JPS60221408A - Production of copolymer - Google Patents

Abstract

PURPOSE:To produce a copolymer having low molecular weight (<=10,000) preventing the deposition of the copolymer to the wall of the reactor, by the radical polymerization of an aromatic vinyl compound and maleic anhydride using a copolymer of an aromatic vinyl compound and maleic anhydride as a dispersant. CONSTITUTION:The objective copolymer having a weight-average molecular weight of <=10,000 can be produced by the copolymerization of an aromatic vinyl compound (preferably styrene) and malieic anhydride using a copolymer of an aromatic vinyl compound (e.g. styrene) and maleic anhydride (preferably having a weight-average molecular weight of 3,000-50,000) wherein the molar ratio of the aromatic vinyl compound S to the maleic anhydride M (S/M) is 2-20, in a solvent (e.g. toluene) which dissolves the monomers but cannot dissolve the resultant copolymer, in the presence of a radical polymerization initiator (e.g. azobisisobutyronitrile).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a copolymer of an aromatic hinyl compound and maleic anhydride, particularly a copolymer having a weight average molecular weight (hereinafter referred to as molecular weight) I
Styrene and anhydrous maro of less than O,000.

1→Beiyu, What are aromatic vinyl compounds and maleic anhydride?
Precipitation polymerization can be carried out using a radical polymerization initiator such as peroxide or an azo compound in a solvent that is inert to these monomers and dissolves the monomers but not the copolymer. . Generally, the copolymer obtained in this way is a polymeric alternating copolymer, with pour point depression 1) I
It is widely used as solid dispersants for coal, dyes, pigments, etc., adhesives, and paper sizing agents. However, if the above-mentioned copolymer has a high molecular bone, the viscosity of the solution will increase, making it difficult to handle, and the performance will deteriorate depending on the application. desired as a product.

Furthermore, in the above precipitation polymerization, when the copolymer precipitates from the solvent, the wall part in the reaction vessel, the stirrer part,
There were disadvantages in that a uniform dispersion liquid could not be obtained due to deposits adhering to and solidifying in the coil portion, etc., or a rock-like mass was formed, and the yield of the copolymer was also significantly reduced.

For this purpose, the use of various dispersants has been considered, but
At present, there are almost no products with sufficiently satisfactory performance, and it is difficult to obtain products with a specified low molecular weight.

The method of the present invention eliminates the above drawbacks by using a specific copolymer compound as a dispersant.

That is, the present invention provides dispersion when copolymerizing an aromatic hynyl compound and maleic anhydride using a radical polymerization initiator in a solvent that dissolves their monomer but does not dissolve the resulting copolymer. Aromatic vinyl compounds (
The molar ratio (S/between) of S) and maleic anhydride) is 2 to
An aromatic vinyl compound having a molecular weight of 10.000 or less and maleic anhydride, characterized by being copolymerized in the presence of a copolymer compound of an aromatic vinyl compound of No. 20 and 71/inic acid anhydride. The present invention provides a method for producing a copolymer.

Examples of the aromatic vinyl compound used in the present invention include styrene, α-methylstyrene, and no-methylstyrene, 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 (On the other hand, any solvent may be used as long as it is an inert and poor solvent, but a solvent that makes the particles of the produced copolymer large and relatively uniform is particularly preferred.

Suitable fJ media include benzene, toluene, xylene/
, the double wound ratio is in the range of I:9 to 321, preferably 1:4 to 1:1.

Examples of the radical polymerization initiator include 7 compounds such as 7/hisine butyronide, benzoyl peroxide, methyl ethyl ketone peroxide, cumene I:I=I
p# peroxide, tanyary-butylperoxy-2
-Organic peroxides such as ethylhexanoate.

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. As a suitable dispersant, the molar ratio (S) of the aromatic vinyl compound (S) and maleic anhydride ((6)
Aromatic vinyl compounds (styrene, α
-methylstyrene, paramethylstyrene) and maleic anhydride. If the molar ratio (S/m) is less than 2, there is no dispersion effect, and if it exceeds 2o, synthesis is difficult and there is no dispersion effect. In this case, the copolymer compound of an aromatic vinyl compound and maleic anhydride means a copolymer having a molecular path of about 3,000 to 50,000, and a copolymer in which the acid anhydride group is modified. A particularly preferred example is a styrene-maleic anhydride copolymer, and its esterified products, amidated products, imidized products, and hydrolyzed products with alkali hydroxide or ammonium can also be used.

The amount of the dispersant used is 01 to 50% by weight, preferably 02 to 5% by weight, based on the total weight of the extender.

If this amount is less than 0.1% by weight, there is no effect of preventing the adhesion of precipitates, and if it is 50% by weight, it is economically disadvantageous and
The quality of the resulting product may be compromised, or the dispersed particles may become too fine to filter, resulting in 1 ton.

Delicious. Furthermore, 5 hours is sufficient for the polymerization time, including the time for gradually adding the monomer to the reaction vessel.

Further, although it is generally thought that the stirring speed affects the dispersion effect, this effect is small in the method of the present invention, and the reaction solution may be stirred at -1 to 8 times.

In carrying out the present invention, first, a solvent containing a dispersant 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 above was added dropwise into the solution, and a uniform dispersion state was maintained throughout the polymerization temperature, preventing the copolymer from adhering inside the reaction vessel. It is easy to take out the copolymer from the reaction container, and the copolymer has good liquid removal properties, so less thermoelectric power is required in the drying process, and at the same time, a dry dispersion can be obtained. , a copolymer of an aromatic hinyl compound with a molecular i of 10,000 or less and maleic anhydride can be produced in good yield.

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. molecule-
was measured by gel permeation chromatography.

Next Example 1 A fc1t flask equipped with a stirring device, a temperature needle, a steam condenser, a nitrogen introduction tube, and a dropping tank was equipped with 354 parts of toluene, 64 parts of maleic anhydride, and a dispersant with a molecular weight of 12,400.
Styrene-maleic anhydride copolymer (molar ratio (S/M)
3) Hafestel compound 1 with C20 alcohol
2 parts were added and the temperature was raised to the boiling point (approximately 11 otl:').

126 parts of toluene, 56 parts of styrene, and 3 parts of benzoyl peroxide were placed in a 300-liter dropping tank, and the mixture was dropped into the flask mentioned above over a period of 2 hours. After the dropping was completed, the humidity was kept at the same level for 3 hours. After cooling, a part of the reaction product was volatilized in a vacuum volatilization furnace at 230C for 30 minutes to collect the remaining solid content.19
It was 2% by weight. The remaining reaction product was easily removed by filtration and dried under vacuum to obtain a solid content. The vacuum-dried solid content was confirmed to be an alternating copolymer of styrene and maleic anhydride by measurements using an infrared spectrophotometer and a nuclear magnetic resonance absorption meter. The molecular weight was 5100, and the vacuum-dried solid yield was 915% by weight.

Example 2 The procedure of Example 1 was repeated except that the dispersant was changed to 12 parts of a styrene and maleic anhydride copolymer (mole ratio (S/M) of 3) with a molecular weight of 12,400. . The residual solid content was 20.Q% by weight, the molecular weight was 4900, and the yield of the vacuum-dried solid content was 913% by weight.

Example 3 The procedure of Example 1 was followed except that the dispersant was changed to 1.2 parts of a styrene and maleic anhydride copolymer (mole ratio (S/M) of 15) with a molecular weight of 19,300. carried out. The total remaining solid content was 202% by weight, the molecular weight was 4300, and the yield of vacuum-dried solids was 913% by weight.
Met.

Comparative Example 1 In Example 1, the dispersant was prepared using dimethylaminopropylene having a molecular weight of 11,000 and a styrene-maleic anhydride copolymer (molar ratio (S/M) of 1). 15 minutes after starting dropping, the bales were observed to be attached to the walls of the reaction vessel, and after another 15 minutes, the bales appeared to be floating in the reaction product, and the amount of adhesion to the walls of the reaction vessel was increasing. Since stirring became difficult, the reaction was stopped 1 hour after starting the dropwise addition.

Comparative Example 2 In Example 1, the dispersant had a molecular weight of 6200 and a styrene/-maleic anhydride co-compound (molar ratio (S/M) of 1).
) The procedure of Example IK was repeated except that 06 parts were used. 10 minutes after starting dropping, adhesion to the reaction vessel wall was observed, and after another 10 minutes, lumps became suspended in the reaction product, making it impossible to obtain a uniform dispersion, so the reaction was stopped. .

Patent applicant: Nippon Oil & Fats Co., Ltd.

Claims (1)

[Claims] When copolymerizing an aromatic vinyl compound and maleinoic anhydride using a radical polymerization initiator in a solvent that dissolves these monomers but does not dissolve the resulting copolymer, the aromatic vinyl compound is used as a dispersant. (Characterized by copolymerization in the presence of a copolymer compound of an aromatic vinyl compound and maleic anhydride in which the molar ratio (S/M) of Sl and maleic anhydride (S/M) is 2 to 20, Weight average molecular weight 1!1
．． A method for producing a copolymer of an aromatic hinyl compound having a molecular weight of 0.000 or less and an-k maleic acid.