JPH0374246B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method most suitable for producing a copolymer of an aromatic vinyl compound and maleic anhydride, particularly a copolymer of styrene and maleic anhydride.

Generally, aromatic vinyl compounds and maleic anhydride are mixed in a solvent that is inert to these monomers and that dissolves the monomers but not the copolymer.
Precipitation polymerization can be carried out using a radical polymerization initiator such as a peroxide or an azo compound. A high molecular weight copolymer can be obtained by separating or centrifuging the obtained copolymer slurry and then drying it.

However, when the copolymer precipitates from the solvent, the precipitate may adhere to the wall, stirrer, coil, etc. in the reaction vessel, solidify, or form block-like solids, resulting in uniform production. However, there were disadvantages in that a suitable dispersion liquid could not be obtained and the yield of the copolymer was significantly reduced.

The method of the present invention eliminates these drawbacks by combining an aromatic vinyl compound and maleic anhydride with an inert organic solvent (hereinafter simply referred to as "maleic anhydride") which dissolves these monomers but not the resulting copolymer. When polymerizing using a radical polymerization initiator in a solvent (abbreviated as "solvent"), a dispersant is dissolved in advance in the solvent to obtain a uniform dispersion of the copolymer. This is a method for producing a copolymer of a compound and maleic anhydride.

Examples of the aromatic vinyl compound used in the present invention include styrene, α-methylstyrene, and paramethylstyrene, among which styrene is most preferred.

The solvent used in the present invention is not particularly limited, and it is inert and has excellent solubility for the reacting monomers (namely, aromatic vinyl compound and maleic anhydride), and the resulting copolymer Any solvent may be used as long as it is inert and poor solvent for the copolymer, but a solvent that makes the particles of the produced copolymer large and relatively uniform is particularly preferred. Suitable solvents include aromatic solvents such as benzene, toluene, xylene, ethylbenzene, cumene, paracymene, and the like. The ratio of solvent to total amount of monomer is
The weight ratio ranges from 1:9 to 3:1, preferably from 1:4 to 1:1.

Examples of the radical polymerization initiator include azo compounds such as azobisisobutyronitrile and peroxides such as benzoyl peroxide.

As the dispersant used in the present invention, since this reaction is a reaction between a nonpolar monomer and a polar monomer, the dispersant also has a nonpolar part and a polar part in the molecule, It is preferable to use one that is also soluble in a solvent. Suitable dispersants include polyalkylene glycol compounds having a molecular weight of 3,000 to 50,000. molecular weight
If it is less than 3,000, there is no dispersion effect, and if it is more than 50,000, it is difficult to synthesize and difficult to obtain. The polyalkylene glycol compound in this case is a copolymer of alkylene oxide, and particularly preferably a block copolymer or random copolymer of ethylene oxide and propylene oxide. It is also possible to use terminal-modified compounds of these copolymers, such as etherification products or esterification products of the above-mentioned copolymers with alkyl or alkylphenols, among which esterification products with fatty acids having 8 to 20 carbon atoms are preferred.

The amount of dispersant used is 0.1 based on the total amount of monomers.
-20% by weight, preferably 0.2-5% by weight. 0.1
If it is less than 20% by weight, there is no effect of preventing deposits from adhering.
If it exceeds % by weight, it is not only economically disadvantageous, but also the quality of the product obtained may be impaired, or the dispersed particles may become too fine and difficult to filter.

Polymerization temperature is about 80-200℃, preferably about 90-140℃
℃ and is desirable to be uniform throughout the polymerization time. Further, the polymerization time is sufficient to be 5 hours, including the time when the monomer may be gradually added to the reaction vessel.

In carrying out the present invention, first, a solvent in which a dispersant is dissolved and maleic anhydride are charged into a reaction vessel, and the temperature is raised to the polymerization temperature while stirring.

A mixture of the same solvent, aromatic vinyl compound, and radical polymerization initiator as described above is added dropwise into the mixture to maintain the polymerization temperature. After the reaction is completed, it is cooled, and the resulting copolymer is separately dried to obtain the copolymer of the present invention.

In this case, if polymerization is carried out without adding a dispersant,
As mentioned above, the problem of adhesion of the copolymer inside the reaction vessel occurs, but in the method of the present invention, the dispersant is dissolved in the solvent before polymerization, so a uniform dispersion is obtained from the beginning to the end of the reaction. The condition is maintained, there is no adhesion of the copolymer inside the reaction vessel, it is easy to take out the copolymer from the reaction vessel, and the copolymer has good deliquid properties, so the amount of heat required in the drying process is reduced. At the same time, the drying equipment can be made smaller.

In addition, although it is generally thought that the stirring speed affects the dispersion effect, in the method of the present invention, this effect is small and stirring is sufficient to move the reaction solution, so the reaction solution may not splash up into the reaction container. There is no adhesion to the surface, and the yield is improved.

EXAMPLES The present invention will be specifically explained below using Examples and Comparative Examples, but the present invention is not limited thereto. In the examples, parts refer to parts by weight unless otherwise specified.

Example 1 Toluene 354 was placed in a flask equipped with a stirrer, thermometer, steam condenser, nitrogen introduction tube, and dropping tank.
1 part, 64 parts of maleic anhydride, and 6 parts of oxyethylene oxypropylene block polymer with a molecular weight of 5,000 as a dispersant, and while stirring, lower the boiling point (approx.
110℃). Put 126 parts of toluene, 56 parts of styrene, and 3 parts of benzoyl peroxide into a 300 ml dropping tank, and drop them into the above flask over 2 hours. After finishing dropping, keep at the same temperature for 3 hours. After cooling, a portion of the reaction product was volatilized in a vacuum volatilization furnace at 230° C. for 30 minutes, and the residual solid content was determined to be 19.1% by weight. It is easy to filter out the reaction products;
The solid content was vacuum dried.

The vacuum-dried solid content was confirmed to be a copolymer of styrene and maleic anhydride by measurements using an infrared spectrophotometer and a nuclear magnetic resonance absorption meter. The molecular weight is 7000, and the yield of solid matter after vacuum drying is
It was 91.4% by weight.

Example 2 In Example 1, the dispersant had an average molecular weight of 26600.
Example 1 except that 4.8 parts of oxyethylene oxypropylene random polymer monolaurate was used.
It was carried out in accordance with. When determining the residual solid content
The molecular weight was 6900, and the vacuum-dried solid yield was 91.3% by weight.

Example 3 The procedure of Example 1 was repeated except that 0.6 parts of a dispersant with a molecular weight of 12,700 was used instead of 6 parts of a dispersant with a molecular weight of 5,000. The residual solid content was determined to be 20.2% by weight, the molecular weight was 9500, and the yield of solid content after vacuum drying was 91.0% by weight.

Comparative Example 1 In Example 1, the molecular weight of the dispersant was changed from 5000 to
Example 1 was carried out except that the value was changed to 2000. 20 minutes after the start of dropping, adhesion to the walls of the reaction vessel was observed, and after another 20 minutes, lumps were suspended in the reaction product, and the adhesion to the walls of the reaction vessel was increasing, making stirring difficult. Since it became difficult, the reaction was stopped 1 hour after starting the dropping.

Comparative Example 2 In Example 1, polyoxyethylene lauryl phenol ether with a molecular weight of 4900 was used as the dispersant.
The procedure of Example 1 was repeated except that the parts were changed.

Adhesion to the reaction vessel wall was observed 20 minutes after the start of the dropwise addition, and when the dropwise addition was completed, lumps were suspended in the reaction product, making it impossible to obtain a uniform dispersion, so the reaction was stopped.

Claims (1)

[Claims] 1 Polymerize an aromatic vinyl compound and maleic anhydride using a radical polymerization initiator in an inert organic solvent that dissolves these monomers but does not dissolve the resulting copolymer, resulting in a weight average molecular weight of 10,000.
Molecular weight as a dispersant when obtaining the following copolymers.
A method for producing a copolymer of an aromatic vinyl compound and maleic anhydride, characterized in that a polyalkylene glycol compound of 3000 to 50000 is present in the polymerization system.