JPH08183808A - Suspension polymerization - Google Patents

Abstract

PURPOSE: To obtain a copolymer having an excellent polymn. stability and a uniform particle size distribution by polymerizing an arom. vinyl compd. and an unsatd. nitrile compd. in an aq. suspension contg. a specific suspending agent and a specific suspension aid added thereto. CONSTITUTION: There is prepd. an aq. suspension comprising as the indispensable components (A) an arom. vinyl compd. (e.g. styrene), (B) an unsatd. nitrile compd. (e.g. acrylonitrile), (C) calcium phosphate as a suspending agent, and (D) a saponification product of an alkoxy polyalkyleneoxy phosphate with an alkali (e.g. one of the formula, wherein R is 8-30C alkyl or alkylphenol; and n is 1 to 10) as a suspension aid. The proportions of the components are suitably such that 60-80wt.% component (A) and 40-20wt.% component (B) are used together with 0.2-1 pt.wt. component (C) and 0.001-0.01 pt.wt. component (D), both based on 100 pts.wt. in total of the components (A) and (B). Subsequently, the aq. suspension is subjected to a suspension polymn. reaction to obtain a copolymer of the components (A) and (B). According to the foregoing method, scale deposition in a reactor can be prevented.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a polymer of an aromatic vinyl compound and an unsaturated nitrile compound. More specifically, the present invention, in the aqueous suspension polymerization, by using a specific suspending agent and a suspension aid in combination,
Provided is a method for producing a copolymer having excellent polymerization stability and a uniform particle size distribution.

[0002]

2. Description of the Related Art Conventionally, suspension polymerization, emulsion polymerization, copolymerization of aromatic vinyl compounds and unsaturated nitrile compounds,
Although methods such as bulk polymerization are carried out, an aqueous suspension polymerization method in particular is generally used because of ease of stirring, reaction temperature control and separation. In the aqueous suspension polymerization method,
It is important to prevent agglomeration due to aggregation of oil droplets during polymerization and to maintain a stable dispersed state.

[0003]

Therefore, it is required to prevent the scale from adhering to the polymerization tank and to easily control the particle size of the beads. Therefore, as a result of intensive studies to improve the above points, the present inventor has found a method of carrying out an aqueous suspension polymerization using a specific suspending agent and suspension aid, and arrived at the present invention.

That is, the present invention provides a method for polymerizing an aromatic vinyl compound and an unsaturated nitrile compound in an aqueous suspension, wherein calcium phosphate is used as a suspending agent and alkoxypolyalkylene is used as a suspending agent in the aqueous suspension. The present invention relates to a suspension polymerization method using a saponified product of oxyphosphate and alkali.

[0005]

As the aromatic vinyl compound used in the method of the present invention, styrene, o-ethylstyrene, o-chlorostyrene, p-chlorostyrene, α-
Methylstyrene, o-bromostyrene, or a mixture thereof may be used.

Examples of unsaturated nitrile compounds include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, vinylidene cyanide, and mixtures thereof.

Further, in the method of the present invention, a small amount of a copolymerizable vinyl compound such as acrylic acid ester, methacrylic acid ester, and maleimide is added as another compound for modifying the resulting copolymer. It doesn't matter.

In the method of the present invention, the mixing ratio of the aromatic vinyl compound and the unsaturated nitrile compound is 60 to 80% by weight of the aromatic vinyl compound and 40 to 20% by weight of the unsaturated nitrile compound based on the total amount of both. % Range is preferred. Particularly, the range of 70 to 80% by weight of the aromatic vinyl compound and 30 to 20% by weight of the unsaturated nitrile compound is preferable. If the mixing ratio of the aromatic vinyl compound and the unsaturated nitrile compound is out of the above range, the moldability of the copolymer and the thermal stability during molding are deteriorated, which is not practical.

Further, a saponification product of an alkoxypolyalkylene oxyphosphate and an alkali is used as a suspension aid.

In the method of the present invention, it is important to use the above-mentioned suspending agent and suspension aid together. As a saponified product of an alkoxypolyalkylene oxyphosphate and an alkali, for example, a compound represented by the following general formula is effective.

[0011]

Embedded image Examples of the compound include a saponified product of a compound commercially available from Toho Chemical Industry under the name of "phosphanol" and an alkali such as potassium or sodium.

In the method of the present invention, the amount of the suspending agent used is preferably 0.2 to 1.0 part by weight based on 100 parts by weight of the mixture of the raw material aromatic vinyl compound and unsaturated nitrile compound. Even if the amount used is larger than this, there is no change in the suspended state, and if the amount used is small, the produced polymer is solidified.

The amount of the suspension aid used is preferably 0.001 to 0.01 parts by weight based on 100 parts by weight of the raw material mixture of the aromatic vinyl compound and the unsaturated nitrile compound which are the raw materials. If the amount used is larger than this, the produced polymer will be solidified, and if the amount used is small, the effect will not be exhibited.

The process according to the invention is prepared by adding the abovementioned amounts of suspending agents and suspending aids to the dispersion medium, water. The total amount of water is preferably selected from about 30 to 500 parts by weight with respect to 100 parts by weight of the raw material mixture.

As the polymerization initiator used in the method of the present invention, a conventional polymerization initiator such as benzoyl peroxide, 2,2'-azobisisobutyronitrile, 1-t- is used.
Butylazo-1-cyanocyclohexane, 1,1′-azobiscyclohexanecarbonitrile, 2-t-butylazo-1-cyanobutane and the like can be mentioned.

The polymerization initiator can be added to the reaction system all at once or continuously. The amount and method of use are not particularly limited, but generally, the polymerization initiator is generally used in an amount of 0.05 to 0.5 parts by weight with respect to 100 parts by weight of the raw material.

Known molecular regulators can be used. For example, halogenated alkyl, alkyl sulfide, isotetralin, terpinolene, alkyl mercaptan and the like are preferable. In addition, known lubricants, plasticizers, antioxidants, coloring agents, foaming agents and the like may be used.

In the polymerization reaction of the method of the present invention, the reaction is usually started at about room temperature and gradually raised to 80 to 80 ° C.
The copolymer particles can be obtained by performing the treatment at 140 ° C. for about 5 to 20 hours. The copolymer particles separated by filtration from the aqueous medium can be taken out by washing with an acid such as dilute hydrochloric acid and warm water and drying.

The copolymer obtained by this polymerization reaction is a copolymer obtained from an aromatic vinyl compound and an unsaturated nitrile compound, and examples thereof include styrene-acrylonitrile polymer and ethylstyrene-acrylonitrile polymer. As described above, by carrying out the method of the present invention, it becomes possible to prevent the scale from adhering to the polymerization tank and to easily control the particle diameter of the beads.

[0020]

EXAMPLES Next, the method of the present invention will be specifically described by way of examples.

Example 1 In a 5 L glass-lined autoclave equipped with a turbine stirrer, 75 parts by weight of styrene monomer, 25 parts by weight of acrylonitrile monomer, 100 parts by weight of pure water, 0.5 parts by weight of calcium phosphate, and phosphanol (having 15 carbon atoms). Of alkyl group) and potassium saponified 0.00
4 parts by weight and 0.3 parts by weight of benzoyl peroxide are added,
The suspension polymerization reaction was carried out at 90 ° C. for 10 hours while stirring at 350 rpm. In carrying out this reaction, a stainless steel (SUS316) test piece (30 mm) was placed in the autoclave for the purpose of measuring the amount of scale attached in advance.
× 7 mm × 2 mm) was put and placed. After the reaction was completed, the copolymer was taken out from the autoclave, the polymer beads were separated and obtained by a centrifuge, washed with hydrochloric acid, washed with water, and then dried to obtain a styrene-acrylonitrile polymer (AS polymer beads). Table 1 shows the adhesion amount and particle size of the scale at that time.

Examples 2-4 and Comparative Examples 1, 2 The same amounts of styrene monomer, acrylonitrile monomer, pure water and benzoyl peroxide as in Example 1 were used except that the suspending agent and the suspending aid were changed. Polymerization reaction was carried out under the same conditions. Table 1 shows the results.

[0023]

[Table 1]

[0024]

By carrying out the method of the present invention, it is possible to prevent the scale from adhering to the reactor and to obtain a polymer having an average particle size which is excellent in polymerization stability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Matsuda Oki, Ube City, Yamaguchi Prefecture Ube-oki Okiyama 525-14 Ube Plant, Ube Plant (72) Inventor Junkyu Hisabu Oguchi, Ube City, Yamaguchi Prefecture Mountain 525-14 Ube Computer Corporation Ube Factory

Claims (3)

[Claims] 1. A method of polymerizing an aromatic vinyl compound and an unsaturated nitrile compound in an aqueous suspension, wherein calcium phosphate is used as a suspending agent in the aqueous suspension, and alkoxypolyalkylene oxyphosphate is used as a suspending agent. A suspension polymerization method comprising using a saponified product with an alkali. 2. The suspension polymerization method according to claim 1, wherein the aromatic vinyl compound is 60 to 80% by weight and the unsaturated nitrile compound is 40 to 20% by weight. 3. The amount of calcium phosphate used is 0.2 to 1 part by weight, and the saponification product of alkoxypolyethylene oxyphosphate and potassium is 0.001 with respect to 100 parts by weight of the aromatic vinyl compound and the unsaturated nitrile compound.
The suspension polymerization method according to claim 1, wherein the suspension polymerization method is from 0.01 to 0.01.