JPS60226517A - Preparation of copolymer - Google Patents

Abstract

PURPOSE:To obtain a copolymer having a low molecular weight (<=10,000) in high yield by smooth reaction, by radically copolymerizing an aromatic vinyl compound with maleic anhydride in the presence of polyvinyl butyral resin as a dispersing agent. CONSTITUTION:An aromatic vinyl compound, preferably styrene is copolymerized with maleic anhydride in the presence of a radical polymerization initiator and a polyvinyl butyral resin of the formula (usually having 5,000-300,000 mol.wt as a dispersing agent in a solvent capable of dissolving the monomers but not dissolving the resultant copolymer, preferably at 90-140 deg.C constant temperature to afford the aimed copolymer having <=10,000 weight-average molecular weight. The amount of the dispersing agent to be used is preferably 0.2- 5wt% based on the total amount of the monomers.

Description

Detailed Description of the Invention The present invention provides a copolymer of an aromatic vinyl compound and maleic anhydride, particularly a copolymer having a weight average molecular weight (hereinafter referred to as molecular weight) of 10.
,000 or less and a method suitable for producing a copolymer of styrene and maleic anhydride.

Aromatic vinyl compounds and maleic anhydride are inert to these monomers, and can be radically polymerized with peroxides or azo compounds in a solvent that dissolves the monomers but not the copolymer. Precipitation polymerization can be carried out using an initiator. Generally, the copolymers thus obtained are high molecular weight alternating copolymers, containing pour point depressants, coal, dyes,
It is widely used as a solid dispersant for pigments, adhesives, and paper sizing agents. However, if the molecular weight of the above-mentioned copolymer is high, the viscosity of the solution becomes high, making it difficult to handle, and depending on the application, the performance may deteriorate, so copolymers with a molecular weight of 10,000 or less are desired as products. ing.

Furthermore, in the above precipitation polymerization, when the copolymer is precipitated from the solvent, the wall portion in the reaction vessel, the stirrer portion,
This method has disadvantages in that a uniform dispersion cannot be obtained because precipitates adhere to and solidify in the coil portion, or block-like solids are formed, and the yield of the copolymer is 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 uses a specific copolymer as a dispersant.

That is, the present invention is characterized in that a polyvinyl butyral resin is used in which an aromatic vinyl compound and maleic anhydride are dissolved in these monomers, and the molecular weight is 10. The present invention provides a method for producing a copolymer of OOO or less aromatic vinyl 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 (i.e., aromatic vinyl compound and maleic anhydride), and Any solvent may be used as long as it is inert to the polymer and is a poor solvent, but aromatic solvents such as tilbenzene, cumene, and paracymene are used because the particles of the copolymer produced are large. The ratio of the total amount of monomers to the solvent is 1:9 to 3:1 by weight, preferably 1:4 to 1:azo compound such as tyronitrile, benzoyl peroxide,
Examples include organic peroxides such as methyl ethyl ketonovel oxide, cumene hydroperoxide, and tert-butyl peroxy-2-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. The polyvinyl butyral resin used in the present invention as a suitable dispersant is a polyvinyl alcohol derivative represented by the following general formula, which is obtained by reacting polyvinyl alcohol obtained by saponifying polyvinyl acetate with butyraldehyde. It is. In this case, trm and n are arbitrary, but those having a molecular weight of about 5,000 to 300,000 are generally commercially available or can be obtained by synthesis, and both can be preferably used in the present invention.

The amount of dispersant used is 0.61 to 50% based on the total amount of monomers.
The weight percent is preferably 0.2 to 5 weight percent.

If this amount is less than 0.1% by weight, there is no effect of preventing the adhesion of precipitates, and if it exceeds 50% by weight, it is economically disadvantageous and
This may impair the quality of the resulting product or make the dispersed particles too fine to filter.

The polymerization temperature is about 80 to 200"C, preferably about 90 to 1
Desirably, the temperature is 40°C and remains constant during the polymerization time. Furthermore, 5 hours is sufficient for the polymerization time, including the time for gradually adding the monomer to the reaction vessel.

Furthermore, although stirring speed is generally thought to affect the dispersion effect, this effect is small in the method of the present invention, and stirring to the extent that the reaction solution is moved is sufficient.

In carrying out the present invention, first, a solvent in which a dispersant is dissolved and maleic anhydride are placed in 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, the dispersion is cooled and produced. In the method of the present invention, a specific dispersant is dissolved in a solvent before polymerization, so a uniform dispersion state is maintained from the beginning to the end of the reaction. There is no adhesion of the copolymer inside the container, it is easy to take out the copolymer from the reaction container, and the copolymer has good liquid removal properties, which reduces the amount of heat required in the drying process. , the drying device can also be made smaller.

According to the method of the present invention, by using a specific dispersant, the polymerization reaction proceeds smoothly and a thick, uniform dispersion liquid is obtained. Polymers can be produced with good yield.

Hereinafter, the present invention will be explained in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these. The molecular weight was measured by gel permeator chromatography.

Example 1 A 117Y Scooter equipped with a stirring device, temperature It, a steam condenser, a nitrogen introduction tank, and a dropping tank was equipped with toluene 354-/, maleic anhydride 64J', S-LEC BL-1 (butyral resin manufactured by Tsukisui Kagaku Kogyo ■): 63 moles of butyral groups4)6.
The temperature was raised to the boiling point (approximately 110"C) while stirring. Next, toluene 126F and styrene 56t% were added.
Incyl peroxide 3. Mix the OI at room temperature,
0 m/dropping tank, and 2. into the flask below the boiling point.
It was added dropwise at 0 hours. After the dropping was completed, the mixture was kept in the same temperature eaves for 3.0 hours.

During this time, the produced polymer precipitated and turned into a milky white slurry, and the reaction solution was stirred very smoothly. Furthermore, the resulting polymer after cooling was extremely easy to filter, and was dried under vacuum to obtain a dry polymer of 119.8P.

This polymer was confirmed to be a styrene-maleic anhydride copolymer by infrared absorption spectrum and nuclear magnetic resonance absorption spectrum. Moreover, its molecular weight was 6,900.

Example 2 The same procedure was carried out in the same shuttle as in Example 1, except that Eslec BM-8 (butyral resin manufactured by Block Chemical Industry Co., Ltd., butyral group 70 mole or more) 4.8J' was used instead of Esle and BL-1+D. I did it. Stirring of the system during polymerization was extremely smooth, and filtration of the produced polymer was extremely easy. The yield of dry boria is 119.57', its molecule lt is 5
It was 300.

Comparative Example 1 Example 1 was carried out except that no dispersant was used. 10 minutes after the start of dropping, the produced polymer was observed to adhere to the container wall, and as the dropping progressed, this became more noticeable. When about half of the liquid in the dropping tank was dropped, the precipitated polymer covered the entire surface of the container wall and the stirring blade. The reaction was stopped because it became impossible to stir.

Comparative Example 2 In Example 1, vinyl acetate polymer 6. with a molecular weight of about 40,000 was added to S-LEC BL-1 glue 9 as a dispersant. The procedure of Example 1 was followed except that OP was used.

20 minutes after the start of dropping, adhesion of the produced polymer to the container wall was observed, which became more noticeable as the dropping progressed, and near the end of the dropping, the deposited polymer was so attached that it was difficult to continue the reaction, so the reaction was stopped.

Patent applicant Nippon Oil & Fats Co., Ltd.

Claims (1)

[Claims] Polyvinyl butyral resin is used as a dispersant when copolymerizing an aromatic vinyl compound and maleic anhydride using a radical polymerization initiator in a solvent that dissolves these monomers but does not dissolve the resulting copolymer. 1. A method for producing a copolymer of an aromatic vinyl compound having a weight average molecular weight of 10,000 or less and maleic anhydride, the method comprising using the following.