KR100587648B1 - Continous Polymerization Process of High Impact Polystyrene Resin with Good High Gloss and Falling Dart Impact - Google Patents

Abstract

The continuous production method of the high impact polystyrene resin of the present invention comprises (1) 1 to 88 parts by weight of a styrene monomer and 6 to 12 parts by weight of a rubber component and an initiator in a first reactor at 90 to 120 ° C. Reacting for two hours before the phase change to produce a first polymer having a monomer conversion of 5 to 15%; (2) continuously introducing the first polymer into the second reactor to polymerize at 120 to 140 ° C. for 1 to 2 hours to produce a second polymer having a monomer conversion of 15 to 30%; (3) continuously adding the second polymer to the third reactor and reacting at 140 to 160 ° C. for 0.5 to 1.5 hours to produce a third polymer having a monomer conversion of 30 to 60%; (4) continuously adding the third polymer to the fourth reactor and reacting in the range of 150 to 180 ° C. to produce a fourth polymer having a monomer conversion of 60 to 90%; And (5) removing the unreacted monomer and solvent by introducing the fourth polymer into a volatile remover.

HIPS, full charged continuous stirring reactor, surface gloss, practical impact strength

Description

Continous Polymerization Process of High Impact Polystyrene Resin with Good High Gloss and Falling Dart Impact}             

1 is a process diagram schematically showing a continuous polymerization apparatus for producing a high impact polystyrene resin according to the present invention.

Field of invention

The present invention relates to a continuous production method of high impact polystyrene (HIPS) resin having excellent surface gloss and practical impact strength. More specifically, the present invention uses an inexpensive high-viscosity rubber and an appropriate amount of initiator, introduces a suitable reactor before and after the phase transition and gives optimum reaction conditions, thereby providing excellent surface gloss and practical impact strength and low manufacturing cost. It relates to a continuous production method of this excellent high impact polystyrene resin.

Background of the Invention

Styrene-based resins have been produced commercially a lot of excellent transparency, thermal stability, processability. In particular, high impact polystyrene (HIPS) resins having enhanced impact resistance have been developed by introducing rubber particles into styrene resins. These HIPS resins disperse rubber having a low glass transition temperature (Tg) in monovinylidene aromatic compounds such as styrene, alpha-methyl styrene, and ring-substituted styrene, in particular polybutadiene particles, in a matrix of styrene polymers for impact resistance. It is reinforced.

In particular, as consumer preferences for large products have increased in recent years, home appliance companies have increased the output of large products, and at the same time, there are attempts to reduce the thickness of products to reduce the weight and manufacturing cost of large products. In addition, the demand for products with excellent surface gloss for the beautiful appearance of injection products is increasing. However, if the rubber particle size of the high impact polystyrene resin is reduced in order to reduce the thickness of the product and improve the surface glossiness, there is a problem that cracks occur in the appearance of the molded article even in a small impact due to a drop in practical impact strength. Therefore, the resin manufacturer is focusing on researching and developing a product having a small enough rubber particle size and excellent practical impact strength in manufacturing a high impact polystyrene resin to compensate for these disadvantages.

Therefore, in order to compensate for the disadvantage of low practical impact strength, a method of improving the practical impact strength by adding polydimethylsiloxane to the styrene resin and increasing the flexibility of the resin, such as Japanese Patent Application Laid-Open No. 60-217254, has been tried. I have a problem.

Another conventional technique for increasing the practical impact strength is to disperse the particle size of the rubber phase, which is a dispersed phase of high-impact polystyrene (HIPS) resin, in the form of bimodal or trimodal, and thus have different rubber particle sizes. There is a method of pre-polymerizing the impact polystyrene (HIPS) resin and then mixing in a reactor after the phase transition. However, in order to make different particle diameters, not only reactors having different polymerization raw material costs are required in the previous phase transition, but also have disadvantages of complicated control for polymerization and insufficient practical impact strength, and satisfactory surface gloss. There is a disadvantage that it is difficult to obtain a product having a degree.

Another conventional technique for increasing the practical impact strength is a method of increasing the binding force of the rubber phase in the dispersed phase and the polystyrene phase in the continuous phase by improving the graft ratio. However, the method of increasing the graft ratio of the rubber phase and the polystyrene phase by using the initiator has a problem that the continuous bulk polymerization is difficult due to the increase of the reactivity with the use of the initiator, and the appearance of the product is deteriorated.

Meanwhile, in order to obtain high impact polystyrene resin having excellent surface glossiness, expensive low viscosity special rubber has been used. The high-priced low-viscosity special rubber is a low-cis polybutadiene rubber, which is dissolved in a styrene monomer and prepared in 5 parts by weight. The viscosity of the rubber solution is 30-45 centipoise.

However, in the case of using such expensive low-viscosity special rubber, the production cost of high impact polystyrene resin is increased, and the price competitiveness is lowered, and the graft efficiency is low, and thus the practical impact strength is low. In addition, when the initiator is used to improve the graft efficiency, the rubber particle size of the final product is less than 0.35㎛, which makes it difficult to control the rubber particles of the final product and has disadvantages in the physical properties of the final product.

In order to overcome the above problems, the present inventors have lowered the manufacturing cost by using a low-cost high viscosity rubber, and introduced an appropriate amount of initiator within the range that the appearance of the final product does not deteriorate, thereby improving the graft ratio of the final product, By introducing an appropriate reactor in the previous and subsequent steps, and giving the optimum reaction conditions, it has been developed a method for producing a high impact polystyrene resin having excellent surface gloss and practical impact strength.

An object of the present invention is to provide a continuous production method of a high impact polystyrene resin excellent in surface glossiness and practical impact strength.

Another object of the present invention is to provide a continuous production method of a high impact polystyrene resin having excellent price competitiveness by lowering the manufacturing cost by using a low cost high viscosity rubber in manufacturing a high impact polystyrene resin.

The above and other objects of the present invention can be achieved by the present invention described below. Hereinafter, the content of the present invention will be described in detail.

The continuous production method of the high-impact polystyrene resin having excellent surface glossiness and practical impact strength of the present invention comprises (1) a rubber mixture solution in which 88 to 94 parts by weight of a styrene monomer and 6 to 12 parts by weight of a rubber component and an initiator are dissolved in a first reactor. Reacting at 90-120 ° C. for 1-2 hours to a previous point in time to produce a first polymer having a monomer conversion of 5-15%; (2) continuously introducing the first polymer into the second reactor to polymerize at 120 to 140 ° C. for 1 to 2 hours to produce a second polymer having a monomer conversion of 15 to 30%; (3) continuously adding the second polymer to the third reactor and reacting at 140 to 160 ° C. for 0.5 to 1.5 hours to produce a third polymer having a monomer conversion of 30 to 60%; (4) continuously adding the third polymer to the fourth reactor and reacting in the range of 150 to 180 ° C. to produce a fourth polymer having a monomer conversion of 60 to 90%; And (5) removing the unreacted monomer and solvent by introducing the fourth polymer into a volatile remover. Detailed description of each of these steps is as follows.

Preparation of First Polymer

In the method of manufacturing a high impact polystyrene resin according to the present invention, first, a styrene monomer and a rubber are dissolved in a dissolution tank to prepare a rubber mixture solution, and then the rubber mixture solution is transferred to a full charge reactor, which is a first reactor. At this time, during continuous transfer of the rubber mixture solution to the first reactor, 100-300 ppm of the initiator (TBPA) is continuously supplied.

The rubber mixture solution is composed of 88 to 94 parts by weight of the styrene monomer and 6 to 12 parts by weight of the rubber component.

The styrene monomers include styrene, α-methyl styrene, α-ethyl styrene, p-methyl styrene, and the like.

The rubber of the present invention is preferably low cis polybutadiene rubber (Low Cis Polybutadiene Rubber) is used in that the viscosity of the rubber solution prepared by dissolving in styrene monomer to 5 parts by weight is 150-200 centipoise.

Conventionally, expensive low viscosity special rubber was used to obtain a high impact polystyrene resin having excellent surface glossiness. However, when expensive low viscosity low sheath polybutadiene rubber is used, the manufacturing cost increases and the price competitiveness is lowered, and the graft efficiency is low, thus the practical impact strength is low. On the other hand, inexpensive high viscosity low sheath polybutadiene rubber is generally known to be disadvantageous in producing a high impact polystyrene resin having high surface glossiness due to the high viscosity of the rubber solution.

In the present invention, a low-cost, high-viscosity low sheath polybutadiene rubber is used to lower the manufacturing cost, add an appropriate amount of initiator within a range that does not deteriorate the appearance of the final product, and introduce an appropriate reactor before and after the phase transition, and optimum reaction. By providing conditions, it is possible to provide a high impact polystyrene resin excellent in both surface gloss and practical impact strength.

As a solvent according to the present invention, aromatic compounds such as ethyl benzene, benzene, toluene, methyl ethyl ketone, and the like may be used.

As the initiator used in the first polymerization reactor, tertiary butyl peroxyacetate, tertiary butyl peroxybenzoate and the like are used.

The first reactor of the present invention is a full charge type in which the polymerization mixture is fed to the bottom of the reactor in a continuous flow stirred reactor (CSTR) and the reactant is discharged upwards to the reactor. The polymerization temperature is carried out for 1 to 2 hours at 90 to 120 ℃. At this time, the conversion rate is 5 to 15% and the reaction is transferred to the second polymerization reactor after the phase transfer reaction.

The product of the first polymerization reactor is a polystyrene polymerized in a continuous rubber phase in the dispersed phase.

Preparation of Second Polymer

The first polymer is continuously introduced into a second reactor, which is a phase transfer reactor, to prepare a second polymer having a monomer conversion of 15 to 30%. The second reactor is a continuous flow stirred reactor (CSTR) as a phase transfer reactor.

The polymerization temperature in the second reactor is proceeding for 1 to 2 hours at 118 to 140 ℃, the conversion rate at this time is 15 to 30%.

An important role of the second polymerization reactor of the present invention is to disperse the rubber particles on the continuous polystyrene. The reactants of the first polymerization reactor are dispersed in the polystyrene phase on the continuous rubber, but at the time when the volume volume of the polystyrene produced by the second polymerization reactor polymerization and the volume volume of the initially charged rubber (including polystyrene grafted to rubber) are the same. The phase transition starts and a rubber dispersed phase is formed in the polystyrene continuous phase.

The particle diameter and distribution of the rubber particles produced by the phase transition process and the occlusion of polystyrene in the rubber particles are important factors for determining the physical properties of the high impact polystyrene resin.

Preparation of Third Polymer

The second polymer is continuously introduced into a third reactor to prepare a third polymer having a monomer conversion of 30 to 60%.

The third reactor is a flow flow of reactants using a horizontal reactor and reacts at a reaction temperature of 140 to 160 ° C. for 0.5 to 1.5 hours, and the conversion rate is 30 to 60%.

Then, 0.1-0.3 parts by weight of silicone oil having a viscosity of 500,000-1,000,000 centistokes at room temperature is continuously supplied to the third reactor.

Preparation of Fourth Polymer

The third polymer is continuously added to the fourth reactor to prepare a fourth polymer having a monomer conversion of 60 to 90%.

The fourth reactor of the present invention is divided into four regions from the inlet to the outlet, and is a full-charged flow flow reactor capable of temperature control and easy control of reaction heat generated by polymerization.

The fourth reactor is a final reactor in the polymerization step and polymerizes at a conversion rate of 60 to 90% at a temperature of 150 to 180 ° C.

The polymer having a conversion rate of 60 to 90% through the fourth reactor is transferred to a devolatilizer to remove unreacted monomers and solvents, thereby preparing a final high impact polystyrene resin. The rubbery particle size distribution of the final product of the invention ranges from 0.35 μm-0.5 μm.

The invention can be better understood by the following examples, which are intended for the purpose of illustration of the invention and are not intended to limit the scope of protection defined by the appended claims.

Example 1

88.6 parts by weight of styrene monomer, 6.4 parts by weight of raw sheath polybutadiene rubber having a viscosity of 170 centipoise, and 5.0 parts by weight of ethyl benzene were dissolved in a complete mixing tank to prepare a reaction raw material solution, which was then supplied to the first reactor. The initiator (TBPA) was continuously supplied at 100 ppm per hour to the raw material solution fed to the first reactor during continuous transfer to one reactor. The first reactor was reacted at 106 ° C. for 1 hour.

The reactant passed through the first reactor was reacted for 2 hours in a second reactor at 120 ° C. and 50 RPM, and then introduced into a third reactor.

In the third reactor, 0.2 parts by weight of silicon oil was continuously supplied into the third reactor, reacted at 150 ° C. and 15 RPM for 0.8 hours, and then the reactants were transferred to the fourth reactor. The fourth reactor was reacted by increasing the temperature step by step, and the reaction temperature was reacted at 161, 163, 165, and 167 ° C, respectively. The polymers passed through the four reactors were removed by pelletization and unreacted monomers through a volatilizer to prepare a final polymer. Resin characterization for the final polymerized product and physical property analysis for the injection molded product were performed.

The reaction conditions and the results at each step are shown in Table 1, and the physical property evaluation method is as follows.

(1) Izod impact strength was measured by ASTM D-256.

(2) Flowability: measured by ASTM D-1238.

(3) Glossiness: Measured by ASTM D-523.

(4) Rubber particle size: measured by Malvern's Mastersizer S Ver 2.14.

(5) Practical impact strength: measured by ASTM D-3029.

(6) Graft rate (%): It calculated | required by the following formula.

Graft Rate (%) = 100 × {[MEK Solvent Insoluble (%)-Polybutadiene Input (%)]} / {Polybutadiene Input (%)}

Example 2

200 ppm of the initiator (TBPA) was continuously supplied, and the same procedure as in Example 1 was carried out except that the temperature of the first reactor was changed to 104 ° C and the temperature of the second reactor was changed to 119 ° C.

Example 3

In the same manner as in Example 1, except that 300 ppm of an initiator (TBPA) was continuously supplied and the temperature of the first reactor was changed to 102 ° C., and the temperature of the second reactor was changed to 118 ° C.

Comparative Example 1

The initiator (TBPA) was carried out in the same manner as in Example 1 except for continuously supplying 0 ppm per hour and changing the temperature of the first reactor to 110 ° C. and the temperature of the second reactor to 125 ° C.

Comparative Example 2

      The initiator (TBPA) was carried out in the same manner as in Example 1 except for continuously supplying 400 ppm per hour and changing the temperature of the first reactor to 100 ° C. and the temperature of the second reactor to 117 ° C.

Comparative Example 3

The polybutadiene rubber was changed to a low-cost polybutadiene rubber, which is an expensive low-viscosity special rubber (which is characterized by a viscosity of 40 centipoise of a rubber solution prepared by dissolving in styrene monomer at 5 parts by weight) and the initiator (TBPA) per hour The process was carried out in the same manner as in Example 1 except that the feed was continued at 0 ppm and the temperature of the first reactor was 110 ° C. and the temperature of the second reactor was 125 ° C.

Comparative Example 4

The polybutadiene rubber was changed to a low-cost polybutadiene rubber, which is an expensive low-viscosity special rubber (which is characterized by a viscosity of 40 centipoise of a rubber solution prepared by dissolving in styrene monomer at 5 parts by weight) and the initiator (TBPA) per hour It was carried out in the same manner as in Example 1 except that it was continuously supplied at 200 ppm and the temperature of the first reactor was 104 ° C. and the temperature of the second reactor was 119 ° C.

division Example Comparative Example One 2 3 One 2 3 4 First reactor % Conversion 8.6 8.4 8.5 8.3 8.5 8.4 8.5 Reaction temperature (℃) 106 104 102 110 100 110 104 Stirring Speed (RPM) 110 110 110 110 110 110 110 Retention time (hr) One One One One One One One Initiator (ppm) 100 200 300 0 400 0 200 Second reactor % Conversion 26.2 26.0 26.5 26.4 26.0 26.3 26.1 Reaction temperature (℃) 120 119 118 125 117 125 119 Stirring Speed (RPM) 50 50 50 50 50 50 50 Retention time (hr) 2 2 2 2 2 2 2 Third reactor % Conversion 55.2 54.9 55.0 55.2 58.9 55.1 55.3 Reaction temperature (℃) 150 Stirring Speed (RPM) 15 Retention time (hr) 0.8 Fourth reactor % Conversion 74.8 74.5 74.7 74.0 74.6 74.5 74.3 Reaction temperature (℃) 1 zone / 2 zone / 3 zone / 4 zone = 161/163/165/167 Retention time (hr) 0.7 Property results Impact Strength (kgfcm / cm) 12.5 12.8 13.2 14.0 10.5 11.0 9.5 Fluidity (g / 10min, 5kg, 200 ℃) 8.5 8.4 8.6 8.7 8.6 8.4 8.3 Rubber Particle Size (㎛) 0.45 0.42 0.40 1.5 0.33 0.42 0.27 Glossiness (%, 60 °) 95 96 97 45 97 96 98 Graft Rate (%) 160 167 175 120 182 115 160 Practical Impact Strength (J) 12.0 12.5 13.2 8.0 4.5 3.0 3.5

As shown in Table 1, when the low-cost high-viscosity rubber was used by adding 100-300 ppm of an initiator (TBPA), it was possible to obtain high-impact polystyrene having excellent surface gloss and practical impact strength and excellent appearance of the injection molded product. In Comparative Example 1, although high viscosity rubber was used but no initiator was added, the rubber particle size of the final product was so large that the surface glossiness was low and the graft ratio was low, and thus the practical impact strength could not be satisfied. In Comparative Example 2, a high viscosity rubber was used and the initiator was 400 ppm, and the surface gloss and graft ratio were excellent. However, the rubber particle size of the final product was too small to satisfy the practical impact strength. In the case of Comparative Example 3, an expensive low-viscosity special rubber was used and no initiator was added, but the surface gloss was excellent, but the graft ratio was low, so that the practical impact strength was very low. In the case of Comparative Example 4, the use of expensive low-viscosity special rubber and the use of 200ppm of initiator showed excellent surface gloss and graft rate, but the practical impact strength was low because the rubber particle size of the final product was very small.

The present invention uses low-cost, high-viscosity rubber and a suitable amount of initiator (TBPA), introduces an appropriate reactor before and after the phase transition and gives optimum reaction conditions, thereby providing excellent surface gloss and practical impact strength and low manufacturing cost. It has the effect of the invention which provides the continuous manufacturing method of this excellent high impact polystyrene resin.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (8)

(1) Conversion rate of monomer by reacting the rubber mixture solution in which 88 to 94 parts by weight of styrene monomer and 6 to 12 parts by weight of rubber component and initiator were reacted in the first reactor at 90 to 120 ° C. for 1 to 2 hours before the phase transition. To yield a first polymer of 5-15%; (2) continuously introducing the first polymer into the second reactor to polymerize at 118 to 140 ° C. for 1 to 2 hours to produce a second polymer having a monomer conversion of 15 to 30%; (3) continuously adding the second polymer to the third reactor and reacting at 140 to 160 ° C. for 0.5 to 1.5 hours to produce a third polymer having a monomer conversion of 30 to 60%; (4) continuously adding the third polymer to the fourth reactor and reacting in the range of 150 to 180 ° C. to produce a fourth polymer having a monomer conversion of 60 to 90%; And (5) adding the fourth polymer to a volatile remover to remove unreacted monomers and solvents; A continuous production method of high impact polystyrene resin, characterized in that consisting of steps. The method of claim 1, wherein the rubber component is a low-sea polybutadiene rubber, and the viscosity of the rubber solution prepared by dissolving in a styrene monomer at 5 parts by weight is 150-200 centipoise. . The method of claim 1, wherein the initiator is continuously introduced at 100-300 ppm per hour to the rubber mixture solution continuously transferred to the first reactor. The method of claim 1, wherein the first reactor is a full-charge reactor, a continuous flow stirred reactor. The method of claim 1, wherein the second reactor is a continuous flow stirred reactor as a phase transfer reactor. The method of claim 1, wherein the third reactor is a horizontal reactor for producing a flow of a flow of reactants. According to claim 1, The third reactor is a continuous method of producing a high impact polystyrene resin, characterized in that continuously supplying 0.1-0.3 parts by weight of silicone oil having a viscosity of 500,000-1,000,000 centistokes at room temperature into the third reactor. . The method of claim 1, wherein the fourth reactor is divided into four zones from the inlet to the outlet, each of which is a full-charged flow flow reactor capable of temperature control, easy to control the heat of reaction generated by polymerization Continuous production method of a high impact polystyrene resin.

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