JP2678637B2 - Polymerization method of vinyl monomer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for effectively polymerizing vinyl monomers.

[Background of the Invention]

Peroxide compounds and azo compounds have been generally well known as polymerization initiators for vinyl monomers. Of these, azo-based polymerization initiators are relatively stable in spite of their high activity as a whole, do not undergo the self-induced decomposition as seen in organic peroxides, and can be decomposed accurately in the primary reaction to control. It has excellent properties such as ease of use and is widely used in the polymerization of various vinyl monomers.

For example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis (methyl 2-methylpropionate), etc. are generally widely used as a polymerization initiator in a methanol solution polymerization of vinyl acetate. It is used. However, since these azonitriles and azoesters do not necessarily have sufficiently high polymerization activity, it takes a long time to obtain a high polymerization rate and a relatively high polymerization temperature is required. In addition, since the amount of addition as a catalyst is inevitably large, the problem of contamination of the polymer with residual catalyst, decomposition products, and the like tends to occur.

On the other hand, azoamidine hydrochlorides such as 2,2'-azobis (2-amidinopropane) dihydrochloride and 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride are the above AIBN. Although it has a higher polymerization activity than that of the above, it is not yet widely used because it is a hydrochloride and therefore has a problem of corrosion of reaction equipment and the like.

Also, the formula 2,2'-azobis [2- (2-imidazolin-2-yl) propane] represented by and various cyclic azoamidines described in, for example, JP-A-63-115869 or JP-A-63-146866. The group (free form) has been attracting attention recently because it has high polymerization activity and at the same time has been selected for its solubility in water and various organic solvents, but its effective use has not yet been examined. The current situation is that it has not been done enough.

[Object of the invention]

An object of the present invention is to provide a more effective polymerization method of a vinyl monomer using a cyclic azoamidine compound (free form) as a polymerization initiator.

[Configuration of the invention]

The present invention provides a compound represented by the general formula [I]: (In the formula, R ¹ represents a methyl group or an ethyl group, R ² represents a hydrogen atom or a lower hydroxyalkyl group, and R ³ represents a lower alkylene group which may have a substituent.) A method for polymerizing a vinyl monomer, which comprises polymerizing in the presence of an organic acid using a cyclic azoamidine compound as a polymerization initiator.

That is, the inventors of the present invention are keenly researching an effective polymerization method of a vinyl monomer using the cyclic azoamidine compound as a polymerization initiator. The present invention has been completed by discovering a phenomenon in which the activity of is increased.

R ¹ of the cyclic azoamidine compound represented by the general formula [I]
Include a methyl group or an ethyl group, R ² includes a hydrogen atom or a hydroxyalkyl group such as a hydroxymethyl group, a hydroxyethyl group, and a hydroxypropyl group, and R ³ includes, for example, —CH ₂ · -CH _2, -CH ₂
.CH ₂ .CH _2-, etc., or a lower alkylene group such as CH ₂ --CH _2- , or some of the hydrogen atoms of these lower alkylene groups are replaced by a lower alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group or a hydroxyl group There are things.

Typical structural examples of the cyclic azoamidine compound represented by the general formula [I] are shown below.

As for the cyclic azoamidine compound represented by the general formula [I], when there is a commercially available product, it can be used as it is. When there is no commercially available product, for example, JP-A-56-6134 can be used.
JP-A-63-115869, JP-A-63-146866
This may be synthesized by the following synthesis route according to the method described in Japanese Patent Publication No.

(In the formula, R ′ represents a lower alkyl group, and R ¹ , R ² and R ³
Is the same as above. That is, for example, the corresponding azonitrile is used as a starting material, and hydrogen chloride gas and alcohol are reacted with this as a starting material to obtain an azoimino ether hydrochloride. Next, this is reacted with ammonia gas in an appropriate reaction solvent to obtain a free azoimino ether, and then reacted with a corresponding diamine to produce a desired free azoamidine compound.

The reaction between the free azoimino ether and the diamine is as follows:
Usually, the azoimino ether educt and the theoretical amount or a slight excess amount of the diamine relative to it are required in a lower alcohol solvent such as methanol or ethanol, or in the presence of these lower alcohols in another suitable organic solvent. For example, a small amount of acetic acid may be used as a reaction accelerator and contact may be carried out at room temperature or, if necessary, with slight cooling for several hours to several days, and stirring may be optionally performed. After the reaction, post-treatment is performed according to a conventional method to isolate the cyclic azoamidine compound.

In order to carry out the method of the present invention, the cyclic azoamidine compound may be used as a polymerization initiator and a polymerizable vinyl monomer may be polymerized or copolymerized in the presence of an organic acid. Examples of the acid include formic acid, acetic acid, propionic acid, malonic acid, succinic acid, lactic acid,
Glutaric acid, adipic acid, mucus acid, methanesulfonic acid,
Typical examples include p-toluenesulfonic acid, benzoic acid, acrylic acid, methacrylic acid and the like.

The amount of the acid used varies depending on the type of the acid, the type of the monomer used or the polymerization method.
About 0.1 to 20 times mol (may be more than that in some cases) It is preferable to use about 0.4 to 10 times mol. If it is too small, improvement of polymerization activity cannot be expected so much, and if it is too large, efficiency and economy are increased. There is a problem in terms of sex.

As the polymerizable vinyl monomer to which the method of the present invention is applicable, for example, various olefins, styrene, methyl acrylate, methyl methacrylate, acrylonitrile,
Acrylamide, vinyl acetate, vinyl chloride, vinyl pyrrolidone, vinyl pyridine, acrylic acid, methacrylic acid,
Methacrylamide and the like can be mentioned, and as the monomer which can be copolymerized with them, maleic anhydride, maleic acid, fumaric acid and the like can be mentioned in addition to the above vinyl monomers.

The polymerization method itself according to the present invention may be carried out according to a polymerization method known per se, depending on the properties of the monomer and the properties of the polymer to be produced, the application, etc., and select the most suitable method therefor, solution polymerization, emulsification, Polymerization or suspension polymerization may be used.

Examples are described below, but the present invention is not limited by these examples.

〔Example〕

Example 1. As the polymerization initiator, the formula 2,87 'of 2,2'-azobis [2- (2-imidazolin-2-yl) propane] (hereinafter abbreviated as VA-061) and 0.09 g of acetic acid as an organic acid were used. Dissolved in 200 ml of methanol with 200 ml of vinyl,
Polymerization was carried out in an N ₂ atmosphere at a polymerization temperature of 50 ° C. The results are shown in Table 1 and FIG. In addition, for comparison, the results when acetic acid was not added and when AIBN was used as an initiator are also shown in Table 1 and FIG. The numerical values in the table indicate the polymerization rate.

As is clear from Table 1 and FIG. 1, the polymerization activity is obviously different between the case where the acetic acid is added and the case where the acetic acid is not added, and the addition of acetic acid significantly increases the polymerization activity. Understand. Also, it can be seen that AIBN has no effect of adding acetic acid.

Example 2. 0.187 g of VA-061 and acetic acid were used in the respective addition amounts shown in Table 2,
These were dissolved in 200 ml of methanol together with 200 ml of vinyl acetate and polymerized at a polymerization temperature of 50 ° C. under N ₂ atmosphere. The results are shown in Table 2 and FIG. The numerical values in the table indicate the polymerization rate.

As is clear from Table 2 and FIG. 2, it is understood that the polymerization activity is increased as the addition amount of acetic acid is increased.

Example 3. VA-061 and acetic acid were added in the amounts shown in Table 3 and dissolved in 200 ml of methanol together with 200 ml of vinyl acetate.
Polymerization was carried out in an N ₂ atmosphere at a polymerization temperature of 50 ° C. The results are shown in Table 3 and FIG. For comparison, the results when AIBN is used are also shown in Table 3 and FIG. The numerical values in the table indicate the polymerization rate.

As is clear from Table 3 and FIG. 3, VA added with acetic acid
It can be seen that the polymerization activity of −061 is higher than that of conventional AIBN and the amount of the initiator added can be reduced as compared with the case of using AIBN.

Example 4. Using 0.187 g of VA-061 and 0.09 g of acetic acid, these were dissolved in 200 ml of methanol together with 200 ml of vinyl acetate and polymerized at a polymerization temperature shown in Table 4 under N ₂ atmosphere. The results are shown in Table 4 and FIG. For comparison, the results when AIBN is used are also shown in Table 4 and FIG. The numerical values in the table indicate the polymerization rate.

As apparent from Table 4 and FIG. 4, acetic acid was added.
It can be seen that the polymerization activity of VA-061 is higher than that of conventional AIBN, and the polymerization temperature can be lowered as compared with the case of using AIBN.

Example 5. 0.187 g of VA-061 was used as a polymerization initiator, and the organic acid shown in Table 5 was used as an organic acid in an amount of 2 times the moles of VA-061, respectively, and dissolved in 200 ml of methanol together with 200 ml of vinyl acetate. Polymerization was performed at a polymerization temperature of 50 ° C. in an N ₂ atmosphere. The results are shown in Table 5 and FIG. The numerical values in the table indicate the polymerization rate.

As is clear from Table 5 and FIG. 5, the same effect as in the case of using acetic acid, that is, the effect of increasing the polymerization activity was obtained when an organic acid other than acetic acid was used. The effect is great.

Example 6. As a polymerization initiator, a formula 0.12 g of 2,2'-azobis [2- (2-imidazolin-2-yl) butane] represented by is used, and methanesulfonic acid or p-toluenesulfonic acid is used as an organic acid in a 2-fold molar amount with respect to the polymerization initiator. It was dissolved in 200 ml of methanol together with 200 ml of vinyl acetate and polymerized at a polymerization temperature of 50 ° C. under N ₂ atmosphere. The results are shown in Table 6 and FIG. The numerical values in the table indicate the polymerization rate.

As is clear from Table 6 and FIG. 6, even when a cyclic azoamidine compound other than VA-061 is used as a polymerization initiator, the effect of increasing the polymerization activity is remarkably recognized by the addition of the organic acid.

〔The invention's effect〕

The present invention provides an effective polymerization method of a vinyl monomer using a cyclic azoamidine compound as a polymerization initiator, and when the polymerization is carried out in the presence of an organic acid by the method of the present invention, AIBN or the like is added. Polymerization activity is significantly increased compared to the conventional method used, and with a smaller amount of initiator than the conventional method,
At a lower temperature and a shorter polymerization time than before,
A remarkable effect is obtained in that a desired polymer is obtained.

[Brief description of the drawings]

FIG. 1 shows the polymerization rate curve obtained in Example 1, which is obtained by connecting the points plotted along the vertical axis with the polymerization rate (%) at each polymerization time (hr.) On the horizontal axis. is there. However, − ● −
Is 2,2'-azobis [2- (2-imidazolin-2-yl) propane] (hereinafter abbreviated as VA-061) as a polymerization initiator, and when acetic acid is added,-○-is the same. In the case of no addition,-■-is in the case of adding acetic acid using azobisisobutyronitrile (AIBN) as a polymerization initiator.
-Indicates the results in the case of no addition. FIG. 2 shows the polymerization rate curve obtained in Example 2, where − ▽
-When acetic acid is used at 20 times mol,-□-is at 10 times mol,-○-is at 2 times mol,-△-is at 0.4 mol times, Shows the results when acetic acid was not added. Also, ---
Shows the results when AIBN was used as a polymerization initiator (without addition of acetic acid). FIG. 3 shows the polymerization rate curve obtained in Example 3, and
-In the case of adding VA-061, 0.5 wt%,-□-in the case of 0.1 wt%, -4 △-in the case of 0.05 wt%, Is the same as 0.02 wt%, − ▽ − is the same as 0.01 wt%, − ●
− Indicates the result when AIBN and 0.5 wt% were added, and − ■ − indicates the result when 0.1 wt% was added. FIG. 4 shows the polymerization rate curve obtained in Example 4, and
− Is for polymerization temperature of 50 ° C, − □ is for same temperature of 45 ° C, − △
-Indicates the results at the same temperature of 40 ° C, and- ● -indicates the results when polymerized at 50 ° C using AIBN as the polymerization initiator. FIG. 5 shows the polymerization rate curve obtained in Example 5, where − □
-In the case of using p-toluenesulfonic acid as the organic acid, Indicates the results when methanesulfonic acid was used,-○-when acetic acid was used, -Δ- when benzoic acid was used, and-●-when organic acid was not added. FIG. 6 shows the polymerization rate curve obtained in Example 6, and
-Is the case where methanesulfonic acid is used as the organic acid,-□
-Indicates the results when p-toluenesulfonic acid was used.

Claims (1)

(57) [Claims] 1. A compound of the general formula [I] (In the formula, R ¹ represents a methyl group or an ethyl group, R ² represents a hydrogen atom or a lower hydroxyalkyl group, and R ³ represents a lower alkylene group which may have a substituent.) A method for polymerizing vinyl monomers, which comprises polymerizing in the presence of an organic acid using a cyclic azoamidine compound as a polymerization initiator.