JPS60250004A - Continuous production of styrene resin of excellent releasability - Google Patents

Abstract

PURPOSE:To obtain the titled resin excellent in heat (distortion) resistance and hue, by continuously adding a mixture of a specified higher fatty acid amide and a fatty acid metallic soap between the step of polymerization of a styrene monomer and the step of pelletization. CONSTITUTION:A molten mixture is obtained by melting 10-90wt% (a) higher fatty acid amide of formula I or II (wherein R1-3 are each an 8-22C alkyl, R' is H or hydroxy-methyl and R'' is a group of the formula: -(CH2)n-, wherein n is 1-2), and (b) 90-10wt% 8-22C higher fatty acid metallic soap (e.g., calcium stearate). A styrene monomer is continuously polymerized in bulk or solution, and the solution after polymerization is continuously withdrawn, devolatilized, and pelletized through an extruder. In performing the above steps, 0.1-10pts.wt., per 100pts.wt. formed resin, above-described molten mixture is added through a constant-volume pump to any of the reaction tank, a place before devolatilization, and the extruder to obtain the titled resin low in deposition of greasy material on a mold and a die.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously producing a styrenic resin with improved mold release properties.

More specifically, styrenic resin is manufactured continuously by bulk or solution polymerization, and during the process, a mixture of higher fatty acid amide and higher fatty acid metal soap is continuously added in a molten state to release the mold. It has excellent properties, has almost no decrease in heat resistance, and has little resin adhesion to molds and dies.
Moreover, the present invention relates to a method for continuously producing a styrenic resin having a good hue and improved resistance to heat discoloration.

Generally, polystyrene (PS), styrene-acrylontrile copolymer (AS), rubber-modified polystyrene (Hl
-PS), styrene-acrylontolyl-butadiene copolymer (ABS), etc.
It is used in a wide range of applications because it has well-balanced properties such as strength, rigidity, formability, and dimensional stability. However, in recent years, as its uses have expanded, molded products have become larger, more complex, and thinner. Therefore, it may not be possible to obtain a good molded product. In such cases, the molded product may be released from the mold by coating the mold surface with a silicone-based mold release agent, or by adding a mold release agent such as higher fatty acids or higher fatty acid metal soaps. Improving sex. However, when applying a silicone-based mold release agent to the mold surface, the effect is temporary, so it is necessary to apply it every molding shot or at most once.
It is necessary to apply the coating for every 0 molding shots, which is time-consuming and cannot be said to be an economically advantageous method.

Styrenic resins are also produced by suspension polymerization, bulk-suspension polymerization, emulsion polymerization, and other methods, but as a recent trend, they are often produced by continuous bulk polymerization or solution polymerization. When producing a resin using a continuous polymerization method, there is a method of adding a mold release agent by triblending it into a pellet, but there is a limit to the amount added. Another method is to add a release agent to the resulting pellets, blend them, and then extrude them again, but this is time-consuming and results in poor color of the product. In the case of a continuous polymerization method, a preferred addition method is a method of continuously supplying the mold release agent before the granulation step.

If the mold release agent is liquid and the viscosity is not very high, it can be added continuously using a commonly used metering pump.
Most mold release agents are solid at room temperature, and if continuously fed, the mold release agent must be fed in a molten state. Higher fatty acids have a relatively low melting point and a low viscosity in the molten state, so it is relatively easy to add them by melting, and in fact, they are often used, but higher fatty acid metal soaps, especially calcium soaps, magnesium soaps, etc. has a high viscosity of several hundreds of thousands of voids when melted, making it difficult to melt and add with a normal pump. When higher fatty acids are used as mold release agents, mold release properties are certainly improved, but they also cause corrosion of extruders and molding machines, resin adhesion to die nozzles or molds during extrusion or molding, deterioration of product hue, This method cannot be said to be a preferable method because it causes discoloration due to heat.

The present invention produces styrenic resin continuously by bulk or solution polymerization, and at that time, it releases from the mold by continuously supplying a mixture of higher fatty acid amide and higher fatty acid metal soap in a molten state. To provide a method for continuously producing a styrenic resin that has excellent properties, almost no decrease in heat resistance, little tar adhesion to molds and dies, extremely good hue, and improved heat discoloration resistance. It is something. That is, the present invention uses a continuous bulk or solution polymerization method in the method of producing styrenic resin, and during this process, the general formula % (where R, &R,, Alkyl group, R
' is hydrogen or oxymethyl group, '(C)I2hn=1
．． A mixture of higher fatty acid amide (A) shown in 2) and metal soap (B) of higher fatty acid having 8 to 22 carbon atoms in a mixing ratio of (A)/(B) of 10/90 to 80/10. B) is continuously added in a molten state so that the weight of B) is 0.1 to 1.0 parts by weight per 100 parts by weight of the resin.It has excellent mold release properties and good heat resistance. This is a continuous method for producing styrenic resins with almost no deterioration, little tar adhesion to molds and dies, very good hue, and improved heat discoloration resistance.

The styrene resin referred to in the present invention is PS resin.

^S resin, II-PS resin, ABS resin, etc., which are generally widely used in industry, and in which some or all of the styrene is replaced with styrene derivatives such as α-methylstyrene, para-methylstyrene, etc. It may also be a resin copolymerized with other copolymerizable monomers such as acrylic acid or methacrylic acid and its alkyl esters, maleic anhydride, and the like.

In the method of the present invention, it is necessary to use a mixture of higher fatty acid metal base and fatty acid amide. Higher fatty acid metal soap and higher alcohol or higher fatty acid,
Alternatively, even when a mixture with a fatty acid polyhydric alcohol partial ester is used, the melting point and viscosity of the higher fatty acid metal soap are lowered, and it can be continuously supplied using an ordinary metering pump, but an extruder , corrosion of molding machine,
This is undesirable because tar adhesion may occur, and the resulting resin may exhibit a decrease in heat resistance and a deterioration in hue.

The higher fatty acid amide used in the present invention has the general formula:
0NHR' or L C0NHR' NHCOR
s (However, Rx, Rtla are alkyl groups having 8 to 22 carbon atoms, K is hydrogen or oxymethyl group, "(C)h)-1
n=1.2). Compounds represented by the above general formula include lauric acid amide, stearic acid amide, behenic acid amide, methylene bis lauric acid amide, ethylene bis lauric acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, and methylene bis behenin. Examples include acid amide, ethylene bisbehenic acid amide, and the like.

The higher fatty acid metal soaps used in the present invention include aluminum stearate, calcium stearate, zinc stearate, magnesium stearate, calcium laurate, etc., and calcium soaps and magnesium soaps are particularly effective.

In the mixture of fatty acid amide (A) and higher fatty acid metal soap (B) of the present invention, the mixing ratio (A) of the mixture
/(B) must be in a weight ratio of 10/90 to 90/10. When (A)/(B) is smaller than 10/90, the melting point and melt viscosity of the higher fatty acid metal soap do not decrease significantly, making it difficult to melt and add the higher fatty acid using a regular metering pump. Also, if (A)/(B) is greater than 80710,
The amount of higher fatty acid metal soap is small and the mold release properties are not that good. Further, the amount added must be such that the weight of (B) is 0.1 to 1.0 parts by weight per 100 parts by weight of the resin. If it is less than 0.1 part by weight, the mold releasability will be poor, and if it is added 1.0 part by weight or more, the mold releasability will not improve even if it is added more than that, and the degree of elasticity of (B) in the mixture will be poor. becomes high, which is not desirable. In the mixture, two or more of each of (A) and (B) may be mixed.

In the present invention, it is necessary to use a continuous bulk or solution polymerization method to produce the styrenic resin.

When manufacturing using a batch polymerization method, for example, in the case of a suspension polymerization method, when the product is in the form of beads, or in the case of an emulsion polymerization method, when it is in a powder state, a release agent, etc. is added, blended, and then extruded. Although pellets with good mold releasability can be obtained by this method, it is necessary to carry out a blending process, which makes the process complicated. Moreover, if a large amount is added, a general extruder will
In some cases, the biting may become poor, and it becomes necessary to use a special extruder, such as a twin-screw extruder. Also, in suspension polymerization and emulsion polymerization, suspending agents, emulsifying agents, etc. are usually used.
The residue remains as an impurity in the resulting resin, and if fatty acid amide or the like is added, the hue of the product will deteriorate during extrusion, molding, etc. Furthermore, the heat discoloration resistance of the obtained molded product is also poor.

In the present invention, the method of continuous bulk or solution polymerization means continuous polymerization of 7mer alone, a mixture of monomers and a solvent, or a solution of a rubber polymer such as polybutadiene dissolved therein. Thereafter, the polymerization solution is fed into two reaction vessels to perform a polymerization reaction, and the polymerized solution after polymerization is continuously extracted and unreacted monomers and solvent are devolatilized at high temperature and under vacuum, and then processed using an extruder or the like. A method of pelletizing resin.

The method of adding the mixture of the present invention is to mix higher fatty acid amide and higher fatty acid metal soap in advance, heat and melt the mixture, and then continuously supply the molten mixture to an extruder etc. using a metering pump to make the resin. and knead. The molten mixture is preferably added after the devolatilization step, for example in an extruder, but if the amount to be added is large and sufficient kneading in the extruder is difficult, add the molten mixture from the reaction tank or the final reaction tank to the devolatilization step. It may also be supplied to the line between.

The viscosity of the mixture of the present invention decreases in the molten state, so it can be supplied with a regular metering pump, and since it is added in the middle of a steady continuous flow, there is no need for processes such as blending, and the amount of supply is small. Since it is quantitative, extremely stable products can be obtained. In addition, in continuous bulk or solution polymerization, there are almost no impurities because suspending agents, emulsifiers, etc. are not used, and the method according to the present invention does not require the blending step or re-extrusion step. Even when a mixture of the following is added, the color of the product is very good, and there is almost no deterioration in the color of the molded product when the product is molded. Furthermore, the heat discoloration resistance of the obtained molded product is also good.

In the present invention, the effect is exhibited in the combination of higher fatty acid amide and higher fatty acid metal soap.

Although higher fatty acid metal soap alone has a mold release effect, it is not possible to continuously add magnesium, calcium, etc. in a molten state, but they can be melted and added by mixing with higher fatty acid amide. Furthermore, the combination of the two also exhibits excellent properties that cannot be seen with higher fatty acid metal soaps alone. That is, improved fluidity of the resin, improved product appearance, improved moldability, improved heat discoloration resistance, etc. are observed.

According to the present invention, a mixture of higher fatty acid amide and higher fatty acid metal soap is used as an additive for styrenic resin produced by continuous bulk polymerization or solution polymerization, which has almost no impurities, thereby improving moldability during molding. The blending process
The re-extrusion step can be omitted.

Furthermore, the hue of the pellets is better compared to other addition methods.
Furthermore, there is almost no deterioration in the hue of the molded product when it is molded. Also, compared to other additives or combinations of additives, extruders,
Corrosion of the molding machine, tar adhesion, deterioration of color, heat resistance,
There is almost no decrease in heat resistance, and fluidity, moldability, etc. are also improved.

EXAMPLES Hereinafter, the present invention will be further explained with reference to Examples, but the present invention is not limited to these Examples. In the following, parts indicate parts by weight.

Example 1 6.0 parts of polybutadiene (manufactured by Fukaisei: trade name Diene N)
F35A) was dissolved in 84.0 parts of styrene to prepare a raw material solution. After adding 0.2 part of 2,6-di-tert-butylphenol as an antioxidant to this raw material solution, it is continuously fed at a speed of IIQ/HR to the first reaction tank equipped with a screw-type stirring blade with a draft. did.

In the first reactor, polymerization was carried out at 130° C. to phase transform the rubber component and form small dispersed particles of rubber. The reaction liquid obtained in the first reaction tank was continuously taken out from the reaction tank and supplied to the second reaction tank.

A mixture of styrene and ethylbenzene at a mixing ratio of 25/75 was supplied at 2.017 HR before the second reaction tank, and the reaction liquid from the first reaction tank was combined. The second reaction tank was also of the same type as the first reaction tank.

Furthermore, the reaction solution polymerized in the second reaction tank was continuously taken out and supplied to third, fourth, and fifth reaction tanks to continue polymerization. The third, fourth, and fifth reaction vessels were also of the same type as the first and second reaction vessels. After removing unreacted monomers and solvent from the reaction liquid taken out from the fifth reaction tank using a conventionally known devolatilization device, the resin component was quantitatively supplied to an extruder using a gear pump. On the other hand, a 50/50 mixture of ethylene bisstearylamide and magnesium stearate was melted at 170°C and heated at a rate of 28 g/HR using a jacketed plunger pump so that the mixture amounted to 0.3 parts per 100 parts of resin. It is continuously fed to an extruder, kneaded with resin, and made into pellets.
A HI-PS resin was obtained.

The viscosity of the mixed portion of 50150 of ethylene bis stearylamide and magnesium stearate at 170°C is 0.
It was 5 poise and could be supplied continuously with a plunger pump without any problems. Almost no resin was observed on the nozzle at the tip of the extruder during pelletization. The obtained pellets had good color, and the pellets were molded into molds at 190°C using a 4-ounce injection molding machine, and the force required to take the molded product out of the mold was measured as hydraulic pressure. Mold release pressure) As a result, the compact mold release pressure was lowered to that in the case of no additive shown in Comparative Example 1 below, and the mold release property was improved. In addition, a test piece was molded using the same molding machine and the Hikant softening point was measured, and it was almost the same as that without the additive, and there was no decrease in heat resistance. Summarize the results in a table.

Below, the results of both Examples and Comparative Examples are summarized in a table.

Comparative Example 1 Old-PS resin without additives was obtained in the same manner as in Example 1 except that the mixture of ethylene bisstearylamide and magnesium stearate was not added. Although the hue was good, the molding of the molded product The mold releasability was poor.

Comparative Example 2 0.15 parts of magnesium stearate was added to 100 parts of the pellets obtained in Comparative Example 1, blended, and then extruded to produce a former PS resin containing a mold release agent. Although the mold releasability was improved, the re-extruded pellets were slightly darkened and the hue deteriorated.

Comparative Example 3 Example 1 except that instead of the mixture of ethylene bisstearylamide and magnesium stearate, stearic acid was melt-added in an amount of 0.15 parts per 100 parts of resin.
An old-PS resin was prepared in the same manner as in the above. Although the mold releasability was improved, the hue of the pellets was poor and resin was observed on the nozzle of the extruder. Furthermore, when the molded product was left at 80°C for two weeks, the molded product turned yellow.

Comparative Example 4 The same procedure as in Example 1 was carried out, except that instead of the mixture of ethylene bis stearylamide and magnesium stearate, ethylene bis stearyl amide was melted and added to 0.3 parts per 100 parts of the resin. I made PS resin. There were no problems with the hue of the pellets, but the mold releasability was insufficient.

Comparative Example 5 A piece of H-knee PS resin was obtained by dissolving polybutadiene in styrene and using a bulk-suspension polymerization method. To the beads, a 50/50 mixture of ethylene bisstearylamide and magnesium stearate was added to 100 parts of resin.
．． After adding 3 parts and blending, extrusion was performed to obtain pellets. The pellets had a slight yellowish tinge, and the molded product also had a slight yellowish tinge in a 2-week heat discoloration test at 90°C.

Example 2 6.0 parts of styrene-butadiene copolymer (manufactured by Asahi Kasei:
A raw material solution was prepared by dissolving Tuffden 200OA (trade name) in 55.5 parts of styrene, 18.5 parts of 7-crylonitrile, and 20.0 parts of ethylhensen. To this raw material solution, 0.1 part of tertiary dodecyl mercaptan, 0.02 part of benzoyl peroxide as a radical polymerization initiator,
After adding 0.2 part of 2,6-ditertiarybutylphenol as an antioxidant, using the same reaction apparatus as in Example 1,
ABS resin was produced continuously in a similar manner. The amount of raw material solution supplied to the first reaction tank was 18 fL/HR1, and the polymerization temperature in the first reaction tank was 110°C. Further, as an additive, a mixture of 50150 ethylene bisstearylamide and magnesium stearate was melted at 170°C so that the mixture was 0.6 parts per 100 parts of resin.
The mixture was continuously fed to an extruder at a rate of g/HR, kneaded, and pelletized to obtain an ABS resin. The obtained resin had good mold releasability and good hue.

Examples 3 to 6 ABS resins were produced in the same manner as in Example N2. but,
In Examples 3 and 4, the ratio of ethylene bisstearylamide and stearin-ugly magnesium was changed. Further, in Examples 5 and 6, a mixture of a higher fatty acid amide and a higher fatty acid metal sec as shown in the table was used as an additive. In addition, in Example 3, it was added before the final reaction tank. In all cases, the mold releasability was improved and the hue was also good.

Comparative Example 6 An additive-free ABS resin was obtained in the same manner as in Example 2, except for the vehicle weight, in which the mixture of ethylene bisstearylamide and magnesium stearate was not added. Although the hue was good, the releasability of the molded product from the mold was poor.

Comparative Example 7.8 0.3 parts of magnesium stearate was added to 100 parts of ABS resin pellets obtained without additives in the same manner as in Comparative Example 6.
or 0.6 parts of a 50/50 mixture of ethylene bisstearylamide and magnesium stearate, blended and then extruded to form A containing a mold release agent.
I made BS81 fat. Although the JLL moldability was improved, the re-extruded pellets became dark and the hue deteriorated.

Comparative example 9. lO Instead of the mixture of ethylene bis stearylamide and magnesium stearate, 0.3 part of stearic acid or 0.5 part of a 30/70 mixture of stearic acid and magnesium stearate is melted per 100 parts of resin. An ABS resin was produced in the same manner as in Example 2 except that it was added to the extruder. Although the mold releasability was improved, the hue of the pellets was poor and the heat discoloration resistance was also poor. Also, resin was observed on the nozzle of the extruder.

Comparative Example 11 An ABS resin was produced in the same manner as in Example 2, except that instead of the mixture of ethylene bis stearylamide and magnesium stearate, 0.6 parts of ethylene bis stearylamide was melt-added to 100 parts of the resin. Although the hue was good, the mold releasability was insufficient.

Comparative Example 12 Styrene and acrylonitrile were polymerized by emulsion polymerization in the presence of polybutadiene latex to obtain ABS resin powder. This powder contains 50/50 ethylene bisstearylamide and magnesium stearate.
After blending, 0.6 parts of the mixture was added to 100 parts of resin, and extrusion was performed to obtain pellets. Although the mold releasability was improved, the pellets were slightly yellowish, and the Vicat softening point of the six-pronged molded product, which was slightly yellowish, was also lower than that of Example 2 in the heat discoloration test. became.

Example 7 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 tertiary dodecyl mercaptan to this raw material solution, Example 1 Using the same reactor as
AS resin was produced continuously in a similar manner. The amount of raw material solution supplied to the first reaction tank was 18 mm/HR.The polymerization temperature in the first reaction tank was 135°C. As an additive, 36 g of a 50150 mixture of ethylene bis stearylamide and magnesium stearate was melted at 170°C so that the amount of the mixture was 0.4 parts per 100 parts of resin.
The mixture was continuously fed to an extruder at a speed of /HR and kneaded with resin to form pellets to obtain an AS resin. The obtained resin had good mold releasability, and had good hue and transparency.

Comparative Example 13 AS resin 5 without additives was obtained in the same manner as in Example 7 except for the weight of the vehicle, in which the mixture of ethylene bisstearylamide and magnesium stearate was not added. Although the hue was good, the releasability of the molded product from the mold was poor.

Comparative Example 14 AS resin was produced in the same manner as in Example 7, except that 0.2 parts of stearic acid was added to the extruder in a molten state per 100 parts of resin instead of the mixture of ethylene bis stearylamide and magnesium stearate. Manufactured. Although the mold releasability was improved, the hue of the pellets was poor and the heat discoloration resistance was also poor. Also, resin was observed on the die nozzle of the extruder.

Comparative Example 15 After mixing styrene and acrylonitrile, AS was produced using a suspension polymerization method.
Resin beads were obtained. A mixture of 50150 ethylene bisstearylamide and magnesium stearate was added to the beads in an amount of 0.4 parts per 100 parts of the resin, and the mixture was blended and then extruded to obtain pellets. The pellets had a slight yellowish tinge, and the molded product also showed a slight yellowish tinge in the heat discoloration test.

Claims (1)

[Claims] In the method of producing styrenic resin, a method of continuous bulk or solution polymerization is used, and during this process, the general formula % is used. an alkyl group, R' is hydrogen or an oxymethyl group, and a higher fatty acid amide (A) with a carbon number of 8 to 22
Mixing ratio (A) of metal soap (B) of higher fatty acids /
(B) has a weight ratio of 10/130 to 80/10
B) is added continuously in a molten state so that the weight of B) is 00 to 1.0 parts by weight per 100 parts by weight of the resin. A method for continuously producing a good styrenic resin.