JP2000198810A - Production of styrenic polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the subject styrenic polymer that is accurately controlled in its primary structure and can obtain the polymer of high functions and high performance at a low cost by using a radical polymerization initiator and a specific polymerization catalyst. SOLUTION: (A) A radical polymerization initiator and (B) a polymerization catalyst comprising iodine are used to produce a polymer, preferably at a rate of (weight-average molecular weight/number-average molecular weight) of 1.05-1.9. For example, a styrene monomer, for example, styrene or the like, and a monomer copolymerizable with the styrenic monomer, for example, methyl acrylate and azobis (isobutyronitrile), or benzoyl peroxide or the like is used as component A and its amount is in the range from 0.02-20 moles per 1 mol of the iodine to be used, and the radical polymerization is carried out at about -30-120 deg.C under atmospheric pressure or under pressurization through the bulk polymerization of the like.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a styrene-based polymer 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). It relates to a manufacturing method.

[0002]

2. Description of the Related Art It is necessary to arbitrarily control the molecular weight and molecular weight distribution of a homopolymer of a styrene-based monomer or a copolymer of a styrene-based monomer, control its terminal group, and obtain a block polymer. High functionality,
This is an indispensable technology for achieving high performance.

[0003] That is, by controlling the molecular weight and molecular weight distribution, for example, mechanical strength, flow characteristics, thermal stability, thermal melting characteristics, compatibility with other resins, plasticization efficiency, dispersion stabilizing effect, etc. are controlled. For example, by narrowing the molecular weight distribution and reducing the number of low molecular weight components, it is possible to improve mechanical strength, flow characteristics, adhesion performance, and the like.

Further, by obtaining a terminal functional polymer, synthesis of a macromonomer utilizing the reactivity of the terminal group,
Use as a cross-linking point, creation of a block polymer, and the like are possible, and new physical properties different from homopolymerization of a monomer can be expressed. For example, a thermoplastic elastomer made of a triblock copolymer such as ABA can be obtained. It becomes possible.

Therefore, the styrene-based polymer obtained by precision polymerization can have high performance and high performance even if the same monomer is used as a starting material, and aim at high performance in applications which have been used up to now. Not only can it be used, but it can be expanded to entirely new applications due to its high functionality.

As a method of 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.

[0007] Among these polymerization methods, the method using an iodine compound has less chain transfer reaction and is excellent in controllability of molecular weight distribution as compared with the iniferter method, and is superior to the method using an organometallic complex. Since it has the advantage that there is no need to remove metals, it can be said that the polymerization method is excellent in controllability of molecular weight distribution and highly practical.

JP-A-7-126322 discloses a method of polymerizing a styrene monomer in the presence of an iodine compound having at least one carbon-iodine bond in a molecule. Although various iodine compound names are listed, compounds having an iodine-iodine bond,
That is, no description of the iodine molecule is found. Therefore, it is presumed that the method of controlling the polymerization using iodine has not been studied because it is basically difficult.

[0009]

DISCLOSURE OF THE INVENTION The present inventors, in addition to a commonly used iodine compound, use iodine itself to polymerize a styrene-based monomer using an iodine compound or a styrene-based monomer and another monomer. Various studies were made on the copolymerization. As a result, usually, even if iodine is added to the polymerization system, radical cleavage of iodine itself and chain transfer to the monomer are unlikely to occur, so although there is a certain polymerization induction period, polymerization occurs and the polymer is degraded with time. The inventors have found that a polymer having an increased molecular weight and a precisely controlled primary structure can be obtained, thereby completing the present invention. That is, an object of the present invention is to provide a method for producing a styrene polymer in which a styrene polymer whose primary structure is precisely controlled can be produced at lower cost than in the past.

[0010]

The styrenic polymer in the present invention includes not only the following styrenic monomer homopolymers but also copolymers of styrenic monomers and other monomers. . The styrene-based monomer constituting the styrene-based polymer of the present invention includes 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 a polymer widely used industrially and is preferably used.

These styrene monomers may be used alone or in combination of two or more. The monomer may be added to the polymerization solution in its entirety from the beginning, or may be added sequentially as the polymerization proceeds.

The monomer constituting the styrene copolymer other than the styrene monomer is not particularly limited as long as it is a monomer copolymerizable with the styrene monomer. Monomers, vinyl ester monomers, acrylic acid, methacrylic acid, acrylamide, methacrylamide, acryloyl morpholine, methacryloyl morpholine, N-vinyl-2-pyrrolidone, acrylonitrile, methacrylonitrile, maleic acid, maleic anhydride, maleic imide, and the like. Can be

The (meth) acrylate monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n- (meth) acrylate. Butyl,
Isobutyl (meth) acrylate, se (meth) acrylate
c-butyl, tert-butyl (meth) acrylate, (meth)
N-hexyl acrylate, cyclohexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, (meth) acrylic acid Lauryl, isobornyl (meth) acrylate, (meth)
Examples include, but are not limited to, benzyl acrylate and dimethylaminoethyl phenyl (meth) acrylate.

The vinyl ester monomers include vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate,
n-vinyl caproate, vinyl isocaproate, vinyl caprylate, vinyl caprate, vinyl octanoate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl pivalate, vinyl trimethyl acetate, vinyl chloroacetate, Examples include, but are not limited to, vinyl trichloroacetate, vinyl trifluoroacetate, vinyl benzoate, and the like. These monomers may be used alone or in combination of two or more.

The amount of these monomers to be used is usually 90 parts by weight or less based on 100 parts by weight of the styrene copolymer. If the amount of the styrene-based monomer in the styrene-based copolymer is less than 10 parts by weight, the polymerization controllability is deteriorated and the molecular weight distribution of the obtained polymer is often widened. It is preferably at most 80 parts by weight, more preferably at most 70 parts by weight.

The molecular weight distribution (Mw / Mn) of the polymer obtained according to the present invention is more controlled than that obtained by conventional ordinary radical polymerization, and is usually 1.05 to 1.9.
It is. Particularly, a polymer having a molecular weight distribution of 1.05 to 1.8 is preferable.

The amount of iodine can be appropriately determined with respect to the molecular weight of the polymer to be obtained. If the amount of iodine is too small, the structure of the polymer cannot be controlled. Therefore, it is preferable to add 0.0005 to 0.5 mol per 1 mol of the monomer. In particular, it is preferable to add at a ratio of 0.001 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 polymer obtained by the present technique can be adjusted by the concentration of iodine, and a polymer having a number average molecular weight of 500 to several hundred thousand can be preferably obtained. In particular, the range of the molecular weight which is preferably obtained is a number average molecular weight of 1,000 to 100,000.

Examples of the method of performing a radical polymerization reaction used in the present invention include use of a usual radical polymerization initiator, use of a photopolymerization initiator and irradiation with light, irradiation with radiation, laser light, light, and heating. . In particular, it is preferable to use a radical polymerization initiator industrially, and as its type, generates a radical, reacts with a monomer, iodine,
There is no particular limitation as long as it can cause polymerization, and it is selected from compounds that generate radicals by the action of heat, light, radiation, an oxidation-reduction chemical reaction, or the like.

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, a photopolymerization initiator such as an acetophenone type, a benzoin ether type, or a ketal type may be added. One or more radical polymerization initiators for generating radicals can be used as long as they do not adversely affect the progress of polymerization due to interaction. 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 the polymerization can be caused, but it is preferably in the range of 0.02 to 20 mol per mol of iodine. 0.00005 to mole
It is preferred that the amount be from 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 may be 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 mol of iodine, and is 0.0001 to 0.2 mol per mol of monomer. It is particularly preferable to use the radical initiator in the range of 0.1 to 5 mol per 1 mol of iodine.

The polymerization temperature has a suitable range depending on the kind of the radical polymerization reaction, and is not particularly limited. However, it is general that the polymerization is carried out at a temperature of about -30 ° C to about 120 ° 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 polymerization, solution polymerization, suspension polymerization, emulsion polymerization and the like can be adopted.
From the viewpoint of obtaining a better controlled polymer by suppressing chain transfer, bulk polymerization is preferably used. Also,
Continuous polymerization using an extruder can also be used. Further, as a solvent for solution polymerization, a commonly used solvent such as alcohol, toluene and benzene can be used.

Most of the growing terminals of the polymer obtained according to the present invention have been confirmed to be iodine by ¹ H-NMR. Therefore, utilizing the reactivity of terminal iodine,
Conversion to other functional groups is also possible. 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 polymer obtained in the present invention, iodine existing at the growing terminal of the polymer by adding methanol, ammoniacal methanol, lithium borohydride or the like to the polymerization system at the time of termination of the polymerization. May be desorbed. Further, the obtained polymer may be irradiated with ultraviolet rays in the presence of isopentane or the like to stabilize the polymer by replacing iodine with hydrogen. After obtaining a styrenic homopolymer or copolymer by the method disclosed in the present invention, it is also possible to obtain a block copolymer by adding another monomer to the polymerization system and polymerizing it.

[0027]

EXAMPLES The present invention will be specifically described below based on examples and comparative examples. [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 the weight average molecular weight were measured by gel permeation chromatography (GPC) in terms of polystyrene. (G
PC: manufactured by Tosoh, LS8000 system, column: manufactured by Showa Denko, polystyrene gel KF-802, 803, 80
4, solvent: chloroform, flow rate: 1 ml / min) The ratio between the weight average molecular weight (Mw) and the number average molecular weight (Mn) was defined as a molecular weight distribution (Mw / Mn).

(Example 1) In a 500 ml flask equipped with a reflux condenser and stirring blades, 8.22 g of AIBN, 6.4 g of iodine, 250 g of styrene, and 1.0 ml of n-heptane were added.
And uniformly mixed, and then aerated with nitrogen gas for 30 minutes to remove dissolved oxygen in the reaction solution. While sending nitrogen,
The reaction solution was heated to 80 ° C., and after about 2 hours, the color of the reaction solution changed from black-brown to pale yellow, thereby confirming the start of polymerization. After polymerization at 80 ° C. 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 polymer. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) were determined by GPC, Mn = 960
0, Mw / Mn = 1.38. The results are shown in Table 1.

(Example 2) In Example 1, 200 g of styrene and 50 parts of n-butyl acrylate were used as monomers.
Except that g was used, a polymerization method and a purification method of the polymer were obtained in the same manner as in Example 1 to obtain a polymer. The results are shown in Table 1. (Example 3) A polymer was obtained in the same manner as in Example 1 except that 150 g of styrene and 100 g of methyl methacrylate were used as the monomers in Example 1, and a polymer was obtained. 1 is shown.

Example 4 A polymer was obtained in the same manner as in Example 1 except that 150 g of styrene and 100 g of acrylonitrile were used as monomers in the same manner as in Example 1 to obtain a polymer. Are shown in Table 1. (Example 5) A polymer was obtained in the same manner as in Example 1 except that 150 g of styrene and 100 g of methacrylonitrile were used as the monomers in Example 1, and a polymer was obtained. The results are shown in Table 1.

Example 6 In Example 1, after polymerization was carried out at 80 ° C. for 5 hours using the same raw materials, 200 g of styrene monomer was added to the polymerization solution, and polymerization was further carried out for 10 hours. The resulting polymer had Mn = 15700, Mw
/Mn=1.75. The results are shown in Table 1.

Comparative Example 1 Polymerization and polymer purification were carried out according to Example 1 except that iodine was not used. The polymerization rate after 5 hours was 95%. When the number average molecular weight (Mn) and molecular weight distribution Mw / Mn) were determined by GPC, Mn = 36000 and Mw / Mn = 2.2.
It was one. The results are shown in Table 1. (Comparative Example 2) Polymerization and polymer purification were performed according to Example 2 except that iodine was not used. The polymerization rate after 7 hours was 97%. When the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) were determined by GPC, Mn was 47,800 and Mw / Mn was 2.35. The results are shown in Table 1.

[0033]

[Table 1]

[0034]

According to the production method of the present invention, a styrene-based polymer whose primary structure is precisely controlled can be obtained.
That is, for example, (weight average molecular weight / number average molecular weight)
A styrene-based polymer having a narrow molecular weight distribution, a styrene-based polymer having a controlled molecular terminal, and a block copolymer represented by the formula (1) can be obtained by an industrially simple method.

Further, by using cheaper iodine than the conventional iodine compound, it is possible to reduce the cost of the obtained polymer. The obtained polymer can have higher functions and higher performance than those obtained by a usual radical polymerization method.

Claims (2)

[Claims] 1. A method for producing a styrene-based polymer, comprising using a polymerization catalyst comprising a radical polymerization initiator and iodine. 2. The method according to claim 1, wherein (weight average molecular weight / number average molecular weight) of the styrene polymer is 1.05 to 1.9.