JPH0627135B2 - Method for producing methacrylic polymer having functional group at one end - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Purpose of the invention [Industrial field of application] The present invention aims to improve the performance and functionality of products in the field of manufacturing molding materials, paints, adhesives and other polymeric materials. A methacrylic polymer having a functional group at one end, which is an important means and is particularly important as a synthetic intermediate for a graft polymer,
The present invention relates to a method for producing a so-called prepolymer or macromonomer.

[Conventional technology and its problems]

Attempts have been made for a long time to use block polymers and graft polymers to enhance the functionality of polymeric materials, but block polymers by ionic polymerization have many restrictions in production, so the development of functional polymers requires graft polymers. Was desired.

The macromonomer means an oligomer or polymer having a polymerizable functional group at the terminal and is an abbreviation of Macromolecure Monomer. Since about 20 years ago, research on oligomers having a double bond at one end has been made.
It became a topic after a study by Milkovich et al. Their method is to allow allyl chloride, epichlorohydrin, methacrylic acid chloride, etc. to act on living polymer anions such as styrene, α-methylstyrene, butadiene, isoprene, and the like to obtain various terminal polymerizable groups such as allyl group, methacryloyl group, We synthesize macromonomers such as styryl and glycidyl groups. Corn Product has filed numerous patents under the Macromer trademark for this type of oligomer. (Japanese Patent Publication No. 50-116586, etc.) Industrially important macromonomers were ICI in the UK
This is after the research as a dispersant for the production of high solid paint by the company. Typically, a radical polymerizable monomer such as methyl methacrylate is polymerized in the presence of mercaptoacetic acid as a chain transfer agent to obtain an oligomer of a terminal carboxylic acid, which is converted into a macromonomer with glycidyl methacrylate (hereinafter abbreviated as GMA). Yes (Japanese Patent Publication No. 43-1122)
No. 4, Japanese Patent Publication No. 43-16147, etc.). This ICI
As a method similar to the above method, there is a du Pont method in which a hydroxyl group-terminated oligomer with mercaptoethanol is converted into an isocyanate with toluylene diisocyanate and then converted into a macromonomer with hydroxyethyl methacrylate.

In Japan, the energetic research of Yamashita et al.
General interest has also grown significantly over the last few years. They synthesized various comb-shaped graft polymers using several kinds of macromonomers synthesized by the above-mentioned Milkovich ionic polymerization method and ICI radical polymerization method, and applied them to surface modification of polymer materials. Their research shows the usefulness of a graft polymer using a macromonomer, that is, the structure of the polymer is clearly controlled and the content of the homopolymer can be easily produced. It has been clarified that the excellent effect of quality is exhibited (Japanese Patent Laid-Open No. 57-179).
246, Macromolecule 13, 216 (198
0) Other).

As mentioned above, the importance of macromonomers is clear, and in the last few years, their importance in the polymer manufacturing industry has been deeply recognized, and the development of practical applications has also been promoted. It is progressing.

Since methacrylic resins have a wide range of uses as general-purpose plastics, there are many examples of synthesizing and applying methacrylic macromonomers found in the literature and patents in the synthesis of macromonomers.

However, the methacrylic polymer having a desired functional group at one end can only be obtained in an amount of 40 to 70% of the produced polymer by a method in which the monomer and the chain transfer agent are simultaneously initially charged or continuously fed at the same speed.
When a polymerization initiator having a functional group is used in combination as in the method described in Japanese Patent Publication No. 43-11224, the production of a polymer having no functional group is reduced, but a polymer having a functional group at both ends is produced. When used as a synthetic intermediate for a graft polymer, it causes a side reaction and is not practical.

(B) Configuration of the Invention [Means for Solving Problems] The present inventors have completed the present invention as a result of repeated studies on the above problems.

That is, the present invention uses a methacrylic monomer in an amount of 50
% Or more continuously, the supply of the functional group-containing mercaptan-based chain transfer agent is completed at a polymerization conversion rate of 80% or less of the methacrylic monomer, and radical polymerization of the methacrylic monomer is carried out. It is a method for producing the methacrylic polymer.

[Reaction material]

The methacrylic monomer used in the present invention is mainly composed of methacrylic acid ester, and examples of the methacrylic acid ester include methyl methacrylate, butyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, stearyl methacrylate, lauryl methacrylate, benzyl methacrylate, NN-dimethyl. Examples include aminoethyl methacrylate and hydroxyethyl methacrylate. These may be used alone or in combination of two or more, and the methacrylic monomer may be a commonly available one used for polymerization or other purposes, and there is no particular limitation on purity or the like. Also, a small amount of a monomer other than the methacrylic monomer may be added for the purpose of copolymerization. Acrylic acid ester, acrylonitrile, styrene-based monomer and the like can be used as the copolymerization monomer. It is necessary to continuously supply 50% or more of the methacrylic monomer from the viewpoint of the balance between the heat of polymerization generated and the heat removal capacity of the reactor.

Next, the functional group-containing mercaptan chain transfer agent will be described. One of the examples is a chain transfer agent having an arboxyl group as a functional group at the terminal, and specifically, mercaptoacetic acid, 2-mercaptopropionic acid, 3 -A mercaptan compound having a carboxyl group such as mercaptopropionic acid is used. Regarding the carboxyl group-containing mercaptan compound, 2-mercaptopropionic acid or 3-mercaptopropionic acid is preferably used because of the problem of coloring the macromonomer and the availability.

Another example of the chain transfer agent suitable for use is a chain transfer agent having a hydroxyl group at the terminal, and there is a hydroxyl group-containing mercaptan compound, and among them, 2-mercaptoethanol is preferable because of its easy availability. Used for.

The functional group-containing mercaptan chain transfer agent, various mercaptan compounds can be used according to the type of the terminal functional group of the target methacrylic polymer, for example, if the group to be introduced at the polymer terminal is a carboxyl group As mercaptopropionic acid, thiomalic acid as a chain transfer agent for dicarboxyl groups, 2-mercaptoethanol as a chain transfer agent for hydroxyl groups, thioglycerin as a chain transfer agent for dihydroxyl groups, and 2-aminoethane as a chain transfer agent for amino groups. Thiol may be used, and in other cases, a desired methacrylic polymer can be obtained by selecting a mercaptan compound having a desired functional group.

When the number average molecular weight of the resulting methacrylic polymer having a functional group at one end is about 10,000 or less, it is preferable to charge the functional group-containing mercaptan chain transfer agent in the initial amount.

As a polymerization solvent for producing the methacrylic polymer, a general organic solvent capable of dissolving the methacrylic polymer may be used. From the viewpoint of the problem of coloration of the solution after production of the methacrylic polymer, availability, economic efficiency, and ease of handling, etc., usually toluene, xylene, benzene, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate,
N, N-dimethylformamide and the like are preferably used, and toluene and butyl acetate are particularly preferable.

As the polymerization initiator during the production of the methacrylic polymer, a usual azo initiator or peroxide initiator can be used, but an azo initiator is preferred in order to avoid reaction with the mercaptan compound of the chain transfer agent. 2,2'- as the azo initiator
Azobisisobutyronitrile (hereinafter abbreviated as AIBN) 4,4′-azobis-4-cyanovaleric acid (hereinafter abbreviated as ACVA), 1,1′-azobis-1
-Cyclohexanecarbonitrile (hereinafter abbreviated as ACHN) and the like are preferably used.

The polymerization initiator is preferably continuously supplied in order to smoothly carry out the polymerization reaction.

[Production of methacrylic polymer having a functional group at one end]

Synthesis of a methacrylic polymer having a functional group at one end, that is, radical polymerization of a methacrylic monomer, is a solution polymerization in the presence of a suitable solvent or a bulk polymerization without a solvent,
Although it is carried out by dispersion polymerization or the like, it is preferable to use solution polymerization because of the ease of controlling the polymerization reaction. Regarding the method of charging the methacrylic monomer, 50% or more of the used amount is continuously supplied according to the target molecular weight so that the chain transfer agent is uniformly taken in.

The molecular weight of the methacrylic polymer having a functional group at one end is not particularly limited, but the number average molecular weight is 1000 to 3000.
0 is preferred. When the number average molecular weight is less than 1000, the amount of the mercaptan compound as the chain transfer agent used is large, so that the amount of unreacted mercaptan compound increases, which is not preferable because it causes a side reaction when the produced polymer is used as a synthetic intermediate for a graft polymer. The number average molecular weight is 30,000.
If it exceeds, the amount of the polymer that does not incorporate the mercaptan compound of the chain transfer agent increases, and the ratio of the methacrylic polymer having a functional group at one end decreases, which is not preferable.

The number average molecular weight referred to in the present invention is a value measured by gel permeation chromatography (hereinafter referred to as GPC) under the following conditions.

Column: Polystyrene gel (for example, Toyo Soda Kogyo Co., Ltd. trade name G4000H8, G3000H8) Elution solvent: Tetrahydrofuran Outflow rate: 1.0 m / min Column temperature: 40 ° C Detector: RI detector The method of charging the chain transfer agent is From the viewpoint of the purity of the obtained methacrylic polymer, it is necessary to finish the polymerization conversion of the methacrylic monomer at 80% or less, and the polymerization conversion is 60%.
% Or less is preferable to finish.

The polymerization conversion rate of the methacrylic monomer in the present invention is calculated by the following formula.

However, the amount of residual monomer is confirmed by performing analysis under the following conditions by gas chromatography.

Apparatus: Shimadzu Corporation GC-7A Column: Silicone GE SE-30 10% Chromosorb W (AW-DMCS) 60-80mesh 2m The method of charging the polymerization initiator is not particularly limited, but a carboxyl group is used as a polymerization initiator. Things that don't have eg AIB
When N, ACHN or the like is used, it is preferable to keep the total amount of the polymerization initiator charged to a lower level than the total amount of the chain transfer agent charged. The reason for this is that when a large amount of the polymerization initiator is present with respect to the chain transfer agent, the probability of initiating the polymerization directly from the polymerization initiator becomes high, and as a result, the polymerization initiator has a segment of the polymerization initiator instead of the intended functional group. This is because the number of polymer molecules increases and the purity of the methacrylic polymer having a functional group at one end decreases.

In this case, the amount of the polymerization initiator that is acceptable is the type,
Since it is influenced by the type of chain transfer agent, the concentration of the monomer, the polymerization initiator / chain transfer agent, the reaction temperature, the charging method, etc., it cannot be generally stated, but as a guide, it is less than the charged amount of the chain transfer agent. In the case of a polymerization initiator having a carboxyl group in the molecule, such as ACVA, there is no such restriction on the amount of the polymerization initiator, but on the other hand, the solubility in ordinary organic solvents is poor, so that there is a limitation in use.

[Use of methacrylic polymer having a functional group at one end] A methacrylic polymer having a functional group at one end is used by itself as an adhesive or a paint, but is mainly used as a synthetic intermediate for a graft polymer. It

The macromonomer used when synthesizing a graft polymer by radical polymerization is a radical-polymerizable dual group and another functional group that can react with a functional group derived from a chain transfer agent in a methacrylic polymer having a functional group at one end. It can be easily obtained by reacting a polymerizable compound having both bonds with a conventional method.

As the compound having a polymerizable functional group used in the production of the macromonomer, when the terminal of the methacrylic polymer is a carboxyl group, a compound having an epoxy group which easily reacts with a carboxyl group and a polymerizable functional group is used. . For example, GMA, glycidyl acrylate, allyl glycidyl ether, chloromethyl vinylbenzene and the like are preferably used.

Further, when the terminal functional group of the methacrylic polymer is a hydroxyl group, a compound having both an isocyanate group and a polymerizable functional group, which have good reactivity with the hydroxyl group, is used. For example, isocyanate ethyl methacrylate is preferably used.

As the reaction catalyst used during the production of macromonomers,
Tertiary amines and quaternary ammonium salts can be used. In order to prevent coloring of the macromonomer, it is preferable to use a quaternary ammonium salt such as tetrabutylammonium bromide (hereinafter abbreviated as TBAB).

Any reaction solvent may be used as long as it can dissolve the macromonomer, and the solvent used in the production of the methacrylic polymer can be used.

In addition to these, in order to prevent polymerization during the production of the macromonomer, it is preferable to add a radical polymerization inhibitor such as hydroquinone or hydroquinone monomethyl ether (hereinafter abbreviated as MQ) at the macromonomerization reaction stage.

The molecular weight of the macromonomer is the molecular weight of the methacrylic polymer plus the molecular weight of the polymerizable compound that reacts with the methacrylic polymer, and the range is almost the same as that of the methacrylic polymer. The molecular weight ratio Mw / Mn of the macromonomer is almost the same as that of the methacrylic polymer.

As mentioned above, there are two types of reaction: a) a methacrylic polymer having a carboxyl group at the terminal + an epoxy group-containing compound b) a methacrylic polymer having a hydroxyl group at the terminal + an isocyanate group-containing compound In practice, a) is particularly preferable. This is because the isocyanate compound used in the reaction b) is sensitive to water and easily produces a bifunctional compound.

In the case of a), the reaction is carried out in the reaction solution after the production of the methacrylic polymer as it is, after substitution with an appropriate solvent, or after taking out as a solid methacrylic polymer. When directly reacting with the reaction liquid after the production of the methacrylic polymer, a radical polymerization inhibitor such as MQ, an epoxy compound such as GMA, a catalyst such as TBAB may be charged and allowed to react.

In this case, the amount of MQ charged is 10 to the total amount of the reaction solution.
1000 PPM is preferred. The amount of GMA charged is preferably 0.9 to 3.0 times equivalent to the carboxyl groups in the reaction solution. The amount of TBAB is 0.1 to 5.0% by weight with respect to the total amount of the reaction solution.
Is preferred.

Further, during the reaction, it is preferable to bubble the reaction system with an oxygen-containing gas in order to prevent polymerization of the generated macromonomer, and the reaction temperature is usually preferably in the range of 50 ° C to 200 ° C, and more preferably 70 ° C to 150 ° C. Is more preferable.

As an example of the reaction method in the case of b), in the reaction solution of the methacrylic polymer production, 0.9 to 3.0 times equivalent amount of isocyanate ethyl methacrylate to the hydroxyl group in the reaction solution, 0.01 to the total amount of the reaction solution A target macromonomer can be obtained by charging 3.0 wt% of dibutyltin dilaurate and reacting the mixture at room temperature to 50 ° C. for several minutes to several hours.

The macromonomer produced as described above can be used in the next reaction as it is, or after being purified by precipitation in a poor solvent or by removing volatile components as it is and then dried and taken out as a solid product. Is also good.

The graft polymer can be easily obtained by radically copolymerizing the macromonomer obtained as described above and various radically polymerizable monomers by a conventional method.

The macromonomer used when synthesizing a graft polymer by polycondensation or polyaddition reaction is a functional group derived from a chain transfer agent in the polymer which is a different type of functional group and a group capable of polycondensation or polyaddition reaction. It can be easily obtained by reacting with a compound having both of the above by a conventional method, but can be directly obtained by using a chain transfer agent having a functional group capable of polycondensation or polyaddition reaction.

For example, a methacrylic polymer having a dihydroxyl group at one end synthesized by using a chain transfer agent having a dihydroxyl group can be produced by reacting with a diisocyanate compound or a dicarboxyl compound to produce a polyurethane graft polymer or a polyester graft polymer. You can Further, a polymer synthesized by using a chain transfer agent having a dicarboxyl group can produce a polyurethane graft polymer and a polyester graft polymer by reacting a diisocyanate compound such as tolylene diisocyanate and a diol compound such as butanediol. it can.

〔Example〕

Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the examples,% means% by weight, and part means part by weight.

Example 1 1) Production of Methyl Methacrylate Polymer Having Carboxyl Group at One Terminal A glass flask equipped with a stirrer, a reflux condenser, two dropping funnels, a thermometer, and a gas blowing port was charged with methyl methacrylate monomer (hereinafter referred to as MMA). Abbreviated) 30
, 3-mercaptopropionic acid 1.8 parts Toluene 30 parts were charged, and one dropping funnel (referred to as dropping funnel A)
70 parts of MMA, the other dropping funnel (dripping funnel B
0.15 parts AIBN and 30 parts toluene. After introducing the nitrogen gas, the flask was heated and heated, and the dropping funnel A was dropped for 2 hours and the dropping funnel B was dropped for 3 hours while keeping the reaction liquid at 90 ° C.

Furthermore, 0.8 parts of AIBN and 40 parts of toluene are prepared in the dropping funnel A, and 2 hours after 3 to 5 hours are counted from the start of the first dropping.
It dripped over time. In order to decompose AIBN existing in the reaction system, heating was further performed for 2 hours to obtain an MMA polymer having a carboxyl group at one end. The polymerization conversion rate of MMA determined by gas chromatography was 99.2%. The polystyrene-converted molecular weight by GPC is = 62.
00, = 12500 and /=2.02.

2) Production of macromonomer having methacryloyloxy group at one end 1) After the reaction in the solution, MQ0.04 part, GMA2.66 part, TBAB
1.0 part was charged and the reaction was carried out at 90 ° C. for 5 hours while bubbling nitrogen gas containing 5% oxygen. The reaction conversion calculated from the acid value by titration was 99%. Reaction liquid at 80 ℃
Under reduced pressure to dry solid MMA macromonomer 100
I got a part. The polystyrene reduced molecular weight by GPC is
= 6000, = 12500 and /=2.07
Met.

3) Confirmation of polymerizability 4 parts of MMA macromonomer produced, 6 of MMA monomer
Parts, toluene 5 parts, AIBN 0.01 parts, and t-lauryl mercaptan 0.03 parts were charged into a polymerization tube, and after substitution with nitrogen, reaction was carried out at 80 ° C. for 3 hours. From the gas chromatography of this solution and the GPC chart, the polymerization conversion rate of the MMA macromonomer / the polymerization conversion rate of the MMA monomer = 80%, and the polymerizability of the macromonomer was confirmed.

Comparative Example 1 1) Production of MMA polymer having carboxyl group at one end.

MMA20 in a glass flask equipped with stirrer, reflux condenser, dropping funnel, thermometer and gas inlet.
Parts, 3-mercaptopropionic acid 1.06 parts, toluene 10
0 part was charged, and 80 parts of MMA, 1.06 part of 3-mercaptopropionic acid and 0.5 part of AIBN were put into the dropping funnel. After introducing nitrogen gas, the temperature of the flask is raised by heating and the reaction liquid is heated to 80 ° C.
The dropping solution was added dropwise over 4 hours in a state of being kept at. AIBN existing in the reaction system after being kept at 80 ° C. for 2 hours
In order to decompose the polymer, the temperature was raised to 90 ° C. and the mixture was heated for 1 hour to obtain an MMA polymer having a carboxyl group at one end. At the end of the supply of 3-mercaptopropionic acid, MM
The polymerization conversion rate of A was 83%. The MMA polymerization conversion determined by gas chromatography was 90.5%.

The polystyrene-converted molecular weight by GPC is = 5
It was 800, = 12200, and /=2.10.

2) Production of macromonomer having metacloyloxy group at one end 1) After the reaction, the solution contained 0.04 parts of MQ, 3.15 parts of GMA, TBAB
1.0 part was charged and the reaction was carried out at 90 ° C. for 5 hours while bubbling nitrogen gas containing 5% oxygen. The reaction conversion calculated from the acid value by titration was 98%. Reaction liquid at 80 ℃
It was dried under reduced pressure to obtain 90 parts of a solid MMA macromonomer. The polystyrene reduced molecular weight by GPC is = 57.
00, = 12200 and /=2.14.

3) Confirmation of Polymerization In the same manner as in Example 1, the reaction was carried out at 80 ° C. for 3 hours. The product was gelled and not soluble in THF.

In addition, 3 parts of MMA macromonomer, 7 parts of MMA monomer, 5 parts of toluene, 0.01 part of AIBN, and 0.035 part of t-lauryl mercaptan produced were charged into a polymerization tube, and after replacement with nitrogen, 8
When the reaction was carried out at 0 ° C., the conversion of MMA macromonomer / the conversion of MMA monomer = 53% from the gas chromatography and GPC chart of the solution. From these results, the method of finishing the supply of the chain transfer agent in Example 1 earlier than the monomer has good polymerizability and a small amount of impurities (unreacted mercaptan etc.) involved in gelation, and is excellent in the synthesis of macromonomer. It turns out that it is a different method.

Example 2 1) Production of butyl methacrylate having a carboxyl group at one end A butyl methacrylate monomer (hereinafter abbreviated as BMA) was placed in a glass flask equipped with the same device as in Example 1.
30 parts, 0.9 parts of 3-mercaptopropionic acid, and 30 parts of butyl acetate were charged, and 70 parts of BMA was added to the dropping funnel A, 0.15 parts of AIBN and 15 parts of butyl acetate were added to the dropping funnel B. After introducing the nitrogen gas, the temperature of the flask is raised to 9 by heating the reaction solution.
The dropping funnel A was dropped for 2 hours and the dropping funnel B was dropped for 3 hours while the temperature was kept at 0 ° C. Furthermore, 0.35 parts of AIBN and 55 parts of butyl acetate were prepared in the dropping funnel A and added dropwise over 2 hours from 3 to 5 hours counting from the start of the first dropping.
In order to decompose AIBN existing in the reaction system, it was further heated for 2 hours to obtain a BMA polymer having a carboxyl group at one end. The polymerization conversion ratio of BMA determined by gas chromatography was 98.9%. The polystyrene-equivalent molecular weight measured by GPC is = 10200, = 23000.
/ Was 2.25.

2) Production of macromonomer having methacryloyloxy group at one end 1) After the reaction in the solution, MQ0.04 part, GMA1.33 part, TBAB
1.0 part was charged and reacted in the same manner as in Example 1 2).

The reaction conversion calculated from the acid value by titration was 99%. The reaction solution was dried under reduced pressure at 80 ° C. to obtain 100 parts of solid BMA macromonomer. The polystyrene reduced molecular weight by GPC was = 10000, = 23000 and /=2.30.

3) Confirmation of Polymerization The same procedure as 3) of Example 1 was performed. Polymerization conversion rate of BMA macromonomer / polymerization conversion rate of MMA monomer = 78
%, Confirming the polymerizability of the macromonomer.

Comparative Example 2 1) Production of BMA polymer having a carboxyl group at one end BMA 100 parts and butyl acetate 9 parts in a glass flask equipped with a stirrer, a reflux condenser, a thermometer and a gas inlet.
0 part and 0.9 part of 3-mercaptopropionic acid were charged, and after introducing nitrogen gas, the flask was heated and heated. Reaction liquid is 90 ℃
Then, a solution prepared by dissolving 0.5 part of AIBN in 10 parts of butyl acetate was added, and the reaction solution was kept as it was at 90 ° C. for 7 hours to obtain a BMA polymer having a carboxyl group at one end. The BMA polymerization conversion determined by gas chromatography was 90.2%. Moreover, the polystyrene-reduced molecular weight by GPC is = 11500, = 22800
And / = 1.98.

2) Production of Macromonomer Having Methacryloyloxy Group at One Terminal The reaction was carried out in the same manner as in Example 2. The reaction conversion rate was 99%. The reaction liquid was dried under reduced pressure at 80 ° C. to obtain 90 parts of a solid BMA macromonomer. The polystyrene reduced molecular weight by GPC was = 11300, = 22700 and /=2.01.

3) Confirmation of Polymerization The same procedure as in 3) of Example 2 was performed. Polymerization conversion rate of BMA macromonomer / polymerization conversion rate of MMA monomer = 49%
Met.

From the above results, it can be seen that the method of finishing the supply of the chain transfer agent in Example 2 earlier than the monomer is an excellent method for synthesizing the macromonomer having good polymerizability.

Example 3 Production of BMA Polymer Having Dihydroxy Group at One End BMA30 in a glass flask equipped with a stirrer, a reflux condenser, two dropping funnels, a thermometer and a gas blowing port.
Part, thioglycerol 0.9 part, and toluene 30 parts were charged, and one of the dropping funnels (referred to as dropping funnel A) was given BM.
To 70 parts of A, the other dropping funnel (referred to as dropping funnel B) was added 0.15 parts of AIBN and 15 parts of toluene. After introducing the nitrogen gas, the temperature of the flask was increased by heating, the reaction solution was kept at 90 ° C., the dropping funnel A was added for 2 hours, and the dropping funnel B was changed to 3 times.
It dripped over time.

Furthermore, AIBN 0.35 parts and toluene 55 parts are added to the dropping funnel A.
And was added dropwise over a period of 2 hours from 3 to 5 hours from the start of the first dropping.

In order to decompose AIBN existing in the reaction system, it was further heated for 2 hours to obtain a BMA polymer having a dihydroxy group at one end. The polymerization conversion ratio of BMA determined by gas chromatography was 98.9%. Moreover, the polystyrene reduced molecular weight by GPC is Mn = 10200, Mw = 230.
00 and Mw / Mn = 2.25.

Example 4 Production of MMA / Hydroxyethyl Methacrylate Copolymer Having Dicarboxyl Group at One End MMA25 in a glass flask equipped with a stirrer, a reflux condenser, two dropping funnels, a thermometer and a gas blowing port.
Parts, hydroxyethyl methacrylate (hereinafter abbreviated as HEMA) 5 parts, thiomalic acid 2.5 parts, toluene 20
Part, 10 parts of ethanol were charged, and one part of the dropping funnel (referred to as dropping funnel A) had 60 parts of MMA and 10 parts of HEMA.
Part, the other dropping funnel (referred to as dropping funnel B) was charged with 0.15 parts of AIBN and 30 parts of toluene. After introducing the nitrogen gas, the flask was heated and heated, and the dropping funnel A was dropped for 2 hours and the dropping funnel B was dropped for 3 hours while keeping the reaction liquid at 90 ° C. Further, 0.8 part of AIBN and 40 parts of toluene were prepared in the dropping funnel A and added dropwise over 2 hours from 3 to 5 hours counting from the start of the first dropping. In order to decompose AIBN existing in the reaction system, heating was further performed for 2 hours to obtain an MMA / HEMA copolymer having a carboxyl group at one end. The polymerization conversion rates of MMA and HEMA determined by gas chromatography were 99.2% and 98.8%. Further, the polystyrene reduced molecular weight by GPC is = 620
0, = 12400 and / = 200.

Example 5 In Example 1, the initial charge was 25 parts of MMA, 23 parts of toluene, 1 part of mercaptopropionic acid, 75 parts of MMA and 0.8 part of mercaptopropionic acid were fed for 2 hours from the initial polymerization, and 5.5 hours from the initial polymerization. Until 60.5 parts of toluene and 0.33 parts of AIBN are added, and then up to 7 hours by supplying 16.5 parts of toluene and 0.6 parts of AIBN at a polymerization temperature of 80 ° C.
Polymerization was carried out for 6 hours at 90 ° C. for 3 hours to obtain an MMA polymer having a carboxyl group at one end.

The polymerization conversion rate of MMA at the end of the supply of mercaptopropionic acid was 43%.

In addition, in confirming the polymerizability after conversion to macromonomer, the polymerization conversion rate of macromonomer / the polymerization conversion rate of MMA = 83
%Met.

(C) Effect of the Invention According to the present invention, a highly pure methacrylic polymer having a functional group at one end can be obtained by a simple operation, and is industrially useful. Further, the graft polymer obtained by using the methacrylic polymer having a functional group at one end is effectively used as a molding material, paint, adhesive, etc.

Claims (1)

[Claims] 1. A methacrylic monomer is used in an amount of 50% of the amount used.
The above is continuously supplied, and the supply of the functional group-containing mercaptan-based chain transfer agent is terminated at a polymerization conversion rate of 80% or less of the methacrylic monomer, and radical polymerization of the methacrylic monomer is carried out. Method for producing methacrylic polymer.