JP3025235B2 - Polymerization initiator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymerization initiator used for producing various polymers such as polystyrene and acrylate.

[0002]

2. Description of the Related Art
Various compounds are known as azo-based polymerization initiators, and these compounds have been distributed and used in the form of crystalline powder. However, since these compounds are generally highly reactive, there is a danger of explosion during transportation or use, and strict attention has been required for handling.

[0003] In addition, it is difficult to measure at the time of use because of the crystalline powder form, and it is difficult to automate since it requires a mixing and stirring step with a monomer to be polymerized. Further, there is a problem that the working environment is deteriorated due to dust generation and the like.

[0004] In view of the above, an object of the present invention is to provide an azo-based polymerization initiator which can be easily handled at the time of use and has high safety.

[0005]

Means for Solving the Problems The present inventor has conducted intensive studies in view of the problems of the prior art, and as a result, has found that a polymerization initiator obtained by dissolving five specific azo compounds among various azo compounds in an organic solvent. As a result, the present inventors have found that the conventional problems can be solved and completed the present invention.

[0006] That is, the present invention is selected from the group consisting of 2,2'-azobis (2
-Methylbutyronitrile), 2,2'-azobis (2,
4-dimethylvaleronitrile), dimethyl-2,2'-
Azobis (isobutyrate), dimethyl-2,2'-azobis (2-methylbutyrate) and dimethyl-2,2
At least one azo compound selected from 2'-azobis (2,4-dimethylpentanoate);
2'-azobis (2,4-dimethylvaleronitrile) 1
Except for the azo compound consisting of seeds, the present invention relates to a polymerization initiator dissolved in 25% by weight or more. Further, the azo compound is
The present invention relates to a polymerization initiator which is 2,2'-azobis (2-methylbutyronitrile) and the organic solvent is ethylbenzene. Furthermore, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis (isobutyrate), dimethyl-2,2 '-Azobis (2-
Methyl butylate) and dimethyl-2,2'-azobis (2,4-dimethylpentanoate) at least 5 ° C with respect to the azo compound.
In a mixed solvent of at least one organic solvent having a saturation concentration of 40% by weight or more and at least one organic solvent having a boiling point not lower than the decomposition temperature of the azo compound to be dissolved. It relates to a polymerization initiator.

The main component of the polymerization initiator according to the present invention is 2,2.
2'-azobis (2-methylbutyronitrile) (2,2'-A
zobis-2-methylbutyronitrile. Hereinafter, abbreviated as “AMBN”), 2,2′-azobis (2,4-dimethylvaleronitrile) (2,2′-Azobis-2-dimethylvaleronitril)
e. Hereinafter, abbreviated as “ADVN”), dimethyl-2,
2'-azobis (isobutyrate) (Dimethyl-2,2'-az
obisisobutyrate. Hereinafter, abbreviated as "MAIB"),
Dimethyl-2,2'-azobis (2-methylbutyrate) (abbreviation "MAMB") and dimethyl-2,2'-azobis (2,4-dimethylpentane) Noate) (Dimethyl-2,2'-
azobis-2,4-dimethylpentanate. Abbreviation "MAMP").

The azo compound which can be generally used as a polymerization initiator is 2,2'-azobis (isobutyronitrile) (2,2'-Azobis-isobutyronitrile.
Various types of azo compounds are known, such as “AIBN”), and among them, only five specific azo compounds used in the present invention are used to produce a highly concentrated and highly safe polymerization initiator. These can be used alone or in combination of two or more.

As the organic solvent usable in the present invention, the azo compound to be dissolved has a saturated concentration at 5 ° C. of 30% by weight.
The above organic solvents are preferred. Examples of such organic solvents include ethylbenzene (saturation concentration at 5 ° C. with respect to AMBN is 30.2% by weight), acetone (56.7% by weight with respect to AMBN), methyl ethyl ketone (AMBN).
51.7% by weight, ethyl acetate (42.2% by weight based on AMBN), toluene (39.3% by weight based on AMBN), dimethylformamide, methanol, normal hexane, benzene , Xylene, dimethylsulfoxide, dimethylformamide, petroleum benzine, etc., and these can be used alone or as a mixture of two or more.

The organic solvent used in the present invention may include at least one organic solvent having a saturated concentration of the azo compound to be dissolved at 5 ° C. of more than 40% by weight and an organic solvent having a boiling point higher than the decomposition temperature of the azo compound to be dissolved. Solvent (hereinafter,
At least one of "high boiling point solvents")
It is particularly preferable to use a mixed solvent in which a polymerization initiator having a high concentration and a high safety can be obtained.

Examples of the organic solvent in which the azo compound to be dissolved has a saturated concentration of more than 40% by weight at 5 ° C. include acetone, methyl ethyl ketone, and ethyl acetate as described above. These may be used alone or in combination of two or more. Can be used.

The decomposition temperature of AMBN (about 105 to 107
Organic solvents having a boiling point of not less than ethylbenzene (boiling point: about 136 ° C) and xylene (about 138 to 14 ° C).
5 ° C.), toluene (about 111 ° C.) and the like, and these can be used alone or in combination of two or more.

Organic solvents having a boiling point higher than the decomposition temperature of ADVN (about 97-99 ° C.) include ethylbenzene (boiling point about 136 ° C.) and xylene (about 138-145 ° C.).
° C), toluene (about 111 ° C) and the like, and these can be used alone or as a mixture of two or more.

The decomposition temperature of MAIB (about 117 to 121)
Organic solvents having a boiling point of not less than ethylbenzene (boiling point: about 136 ° C) and xylene (about 138 to 145 ° C).
° C) and the like, and these can be used alone or as a mixture of two or more.

The mixing ratio of the high-boiling solvent in the mixed solvent is 10 to 95% by weight, more preferably 20 to 95% by weight.
The content is preferably 95% by weight, more preferably 25 to 50% by weight.

Specific examples of the combination of the mixed solvents include, for AMBN, a mixed solvent of acetone and ethylbenzene, a mixed solvent of acetone and toluene, a mixed solvent of methylethylketone and ethylbenzene, acetone, toluene and ethylbenzene. And the like.

The ratio of dissolving the azo compound in the organic solvent is preferably as high as possible from the viewpoint of transportation costs and storage costs.
It is used by dissolving at least 25% by weight or more.

If the dissolution ratio is higher than the saturation concentration at 5 ° C., precipitation of crystals occurs during cooling,
It is not preferable because danger during storage increases. On the other hand, even if the dissolution ratio is lower than the saturation concentration at 5 ° C., depending on the type of azo compound and the solvent, if the concentration exceeds 45%, the self-reactivity increases, causing a danger of explosion and the like, thus causing such danger. It is preferable that the concentration be within a range not present.

The presence or absence of such a danger can be determined in accordance with the pressure vessel test prescribed in Appendix 13 of the Ministerial Ordinance on Ordinance and Test of Dangerous Goods (Ordinance No. 1 of the Ministry of Home Affairs on February 17, 1989). According to the study of the present inventor, for example, A
The upper limit when MBN is dissolved is less than about 47% by weight.
The upper limit when BN is dissolved is about 55% by weight.

The polymerization initiator according to the present invention has a temperature of less than 10 ° C., preferably 5 ° C. in order to suppress decomposition during transportation and storage.
It is desirable to keep it back and forth. In addition, the above-mentioned specific azo compound and an organic solvent are appropriately selected, and when stored at 10 ° C., a polymerization initiator in which the azo compound does not precipitate as a solid content is preferable because the concentration of the azo compound in a solution is high. ,
Further, a polymerization initiator which does not precipitate an azo compound as a solid content when stored at 5 ° C. is more preferable.

The polymerization initiator according to the present invention comprises a bulk polymerization method,
It can be preferably used as a polymerization initiator in various polymerization methods such as an emulsion polymerization method, a solution polymerization method, and a melt kneading polymerization method.

The monomer polymerizable by the polymerization initiator according to the present invention is not particularly limited as long as it is a monomer having radical polymerizability. Specific examples thereof include styrene, methyl methacrylate, vinyl chloride, vinyl acetate, and vinyl acetate. Acrylonitrile, butadiene, acrylate, acrylamide, polyol, acrylic acid, methacrylic acid, vinyl fluoride and the like are exemplified.

Further, the polymerization initiator according to the present invention can be preferably used for the polymerization of these copolymers, for example, the polymerization of acrylonitrile-butadiene-styrene and the like.

The polymerization initiator according to the present invention has higher safety than conventional polymerization initiators in the form of crystalline powder, is easy to transport and manage, and does not require a dissolving step (equipment). It has the advantage that it can be used immediately for the polymerization reaction. Further, the polymerization initiator according to the present invention can be used in such a form that it is stored in a tank (preferably a refrigeration tank maintained at 10 ° C. or lower) and supplied in a required amount to a polymerization vessel, a polymerization tank, and the like. It can be preferably used also in a continuous polymerization process which has been difficult with a polymerization initiator.

Further, the polymerization initiator according to the present invention is excellent in that no dust is generated in a working environment. In addition, the polymerization initiator according to the present invention is less likely to cause a hydrogen abstraction reaction than a peroxide-based polymerization initiator, and can obtain a high-quality linear and high-molecular-weight polymer.
There is no risk of depolymerization or gelling at 100 ° C. or higher as in the case of peroxide-based polymerization initiators.

The organic solvent in the polymerization initiator according to the present invention can be easily recovered and reused during the polymerization process by providing a devolatilizer following the polymerization reactor.

[0027]

EXAMPLES Examples of the polymerization initiator according to the present invention will be shown below. Various polymerization initiators were prepared as shown below.
In addition, the organic solvent etc. used the thing of the purity generally used industrially.

Example 1 At room temperature (about 25 ° C.), 30 parts by weight of AMBN (hereinafter simply referred to as “parts”) were dissolved in 70 parts of ethylbenzene to obtain a polymerization initiator according to the present invention. Example 2 At room temperature (about 25 ° C.), 50 parts of AMBN were dissolved in 50 parts of acetone to obtain a polymerization initiator according to the present invention. Example 3 At room temperature (about 25 ° C.), 47 parts of AMBN were dissolved in 53 parts of acetone to obtain a polymerization initiator according to the present invention. Example 4 At room temperature (about 25 ° C.), 45 parts of AMBN were dissolved in 55 parts of acetone to obtain a polymerization initiator according to the present invention. Example 5 At room temperature (about 25 ° C.), 40 parts of AMBN were dissolved in 60 parts of acetone to obtain a polymerization initiator according to the present invention. Example 6 At room temperature (about 25 ° C.), 40 parts of AMBN were dissolved in 60 parts of toluene to obtain a polymerization initiator according to the present invention. Example 7 At room temperature (about 25 ° C.), 40 parts of AMBN were added to 60 parts of ethyl acetate.
To obtain a polymerization initiator according to the present invention. Example 8 At room temperature (about 25 ° C.), 40 parts of AMBN were dissolved in 60 parts of methyl ethyl ketone to obtain a polymerization initiator according to the present invention. Example 9 At room temperature (about 25 ° C.), 50 parts of AMBN were dissolved in a mixed solvent of 25 parts of ethylbenzene and 25 parts of acetone to obtain a polymerization initiator according to the present invention. Example 10 At room temperature (about 25 ° C.), 50 parts of AMBN were dissolved in a mixed solvent of 20 parts of ethylbenzene and 30 parts of acetone to obtain a polymerization initiator according to the present invention. Example 11 At room temperature (about 25 ° C.), 50 parts of AMBN were dissolved in a mixed solvent of 15 parts of ethylbenzene and 35 parts of acetone to obtain a polymerization initiator according to the present invention. Example 12 At room temperature (about 25 ° C.), 45 parts of AMBN were dissolved in 55 parts of acetone to obtain a polymerization initiator according to the present invention. Example 13 At room temperature (about 25 ° C.), 40 parts of AMBN were
To obtain a polymerization initiator according to the present invention.

Comparative Example 1 AMBN in the form of solid powder was used as the polymerization initiator of Comparative Example 1. Comparative Example 2 AIBN (2,2'-azobisisobutyronitrile) 2
0 parts was added to 80 parts of acetone and stirred to obtain a polymerization initiator of Comparative Example 2.

Test Example 1 (Low temperature stability test) The polymerization initiators of Examples 1 to 13 and Comparative Example 2 were cooled to 5 ° C. As a result, the polymerization initiators of the examples (the polymerization initiators of Examples 1 to 5 and 8 to 13) except for the polymerization initiators of Examples 6 and 7 all maintained a solution state and generated solid components. (AMB N crystal) was not found.
In the polymerization initiators of Examples 6 and 7, precipitation of AMB N was slightly observed. On the other hand, in the case of the polymerization initiator of Comparative Example 2, precipitation of AIBN crystals was observed despite the low concentration. That is,
It can be seen that even with the same azo-based polymerization initiator, the polymerization initiator of Comparative Example 2 using AIBN could not have a high concentration and was not suitable for refrigerated transportation.

Test Example 2 (Hazard test) In accordance with the pressure vessel test specified in Appendix 13 of the Ministerial Ordinance on Hazardous Materials Testing and Properties (Ordinance No. 1 of the Ministry of Autonomy, February 17, 1989), Example 1 Fire Protection Law Class 5 Dangerous Substances (Self-reactive substances) for the polymerization initiators Nos. 13 to 13 and the polymerization initiator of Comparative Example 1
It was determined whether or not it corresponded. Table 1 shows the results.

[0032]

[Table 1]

From the results shown in Table 1, the polymerization initiator of Example 2 was 8 times out of 10 times, the polymerization initiator of Example 3 was 7 times out of 10 times, and the polymerization initiator of Comparative Example 1 was 10 times. 10 times,
Each of them burst and was classified as a Class 5 dangerous substance. The other polymerization initiators did not burst at all and were not applicable. Further, from the comparison between Example 2 and Example 9, even when the polymerization initiators have the same concentration, when a mixed solvent of a high boiling point solvent (ethylbenzene) is used as in Example 9, polymerization initiation with higher safety is performed. It can be seen that the agent can be obtained. Further, from a comparison between Example 3 and Example 4, it can be seen that there is a remarkable difference between the case where AMBN is dissolved in acetone by 45% by weight and the case where AMBN is dissolved by 47% by weight.

Test Example 3 (Storage property test) The storage stability of the polymerization initiators of Examples 8 and 13 was measured. For the measurement, two samples of each of the polymerization initiators of Examples 8 and 13 were prepared, one at room temperature (25 ° C.), and the other at 5 ° C.
Each sample was stored in a dark place at a temperature of ° C., and the AMBN concentration in each sample was measured at each elapse of a certain period, and the residual ratio (%) to the initial content was calculated. The results are shown in the graph (FIG. 1).

The results of the graph show that the polymerization initiators of Examples 8 and 13 stored at 5 ° C. have excellent storage stability compared to the polymerization initiators of Examples 8 and 13 stored at 25 ° C. I understand.

Test Example 4 (Polymerization performance test) To 100 g of a styrene monomer, 0.5 g of the polymerization initiator of Examples 1 to 13 and the polymerization initiator of Comparative example 1 were added in an amount of 0.5 g in terms of an azo compound, respectively, and stirred. As a result, all of them showed an increase in viscosity and generation of polystyrene was confirmed, and it was found that all of the polymerization initiators functioned sufficiently as polymerization initiators.

[0037]

As described above, the polymerization initiator according to the present invention has the advantages of higher safety and easier transportation and management than conventional polymerization initiators in crystalline powder form. are doing. Further, the azo-based polymerization initiator according to the present invention is in the form of a solution, so that it can be easily measured at the time of use and is easy to handle, and is uniformly mixed with the monomer.
Also functions well as an initiator in continuous polymerization processes. Furthermore, no dust is generated in the working environment,
It also helps improve the working environment.

[Brief description of the drawings]

FIG. 1 is a graph showing the results of a storage test.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-157063 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08F 4/04

Claims (4)

(57) [Claims] 1. A 2, 2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl-2,2'-azobis (isobutyrate), dimethyl - At least one azo compound selected from 2,2'-azobis (2-methylbutyrate) and dimethyl-2,2'-azobis (2,4-dimethylpentanoate), provided that 2,2'- Azobis
Azo consisting of (2,4-dimethylvaleronitrile)
A polymerization initiator , excluding the compound, which is dissolved in an organic solvent in an amount of 25% by weight or more. 2. The method according to claim 1, wherein the organic solvent is ethylbenzene,
Ton, methyl ethyl ketone, ethyl acetate, toluene, di
A few selected from methylformamide and petroleum benzine
2. The polymerization initiator according to claim 1, which is at least one kind . 3. The method of claim 2, wherein the azo compound is 2,2'-azobis
(2-methylbutyronitrile), and the organic solvent
The polymerization initiator according to claim 1, wherein is ethylbenzene. 4. A 2,2′-azobis (2-methylbutyro)
Nitrile), 2,2'-azobis (2,4-dimethyl
Relonitrile), dimethyl-2,2'-azobis (iso
Butyrate), dimethyl-2,2'-azobis (2-meth
Butylbutyrate) and dimethyl-2,2'-azobis
(2,4-dimethylpentanoate)
At least one azo compound at 5 ° C.
Of organic solvents having a saturation concentration of at least 40% by weight
At least one and at least the decomposition temperature of the azo compound to be dissolved
Mixed solvent with at least one organic solvent having a boiling point of
Characterized by being dissolved in an amount of 25% by weight or more.
Co-initiator.