JPH0252923B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improved continuous method for producing rubber-modified styrene-acrylonitrile copolymer resins. More specifically, a rubber-modified styrene-acrylonitrile copolymer resin is manufactured using a continuous bulk or solution polymerization method, and during the process, a high fatty acid amide is continuously added in a dissolved or molten state to form the resin. The present invention relates to a method for producing a resin with improved properties. Conventional technology Rubber-modified styrene-acrylonitrile copolymer resin (ABS stem resin) obtained by polymerizing styrene and acrylonitrile in the presence of a rubbery polymer.
has excellent impact resistance, chemical resistance, heat resistance, rigidity,
It has many uses due to its good surface gloss. This ABS resin is usually manufactured by emulsion polymerization, but in this emulsion polymerization method, the amount of latex that is several times the amount of polymer is used, so the polymerization equipment becomes large, and the emulsification process, coagulation process, and drying process are required. This method requires steps such as extrusion, which complicates process control, and the use of additives such as emulsifiers and coagulants causes problems such as impurities being mixed into the polymer. Therefore, recently, continuous bulk or solution polymerization methods have been proposed due to their advantages such as cost, simple process, and less polluting waste (for example, Japanese Patent Publication No. 45-20303; 47−9144,
Special Publication No. 49-35354, Special Publication No. 49-35355, No. 55-
36201) On the other hand, with the expansion of applications for ABS resin, molded products are becoming larger, more complex, and thinner, and there is a desire to improve the moldability of the resin. One of the additives that improves mold releasability from the mold during molding and improves molding processability.
It has come to be widely used as a compound alone or in combination with other compounds, but the usual method is to blend it into a resin and then knead it in an extruder or the like (for example, Japanese Patent Publication No. 48-23182). In such a case, steps such as blending and kneading are required, making the process complicated. Particularly in continuous polymerization, this advantage cannot be utilized. Moreover, when adding a large amount for the purpose of improving the fluidity of the resin, a general extruder may have poor penetration or reduce productivity, so special extruders, such as a twin-screw extruder, may be required. It may also be necessary to use a machine. In addition, resins obtained by emulsion polymerization methods etc. contain residues of emulsifiers, coagulants, etc. as impurities, and adding higher fatty acid amides etc. may deteriorate the hue of the resin during extrusion, molding, etc. In addition, since the heat discoloration resistance of the obtained molded product is poor, discoloration is prevented by adding a stabilizer such as an organic phosphite at the same time (for example, Japanese Patent Publication No. 47-45192). Problems to be Solved by the Invention As a result of intensive studies aimed at producing a rubber-modified styrene-acrylonitrile copolymer resin with improved molding processability, the present inventors found that using a continuous bulk or solution polymerization method, It has been discovered that the above object can be achieved by continuously adding higher fatty acid amide in a dissolved or molten state during the process, and the present invention has been achieved. Moreover, according to the above method, large amounts can be added without reducing productivity using ordinary equipment, and the color is good and heat discoloration resistance is good even without using other stabilizers etc. Furthermore, it is possible to produce a rubber-modified styrene-acrylonitrile copolymer resin with little decrease in heat resistance and improved impact resistance and gloss. Means for Solving the Problems That is, the present invention uses continuous bulk or solution polymerization in a method for producing a rubber-modified styrene-acrylonitrile copolymer resin, and during the process, polymerization of 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 group, R″ is methylene group or ethylene group). For 100 parts by weight of resin in melted or molten state at a temperature of 60℃ or higher
The object of the present invention is to provide a continuous method for producing a rubber-modified styrene-acrylonitrile copolymer resin with improved moldability, characterized in that it is continuously added in an amount of 1.0 parts by weight or more and 8.0 parts by weight or less. The rubber-modified styrene-acrylonitrile copolymer resin used in the present invention mainly refers to ABS resin, but some or all of the styrene can be substituted with α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, etc. Vinyl aromatic compounds such as styrene, vinyltoluene, o-tert-butylstyrene, m-tert-butylstyrene, p-tert-butylstyrene, and halogen-substituted styrene such as chlorostyrene and bromustyrene may be used instead. Further, part or all of acrylonitrile may be replaced with a vinyl cyanide compound such as methacrylonitrile or α-chloroacrylonitrile. Furthermore, other copolymerizable monomers, such as acrylic acid, methacrylic acid and its alkyl esters, and maleic anhydride, may be added and copolymerized. In the present invention, in producing the rubber-modified styrene-acrylonitrile copolymer resin, it is necessary to use a continuous bulk polymerization method or a solution polymerization method. The continuous bulk or solution polymerization method in the present invention is
A rubber-like polymer is dissolved in styrene and acrylonitrile, and in some cases monomers to replace them, as well as a solvent such as ethylbenzene, toluene, methyl ethyl ketone, etc. to prepare a raw material solution. Continuously supply to one or more reaction vessels to perform polymerization reaction, and continuously extract the reaction liquid after polymerization to devolatilize unreacted monomers and solvent under high temperature and high vacuum. This refers to a method in which the resin is then pelletized using an extruder or the like. During polymerization, molecular weight regulators such as mercaptans, antioxidants such as phenols, etc. may be added as necessary. The higher fatty acid amide used in the present invention has the general formula R ₁ CONHR′ or R ₂ CONHR″NHCOR ₃ (where R ₁ , R ₂ , and R ₃ are alkyl groups having 8 to 22 carbon atoms, and R′ is hydrogen or oxymethyl group). , R″ is 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. These higher fatty acid amides are usually solid at room temperature and are difficult to dissolve in monomers or solvents at room temperature, so it is preferable to supply them in a molten state at a temperature equal to or higher than the melting point of the compound. Alternatively, the compound may be mixed with a monomer or a solvent, heated to 60° C. or higher, and then supplied in a dissolved state. The amount of the higher fatty acid amide added is preferably 1.0 parts by weight or more and 8.0 parts by weight or less, preferably 1.5 parts by weight or more and 6.0 parts by weight or less, based on 100 parts by weight of the resin. If it is less than 1.0 parts by weight, the molding processability of the resin will not be improved sufficiently, and if it is more than 8.0 parts by weight, other physical properties of the resin, such as tensile strength and hardness, will be greatly reduced, which is not preferable. The higher fatty acid amide may be added at any point in the continuous process, but preferably before the devolatilization step to separate the monomer and solvent from the resin.
It is preferable to continuously add 10 parts by weight or more of the monomer and solvent to the remaining reaction mixture based on 100 parts by weight of the resin. Specifically, it is preferable to add it to a pass line between the reaction tank or the final reaction tank and the devolatilization process. When added to pelletizing processes such as extruders, there is no problem if the amount added is small, but
If the amount added increases, poor penetration of the extruder or the like and a decrease in capacity will occur. On the other hand, if added to the reaction mixture before the devolatilization step, the higher fatty acid amide is well mixed into the resin, and further kneaded into the resin through the devolatilization step and pelletizing step. Therefore, the required amount of higher fatty acid amide can be added in a sufficiently kneaded state without reducing the production capacity of the resin. Further, the higher fatty acid amide used in the present invention is stable and non-volatile under normal devolatilization process conditions, so most of the added higher fatty acid amide is contained in the resin, which is efficient. Effects According to the present invention, when producing a rubber-modified styrene-acrylonitrile copolymer resin, higher fatty acids can be efficiently produced without reducing productivity and without going through processes such as blending and kneading. Since only the required amount of amide can be added, it is possible to stably produce a resin with excellent resin fluidity, mold releasability, etc., and extremely improved moldability. Furthermore, according to the present invention, since it does not contain impurities such as coagulants as in emulsion polymerization, even if higher fatty acid amides are added or stabilizers such as organic phosphite esters are not used, the hue remains very low. It is possible to produce a rubber-modified styrene-acrylonitrile copolymer resin with good heat resistance and heat discoloration resistance. In addition, the higher fatty acid amide is sufficiently kneaded into the resin, and the resulting resin has little loss of heat resistance.
Impact resistance and gloss are also improved. Examples The present invention will be further explained with reference to Examples below.
The present invention is not limited to these examples. In the following, parts and % indicate parts by weight and % by weight. Example 1 6.0 parts of polybutadiene "Asaprene 700A"
(trade name, manufactured by 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-ditertiabutylphenol as an antioxidant, the mixture was continuously fed at a rate of 15/ _HR to 18 first polymerization tanks equipped with screw-type stirring blades with draft tubes. . After polymerization was carried out at 115° C. in the first polymerization tank to produce small dispersed particles of rubber, the resulting reaction solution was continuously taken out from the polymerization tank and supplied to the second polymerization tank. Second
The same type of polymerization tank as the first one was also used. 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, so that the polymerization rate in the fifth polymerization tank is 73%. Polymerization was continued. 60% resin, 20% unreacted monomer, and 20% solvent continuously taken out from the 5th polymerization tank
Melt ethylene bisstearic acid amide as a higher fatty acid amide at 160°C in a reaction solution containing
264g/H _R with plunger pump with jacket
After mixing with the reaction liquid that is continuously fed at a high speed, unreacted monomers and solvent are removed using a conventionally known devolatilization device, and then the resin component is continuously fed to the extruder. , pelletized to obtain ABS resin.
In the extruder for pelletizing, there was no decrease in capacity compared to normal, and the ABS resin obtained contained 3.0
% of ethylene bisstearic acid amide and the hue of the pellets was also good. The melt flow of the obtained pellets was improved compared to the case without additives as shown in Comparative Example 1 below, and the pellets were molded into pellets at 220°C using an injection molding machine and the molded product was removed from the mold. The value when the force required at the time was measured as hydraulic pressure (copper mold release pressure) was lower than that of the resin of Comparative Example 1, and the mold release property was also improved.
In addition, test pieces were molded using the same molding machine, and physical properties such as Vicat softening point, gloss, and Izot impact value were measured. Summarize the results in a table. The results of both Examples and Comparative Examples below are summarized in a table. Comparative Example 1 ABS resin was produced in the same manner as in Example 1 except that ethylene bisstearamide was not supplied. Although the hue is good, the moldability such as fluidity and mold releasability of the resin is inferior to that of the resin obtained in Example 1. Comparative Example 2 3.0 parts of ethylene bisstearic acid amide was added to 100 parts of the pellets obtained in Comparative Example 1. After blending, the pellets could not be extruded with a normal single-screw extruder due to poor penetration, so they were re-extruded using a twin-screw extruder. I did this. Even in re-extrusion, the extrusion capacity decreased to about 70%. Furthermore, although the fluidity, mold releasability, etc. of the obtained resin were improved, the re-extruded pellets were slightly darkened and the hue deteriorated. Comparative Example 3 Styrene and acrylonitrile were polymerized by emulsion polymerization in the presence of polybutadiene latex to obtain ABS resin powder. this powder
After blending, 3.0 parts of ethylene bisstearamide was added to 100 parts, and extrusion was performed using a twin-screw extruder to obtain pellets. Although the fluidity, mold releasability, etc. have been improved, the pellets have a slight yellow tinge, and the molded product turned yellow even in a heat discoloration test at 90°C for 2 weeks. Example 2 Addition of ethylene bisstearamide
Example 1 except that it was continuously supplied at 440g/H _R
ABS resin was produced in the same manner. obtained
The ABS resin contained 5.0% ethylene bisstearamide, and both fluidity and mold release properties were better than in Example 1. Example 3 The procedure was the same as in Example 1 except that oleic acid amide was melted at 100°C and added to the outlet of the fifth polymerization tank instead of ethylene bisstearic acid amide.
Manufactured ABS resin. Both fluidity and mold releasability are improved compared to Comparative Example 1. Comparative Example 4 Stearic acid was melted at 80°C instead of ethylene bisstearamide and poured into the outlet of the fifth polymerization tank.
An ABS resin was produced in the same manner as in Example 1 except that the amount was supplied at 264 g/H _R. The added stearic acid was partially scattered together with unreacted monomers and solvent during the devolatilization process, and the resulting ABS resin contained only 2.2% of stearic acid (yield: 73%).
%). The resulting resin has a dark yellowish color,
Even in the heat discoloration test, the color changed to dark brown.
Furthermore, although the fluidity, mold release properties, etc. of the resin were improved, the heat resistance temperature was significantly lowered. 【table】

Claims (1)

[Claims] 1. In a method for producing a rubber-modified styrene-acrylonitrile copolymer resin, a continuous bulk or solution polymerization method is used, and during the process, the 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, and R'' is methylene group or ethylene group). A rubber-modified styrene-acrylonitrile system with improved moldability, which is characterized in that it is continuously added to 1.0 parts by weight or more and 8.0 parts by weight or less per 100 parts by weight of the resin in a melted or molten state at a temperature. Continuous production method of copolymer resin. 2 In the above method, after continuously adding the high fatty acid amide to the reaction mixture in which 10 parts by weight or more of the monomer and solvent remain based on 100 parts by weight of the resin, the monomer and the solvent are added. The method according to claim 1, wherein the rubber-modified styrene-acrylonitrile copolymer resin is obtained by separating the resin from the resin.