JP2000086710A - Method for producing acrylic copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic copolymer whose primary structure is precisely controlled by radical polymerization using an iodine compound, that is, an acrylic copolymer having a narrow molecular weight distribution. A method for producing a polymer is provided. SOLUTION: (Meth) acrylonitrile or (meth) acrylic acid ester 10 to 95 parts by weight, vinyl ester monomer or styrene monomer 90 to 5 parts by weight,
And a method for producing an acrylic copolymer by radical polymerization of a composition containing an iodine compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an acrylic copolymer whose primary structure is precisely controlled, and more particularly, to an acrylic copolymer having a small width of (weight average molecular weight / number average molecular weight). And a method for producing the same.

[0002]

2. Description of the Related Art Acrylic copolymers are widely used as paints, adhesives, adhesives, sealing agents, packaging materials, various molding materials, etc. by utilizing their excellent adhesiveness, heat resistance, weather resistance, and the like. Have been. Acrylic copolymers are industrially widely obtained by radical polymerization, as typified by AS resins and ABS resins. However, in general radical polymerization, termination reactions such as recombination and disproportionation and chain reaction are caused. Since many side reactions such as migration occur, it is difficult to control the terminal groups and the molecular weight, and the resulting polymer has a wide molecular weight distribution.

Controlling the molecular weight and molecular weight distribution of the acrylic copolymer and controlling the terminal groups thereof are indispensable techniques for achieving high functionality and high performance. That is, by controlling the molecular weight and molecular weight distribution,
For example, mechanical strength, flow characteristics, heat stability, heat melting characteristics,
Compatibility with other resins, plasticization efficiency, dispersion stabilization effect, etc. can be controlled.For example, by narrowing the molecular weight distribution and reducing low molecular weight components, improved adhesion performance, improved mechanical strength, flow characteristics Improvement can be achieved.

As a method for realizing such control of a polymer, for example, a living radical polymerization method can be considered.
Unlike the anionic polymerization method, the living radical polymerization method does not require rigorous dehydration and purification of the polymerization solvent and monomer, and it is bulky, so it is inexpensive and can be desolvated. It is. This polymerization method includes a method using an iodine compound, a method using an organometallic complex, an iniferter method, and the like, depending on the method of stabilizing the polymerization growth terminal.

In these polymerization systems, various monomers such as styrene, methacrylate, and acrylate have been actively studied, and it has become widely known that the primary structure of the polymer can be controlled to some extent precisely. However, a polymerization method applicable to any monomer has not been found because reactivity varies greatly depending on the monomer.

[0006] Among these polymerization methods, a method using an iodine compound has an advantage that there is no need to remove a metal as compared with a method using an organometallic complex, and a chain transfer method is compared with the iniferter method. Since the reaction is small and the controllability of the molecular weight distribution is excellent, it can be said that this is a polymerization method which is practically feasible for enhancing the controllability of the molecular weight distribution.

As an example of polymerization in which the primary structure is controlled by narrowing the molecular weight distribution of a polymer by a method using an iodine compound, polymerization of a styrene monomer (JP-A-7-126322)
JP-A-10-210) and polymerization of vinyl acetate monomer (Japanese Unexamined Patent Publication
However, it has not yet been reported that the molecular weight distribution of acrylic polymers and copolymers has been sufficiently controlled.

[0008]

SUMMARY OF THE INVENTION In the present invention, as a result of intensive studies on acrylic monomers which have been considered to be difficult to control polymerization by radical polymerization using an iodine compound, they are polymerized with a small amount of a specific comonomer. As a result, they have found that a copolymer having a precisely controlled primary structure can be obtained, that is, a copolymer having a narrow molecular weight distribution can be obtained.

An object of the present invention is to provide an acrylic copolymer whose primary structure is precisely controlled, that is, an acrylic copolymer having a narrow molecular weight distribution, by radical polymerization using an iodine compound. An object of the present invention is to provide a method for producing a polymer.

[0010]

According to the present invention, there is provided an acrylonitrile or methacrylonitrile.
This is a method for producing an acrylic copolymer by radical polymerization of a composition containing 〜95 parts by weight, a vinyl ester monomer and / or 90-5 parts by weight of a styrene monomer, and an iodine compound.

According to the present invention, there is provided an acrylic or methacrylic ester in an amount of 10 to 95 parts by weight,
Vinyl ester monomer and / or styrene monomer 9
This is a method for producing an acrylic copolymer by radical polymerization of a composition containing 0 to 5 parts by weight and an iodine compound.

According to the present invention, the acrylic copolymer preferably has a weight-average molecular weight / number-average molecular weight of 1.05 to 1.05.
3. The method for producing an acrylic copolymer according to claim 1, wherein the ratio is 1.9. According to a fourth aspect of the present invention, the iodine compound has at least one bond of a carbon-iodine bond, a hydrogen-iodine bond, and a halogen-iodine bond.
A method for producing an acrylic copolymer according to any one of the above items.

Hereinafter, the present invention will be described in more detail. The acrylate or methacrylate used in the present invention includes (meth) acrylic acid and (meth) acrylic acid.
Methyl acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec- (meth) acrylate Butyl, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth)
N-octyl acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth)
Decyl acrylate, lauryl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, phenyl (meth) acrylate, stearyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, etc. However, the present invention is not limited to these.

The vinyl-based monomer used for controlling the primary structure of the copolymer used in the present invention includes a vinyl ester monomer and / or a styrene-based monomer. As vinyl ester monomers,
Vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl n-caproate, vinyl isocaproate,
Vinyl octoate, vinyl laurate, vinyl palmitate, vinyl stearate, vinyl trimethyl acetate, vinyl pivalate, vinyl chloroacetate, vinyl trichloroacetate, vinyl trifluoroacetate, vinyl benzoate, and the like. Among them, in particular, vinyl acetate is widely used industrially and is preferably used.

As the styrene monomer, styrene,
α-methylstyrene, p-methylstyrene, m-methylstyrene, o-methylstyrene, 2,4-dimethylstyrene, 2,
5-dimethylstyrene, p-ethylstyrene, p-isopropylstyrene, p-chloromethylstyrene, p- (2-chloroethyl) styrene and the like. Among them, styrene is widely used industrially and is preferably used. These vinyl ester monomers and styrene-based monomers may be used alone or in combination of two or more.

The amount of addition of these monomers is 5 parts by weight to 90 parts by weight based on 100 parts by weight of the total amount of acrylonitrile or methacrylonitrile or acrylate or methacrylate. When the amount is less than 5 parts by weight, the control of the primary structure of the copolymer such as the molecular weight distribution of the obtained copolymer becomes wide or the terminal living property is lost, and when the amount is more than 90 parts by weight, This is because the properties of the original poly (meth) acrylonitrile or (meth) acrylate resin are lost. For the same reason, the preferred range is from 5 parts by weight to
50 parts by weight.

The monomers used in the polymerization may be added to the polymerization solution in their entirety from the beginning or may be added sequentially as the polymerization proceeds. The iodine compound used in the present invention is selected from compounds having at least one carbon-iodine bond, hydrogen-iodine bond, or halogen-iodine bond.

Examples of the compound having a carbon-iodine bond include alkyl iodide, perfluoroalkyl iodide, an adduct of hydrogen iodide and an alkene, and phenyl iodide. As a compound having a carbon-iodine bond, more specifically, as the alkyl iodide, iodomethane, iodoethane, iodopropane, iodobutane, diiodomethane, 1,2-diiodoethane, iodoform, chloroiodomethane, iodoacetonitrile, iodoacetic acid and the like As the perfluoroalkyl iodide, iodoperfluoropropane, 1-iodoperfluorohexane, 1-iodoperfluorooctane, 1,2-diiodoperfluoroethane, 1,4-diiodoperfluorobutane, Examples of alkenes used in adducts of hydrogen iodide and alkenes include vinyl ester monomers such as vinyl acetate, various vinyl ether monomers such as isobutyl vinyl ether, and styrene monomers. , Iodide The Eniru, iodobenzene, such as 2-iodo ethyl benzene, and the like. As an example of the synthesis of an adduct of hydrogen iodide and an alkene, there is a method of mixing anhydrous hydrogen iodide with an alkene at a low temperature.

The compound having a hydrogen-iodine bond includes hydrogen iodide. Compounds having a halogen-iodine bond include iodine monochloride, iodine trichloride, iodine monobromide and the like. Preferred iodine compounds include iodoform, diiodomethane, alkyl iodides such as iodoacetonitrile, iodide such as 1-iodoperfluorohexane, 1,4-diiodoperfluorobutane, and 1,6-diiodoperfluorohexane. Perfluoroalkyl, adducts of hydrogen iodide and alkenes, hydrogen iodide and the like can be mentioned. In particular, the use of iodoform is particularly preferable because the calculated value of the number average molecular weight, which is assumed to form one polymer molecule from one molecule of iodoform added to the polymerization, and the measured value most accurately. As the iodine compound, one of the above can be used alone, or two or more can be used in combination.

The molecular weight distribution (Mw / Mn) of the copolymer obtained by the present invention can be obtained by a conventional ordinary radical polymerization without addition of an iodine compound, or by a system without addition of styrene and / or vinyl ester monomers. And it is 1.05 to 1.9. In particular,
Polymers having a molecular weight distribution of from 1.05 to 1.8 are preferred.

The amount of the iodine compound can be appropriately determined based on the molecular weight of the copolymer to be obtained. However, if the amount of the iodine compound is too small, the structure of the polymer cannot be controlled, and the amount of the iodine compound cannot be controlled. If it is too much, a copolymer cannot be obtained, so it is preferable to add the copolymer at a ratio of 0.0001 to 0.2 mol per 1 mol of the monomer. In particular, it is preferable to add at a ratio of 0.0002 to 0.1 mol per 1 mol of the monomer.

The method of addition is not particularly limited, but is preferably added to the polymerization system before the start of polymerization, from the viewpoint of controlling the molecular weight distribution and simplifying the operation. The molecular weight of the copolymer obtained by the present invention can be adjusted by the concentration of the iodine compound, the number average molecular weight is 500 ~
Hundreds of thousands of copolymers can be preferably obtained. In particular,
The preferred range of the molecular weight is a number average molecular weight of 100.
0 to 200,000. The present technology is useful in that it is easy to obtain a copolymer having a low molecular weight and a narrow molecular weight distribution, which has been difficult with a conventionally known technology.

The method of the radical polymerization reaction in the present invention includes the use of a conventional radical polymerization initiator, the use of a photopolymerization initiator and irradiation with light, irradiation with radiation, laser light, light, etc., heating, etc. Technology may be employed. In particular, it is preferable to use a radical polymerization initiator industrially,
There are no particular restrictions on the type of the radical, as long as it can generate a radical, react with a vinyl ester monomer or an iodine compound, and cause polymerization. Is selected from compounds that generate

Specifically, azo compounds, organic peroxides,
Examples include inorganic peroxides, organometallic compounds, and photopolymerization initiators. More specifically, azo compounds such as azobisisobutyronitrile (AIBN), azobisisobutyrate, and hyponitrite, and benzoyl peroxide (BP
O), organic peroxides such as lauroyl peroxide, dicumyl peroxide and dibenzoyl peroxide, inorganic peroxides such as potassium persulfate and ammonium persulfate, hydrogen peroxide-ferrous iron system, BPO-dimethylaniline system And redox initiators such as cerium (IV) salt-alcohol. Particularly, AIBN and BPO are preferably used. In the case of photopolymerization, an acetophenone-based, benzoin ether-based, ketal-based photopolymerization initiator may be added.

The radical generating method and the radical polymerization initiator may be used singly or in combination of two or more as long as the interaction does not adversely affect the progress of polymerization. Further, a combination in which the polymerization is advanced to some extent by the action of heat and then the polymerization is completed by light may be used.

The amount of the radical polymerization initiator is not particularly limited as long as it can cause polymerization, but it is preferably in the range of 0.02 to 20 mol per 1 mol of the iodine compound used. 0.00 per mole
It is preferably from 005 mol to 0.5 mol. When the amount is too small, the polymerization is slow and the polymerization rate is low, which is not industrially advantageous.

In addition, when used in excess, it is difficult to control the reaction, which is not preferable. More preferably, the amount of the radical polymerization initiator is in the range of 0.05 to 10 mol per 1 mol of the iodine compound, and is 0.0001 to 0.2 mol per 1 mol of the monomer. The radical initiator is used in an amount of 0.1 mol per mol of the iodine compound.
It is particularly preferred to use from 1 to 5 moles. The preferred range of the polymerization temperature varies depending on the type of the radical polymerization reaction, and is not particularly limited.
It is common to polymerize at a temperature of about 20 ° C. Further, a preferable temperature range is 0 ° C to 100 ° C.
The reaction pressure is usually normal pressure, but it is also possible to increase the pressure.

The polymerization method according to the present invention is not limited to any of those conventionally used, and bulk, solution, suspension, emulsion polymerization and the like are used. In particular, bulk polymerization is preferably used from the viewpoint of suppressing chain transfer and obtaining a better controlled polymer. Further, continuous polymerization using an extruder can also be used. Further, as a solvent for solution polymerization, a commonly used solvent such as alcohol, toluene, benzene, and ethyl acetate can be used.

Most of the starting terminals of the polymer obtained according to the present invention are alkyl groups, perfluoroalkyl groups, phenyl groups and the like derived from iodine compounds, and most of the growing terminals are iodine. Confirmed by measurement. Therefore, by using an iodine compound having a functional group in the main polymerization, a functional group can be introduced to the terminal of the copolymer. It is also possible to convert to another functional group by utilizing the reactivity of the terminal functional group or iodine. These terminal functional polymers can be used as macromonomer synthesis, utilization as crosslinking points, compatibilizers, raw materials for block polymers, and the like.

From the viewpoint of improving the stability of the copolymer obtained in the present invention, methanol, ammoniacal methanol, lithium borohydride, or the like is added to the polymerization system at the time of termination of polymerization so that the copolymer is present at the growing terminal of the copolymer. Iodine may be desorbed. Further, the obtained polymer may be irradiated with ultraviolet rays in the presence of isopentane or the like to stabilize iodine with hydrogen. After the acrylic copolymer is obtained by the method disclosed in the present invention, a monomer such as styrene is further added to the polymerization system and polymerized to obtain a block copolymer.

In the present invention, a multibranched copolymer is obtained by using an iodine compound containing a plurality of iodine which can participate in polymerization, or adding a small amount of various divinyl monomers in the latter stage of polymerization and crosslinking. Is also possible. or,
It is possible to control the design of the dynamic viscoelastic characteristic to be specifically high in a certain temperature range and frequency range, and to control the compatibility. By obtaining a terminal functional polymer, it becomes possible to synthesize a macromonomer utilizing the reactivity of the terminal group, use it as a crosslinking point, create a block copolymer, and the like.

By obtaining a block copolymer, it is possible to obtain a polymer exhibiting new physical properties different from homopolymerization of a monomer. For example, a triblock copolymer such as ABA can obtain a thermoplastic elastomer. Can be done. In other words, the acrylic copolymer obtained by precision polymerization can achieve high performance and high performance even if the same monomer is used as a starting material, and can achieve high performance in applications that have been used up to now. Not only can it be possible, but it can be expanded to entirely new applications due to its high functionality.

(Function) In the method for producing an acrylic copolymer according to the present invention as set forth in claim 1 or 2, the (meth) acrylonitrile or (meth) acrylic acid ester and a vinyl ester monomer and / or a styrene monomer are used. By subjecting a composition containing a specific amount and an iodine compound to radical polymerization, it is possible to obtain a polymer in which the primary structure of an acrylic ester or the like, which has been conventionally difficult, is controlled.

Although the reason for this has not yet been sufficiently elucidated, polymerization control by reversible generation of carbon-iodine bonds at the terminal of polymer growth, which was unstable only with acrylates, was used. It is considered that the property is improved by the vinyl ester monomer and / or styrene monomer added in a specific amount. In particular, by controlling the molecular weight distribution to 1.05 to 1.9 as in the present invention as claimed in claim 3, when compared with an uncontrolled acrylic copolymer conventionally produced industrially, It is clear that an acrylic copolymer having sufficiently improved performance can be obtained.

When a specific iodine compound is used, the acrylic copolymer can be obtained by an industrially simple method. Furthermore, according to the present invention, since it is possible to obtain a terminal functional copolymer, synthesis of a macromonomer utilizing the reactivity of the terminal group, use as a cross-linking point, block copolymer, and the like become possible. Compared to those obtained by the conventional method,
It is possible to produce a high-performance and high-performance polymer.

[0036]

EXAMPLES The present invention will be specifically described below based on examples and comparative examples. Unless otherwise noted, monomers, solvents, etc. were used after removing the polymerization inhibitor and impurities by distillation and purification, and then subjected to deoxygenation treatment.

Measurement method of polymerization rate The polymerization rate was measured by gas chromatography using n-heptane as an internal standard (GC: manufactured by Shimadzu Corporation, column: PEG 1500). Measurement method of molecular weight The number average molecular weight (Mn) and weight average molecular weight (Mw) were measured by gel permeation chromatography (GPC) in terms of polystyrene. (GPC: Tosoh, LS8000 system, column: Showa Denko, polystyrene gel KF-802, 803, 804, solvent: chloroform, flow rate: 1 ml / min) Ratio between weight average molecular weight (Mw) and number average molecular weight (Mn) Was defined as a molecular weight distribution (Mw / Mn).

Example 1 In a 50 ml flask purged with nitrogen, 0.115 g (0.7 mmol) of AIBN, 0.275 g (0.7 mmol) of iodoform, 2.0 g (24 mmol) of vinyl acetate, and methyl methacrylate 8
g (80 mmol) and 1.0 ml of n-heptane (for GPC internal standard) were charged, the vessel was sealed, mixed uniformly, and heated to 60 ° C. to initiate polymerization.

After polymerization for 7 hours, the temperature was lowered to 0 ° C. to terminate the polymerization. The polymerization rate was 95% as determined by gas chromatography. The polymer solution was poured into a large amount of methanol to precipitate the product. After drying, this was purified by reprecipitation with methanol, and dried under vacuum to obtain a copolymer. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) were determined by GPC, Mn = 12,500, Mw
/Mn=1.51. The results are shown in Table 1.

(Example 2) 1,6-difluorohexane 1.1 instead of iodoform as an iodine compound
Except that g was used, the polymerization method and the purification method of the copolymer followed Example 1. The polymerization rate was 97% as determined by gas chromatography. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, Mn = 11600 and Mw / M
n = 1.41. The results are shown in Table 1.

Example 3 A polymerization method and a method for purifying a copolymer were carried out except that 8.0 g of vinyl acetate and 18.0 g of methyl methacrylate were used as polymerization monomers and the polymerization temperature was 80 ° C. Example 1 was followed. The conversion was determined by gas chromatography to be 90%. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, Mn =
30300, Mw / Mn = 1.74. The results are shown in Table 1.

Example 4 A polymerization method and a method for purifying a polymer were the same as those in Example 1 except that 4.0 g of vinyl acetate and 8 g of butyl acrylate were used as polymerization monomers.
Followed. The polymerization rate was 91% as determined by gas chromatography. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, Mn was 14,800 and Mw / Mn was 1.37. The results are shown in Table 1.

Example 5 A polymerization method and a method for purifying a polymer were the same as those in Example 1 except that 2.0 g of styrene and 8 g of methyl methacrylate were used as polymerization monomers.
Followed. The conversion was 96% as determined by gas chromatography. The method for purifying the copolymer was in accordance with Example 1. The polymerization rate was 88% as determined by gas chromatography. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, it was Mn = 11600 and Mw / Mn = 1.58. The results are shown in Table 1.

Example 6 15.0 g of styrene and 20 g of methyl methacrylate were used as polymerization monomers.
Except that the polymerization temperature was set to 80 ° C., the polymerization method and the method for purifying the copolymer followed Example 1. The polymerization rate was 87% as determined by gas chromatography.
Number average molecular weight (Mn) and molecular weight distribution of the obtained copolymer
When (Mw / Mn) was measured by GPC, Mn = 410
00, Mw / Mn = 1.80. The results are shown in Table 1.

Example 7 A polymerization method and a method for purifying a copolymer were the same as those in Example 1 except that 2.0 g of styrene and 10 g of butyl acrylate were used as polymerization monomers.
Followed. The polymerization rate was 95% as determined by gas chromatography. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, Mn was 12,100 and Mw / Mn was 1.35. The results are shown in Table 1.

Comparative Example 1 Polymerization and purification of a polymer were carried out in the same manner as in Example 1 except that only 10 g of methyl methacrylate monomer was used as a polymerization monomer. The polymerization rate after 7 hours was 91%. The number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained polymer were determined by GP.
When measured by C, Mn = 52500, Mw / Mn =
2.11. The results are shown in Table 1.

Comparative Example 2 Polymerization and polymer purification were carried out in the same manner as in Example 1 except that iodoform was not used. The polymerization rate after 7 hours was 86%. Number average molecular weight (Mn), molecular weight distribution (Mw /
When Mn) was measured by GPC, Mn = 6180
0, Mw / Mn = 2.71. The results are shown in Table 1.

Comparative Example 3 Polymerization and purification of a polymer were carried out in the same manner as in Example 1 except that only 10 g of a butyl acrylate monomer was used as a polymerization monomer. The polymerization rate after 7 hours was 90%. The number average molecular weight (Mn) and the molecular weight distribution (Mw / Mn) of the obtained copolymer are represented by G
When measured by PC, Mn = 22100, Mw / Mn
= 2.15. The results are shown in Table 1.

[0049]

[Table 1]

Example 8 Polymerization was carried out under the same conditions as in Example 1, except that 8 g (150 mmol) of acrylonitrile was used instead of 8 g (80 mmol) of methyl methacrylate. The polymerization rate was 91% as determined by gas chromatography. Thereafter, the product was similarly purified to obtain a copolymer.
Number average molecular weight (Mn) and molecular weight distribution of the obtained copolymer
When (Mw / Mn) was measured by GPC, Mn = 118
00, Mw / Mn = 1.58. The results are shown in Table 2.

(Example 9) 1,6-difluorohexane 1.1 instead of iodoform as an iodine compound
Except that g was used, the polymerization method and the purification method of the copolymer followed Example 8. The polymerization rate was 95% as determined by gas chromatography. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, Mn = 12200, Mw / M
n = 1.68. The results are shown in Table 2.

Example 10 A polymerization method and a polymer purification method were the same as those in Example 8 except that 8.0 g of vinyl acetate and 21.0 g of acrylonitrile were used as polymerization monomers and the polymerization temperature was 80 ° C. Followed. The polymerization rate was 85% as determined by gas chromatography. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, Mn =
31500, Mw / Mn = 1.82. The results are shown in Table 2.

Example 11 A polymerization method and a method for purifying a polymer were the same as those in Example 8 except that 4.0 g of vinyl acetate and 8.0 g of methacrylonitrile were used as polymerization monomers. The polymerization rate was 91% as determined by gas chromatography. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, Mn = 15100 and Mw / Mn = 1.6.
It was one. The results are shown in Table 2.

Example 12 The polymerization method and the purification method of the polymer were the same as in Example 8 except that 8.0 g of styrene and 8.0 g of acrylonitrile were used as the polymerization monomers. The conversion was 96% as determined by gas chromatography. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, Mn was 10,900 and Mw / Mn was 1.65. The results are shown in Table 2.

Example 13 A polymerization method and a method for purifying a polymer were the same as in Example 8 except that 15.0 g of styrene and 20.0 g of acrylonitrile were used as polymerization monomers and the polymerization temperature was 80 ° C. Was. The polymerization rate was 87% as determined by gas chromatography. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, Mn =
39000, Mw / Mn = 1.85. The results are shown in Table 2.

Example 14 The polymerization method and the purification method of the polymer were the same as in Example 8 except that 2.0 g of styrene and 10.0 g of methacrylonitrile were used as the polymerization monomers. The polymerization rate was 95% as determined by gas chromatography. When the number average molecular weight (Mn) and the molecular weight distribution (Mw / Mn) of the obtained copolymer were measured by GPC, Mn = 12700 and Mw / Mn = 1.7.
It was one. The results are shown in Table 2.

Comparative Example 4 Example 8 was repeated except that only 10 g of acrylonitrile was used as a polymerization monomer.
, And the polymer was purified. The polymerization rate after 7 hours was 90%. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained polymer were measured by GPC, it was Mn = 33500 and Mw / Mn = 2.15. The results are shown in Table 2.

Comparative Example 5 Polymerization and purification of a polymer were carried out in the same manner as in Example 8 except that iodoform was not used. The polymerization rate after 7 hours was 91%. Number average molecular weight (Mn), molecular weight distribution (Mw /
Mn) was measured by GPC and found to be Mn = 4310
0, Mw / Mn = 2.71. The results are shown in Table 2.

Comparative Example 6 Polymerization and purification of a polymer were carried out according to Example 8 except that only 10 g of methacrylonitrile was used as a polymerization monomer. The polymerization rate after 7 hours was 93%. When the number average molecular weight (Mn) and the molecular weight distribution (Mw / Mn) of the obtained polymer were measured by GPC, it was Mn = 25000 and Mw / Mn = 2.28. The results are shown in Table 2.

[0060]

[Table 2]

[0061]

The method for producing an acrylic copolymer of the present invention has the above-described constitution.
An acrylic copolymer whose primary structure is precisely controlled, that is, an acrylic copolymer having a controlled molecular weight, a narrow molecular weight distribution, and a small width of (weight average molecular weight / number average molecular weight) is industrially advantageous. Can be obtained in a simple way.

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Claims (4)

[Claims] 1. A radical polymerization of a composition comprising 10 to 95 parts by weight of acrylonitrile or methacrylonitrile, 90 to 5 parts by weight of a vinyl ester monomer and / or a styrene monomer, and an iodine compound. A method for producing an acrylic copolymer. 2. A composition comprising 10 to 95 parts by weight of an acrylate or methacrylate, 90 to 5 parts by weight of a vinyl ester monomer and / or a styrene monomer, and an iodine compound is radically polymerized. A method for producing an acrylic copolymer. 3. The method for producing an acrylic copolymer according to claim 1, wherein (weight average molecular weight / number average molecular weight) of the acrylic copolymer is 1.05 to 1.9. . 4. The iodine compound according to claim 1, wherein the iodine compound has at least one of a carbon-iodine bond, a hydrogen-iodine bond, and a halogen-iodine bond. A method for producing an acrylic copolymer.