JPH0377204B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to an improved continuous production method for styrene-acrylonitrile copolymers. More specifically, when producing a styrene-acrylonitrile copolymer using a continuous bulk or solution polymerization method, the higher fatty acid amide is continuously supplied to the polymerization apparatus in a dissolved or molten state. The present invention relates to a method that prevents adhesion of gel-like polymers and also improves the fluidity of the resulting copolymer resin. Conventional technology Generally polystyrene (GP-PS), styrene-
Styrenic resins such as acrylonitrile copolymer (AS), rubber-modified polystyrene (HI-PS), and styrene-acrylonitrile-butadiene copolymer (ABS) have various properties such as strength, rigidity, moldability, and dimensional stability. It is used for a wide range of purposes because of its well-balanced properties. Suspension polymerization, bulk-suspension polymerization, and emulsion polymerization have generally been adopted as methods for manufacturing these styrenic resins, but recently continuous bulk polymerization or solution polymerization has been adopted due to cost and pollution concerns. It has become widely adopted due to the fact that it produces fewer waste materials. However, AS,
When styrene-acrylonitrile copolymers such as ABS are manufactured continuously by bulk or solution polymerization, unlike when manufacturing styrene resins, gel-like polymer builds up in the polymerization tank when the equipment is continuously operated for a long time. The gel-like polymer adheres to the product and reduces the heat transfer capacity and volume of the polymerization tank, impairing operational stability and production capacity. At the same time, some of the gel-like polymer is mixed into the product, significantly reducing the commercial value of the final product. . Therefore, the continuous operation time of the device is shortened,
The operation must be stopped to wash and remove the gel-like polymer, and this washing and removal requires a great deal of time and effort, which has forced a reduction in operating efficiency. A method to improve these problems is, for example, by controlling the amount of water contained in the raw material to 200 to 520 ppm and continuously feeding it to a continuous bulk polymerization system of styrene-acrylonitrile copolymer. There is a method to reduce the formation of polymers (Japanese Unexamined Patent Publication No. 1987-
25310). Also, "Petroleum and Petrochemistry" regarding methods for preventing and removing scale adhesion in general polymerization processes.
Vol20, No.12.P28, Vol21, No.1, P54, Vol21,
No.3, P50, Vol21, No.4.P62, Vol24, No.8,
P70, Vol24, No.9, P62, Vol24, No.10, P62,
Vol.24, No.11, P46 introduces various technologies.
These methods require the use of special equipment or the application or addition of special chemicals, and may not necessarily take advantage of the advantages of continuous bulk or solution polymerization. On the other hand, higher fatty acid amides are generally widely used for styrenic resins, either alone or in combination with other compounds, for the purpose of improving moldability. A method of kneading is used. (For example, Special Publication No. 47-37495). Problems to be Solved by the Invention The present inventors have developed a method to prevent gel-like polymers from adhering to polymerization equipment when continuously producing styrene-acrylonitrile copolymers using bulk polymerization or solution polymerization methods, As a result of intensive studies with the aim of achieving stable operation over time, we found that by continuously supplying higher fatty acid amide, which is commonly used as an additive for styrenic resins, to the polymerization equipment in a dissolved or molten state, we were able to achieve the above objectives. The present invention was achieved by discovering that the present invention can be achieved. Moreover, the fluidity of the resin obtained by adding the above compound to the styrene-acrylonitrile copolymer by the above method is also improved. Means for solving the problems, that is, the present invention provides aromatic vinyl monomers 97 to 50
Styrene is produced by continuous bulk or solution polymerization of a monomer mixture consisting of 3 to 50% by weight of vinyl cyanide monomer or a monomer mixture in which a rubbery polymer is dissolved in this monomer mixture. When producing an acrylonitrile copolymer, the general formula R ₁ CONHR' or R ₂ CONHR''NHCOR ₃ (where R ₁ , R ₂ , R ₃ are alkyl groups having 8 to 22 carbon atoms, R' is hydrogen or oxymethyl (R" is a methylene group or an ethylene group) is continuously supplied to the polymerization apparatus in a dissolved or molten state in an amount of 0.1 to 3.0 parts by weight per 100 parts by weight of the reaction solution. The present invention provides a method for continuously producing a characteristic styrene-acrylonitrile copolymer. As the aromatic vinyl monomer in the present invention, styrene is usually used, but if necessary, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, o-methylstyrene,
- tertiary butyl styrene, m-tertiary butyl styrene, p-tertiary butyl styrene,
Halogen-substituted styrenes such as chlorostyrene and bromustyrene can be used alone or in mixtures. Acrylonitrile is usually used as the vinyl cyanide monomer, but methacrylonitrile, α-chloroacrylonitrile, etc. can be used alone or as a mixture if necessary. The proportion of vinyl cyanide monomer in the monomer mixture is preferably 3 to 50% by weight, particularly 10 to 45% by weight. When the vinyl cyanide content is 3% by weight or less, no formation or adhesion of gel-like polymer is observed even without the method of the present invention, and when the vinyl cyanide content is 45% by weight or more, the resulting styrene-acrylonitrile Copolymers have poor fluidity and poor hue, and are not often used as general molding materials. In addition to the aromatic vinyl monomer and the vinyl cyanide monomer, copolymerizable monomers such as methyl methacrylate, methyl acrylate, methacrylic acid, and maleic anhydride may be added as necessary. Polymerization may also be carried out by dissolving a rubbery polymer in a mixture of these monomers. In this case, the rubbery polymer may be any polymer that can be dissolved in these monomers, such as butadiene. Rubber, styrene-butadiene copolymer rubber, acrylonitrile-butadiene copolymer rubber, chloroprene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, etc. can be used. In the present invention, in addition to the above monomer mixture or the monomer mixture in which the rubbery polymer is dissolved, solvents such as ethylbenzene, toluene, and methyl ethyl ketone, molecular weight regulators such as mercaptans, and phenol-based or phosphorus-based Stabilizers and the like may also be added. In the present invention, the continuous bulk or solution polymerization method refers to a raw material solution containing the monomer mixture described above that is continuously supplied to one or more polymerization tanks to carry out a polymerization reaction and complete the polymerization. This is a method in which the reaction solution is continuously extracted, unreacted monomers and solvent are devolatilized under high temperature and high vacuum, and then the resin is pelletized using an extruder or the like. The higher fatty acid amide used in the present invention has the general formula R ₁ CONHR' or R ₂ CONHR''NHCOR ₃ (wherein R ₁ , R ₂ , and R ₃ are alkyl groups having 8 to 22 carbon atoms, and R' is hydrogen or oxymethyl The group R'' must be an amide compound represented by a methylene group or an ethylene group. Compounds represented by the above general formula include oleic acid amide, lauric acid amide, stearic acid amide,
Examples include behenic acid amide, methylene bis lauric acid amide, ethylene bis lauric acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, methylene bis behenic acid amide, and ethylene bis behenic acid amide. Since these higher fatty acid amides are usually solid at room temperature and are difficult to dissolve in monomers or solvents at room temperature, they are preferably supplied in a molten state at a temperature equal to or higher than the melting point of the compound. Alternatively, the compound may be added to a monomer or a solvent, heated, and then supplied in a dissolved state. The amount of higher fatty acid amide supplied is 0.1 to 100 parts by weight of the continuously flowing reaction solution.
3.0 parts by weight, particularly preferably 0.3 to 2.5 parts by weight. If it is less than 0.1 part by weight, the prevention effect of gel polymer adhesion is not sufficient, and if it is more than 3.0 parts by weight,
Adding more than that will not further improve the effect. The higher fatty acid amide is preferably added to a polymerization apparatus, particularly a polymerization tank. By adding it to the polymerization tank, it is possible to prevent the gel-like polymer from adhering there, and at the same time, even if the amount added is large, it will mix with the reaction liquid in the polymerization tank, so it will not be possible to mix it with an extruder etc. It also has the advantage of being able to be added in sufficient amounts even in the most severe cases. This higher fatty acid amide functions not as an impurity of the resin but as a modifier, so there is almost no problem even if it is included in the resin. Furthermore, even if it is added to the polymerization tank, it has almost no effect on polymerization behavior such as polymerization rate. Effects According to the present invention, it is possible to prevent the gel-like polymer from adhering to the polymerization equipment, and therefore the continuous operation time can be extended, making the most of the merits of continuous polymerization and efficiently producing styrene. Acrylonitrile copolymers can be produced. Furthermore, according to the present invention, the compound added to prevent adhesion of the gel-like polymer acts not as an impurity in the resin but also as a modifier for the resin, and the fluidity of the resin can also be improved depending on the amount added. EXAMPLES The present invention will be further explained below with reference to Examples, but the present invention is not limited to these Examples. In the following, parts and % indicate parts by weight and % by weight. Example 1 A mixture of 60.0 parts of styrene, 20.0 parts of acrylonitrile, and 20.0 parts of ethylbenzene was used as a raw material solution, and after adding 0.1 part of tertiarydodecyl mercaptan to this raw material solution, a volume equipped with a screw type stirring blade with a draft tube was prepared. It was continuously fed to 18 first polymerization tanks at a rate of 15/HR. After polymerization was carried out at 135° C. in the first polymerization tank, the resulting reaction solution was continuously taken out from the polymerization tank and supplied to the second polymerization tank. The second polymerization tank was also of the same type as the first. Furthermore, the reaction solution polymerized in the second polymerization tank is continuously taken out and sequentially supplied to the third, fourth, and fifth polymerization tanks, and polymerization is carried out so that the polymerization rate in the fifth polymerization tank is 80%. continued. The third, fourth, and fifth polymerization tanks were also of the same type as the first and second polymerization tanks. During this polymerization reaction, ethylene bisstearic acid amide was melted at 160°C as a higher fatty acid amide, and the first melt was continuously added at a rate of 65 g/HR using a plunger pump equipped with a jacket so that the amount was 0.5 parts per 100 parts of the reaction solution. It was supplied to a polymerization tank and mixed with the reaction solution. The reaction solution continuously taken out from the fifth polymerization tank is used to remove unreacted monomers and solvent using a conventionally known devolatilization device, and then the resin component is continuously supplied to the extruder. This was pelletized to obtain AS resin. This device was operated continuously for 700 hours under the same conditions, but no change was observed in the product obtained. Furthermore, it was obtained
The AS resin contains 0.8% ethylene bis stearamide, and has the same molecular weight but better fluidity than the resin shown in Comparative Example 1 below when ethylene bis stearamide is not supplied. .
When the polymerization tank was inspected after the continuous operation, almost no gel-like polymer was observed. Summarize the results in a table. The results of the following Examples and Comparative Examples are also summarized in a table. Comparative Example 1 AS was carried out in the same manner as in Example 1 except that ethylene bisstearamide was not supplied to the polymerization apparatus.
produced resin. Similarly, continuous operation was carried out for 700 hours, but after about 200 hours from the start of operation, phenomena such as a drop in the external temperature of the polymerization tank and a decrease in production volume began to occur. When the obtained product was molded into a molded object using a molding machine, it was found that 200
Thin stripes were observed in the molded product obtained after the lapse of time. Further, when the polymerization tanks were inspected after the continuous operation was completed, gel-like polymer was found to be attached to the inner walls of the polymerization tanks from the first to the fifth polymerization tanks. The gel-like polymer adhered to the fifth polymerization tank was collected, and approximately
850 mg of gel-like polymer was collected, and this gel-like polymer was insoluble in methyl ethyl ketone, the solvent for AS resin. Example 2 Instead of ethylene bisstearamide,
The AS
produced resin. Continuous operation was carried out for 700 hours in the same manner as in Example 1, but no change was observed in the obtained product, and almost no gel-like polymer was observed to adhere to the inside of the polymerization tank. Example 3 The raw material solution used was 47.0 parts of styrene, 33.0 parts of acrylonitrile, 20.0 parts of ethylbenzene, and 0.2 parts of tertiarydodecyl mercaptan, and the polymerization temperature in the first polymerization tank was set at 132°C.
It was carried out in the same manner as in Example 1. However, styrene was continuously added to adjust the composition of unreacted styrene/acrylonitrile to 59/41 (weight ratio) at the inlet of each of the second to fifth polymerization tanks. Even after 700 hours of continuous operation, no change was observed in the obtained product, and there was almost no adhesion of gel-like polymer inside the polymerization tank. Example 4 6.0 parts of polybutadiene "Asaprene 700A"
(Product name: Asahi Kasei), 55.5 parts of styrene, 18.5 parts of
1 part acrylonitrile and 20.0 parts ethylbenzene to prepare a raw material solution. This raw material solution contains 0.1 part of tertiary dodecyl mercaptan and 0.02 part of benzoyl peroxide as a radical polymerization initiator.
After adding 0.2 parts of 2,6-dithyabutylphenol as an antioxidant, ABS resin was continuously produced in the same manner using the same equipment as in Example 1. The amount of raw material solution supplied to the first polymerization tank is 15
/HR, the polymerization temperature in the first polymerization tank was 110°C, and polymerization was carried out in the second and subsequent polymerization tanks so that the polymerization rate in the final polymerization tank was 73%. Also, add ethylene bisstearamide to 1.0 parts per 100 parts of the reaction solution.
was continuously supplied to the first polymerization tank at a rate of 130 g/HR to mix with the reaction solution. The resulting product was an ABS resin containing 10% rubber component and 1.6% ethylene bisstearamide. Long-term operation was performed for 700 hours under the same conditions, but no change was observed in the operating conditions.Also, when the polymerization tank was inspected after the continuous operation, almost no gel-like polymer was observed. The obtained product also had better fluidity than the resin shown in Comparative Example 2 when ethylene bisstearamide was not supplied. Comparative Example 2 The same procedure as Example 4 was carried out except that ethylene bisstearamide was not supplied to the polymerization apparatus.
Manufactured ABS resin. Similar to the time of AS production, the same phenomenon as in Comparative Example 1 began to occur about 200 hours after the start of operation. Also, as a result of inspection of the polymerization tank after 700 hours of operation, the inner wall of the fifth polymerization tank was 10cm x 10cm.
Approximately 1050 mg of gel-like polymer was collected per cm. Example 5 Ethylene bisstearamide was added to the reaction solution at 100%
An ABS resin was produced in the same manner as in Example 4, except that 2.0 parts of ABS resin were continuously supplied. Even after long-term operation, there were no problems and almost no gel-like polymer adhesion was observed. The obtained ABS resin contained 3.2% of ethylene bisstearamide, and its fluidity was even better than that of Example 4.

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Claims (1)

[Scope of Claims] 1. A mixture of 97 to 50% by weight of aromatic vinyl monomer and 3 to 50% by weight of vinyl cyanide monomer, or a monomer mixture in which a rubbery polymer is dissolved in this monomer mixture. Styrene is produced by continuous bulk or solution polymerization.
When producing acrylonitrile copolymer,
General formula R ₁ CONHR′ or R ₂ CONHR″NHCOR ₃ (However, R ₁ , R ₂ , R ₃ are alkyl groups having 8 to 22 carbon atoms, R′ is hydrogen or oxymethyl group, R″ is methylene group or ethylene A styrene-acrylonitrile copolymer, characterized in that a higher fatty acid amide represented by the following formula is continuously supplied to a polymerization apparatus in a dissolved or molten state in an amount of 0.1 to 3.0 parts by weight per 100 parts by weight of the reaction solution. continuous manufacturing method.