JPS60231710A - Production of copolymer - Google Patents

Abstract

PURPOSE:To obtain a copolymer of a predetermined low MW in good yields, by copolymerizing an aromatic vinyl compound with maleic anhydride in a solvent in which the copolymer is not soluble by using a radical polymerization initiator and a specified dispersant. CONSTITUTION:An aromatic vinyl compound (e.g., styrene) is copolymerized with maleic anhydride in a solvent in which the monomers are soluble but the formed copolymer is not soluble (e.g., toluene) by using a radical polymerization initiator and a dispersant comprising a copolymer containing repeating units of formula I (wherein R1 is H or CH3, R2 is a lower alkyl, acyl or the like, X is H, a group of formula II and n is 1-30) in the main chain. In this way, the purpose copolymer having a weight-average MW<=10,000 is obtained. The copolymer having repeating units of formula I can be obtained by copolymerizing a monomer of formula III (e.g., methoxycarbitol acrylate) with another vinyl monomer (e.g., methyl acrylate).

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 1
The present invention relates to a method suitable for producing a copolymer of styrene and maleic anhydride with a molecular weight of 0,000 or less.

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 9 is high, the viscosity of the solution becomes high, making it difficult to handle, and the performance may deteriorate depending on the application, so copolymers with a molecular weight of 10,000 or less are used as products. desired.

Furthermore, in the above precipitation polymerization, when the copolymer precipitates 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 agglomerates 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 eliminates the above drawbacks by using a specific copolymer as a dispersant.

That is, the present invention provides dispersion 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. A copolymer containing repeating units represented by the following general formula (1) in the main chain is used as an agent at ℃・
The present invention provides a method for producing a copolymer of an aromatic vinyl compound having a molecular weight of 10,000 or less and maleic anhydride, which is characterized by the following.

General formula % Formula % (1) () 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 to and a poor solvent; however, a solvent that makes the particles of the copolymer formed are large and relatively uniform is particularly preferred. Suitable solvents include aromatic solvents such as, for example, benzene, toluene, xylene, ethylbenzene, kume/balasimene, and the like. The ratio of total heat to solvent is 1 by weight.
:9 to 3=1, preferably I:4 to ]:1.

Examples of the radical polymerization initiator include ab compounds such as anohisisobutyronitrile, ben/yl peroxide, methyl ethyl ketonovel oxide, cumene hydroperoxide, tert-butyl peroxy-2-ethylhexanoate, 2,5-dimethyl-2 , 5-no(benzoylperoxy)hexane and other organic peroxides.

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 copolymer containing the repeating unit represented by the general formula (1) in the main chain, which is the dispersant used in the present invention, is a copolymer containing a repeating unit represented by the general formula (1) above and a monomer having the structure represented by the following general formula (2) and another vinyl heptad polymer. It can be obtained by radical copolymerization of

For example, (meth)acrylate or malate (fumarate) of methoxycarpitol, (meth)acrylate or malate (fumarate) of methoxytriethylene glycol,
fumarate), and methoxypolyethylene glycol with an increased number of repeating ethylene glycol units (
meth)acrylate or malate (fumarate),
Examples include (meth)acrylate or malate (fumarate) of acetoxytetraethylene glycol.

The partner monomer for copolymerization may be a radically polymerizable vinyl monomer that is insoluble in water and does not have a free hydroxyl group.

Styrene derivatives such as styrene and P-methylstyrene; dimethyl maleate (fumarate), dibutyl maleate (fumarate), diisopropyl maleate (fumarate); and alkyl itaconates.

The above-mentioned copolymer used in the present invention is characterized in that the monomer of general formula (2) is water-soluble, and the monomer to be copolymerized with it is hydrophobic.

For this reason, the molecular form of the copolymer differs depending on the solvent. For example, in a hydrophobic solvent such as toluene or xylene, the water-soluble groups in the copolymer become unstable and may aggregate with each other, or otherwise become hydrophilic. If a functional group exists, it will try to stabilize it by adsorbing it there. Therefore, when an aromatic vinyl compound and maleic anhydride are synthesized in a solvent in which the polymer is insoluble, the hydrophilic acid anhydride group of the resulting polymer causes the water-soluble group to adsorb thereto, and the hydrophobic group on the opposite side It is believed that stable coated polymer particles are produced.

In addition to random copolymers, the copolymer used as a dispersant in the present invention also exhibits excellent dispersant functions in the case of a Plutz copolymer, which has a continuous structure in which the water-soluble group moiety is continuous in the molecule. do.

Random copolymers can be easily obtained by solution polymerization, bulk polymerization, suspension polymerization, etc. using conventional radical catalysts. The synthesis of the 7' lock copolymer was published in Japanese Patent Application Publication No. 58-747.
58) etc.

The dispersant used in the present invention is represented by the general formula (1) and contains repeat units in the copolymer in an amount of [0 to 90% by weight, preferably 20 to 60% by weight,
A value of 0.000 is preferred.

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

If this amount is less than 0.1% by weight, there is no effect of preventing the adhesion of deposits, and if it exceeds 50% by weight, it is economically disadvantageous.
c. The quality of the resulting product may be impaired, or the dispersed particles may become too fine, resulting in a P disaster.

The polymerization temperature is about 80 to 200 [preferably about 90 to 14
0C and preferably constant during the polymerization time. Also,
The polymerization time is not particularly limited, but the monomer is gradually added to the reaction vessel (about 5 hours including the polymerization time is sufficient).

Furthermore, although stirring speed is generally considered to have an influence on the dispersion effect, this influence 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 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, the copolymer is cooled, and the produced copolymer is sent from house to house and then dried to obtain the copolymer that is the object of the present invention.

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, and there is no adhesion of the copolymer inside the reaction vessel. Therefore, the copolymer can be easily taken out from the reaction vessel, and the copolymer has good liquid removal properties, so the amount of heat required in the drying process is small, and the drying equipment 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 specifically explained using production examples, working examples, and comparative examples, but the present invention is not limited thereto. Molecular weight was measured by gel permeation chromatography.

Production Example 1 [Synthesis of random copolymer used as dispersant] Add 100y of xyleno to a flask with a stirrer.

M-9G (manufactured by Shin Nakamura Chemical ■, in general formula (2), X=
H, R, = CH3, n = 9, R2 = CH3 compound product name) 611t, methyl methacrylate 40y, 7
1.0 y of zohisinft nitrile was charged and stirred for 800.5 hours under a nitrogen stream to obtain a copolymer solution.

The copolymer obtained by pouring this solution into a large amount of hexane and precipitating it was a transparent, highly viscous substance in a dry state, and was a random copolymer with a molecular weight of 35,000.

Production Example 2 [Synthesis of block copolymer used as a dispersant] In a flask equipped with a stirrer, 20 y of gtylacetate, 10 y of n-butanol, 30 y of acetoxytetraethylene glycol methacrylate (A), 2,2,5-dimethyl-2
,5-di(benozoylberoxy)hexane 0.6 y
was charged, the temperature was raised to 80CK while blowing nitrogen, and after stirring at the same temperature for 3 hours, 2,5-dimethyl-2,s-2(
01 part of penzoylperoxy)hexane was added, and stirring was continued at the same temperature for 2 hours.

Next, a mixed solution of 407 y of butyl acetate, 20 y of xylene, 10 y of n-butanol, and 70 y of styrene (B) was added, the temperature was raised to 100 C, and after stirring for 5 hours, the polymerization reaction was completed after further stirring at 120 C for 1 hour. I let it happen.

This reaction solution was slowly poured into a large amount of hexane to precipitate a copolymer to obtain an AB type block copolymer consisting of the above monomers (AJ, (II). Its molecular weight was 7.
0. It was OOO.

Example 1 In a 1t flask equipped with a stirrer, a thermometer, a steam condenser, a nitrogen inlet pipe, and a dropping tank, 354 y of toluene, 64 y of maleic anhydride, and 60 y of the random copolymer synthesized in Production Example 1 as a dispersant were added. The temperature was raised to about 110 tl' while stirring.

Next, 7-pool peroxide 3y was placed in a 300 ml dropping tank K)z+=F 1267° styrene 56y1 and dripped into the flask at Kami Station over 2 hours. After the dropwise addition was completed, the same temperature was maintained for 3 hours. During this time, the produced polymer precipitated to become a milky white slurry, and the stirring state of the reaction solution was extremely smooth. After cooling, the reaction product can be easily removed by filtration, which is vacuum dried and subjected to II9. A solid content of OF was obtained.

The vacuum-dried solid content was confirmed to be a copolymer of styrene and maleic anhydride by measurements using an infrared spectrometer and a nuclear magnetic resonance absorption meter. The molecular weight is 4. s o o
Met.

Example 2 In Example 1, a 20:80 (weight ratio) random copolymer of di(methoxycarpitol) malate and styrene (molecular weight 12) synthesized according to Production Example IK was used as a dispersant.
．． 000 ) 4.87 was used, but the same procedure as in Example 1 was carried out. Stirring of the reaction solution was extremely smooth, and filtration of the reaction product was also easy. The yield of solid matter obtained by vacuum drying was 119.9y, and its molecular weight was 6.9y.
It was OOO.

Example 3 The procedure of Example 1 was repeated except that the block copolymer 4.2y synthesized in Production Example 2 was used as a dispersant. Stirring of the reaction solution is extremely smooth;
Filtration of the reaction product was also easy. The solid content obtained by vacuum drying was 119.5y, and its molecular weight was 4.0.
It was 00.

Comparative Example 1 was carried out in accordance with Example 1, except that no multilayer dispersant was used. Adhesion of the polymer formed on the container wall was observed 10 minutes after the start of dropping, and as the dropping progressed, it became more noticeable. When about half of the liquid in the dripping 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, a polymer of stearyl methacrylate was used as a dispersant.
The procedure of Example 1 was carried out except that .

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

Patent applicant: NOF Corporation

Claims (1)

[Claims] 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, A copolymer of an aromatic vinyl compound with a weight average molecular weight of 10° OOO or less and maleic anhydride, characterized in that a copolymer containing repeating units represented by the following general formula (1) in the main chain is used as an agent. Coalescence manufacturing method. General formula % formula %