JPH0977834A - Production of rubber-reinforced styrenic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain rubber-reinforced styrenic resin readily controllable of rubber particulate diameter in a wide range of rubber particulate diameter and having excellent strength, appearance, etc., and productivity. SOLUTION: This polymerization system has an annular reactor (I) comprising a tubular reactor (i) including a static mixer having a flowing path through which a heat medium passes, a reactor (ii) having mixing blades and a pump (iii) transferring a reacting solution, and a tubular reactor (II) including a static mixer having a flowing path through which a heat medium passes. The polymerization is performed by supplying a raw material solution containing a styrenic monomer and a rubbery polymer into the reactor (ii) having mixing blades while circulating a part of the solution in the annular reactor (I) and then supplying the solution to the tubular reactor (II). A volume ratio of a tubular reactor constituting the annular reactor (I) to the reactor having mixing blackes and a volume ratio of the annular reactor (I) to the tubular reactor (II) are (5/1)-(20/1) and (1/1)-(1/5), respectively and an organic peroxide solution is supplied into the tubular reactor (II) from at least one place, then a rubber- reinforcing styrenic resin comprising granularly dispersed rubbery elastomer in a continuous styrenic resin phase is produced by controlling a polymer concentration in the reactor (ii) having mixing blades in the reactor (I).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for controlling the size of rubber-like elastic particles dispersed in the form of particles, and further, is excellent in impact strength, appearance characteristics and the like and has high productivity. Provided is a method for producing a rubber-reinforced styrene resin.

[0002]

The production of rubber-reinforced styrenic resins is relatively old, and the state of the art industrial processes are clearly known to those skilled in the art. According to a typical technique, a rubber solution dissolved in a monomer is polymerized in a first stage reactor under mechanical stirring. Whether the polymerization occurs in a batch or continuous stirred plug flow reactor, or in a continuous stirred tank reactor, almost all prior art and disclosures have resulted in end products. It is clarified that the particle size and particle size distribution of the rubber-like elastic material dispersed in the object are largely determined at an early stage of the process.

As the polymerization proceeds in a batch or continuous stirred plug flow reactor, at some point when the monomer conversion is between 5 and 20%, shearing by mechanical stirring causes a rubbery elasticity. The body becomes the dispersed phase and the polystyrene resin phase becomes the continuous phase. That is, phase inversion occurs and rubber particles are formed. This phase change does not occur instantaneously, but rather over time and space. Typically 20-5
It occurs over 0 minutes or over the reactor space resulting in 2-8% monomer conversion. Therefore, the rubber particle size,
Accurate control of the rubber particle size distribution is difficult.
Also, in the case of a continuous type complete mixing type reactor, rubber particle formation occurs instantaneously, but the residence time distribution due to the dynamic behavior of the reaction system and the same shear history for each unit volume of the reaction system are surely given. As a result, the dispersed rubber particle size distribution is generally the broadest, since this is very difficult, if not impossible.

The physical properties of the rubber-reinforced styrenic resin greatly depend on the particle size and particle size distribution of the dispersed rubber-like elastic material. It is a known fact that accurate control of the rubber particle size and particle size distribution is an important factor controlling the physical properties of the rubber-reinforced styrene resin. Moreover, since the plug flow reactor, the complete mixing type reactor and the like have a small heat transfer area per unit volume, the heat removal capacity of the reaction heat is small, and as a result, improvement in productivity cannot be expected. Also, when the conversion rate of the monomer becomes high,
Heat is generated by stirring the highly viscous solution, increasing the amount of heat removed. As a result, it also has a drawback of lowering productivity.

In order to solve the above-mentioned drawbacks of the agitated plug flow reactor and the complete mixing type reactor, the phase conversion is performed in an annular reactor composed of a tubular reactor having a static mixer. A method for forming rubber particles has been proposed (Japanese Patent Publication No. 7-25856). However, in this method, the shearing force required to form rubber particles depends on the viscosity of the reaction solution flowing in the annular reactor and the flow rate. In order to obtain the above, the reflux rate must be increased, which causes difficulty because the pressure loss in the annular reactor becomes large. In order to solve the drawbacks of this method, a method of introducing a dynamic in-line mixer in the middle of a tubular reactor forming a ring reactor has been proposed (Japanese Patent Publication No. 7-25857).

In this method, since the rubber particles once phase-converted are made smaller by a stronger shearing force, the rubber particles are broken, and the molecular chains of the rubber-like elastic body are broken, resulting in deterioration of physical properties. Connection is not preferable. Also, Japanese Patent Fair 7-2
In the tubular reactor disclosed in Japanese Patent No. 5856 and Japanese Patent Publication No. 7-25857, the heat of reaction is exchanged only by heat transfer in the jacket, and the heat can be removed only to the same extent as in the plug flow reactor. No improvement in productivity can be expected.

[0007]

The present invention provides a method for producing a rubber-reinforced styrene resin which facilitates control of the rubber particle size in a wide rubber particle size range from a large rubber particle size to a small rubber particle size. Depending on the method, it has excellent strength and appearance,
Moreover, a rubber-reinforced styrene resin having excellent productivity can be obtained.

[0008]

That is, the present invention comprises a tubular reactor containing a static mixer having a flow path through which a heat medium passes, a reactor equipped with a stirring blade, and a pump for transferring a reaction solution. And a tubular reactor (II) having a static mixer having a flow path through which a heat medium passes, the raw material solution containing a styrene monomer and a rubbery polymer is provided with a stirring blade. A polymerization method in which the cyclic reactor (I) is supplied to the tubular reactor (I) while partly circulating the cyclic reactor (I), and the tubular reactor and the stirring blade constitute the cyclic reactor (I). The volume ratio of the reactor equipped with is 5/1 to 20/1, and the volume ratio of the annular reactor (I) and the tubular reactor (II) is 1
Tubular reactor (II)
The organic peroxide solution is supplied from at least one or more locations in the reactor, and the polymer concentration in the reactor equipped with a stirring blade in the reactor (I) is 2 to 10 times the concentration of the rubber-like elastic material in the raw material. The present invention is a method for producing a rubber-reinforced styrene-based resin in which a rubber-like elastic material is dispersed in particles in a continuous styrene-based resin phase.

As a tubular reactor having a static mixer having a flow path through which a heat medium that composes the annular reactor (I) is built, a static mixing structure having a structure through which the heat medium can pass is provided. It is fixed inside. The value of the heat transfer area (A / V) per unit volume is preferably 30 (m ² / m ³ ) or more. The tubular reactor jacket is not always necessary. As such a tubular reactor, an SMR reactor manufactured by Sulzer can be preferably used.

The reactor equipped with stirring blades that constitutes the annular reactor is a generally used complete mixing type reactor equipped with stirring blades, or a tower type reactor (plug flow) equipped with stirring blades. Reactor), a rotating cylinder type reactor, etc. can be used. Above all, a tower reactor equipped with a stirring blade and a rotating cylinder reactor can be preferably used. As a tubular reactor (II) having a static mixer having a flow path through which a heat medium passes, a static mixing structure having a structure through which the heat medium can pass is fixed inside. The value of the heat transfer area per unit volume is preferably 30 (m ² / m ³ ) or more. The tubular reactor jacket is not always necessary. Such a tubular reactor is a tubular reactor as shown in the schematic view of FIG. 1, and specifically, an SMR reactor manufactured by Sulzer can be used as a suitable example.

The raw material solution must be fed to a reactor equipped with a stirring blade. Mixability between the raw material solution and the polymerization solution circulating in the annular reactor is the largest factor that determines the rubber particle size. It is necessary to disperse the low viscosity liquid in the high viscosity liquid in a short time. When the raw material solution is fed into the tubular reactor in the annular reactor, it takes a long time to disperse due to the weak shearing force of the static mixer, during which rubber particles are formed, and as a result, the rubber particle diameter is reduced. Only large and relatively wide particle size distributions can be obtained. When the raw material solution and the polymerization solution are mixed in a reactor equipped with a stirring blade for a short time, depending on the mixing degree of the raw material solution and the polymerization solution, in a tubular reactor having a static mixer that gives a weak shearing force. It forms rubber particle sizes from large particles to small particles with a narrow particle size distribution. The mixing degree of the raw material solution and the polymerization solution can be controlled by the number of agitation of the reactor equipped with a stirring blade, but if the number of agitation is increased, a large shear force is applied to the rubber-like elastic body and the rubber particles in the refluxed polymerization solution. If applied, the rubber-like elastic body is cut and the rubber particles are broken, which is not preferable. It is preferable to control the degree of dispersion by utilizing the difference in viscosity between the raw material solution and the refluxed polymerization solution. It can be achieved by decreasing the difference in viscosity between the two solutions to increase the degree of mixing, and increasing the difference in viscosity between the two solutions to decrease the degree of mixing. Therefore, the polymer concentration (the total weight concentration of the styrene resin generated from the rubber-like elastic body and the monomer) in the reactor equipped with the stirring blade is equal to the rubber-like elastic body concentration (weight concentration) of the raw material. It is necessary to control so that it becomes 10 times. When the amount is 2 times or less, the rubber particles in the refluxed polymerization solution are disassembled (phase inversion), the rubber-like elastic body exhibits a quasi-continuous phase morphology, and it becomes very difficult to control the rubber particle diameter. If it exceeds 10 times, it becomes difficult to mix the raw material solution and the polymerization solution, and it becomes difficult to control the rubber particle size. At this time, it is necessary to control the stirring number of the reactor equipped with stirring blades to such an extent that the rubber-like elastic body is not cut and the rubber particles are not broken.

The volume ratio of the tubular reactor constituting the annular reactor and the reactor equipped with a stirring blade is 5/1 to 20/1. If this ratio is less than 5/1, the residence time in the reactor equipped with a stirring blade becomes longer, the particle size distribution is broadened due to the residence time distribution, and the rubber particles become enlarged, etc. Becomes difficult. If this ratio is large, it becomes difficult to control the degree of mixing of the raw material solution and the polymerization solution, and as a result, it becomes difficult to control the rubber particle size.

It is necessary to feed the organic peroxide solution to one or more arbitrary places in the tubular reactor (II). When the monomer conversion rate becomes high, the reaction rate becomes slow, which leads to a decrease in productivity. Further, the rubber particles formed in the ring reactor are not grafted with polystyrene on the surface or are insufficient even if they are grafted with polystyrene. It is necessary to graft polystyrene in the tubular reactor (II) in order to enhance strength and appearance characteristics. In order to achieve these objects, it is necessary to supply an organic peroxide solution to accelerate the reaction rate and accelerate the graft reaction. It is preferable that the supply site of the organic peroxide solution is one or more. The supply site of the organic peroxide solution is not particularly limited, but in the case of one location, the inlet of the tubular reactor (II) and in the case of two locations, the inlet and center of the tubular reactor (II) are preferable. In the case of three or more places, it is preferable to supply the tubular reactor (II) to equally divided sites. The organic peroxide solution may be supplied alone or diluted with a solvent such as ethylbenzene. The organic peroxide used is also not particularly limited, but the 10-hour half-life temperature is 90 to 140 ° C., for example, Perhexa C or Perhexa 3 of NOF Corporation.
M, perbutyl Z, perbutyl D, perhexa 25B,
Perbutyl I and the like are preferably used.

The volume ratio of the annular reactor (I) to the tubular reactor (II) is 1/1 to 1/5. Preferably, 1/1 to 1
/ 3. When this ratio is larger than 1/1, the reaction rate of the annular reactor (I) is limited to some extent from the viewpoint of controlling the rubber particle size, and the load for improving productivity in the tubular reactor (II) becomes large. , The balance between quality and productivity becomes poor. If this ratio is smaller than 1/3, the productivity per unit volume becomes poor. The productivity referred to in the present invention means the production amount per unit time per unit volume. In the conventional manufacturing process and manufacturing conditions, it is 1-2 ton / m ³ / day,
The high productivity referred to in the present invention means a value of about ^{3 to} 5 ton / m ³ / day.

The rubber-reinforced styrene resin referred to in the present invention means a polymer having a continuous phase of styrene, α-methylstyrene or the like, or styrene, a monomer copolymerizable with α-methylstyrene, or (meth) acrylic acid. Esters such as butyl acrylate, methyl methacrylate, butyl methacrylate, methyl acrylate, etc., and acrylonitrile, etc., and the dispersed phase is polybutadiene, styrene / butadiene copolymer, styrene / butadiene block copolymer, ethylene / propylene terpolymer. It is a resin composed of rubber particles formed of a rubber-like elastic body such as a polymer.

The raw material solution referred to in the present invention is a solution in which a rubber-like elastic material is dissolved in a monomer, and if necessary, a polymerization solvent such as ethylbenzene or toluene, a molecular weight modifier, 1
The 0-hour half-life temperature is 90 to 140 ° C., for example, polymerization initiators such as Perhexa C, Perhexa 3M, Perbutyl Z, Perbutyl D, Perhexa 25B and Perbutyl I of NOF CORPORATION, plasticizers such as mineral oil and silicone oil, An antioxidant or the like may be added to the raw material solution.

The raw material solution is supplied to a reactor equipped with a stirring blade, but a pretreatment such as prepolymerization may be carried out at a stage before being supplied to a reactor equipped with a stirring blade. However, it is important that the rubber-like elastic body has a conversion rate that does not form rubber particles. The polymerization temperature of the annular reactor (I) is 100 to 1
A range of 50 ° C is preferably used. The circulation amount of the annular reactor is not particularly limited, but it is necessary to use the static mixer at a minimum flow rate or more at which the mixing capacity of the static mixer used can be fully exhibited.

For example, in the case of an SMR reactor manufactured by Sulzer, it is preferable to circulate the SMR reactor at such a circulation rate that a flow rate of 2 m / h or more can be obtained. A circulation ratio (circulation flow rate / raw material solution supply flow rate) of 2 to 15 is preferably used. It is possible to control the rubber particle size by changing the circulation ratio, but the degree of freedom that can be controlled is small. However, there is no problem in finely adjusting the rubber particle size by the circulation amount while considering the pressure loss and the like.

The polymerization temperature in the tubular reactor (II) is 120.
The range of to 180 ° C is preferably used. The concentration of solids (total of polymer in continuous phase and dispersed phase) at the outlet of the tubular reactor (II) is 70% by weight or more, preferably 80% by weight.
It is preferable to set the polymerization conditions as described above.
When the solid content concentration is low, the load on the recovery capacity becomes large in order to maintain high productivity, which is not preferable.

The polymerization solution discharged from the tubular reactor (II) is sent to a recovery facility where unreacted monomers, polymerization solvent and the like are removed and pelletized. Additives often used in rubber-reinforced styrene resin before entering the recovery system or after exiting the recovery system, for example, antioxidants, plasticizers, colorants, antistatic agents, flame retardants, etc. may be added. it can.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The method of measuring physical properties is as follows. SOLID%: About 5 g of the polymerization solution was precisely weighed, about 5 cc of methanol was added, and after heating for 20 minutes in a vacuum dryer under the conditions of 200 ° C. and 10 mmHg, the weight was precisely weighed to calculate the solid content concentration (% by weight). To do.

Rubber particle size and particle size distribution: Coulter
The measurement is performed using a Coulter counter of the following type manufactured by Corporation. Main body: MULTISIZER II type, Measuring machine: MULT
The volume averaged and number averaged 50% median diameters are determined using an electrolyte solution of ISIZER IIE type, dimethylformamide and ammonium thiocyanate. In the present invention, the rubber particle diameter means the volume average 50% median diameter, and the rubber particle diameter distribution means the ratio of the volume average 50% median diameter and the number average 50% median diameter.

Izod impact strength: ASTM D638
It measured according to I. Appearance: A dumbbell test piece was molded under the conditions of a molding temperature of 220 ° C. and a mold temperature of 60 ° C., and 4 cm from the kate side was JI.
It measured based on SZ8741. FIG. 1 is a schematic flow sheet of the apparatus used to carry out the method of the present invention.
The raw material solution prepared in the tank (1) is sent to the reactor (3) by the pump (2). Reactor (3) has L / D = 1
It is a plug flow type reactor having 0 and 15 stages of rod-shaped blades and a volume of 0.6 L. The polymerization solution exiting the reactor (3) is sent to the reactor (4). The reactor (4) is a tubular reactor of the SMR type of Sruzer Co., Ltd., which has a built-in static mixer having a flow passage through which a heat medium passes. The volume is 6L. A part of the polymerization solution exiting the reactor (4) is pop (5)
Is circulated to the reactor (3). The remaining polymerization solution is sent to the reactor (6). The reactor (6) has the same structure as the reactor (4) and has a volume of 12L. The initiator solution can be additionally added to the inlet part and the intermediate part of the reactor (6) by the pumps (7) and (8). The polymerization solution exiting the reactor (6) is sent to a twin-screw extruder with a two-stage vent (9) to remove unreacted monomers, polymerization solvent and the like, and then pelletized.

[0024]

Example 1 Styrene 81.5% by weight, ethylbenzene 12% by weight, rubber (Asaprene 730A manufactured by Asahi Chemical Industry Co., Ltd.) 6.5% by weight, organic peroxide (Nippon Oil & Fats Co., Ltd., Perhexa C) 300 ppm, A raw material solution is prepared by mixing in the tank (1) so that the α-methylstyrene dimer becomes 200 ppm.

The raw material solution is fed to the reactor (3) at a rate of 3.5 L / H. 12 reactors (3) and reactors (4)
Control to 3 ° C. Revolution of the reactor (3) is 100 rp
m, the circulation ratio (circulation flow rate / raw material solution flow rate) is controlled at 10. The polymerization solution exiting the reactor (4) is sent to the reactor (6), and the reactor (6) is controlled to 145 ° C in the front stage and 160 ° C in the rear stage. 3 for the polymerization solution using the pump (7)
00 ppm organic peroxide (50% by weight of Perhexa C)
Ethylbenzene solution) is added.

The polymerization solution discharged from the reactor (6) is sent to a twin-screw extruder with a two-stage vent (9), treated at a temperature of 240 ° C., and pelletized. The results are shown in Table 1.

[0027]

Example 2 Pellets are obtained in the same manner as in Example 1 except that the stirring number in the reactor (3) is 180 rpm. The results are shown in Table 1.

[0028]

Example 3 Reactor (3) and Reactor (4) were 114 ° C.
In addition, pellets are obtained in the same manner as in Example 1 except that the reactor (6) is controlled at 150 ° C. in the front stage and 170 ° C. in the rear stage. The results are shown in Table 1.

[0029]

Example 4 Pellets are obtained in the same manner as in Example 3 except that the stirring number in the reactor (3) is 180 rpm. The results are shown in Table 1.

[0030]

[Example 5] The reactor (3) and the reactor (4) had a temperature of 119 ° C.
Further, pellets are obtained in the same manner as in Example 1 except that the reactor (6) is controlled at 147 ° C. in the front stage and 165 ° C. in the rear stage. The results are shown in Table 1.

[0031]

Comparative Example 1 In the same manner as in Example 1 except that the reactor (3) is omitted and the raw material solution and the polymerization solution circulated by the pump (5) are directly supplied to the reactor (4) in FIG. To obtain pellets. The results are shown in Table 1.

[0032]

Comparative Example 2 Pellets are obtained in the same manner as in Comparative Example 1 except that the circulation ratio is 15. The results are shown in Table 1.

[0033]

Comparative Example 3 Pellets are obtained in the same manner as in Comparative Example 1 except that the temperature of the reactor (4) is 114 ° C. The results are shown in Table 1.

[0034]

Comparative Example 4 Pellets are obtained in the same manner as in Example 1 except that the organic peroxide is not additionally added using the pump (7).
The results are shown in Table 1.

[0035]

[Comparative Example 5] Pellets are obtained in the same manner as in Example 3, except that the organic peroxide is not additionally added using the pump (7).
The results are shown in Table 1.

[0036]

[Table 1]

[0037]

Example 6 The reactor (6) in FIG. 1 has a capacity of 9 L,
A pump (8) was added with 200 ppm of an organic peroxide (manufactured by NOF CORPORATION, 50% by weight solution of perbutyl D in ethylbenzene), and the latter part of the reactor (6) (volume 3 L) was added 16 times.
Pellets are obtained in the same manner as in Example 1 except that the temperature is controlled to 5 ° C. The position to be added by the pump (8) is ⅔ from the inlet of the reactor (6). The SOLID% of the polymerized solution leaving the reactor (6) is 86%. Table 2 shows the results.

[0038]

Comparative Example 6 Three reactors having a structure similar to that of the reactor (3) and a volume of 6 L are arranged in series, and a raw material solution having the same composition as in Example 1 is supplied at 2.5 L / H. , The temperature of the first stage reactor is 120 ° C-125 ° C, the temperature of the second stage reactor is 1
35 ℃ -145 ℃, the third stage temperature 155 ℃ -165 ℃
The resulting polymerization solution is sent to a twin-screw extruder with a two-stage vent (9), treated at a temperature of 240 ° C., and pelletized. SOLID% of polymerization solution exiting the third stage reactor
Is 73%. Table 2 shows the results.

[0039]

[Table 2]

[0040]

Comparative Example 7 Using the same apparatus as in Comparative Example 6, a raw material solution having the same composition as in Example 1 was supplied at 3.5 L / H, the temperature of the two-stage reactor was 135 to 150 ° C., and the temperature of the three-stage reactor was the same. Temperature 150
While controlling in the range of ~ 170 ° C, the SOLID% of the polymerization solution exiting the third stage reactor was operated to be around 75%, but a runaway reaction and a stall reaction were repeated and stable operation could not be performed. It was High productivity could not be achieved by this process.

[0041]

By using the method for producing a rubber-reinforced styrene resin according to the present invention, it becomes easy to control the rubber particle size in a wide rubber particle size range from a large rubber particle size to a small rubber particle size. Then, a rubber-reinforced styrene-based resin having excellent strength and appearance and excellent productivity can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a tubular reactor.

FIG. 2 is a schematic flow sheet of the apparatus used to carry out the method of the present invention.

Claims (1)

[Claims] 1. A ring reactor (I) comprising a tubular reactor containing a static mixer having a flow path through which a heat medium passes, a reactor equipped with stirring blades, and a pump for transferring a reaction solution, and a heat medium. Tubular reactor with a static mixer (I
I) and a raw material solution containing a styrenic monomer and a rubbery polymer are fed to a reactor equipped with a stirring blade,
Tubular reactor (II) while partially circulating the annular reactor (I)
And a volume ratio of the tubular reactor constituting the annular reactor (I) and the reactor equipped with a stirring blade is 5 /
1 to 20/1, and the volume ratio of the annular reactor (I) to the tubular reactor (II) is 1/1 to 1/5, and the tubular reactor (II) has at least one location. From the above, the organic peroxide solution is supplied, and the concentration of the polymer in the reactor equipped with the stirring blade in the reactor (I) is controlled to be 2 to 10 times the concentration of the rubber-like elastic material in the raw material. A method for producing a rubber-reinforced styrene resin, in which a rubber-like elastic material is dispersed in particles in a continuous styrene resin phase.