably from 5.0 × 10 ^{−4 to} 5.0 × 10 ⁻³ mol.

The polymerization initiator has a relationship with the mixing time of the reactor so that the peak temperature at which the polymer conversion is highest in the relationship between the polymerization temperature and the polymer conversion exists between 110 and 160 ° C. Use to select an appropriate one. That is, by selecting the ratio of the half-life of the polymerization initiator to the mixing time of the reactor so as to satisfy the following equation (1), there is a peak temperature at which the conversion of the polymer becomes highest. The production method of the present invention can be implemented. 0.35 ≦ (τ _1/2 / θ _M ) ≦ 2.0 (1) where τ _1/2 : half-life of the polymerization initiator at the polymerization temperature [sec] θ _M : mixing time of the reactor [sec] That is, a small value of (τ _1/2 / θ _M ) means that
This means that most of the initiator is decomposed before the polymerization initiator fed to the reactor spreads evenly in the reactor. When applying an analytical model of a reactor that is frequently used in the field of reaction engineering, it can be said that although it is a completely mixed type reactor, the reaction behavior cannot be said to be a completely mixed model, but shows an intermediate behavior with the plug flow model. Means. vice versa,
When the value of (τ _1/2 / θ _M ) is large, the polymerization initiator spreads uniformly in the reactor without being substantially decomposed. Therefore, it can be considered as a complete mixing model according to the type of the reactor.

In the polymerization of methyl methacrylate, it is known that the polymerization effect is accelerated by the gel effect when the content of the polymer in the reaction solution exceeds about 30% by weight. Therefore, in a complete mixing type reactor, it is possible to efficiently increase the polymer conversion of the monomer with a very small amount of polymerization initiator, while in a plug flow type reactor, the polymerization initiator is rapidly decomposed. Since it disappears, dead end polymerization occurs, and the polymer conversion rate decreases under the same temperature and the same amount of polymerization initiator. Of course, even with the same amount of polymerization initiator, it is theoretically possible to obtain a high polymer conversion rate by sufficiently lowering the polymerization temperature and slowly decomposing the polymerization initiator. It is difficult to operate stably because the inside is blocked.

From the polymerization behavior of methyl methacrylate as described above, the phenomenon occurring in the complete mixing type reactor will be explained. The same polymerization initiator is used, the concentration of the polymerization initiator to be supplied, and the reaction solution in the reactor are By calculating the polymer conversion rate by changing the polymerization temperature by several points with the same average residence time,
In a low polymerization temperature region where the decomposition rate of the polymerization initiator is slow, it is regarded as a complete mixing model, so that the higher the temperature, the higher the polymer conversion, as in general reaction kinetics. As the temperature was further increased, the polymerization behavior of the plug flow model began to coexist, and the conversion rate of the polymer gradually stopped increasing.When the temperature was further increased, the polymerization behavior of the plug flow model became dominant, and Conversion decreases.

The method of the present invention determines the presence of such a peak polymerization temperature at which the conversion of the polymer becomes the highest, and carries out the polymerization at a constant temperature in the range of ± 10 ° C. around this peak temperature. It has been found that when the polymerization is carried out in the range of ± 10 ° C. around this peak temperature, the change in the polymer conversion is extremely small, and changes only by about 3% by weight.

That is, according to the method of the present invention, even if the polymerization temperature rises or falls for some reason, the conversion of the polymer is almost constant, and the conversion of the polymer is not affected by the polymerization temperature. It is possible to automatically perform the operation of maintaining the constant. In addition, since the calorific value due to the reaction is always constant, the control of the polymerization temperature merely controls the jacket temperature or the monomer supply temperature without affecting the fluctuation of the polymer conversion.

When the conversion of the polymer is almost constant, not only the control of the polymerization step becomes easy, but also the reaction mixture containing the polymer taken out of the reactor and the unreacted monomer or the reaction mixture containing the solvent is further reduced. By supplying the polymer at a constant conversion rate to the volatile removal step following the polymerization step, the operation stability of the volatile removal step is improved.

When a copolymer of methyl methacrylate and another monomer is obtained, the fact that the conversion of the polymer in the reactor is constant means that the composition ratio of the copolymer is always constant and the copolymer composition is constant. This means that the unevenness of the ratio is very small, and the effect on the quality is very large. In particular, methyl methacrylate has many uses as an optical material, and a uniform material without optical distortion is required. Therefore, a constant composition of the copolymer has high commercial value. Above all, the application as a plastic optical fiber is the most demanding in terms of optical performance, and is the field where the effect of the present invention is most exerted as a method for producing a core material and a sheath material.

In the present invention, not only the stabilization of the process but also the composition ratio of the copolymer is automatically kept constant by utilizing the specific phenomenon that the conversion of the polymer does not fluctuate even if the polymerization temperature changes. It is an industrially important point that it has the significance of exhibiting the quality improvement effect of converging to the value.

It is generally known that when a double helical ribbon blade is used as a stirrer in a complete mixing type reactor, the mixing time in the equation (1) can be calculated by the following equation (2). θ _M = 33 / n (2) where θ _M : mixing time [sec], n: stirring speed [1 / sec] Therefore, when stirring with a double helical ribbon blade, equations (1) and (2) The present invention can be carried out by selecting a combination of a polymerization initiator having a stirring rotation speed and a half life so as to satisfy the following. However, when the stirring blade is not a double helical ribbon blade, the formula (2) cannot be applied. Therefore, it is necessary to measure the mixing time of the stirring blade to be used and apply it to the formula (1).

Specific examples of the polymerization initiator used in the method of the present invention include tert-butylperoxyneodecanate, tert-hexylperoxypivalate,
tert-butyl peroxypivalate, 1,1,3,3
-Tetramethylbutyl peroxy-2-ethylhexanate, 1-cyclohexylperoxy-2-ethylhexanate, tert-hexylperoxy-2-ethylhexanate, tert-butylperoxy-2-ethylhexanate, etc. Organic peroxide or 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-
Azobisisobutyronitrile, 2,2′-azobis (2
-Methylbutyronitrile) and azo compounds such as dimethyl-2,2'-azobisisobutyrate, etc., in consideration of the polymerization temperature and the formulas (1) and (2).

One of these polymerization initiators may be used alone, or two or more thereof may be used in combination. However, when two or more polymerization initiators are used, the polymerization mechanism becomes complicated.
One single use is preferred.

In the present invention, the values of the half-life of the polymerization initiator are as follows: for organic peroxides, catalogs issued by NOF Corporation, and for azo compounds, technical bulletins issued by Wako Pure Chemical Industries, Ltd. Can be adopted.

In the production method of the present invention, it is preferable that the stirring and mixing be performed substantially uniformly at a constant polymerization temperature of the reaction solution selected from the range of 110 to 160 ° C. in the complete mixing type reactor. If the polymerization temperature is too low, the acceleration of the polymerization rate due to the gel effect will increase if the temperature is too low. in this case,
In order to avoid the influence of the acceleration phenomenon, it is difficult to operate stably only under the condition that the polymer conversion rate is low, and the productivity is reduced, which is economically disadvantageous. The preferred polymerization temperature is 120 ° C. or higher.

On the other hand, if the temperature is too high, the polymerization reaction becomes stable and the conversion of the polymer can be increased. However, the formation of the dimer becomes so large that the transparency of the polymer after the removal of volatile components becomes high. Properties and mechanical strength are reduced. The polymerization temperature is more preferably set to 140 ° C. or lower.

Further, the polymerization temperature in the present invention is the highest in the relationship between temperature and polymer conversion rate under the condition that the average residence time of the reaction solution in the reactor and the supply concentration of the polymerization initiator are constant. The peak temperature at which the rate increases is 110
It is important to set the polymerization temperature at a constant temperature in the range of ± 10 ° C. with the peak temperature as the center.

Under the condition that the average residence time and the concentration of the polymerization initiator supplied are constant, in the range of ± 10 ° C. around the peak temperature at which the polymer conversion becomes highest in the relationship between temperature and polymer conversion. The polymer conversion hardly changes even if the polymerization temperature fluctuates due to some factors. Therefore, the operational stability is remarkably improved. More preferably, the polymerization temperature is set within a range of ± 5 ° C. around the temperature at which the conversion of the polymer becomes highest. If the polymerization temperature exceeds the range of ± 10 ° C. around the peak temperature, it is necessary to control the polymerization conditions strictly because the fluctuation of the polymer conversion with respect to the fluctuation of the temperature is large.

Further, in the method of the present invention, it is preferable to carry out the polymerization at a temperature lower than the peak temperature at which the conversion of the polymer becomes highest. As mentioned earlier, the phenomenon that there is a peak temperature at which the polymer conversion rate is the highest occurs because the polymerization behavior changes from a completely mixed model to a plug flow model, and the generation of oligomers and other low-molecular-weight substances occurs. Is likely to occur. Therefore, as the temperature becomes higher than this peak temperature, the formation of a low molecular weight substance is promoted. As a result, a reduction in the heat distortion temperature of the polymer after the removal of volatile components and a reduction in the thermal decomposition resistance are brought about. Therefore,
The polymerization is preferably carried out at a temperature lower than the peak temperature.

The amount of the polymerization initiator used depends on the polymerization temperature, the average residence time of the reaction solution in the reactor, and the target conversion of the polymer. In order to obtain an excellent polymer, the upper limit of the amount used is 1.0 × 10 ⁻⁴ mol per mol of the monomer, and the lower limit is 5.0 × 10 ^{−6 in} consideration of industrial productivity.
It is preferable to supply in a molar range.

The average residence time of the reaction solution in the complete mixing type reactor is preferably 1 to 6 hours. When the content is within this range, the polymerization control can be stabilized, and a polymer having excellent moldability can be produced. If the residence time is too short, it is necessary to increase the amount of the polymerization initiator, and it becomes difficult to control the polymerization reaction due to the increase in the polymerization initiator, and the amount of terminal double bonds in the polymer increases, so that the heat decomposition resistance is increased. A polymer excellent in the above is not obtained. More preferably, it is 2 hours or more. On the other hand, if the average residence time is too long, the productivity decreases and the production of dimers increases, which is not preferable. More preferably, it is 5 hours or less. The average residence time of the reaction solution must be kept constant during the polymerization reaction. If the average residence time fluctuates, the peak temperature at which the polymer conversion becomes highest in the relationship between the temperature and the polymer conversion also fluctuates, so that the method of the present invention cannot be carried out.

When performing solution polymerization in the present invention, toluene, xylene, acetone, methyl ethyl ketone, methanol, ethanol, ethyl benzene, methyl isobutyl ketone, n-butyl acetate and the like can be used as a solvent. Among them, methyl ethyl ketone, methanol, ethanol, n-butyl acetate and the like are preferable. The content of the solvent with respect to the raw material containing the solvent is preferably 20% by weight or less, more preferably 10% by weight or less.

Since heat is generated in the reactor due to the polymerization reaction and stirring and mixing, the heat is removed, and in some cases, the temperature is controlled by heating to a predetermined polymerization temperature. Temperature control can be performed by a known method. For example, a method such as heat transfer heat removal or heat transfer heating by circulating a heat medium to a draft tube or a coil installed in a jacket, a reactor, or the like, cooling and supply of raw materials, and reflux cooling of monomer vapor can be employed.

The content of the polymer in the reaction solution in the reactor of the present invention is preferably in the range of 30 to 70% by weight. If the content of the polymer is too high, the viscosity is so high that the polymerization speed is greatly accelerated by the gel effect, so that stable operation is difficult.

On the other hand, if the content of the polymer is too low, the cost increases due to the separation of volatiles mainly composed of unreacted monomers, which is industrially disadvantageous. Furthermore, the conditions for more stable and economically advantageous production are preferably such that the polymerization temperature is 1
It is in the range of 40 to 55% by weight in the range of 20 to 140 ° C.

As the complete mixing type reactor used in the present invention, a tank type reactor equipped with a raw material supply port, a reaction mixture take-out port and a stirrer can be used, and the stirrer extends throughout the reactor. It is necessary to have mixing performance. As a preferable stirring device, a double helical ribbon blade or a max blend blade (Sumitomo Heavy Industries, Ltd.)
Manufactured).

In the present invention, after such a polymerization step,
Usually, it has a volatiles separation step mainly composed of unreacted monomers or unreacted monomers containing a solvent, the reaction mixture having a predetermined polymer conversion that is continuously sent, under reduced pressure By heating to 170 to 290 ° C, most of the volatiles are continuously separated and removed, and the residual monomer content in the obtained polymer is preferably 1.0% by weight or less, more preferably 0.3% by weight. % Or less.

In the volatile separation step, dimers are also removed. The dimer is preferably small because it causes coloring during the heat molding of the polymer and lowers the heat distortion temperature. The residual dimer content in the obtained polymer is preferably adjusted to 0.1% by weight or less, more preferably 0.05% by weight or less.

When the methacrylic polymer thus produced is used as a molding material, a lubricant such as a higher alcohol or a higher fatty acid ester can be added. If necessary, an ultraviolet absorber, a heat stabilizer, a coloring agent, an antistatic agent and the like can be added.

[0043]

The present invention will be described in more detail with reference to the following examples, which do not limit the present invention.

The thermal decomposition resistance of the polymers of Examples and Comparative Examples was evaluated by using a differential thermoelectric balance (SSC500) manufactured by Seiko Denshi Kogyo Co., Ltd. The bending temperature (° C.) when the temperature was raised to 400 ° C. at a temperature rising rate of ° C./min was measured, and this was used as an index of whether or not thermal decomposition was easy.

Examples 1-4 and Comparative Example 1 1.71 × 10 ^-3 mol (0.25%) of n-octyl mercaptan per mol of a monomer mixture consisting of 98% by weight of methyl methacrylate and 2% by weight of methyl acrylate. % By weight) and 1.95 × 10 ^-5 mol (45 pp) of dimethyl-2,2′-azobisisobutyrate as a polymerization initiator.
2) dissolved raw material 2 ppm
It was continuously fed to the complete mixing reactor as follows. The raw materials supplied into the reactor were stirred and mixed at 65 rpm by a double helical ribbon blade. Assuming that the average residence time of the reaction solution in the polymerization vessel is 4 hours, only the polymerization temperature is 125
The polymerization was carried out at constant temperatures of 130 ° C., 130 ° C., 135 ° C., 140 ° C. (Examples 1 to 4) and 145 ° C. (Comparative Example 1) (all other conditions remained the same).

The reaction mixture was continuously taken out of the reactor, fed with a pump, and continuously supplied to a vent extruder extruder to separate and remove volatiles to obtain a polymer.

From the reaction mixture immediately after being taken out of the reactor, the polymer conversion of the monomer in the reactor, the residual monomer content, the residual dimer content and the thermal decomposition temperature of the obtained polymer were measured. The results of Table 1 and FIG. 1 were obtained. From FIG. 1, it was confirmed that the temperature at which the conversion of the polymer became highest was around 133 ° C. In addition, although the operation was continuously performed for 100 hours at each temperature (500 hours in total), the operation was extremely stable in Examples 1 to 4 because the change in the polymer conversion with respect to the change in the polymerization temperature was small. When the inside of the reactor was observed after the completion of the operation, adhesion of the polymer to the apparatus and generation of foreign matters were not recognized. However, the residual dimer content increased as the polymerization temperature increased. Further, the higher the polymerization temperature, the lower the thermal decomposition temperature of the polymer, and 125 ° C. and 130 ° C.
The polymer produced at the polymerization temperature was high in thermal decomposition temperature and excellent in thermal decomposition resistance.

Comparative Examples 2 to 6 The polymerization initiator was replaced with tert-butylperoxy-3,5,5-trimethylhexanoate, and 2.2 × 10 6 mol per 1 mol of the monomer mixture.
Except that ^-5 mol (50 ppm) was added.
25 ° C, 130 ° C, 135 ° C, 140 ° C and 145 ° C
Was carried out at a constant polymerization temperature, and the conversion of the polymer was measured. The results shown in Table 1 and FIG. 2 were obtained. As is evident from FIG. 2, the polymer conversion rate increases as the polymerization temperature increases, which is consistent with the common sense of reaction kinetics. It was large compared to Examples 1-4. Therefore, the operation was continuously performed at each temperature for 100 hours (total of 500 hours).
Time), the operation was unstable compared to Examples 1-4.

[0049]

[Table 1]

[0050]

According to the production method of the present invention, the polymerization reaction is controlled by continuously polymerizing methyl methacrylate or a monomer mixture containing methyl methacrylate as a main component under specific conditions using a complete mixing reactor. Can be simplified, and a methacrylic polymer useful as an optical material having an extremely small copolymer composition ratio can be produced.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the polymerization temperature and the conversion of a polymer when the method of the present invention is carried out.

FIG. 2 is a diagram showing a relationship between a polymerization temperature and a polymer conversion rate in a method of a comparative example.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hajime Okutsu 20-1 Miyukicho, Otake City, Hiroshima Pref. Mitsubishi Rayon Co., Ltd. Central Research Laboratory (72) Inventor Shigeaki Sasaki 3 Kaigandori, Toyama City, Toyama Prefecture Mitsubishi Rayon F-term in Toyama Works Co., Ltd. (reference) 4J011 AA01 AA02 AA09 AB01 AB02 AB15 BA01 BB04 BB09 BB10 FA02 FA04 FA05 FB05 FB11 HA03 HA04 HB02 HB07

Claims (2)

[Claims] 1. A method of performing bulk polymerization or solution polymerization by continuously supplying a raw material containing methyl methacrylate or a monomer mixture containing methyl methacrylate as a main component and a polymerization initiator or a raw material further containing a solvent to a complete mixing reactor. In, the average residence time of the reaction solution in the reactor is constant, and the peak temperature at which the polymer conversion rate is highest in relation to the polymerization temperature and the polymer conversion rate is 110 to 110.
The polymerization initiator and the mixing time of the reactor are selected to be between 160 ° C. and ± 10% around the peak temperature.
A method for producing a methacrylic polymer, comprising polymerizing at a constant temperature in the range of ° C. 2. The method for producing a methacrylic polymer according to claim 1, wherein the polymerization is performed at a temperature lower than the peak temperature.