JPH03199212A - Continuous production of impact-resistant styrene-based resin - Google Patents

Abstract

PURPOSE:To continuously obtain the subject resin having excellent appearance of molding, impact resistance and two-peaks type particle size distribution by adding rubber particle and a monomer to a rubbery polymer and a vinyl aromatic monomer in each of plural reaction tanks and subjecting to multistage polymerization in specific conditions. CONSTITUTION:A vinyl aromatic monomer containing 2-12wt.% rubbery polymer is continuously supplied to a first reaction tank and polymerized, then 10-30wt.% of the monomer is polymerized to give a reacting solution containing rubber particles having 0.5-2.0mu average particle diameter. Next, said solution is continuously supplied to a second reaction tank and the vinyl aromatic monomer containing 5-20 pts.wt. styrene-butadiene block copolymer rubber is added, polymerized to attain 15-50wt.% conversion of the whole monomer to give a reacting solution containing rubber particles having a two-peaks type particle size distribution having two peaks at 0.5-20mu and 0.1-0.5mu average particle diameters. Further, said solution is continuously supplied to a third reaction tank and polymerized to attain 60-90wt.% conversion of the whole monomer, then said solution is sent to a volatile remover, thus unreacted monomer are removed to afford the aimed resin containing rubber particles having a two-peaks type particle size distribution as a dispersed phase and a vinyl aromatic polymer as a continuous phase.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to the continuous production of impact-resistant styrenic resins that have excellent molded appearance and impact resistance. More specifically, the present invention relates to a method for continuously producing an impact-resistant styrenic resin having rubber particles as a dispersed phase having a bimodal particle size distribution of small particle size and large particle size.

[Conventional technology]

Rubber modified styrene resin (high impact polystyrene)
is used in a wide range of applications due to its well-balanced physical properties and ease of molding.

In high-impact polystyrene, the particle size of the dispersed rubber particles has an important effect on product performance, and the smaller the rubber particle size, the higher the gloss of the molded product.

Normally, the rubber particle size in high impact polystyrene is 1
．． The particle diameter is approximately 0 to 5.0 ξ microns, but recently resins having rubber particles of 1.0 micron or less have been developed in order to improve the gloss of molded products. However, when it comes to high-impact polystyrene resins, when the rubber particle size becomes 1.0 microns or less, the impact strength normally decreases significantly, and there is a limit to reducing the particle size. There was a limit to how much gloss could be improved.

In order to improve these, a method of blending high-impact polystyrene with rubber particles of 1.0 microns or less and high-impact polystyrene with particles of 1.0 microns or more was proposed in Japanese Patent Publication No. 46-41467,
519, JP 63-241053, U.S. Patent No. 4.14
6,589 etc. These methods have problems such as insufficient gloss and poor balance between impact and gloss.

On the other hand, it is well known that when a styrene-butadiene broth copolymer with a high styrene content is polymerized as a rubber component, rubber particles of 0.5 microns or less with a single occlusion structure are formed ( ExampleAnge
w, MakroeAo1. Chem, +58/5
9P175-198 (1977)), and a method for producing high-impact polystyrene with excellent gloss and transparency for molded products using these was published in Japanese Patent Publication No. 48wt85.
94, JP-A-61-500497, JP-A-63-483
17, JP-A No. 64-74209, etc. With these methods, it is true that the surface gloss and transparency of molded products have been significantly improved compared to conventional high-impact polystyrene, but although attempts have been made to improve impact strength, it has not yet been sufficient.

In addition, by blending high-impact polystyrene having rubber particles with a single occlusion structure formed using the above-mentioned styrene-butadiene copolymer rubber with ordinary high-impact polystyrene having a small amount of rubber particles having a salami structure, molding is possible. An attempt to improve impact while maintaining a high level of gloss was published in U.S. Patent No. 4,493.
, 922, and JP-A-63-12646. In these methods, although the impact strength is certainly improved, the gloss is still insufficient or it is necessary to add polydimethylsiloxane to the resin. In these methods, resins produced separately are blended using an extruder, or polymerization liquids of small-particle rubber and large-particle rubber are mixed in a polymerization reaction tank.

[Problem that the invention seeks to solve]

The purpose of the present invention is to provide a continuous process for producing impact-resistant styrenic resins that have significantly improved appearance of molded products and excellent impact strength compared to conventional high-impact polystyrenes, extremely efficiently and at low cost. The purpose is to provide a method.

[Means to solve the problem]

That is, the present invention provides a method for continuously producing an impact-resistant styrenic resin having rubber particles with a bimodal particle size distribution as a dispersed phase. Polymerization is carried out by continuously feeding a first raw material solution consisting of an aromatic monomer into a first reaction tank at an amount of P, 1/hour, and converting 10 to 30 wt% of the monomer into a polymer. Convert it to 0.
having rubber particles with an average particle size of 5 to 2.0 microns,
(B) The first reaction solution is continuously supplied to a second reaction tank of a complete mixing tank type, and at the same time, the bound styrene content is 20 wt%.
A second raw material solution made of a vinyl aromatic monomer containing 5 to 20 parts by weight of a styrene-butadiene block copolymer rubber having a block styrene content of 60% or more of the total bound styrene content and a content of 50% or less by weight. (C) In the second reaction tank, the first reaction solution and the second raw material solution are continuously supplied to the second reaction tank at a rate of 15 to 50 w of total monomers. Polymerization is carried out to a conversion rate of t%, and the rubber component in the second raw material solution is also made into particles, so that rubber particles with an average particle diameter of 0.5 to 2.0 microns are 5 to 35 wt%, O0I to a second reaction solution having rubber particles with a bimodal particle size distribution of 95 to 55 wt% rubber particles with an average particle diameter of 0.5 microns; (D) the second reaction solution is used in a third reaction; (E) The reaction solution in the final reaction tank is continuously supplied to the reaction tank and, if necessary, to subsequent reaction tanks to carry out polymerization until the monomer conversion rate reaches 60 to 90 wt%. Continuously sent to a devolatilizer to separate the polymer containing the rubber component from the unreacted monomer, the rubber particles having a bimodal particle size distribution as the dispersed phase, and the total amount of the rubbery polymer Ratio to resin is 8w
impact resistant styrenic resin in which the molecular weight distribution index of the vinyl aromatic polymer in the continuous phase is in the range of 1.9 to 3.0 and the crosslinking degree index in the dispersed phase is in the range of 10 to 20. It is a continuous manufacturing method characterized by obtaining.

Examples of the vinyl aromatic monomer as a raw material in the present invention include styrene, methylstyrene, ethylstyrene, isopropylstyrene, alkylstyrene such as butylstyrene, vinyl group-substituted or nuclear-substituted alkylstyrene such as chlorstyrene, bromstyrene, etc. At least one styrene monomer such as halogenated styrene or halogenated alkylstyrene is used, and styrene, alpha-methylstyrene, and para-methylstyrene are particularly preferably used.

The rubbery polymer used in the first raw material solution in the present invention may be any substance that is rubbery at room temperature, such as polybutadiene, styrene-butadiene copolymer rubber, ethylene-propylene copolymer rubber, etc. Examples include composite rubber, ethylene-propylene-terpolymer copolymer rubber, butadiene-acrylonitrile copolymer rubber, etc.
These may be used alone or in combination of two or more.

The second raw material in the present invention? Styrene used in liquid 8
The bound styrene content of the butadiene block copolymer rubber is preferably 20 wt% or more and 50 wt% or less, more preferably 30 wt% or more and 45 wt% or less. The content of block styrene in fully bound styrene is 60%
The above is preferable. The content of bound styrene is less than 20 wt% or the content of block styrene in the total bound styrene is 6
If it is less than 0%, the rubber particles formed in the second reaction tank will be particles with a single occlusion structure, and rubber particles with an average particle size of 0.5 microns or less cannot be obtained, which is not preferable. . On the other hand, the content of bound styrene is 50w
If it exceeds t%, the resulting impact resistant styrenic resin will have a low impact strength, which is not preferable.

In the present invention, the first or second Hara Zero 4 Fusa means
It refers to a product obtained by dissolving the above-mentioned rubbery polymer or styrene-butadiene block copolymer rubber in a styrene monomer, and adding a solvent as necessary.

Examples of solvents that can be used include toluene, ethylhenzene, xylene, ethyltoluene, ethylxylene, and diethylbenzene. There is no particular limit to the amount of such a solvent used, but the monomer supplied to the polymerization reaction tank! It is preferable not to exceed 50 parts by weight per 00 parts by weight. The reason for this is that if the amount exceeds 50 parts by weight, the effective reaction volume of the reaction tank will be reduced by the solvent, and excessive energy will be required to recover the solvent.

In the present invention, the proportion of the rubbery polymer in the first raw material solution is preferably 2 to 12 wt%, preferably 4 to 0 wt%, based on the entire first raw material solution. The proportion of rubbery polymer is 1
If the amount is 2 wt% or more, when forming rubber particles in the first reaction tank, dispersed particles will not be formed, or even if dispersed particles are formed, large particles will be likely to be formed, and the average particle size will be 0.
．． It becomes difficult to obtain rubber particles of 5-2.0 microns. On the other hand, if the proportion of the rubbery polymer is less than 2 wt%, the resulting resin will have low impact strength, which is undesirable.

In the present invention, the proportion of the styrene-butadiene block copolymer rubber in the second raw material solution is preferably 5 to 20 wt%, preferably 6 to 15 wt%, based on the entire second raw material solution. The proportion of styrene-butadiene block copolymer is 2
In the case of 0 wt% or more, when rubber particles are formed in the second reaction tank, even if the particles have a single occlusion structure, the particle size is unlikely to be 0.5 microns or less,
Undesirable.

On the other hand, if the proportion of the rubbery polymer is less than 5 wt%, the impact strength of the resulting resin is undesirably low.

In the present invention, the first raw material solution is continuously supplied to the first reaction tank for polymerization, and the first reaction tank may be a completely mixed tank type stirred tank type reaction tank or a plug flow type formal reaction tank. Any type of reaction tank may be used. When a stirred tank type reaction tank is used as the first reaction tank,
In the first reactor, 10 to 30 wt% of the monomer must be converted to polymer. When a formal reaction tank is used as the first reaction tank, 10 to 30 wt % of the monomers in the reaction solution at the outlet of the first reaction tank must be converted into polymers. Conversion rate in reaction solution is 30w
t% or more, when the rubbery polymer becomes dispersed particles in the first reaction tank, giant particles are likely to be generated, making it difficult to obtain rubber particles with an average particle size of 0.5 to 2.0 microns. Become. On the other hand, when the conversion rate in the reaction solution is 10 wt% or less, the monomer conversion rate is low and the rubbery polymer cannot be formed into particles in the first reaction tank.

In the present invention, polymerization is carried out by continuously supplying the first raw material solution to the first reaction tank, but if necessary, a polymerization initiator such as an organic peroxide is added to the first raw material solution simultaneously with the first reaction. It may also be supplied to a tank. Here, the conversion rate of the monomer in the first reaction tank can be adjusted by operating conditions such as the polymerization salinity of the first reaction tank, the raw material density, the raw material supply rate, and the amount of polymerization initiator supplied.

In the present invention, it is necessary to form rubber particles in the first reaction tank, and the average particle diameter of the formed rubber particles is 0.5 to 2.0 s, preferably 0.7 to 1. It needs to be .5 microns. The average particle diameter here is measured as follows. That is, an electron micrograph of the resin was taken using an ultra-thin section method, and the particle diameters of 500 to 700 rubber particles in the photograph were measured and averaged using the following formula.

Average particle size = ΣnD'/ΣnD3 (However, n is the number of rubber particles with a particle size of 0 microns.) When this average particle size is 0.5 microns or less, the impact strength of the resulting impact-resistant styrene resin is In addition, the appearance of the molded product, especially the surface gloss, is unfavorable in case of 2.0 fruit quakron. Most of the rubber particles produced in the first reaction tank have a salami structure found in general high-impact polystyrene.

In the present invention, the first reaction solution and the second raw material solution are simultaneously supplied to the second reaction tank for polymerization, and the second reaction tank is a completely mixed tank type stirred tank type reaction tank. The conversion rate of the first raw material solution and the second raw material solution relative to the total weight needs to be maintained at 15 to 50 wt%, preferably 20 to 40 wt%. At this time, if the second reaction tank is a reaction tank other than a stirred tank type reaction tank, such as a piston flow type formal reaction tank, or even if the second reaction tank is a stirred tank type reaction tank, the reaction in the reaction tank When the monomer conversion rate of the liquid is 15 wt% or less, when the styrene-butadiene block copolymer rubber in the second raw material solution becomes particles, it is difficult to form small particles with an average particle size of 0.5 microns or less. Further, rubber particles having an average particle diameter of 0.5 to 2.0 microns in the first reaction solution also become enlarged, making it difficult to maintain the original particle diameter, which is not preferable. On the other hand, if the monomer conversion rate of the reaction solution in the second reaction tank is 40wt% or more, the particle size of the rubber particles in the first reaction solution is almost maintained, but the The average particle diameter of the rubber particles produced from the styrene-butadiene procopolymer rubber becomes large, which is not preferable. The stirred tank type reaction tank used as the second reaction tank may be any reaction tank in which the reaction liquid in the reaction tank is mixed in a stirring tank so that the composition and temperature are almost uniform, and is well known in the art. For example, there is a reaction tank having a screw type stirring blade with a draft or a double helical type stirring blade. The reaction tank needs to be sufficiently stirred in order to keep the inside uniform and to make the rubber component in the second raw material solution particulate.

In the present invention, the first reaction solution and the second raw material solution are simultaneously supplied to the second reaction tank to perform polymerization, but if necessary, a polymerization initiator such as an organic peroxide is added together with the second raw material solution. may be supplied. Here, the monomer conversion rate in the second reaction tank is:
It can be adjusted by operating conditions such as the polymerization temperature of the second reaction tank, the composition of the first reaction solution, the composition of the second raw material solution, the supply amount of each, and the supply amount of the polymerization initiator.

In the present invention, in the second reaction tank, while the rubber particles in the first reaction liquid maintain their particle size and remain as they are, the rubber component in the raw material solution of method 2 is made into particles, and the average particle size is is 0.1 to 0.5 micron, preferably 0.2 to 0.5 micron
It needs to be 0.4 microns. Here, it is thought that the rubber particles having a flat structure produced in the first reaction tank are retained for a longer time in the low conversion area of the second reaction tank, so that the graft reaction etc. proceed better. The impact strength of impact-resistant styrenic resins is improved. The rubber particles newly generated in the second reaction tank have an average particle diameter of 0.
If the particle size is 5 microns or more, the resulting impact-resistant styrene resin is not desirable because the appearance, especially the surface gloss, when molded is insufficient. On the other hand, when the average particle diameter of the rubber particles is 0.1 micron or less, the surface gloss of the molded product is excellent, but the impact strength is low, which is not preferable. The rubber particles newly generated in the second reaction tank are preferably particles having a single occlusion structure. As mentioned above, it is known that small rubber particles having such a structure can be formed by polymerizing a styrene-butadiene block copolymer rubber having a certain structure. In this method, the desired rubber particles can be formed by satisfying all of the above conditions. In the present invention, the reaction solution in the second reaction tank contains 5 to 35 wt% of rubber particles with an average particle diameter of 0.5 to 2.0 microns, and 5 to 35 wt% of rubber particles with an average particle diameter of 0.1 micron.
There are rubber particles with a bimodal particle size distribution of 95 to 65 wt% rubber particles of ~0.5 microns.

Rubber particles with an average particle size of 0.5 to 2.0 microns are 35w
When the amount of the rubber particles is less than 5iit%, the impact strength of the resulting impact resistant styrenic resin is improved, but the surface gloss of the molded product is not sufficient. Although the surface gloss is excellent, the impact strength is low, which is not preferable. The ratio of rubber particles with an average particle diameter of 0.5 to 2.0 microns and the rubber particles with an average particle diameter of 0.1 to 0.5 microns is the ratio of the rubbery polymer in the first raw material solution x 1 and the rubber particles with an average particle diameter of 0.1 to 0.5 microns. The supply amount F of the raw material, the ratio of the styrene-butadiene copolymer rubber in the second raw material solution x 2, and the supply amount F of the raw material
It can be adjusted by 2. At that time, the ratio p+/pg of the supply amount of the first raw material solution and the second raw material solution is 5/95 to 40/6.
0 is preferred. If the ratio is less than 5/95, the first
This is not preferable because it is necessary to increase the ratio of rubber components in the raw material solution.
This is not preferable because the ratio of the rubber component in the second raw material solution becomes too low or it is necessary to increase the ratio of the rubber component in the second raw material solution. Also, supply I of the first and second raw material solutions
F, Xχ1 which is the product of F+, h and the ratio of rubber components in the raw material solution ×1, ×2, and the ratio of F2
/ F 2 X On the other hand, if the ratio is more than 30/70, some of the rubber particles newly generated in the second reaction tank tend to be larger than 0.5 microns, resulting in 0.1-0. .5 The proportion of rubber particles with a diameter of 5 microns decreases, which is undesirable.

In the present invention, the second reaction solution polymerized in the second reaction tank is continuously extracted from the second reaction tank and continuously supplied to the third reaction tank and, if necessary, subsequent reaction tanks. Polymerization is carried out until the polymer conversion rate reaches 60 to 90 iet%, and the reaction solution in the final reaction tank is continuously heated to, for example, 200 to 90 iet%.
The polymer containing the rubber component is separated from the unreacted monomers and solvent by sending it to a devolatilizer that evaporates unreacted monomers and solvents under vacuum at a temperature range of 290°C to produce high-impact styrene. Obtain a system resin. The rubber-like polymer in the resin obtained at this time must be 8 wt % or more. If the proportion of the rubbery polymer is 8wt% ungrooved, the impact strength of the resin is low, which is undesirable. It can be adjusted by determining the rate.

In the impact-resistant styrenic polymer of the present invention, the crosslinking degree index of the dispersed phase must be maintained in the range of 10 to 20. The crosslinking degree index of this dispersed phase is measured by the following method. 0.4 g of impact resistant styrenic resin is partially dissolved in 30 d of toluene. After centrifugation, the weight of the insoluble matter swollen with the solvent is weighed.

After weighing, vacuum dry the insoluble matter and weigh it again (No. 2).
The crosslinking degree index is obtained as -, 10-2. The degree of crosslinking index depends on the amount and type of polymerization initiator, the temperature during devolatilization treatment,
Depending on the residence time, a person skilled in the art can set an appropriate degree of crosslinking index by selecting these manufacturing process conditions by trial and error. The degree of crosslinking index is 20
If it exceeds 10, the appearance of the molded piece, especially the surface gloss, will be poor, which is undesirable.If it is less than 10, the impact strength will decrease, which is not preferable.

In the impact-resistant styrenic resin of the present invention, the continuous phase vinyl aromatic polymer has a molecular weight distribution index of 1.9 to 3 as determined by gel permeation chromatography (GPC).
．． Must be in the range 0.

The molecular weight distribution index is the value of weight average molecular weight/number average molecular weight. Note that in the measurement, polymers with a molecular weight of 1000 or less are excluded. Such a molecular weight distribution can preferably be achieved by continuous bulk or solution polymerization.

In particular, this is preferably achieved by controlling the final conversion rate of the monomers in the polymerization reaction to 90 wt% or less and subjecting the final reaction solution of the polymerization to a devolatilization treatment. Limiting the molecular weight distribution index is important in maintaining high fluidity.

〔Example〕

Next, examples of the invention will be shown.

Example 1 7.0 parts by weight of polybutadiene (manufactured by Asahi Kaei, trade name Diene 35) was dissolved in 78.0 parts by weight of styrene and 15.0 parts by weight of ethylbenzene as a solvent to form a first raw material solution. did. Add 2 to this first raw material solution as an antioxidant.
．． 0.1 part by weight of 6-ditertiarybutylphenol,
Benzoyl peroxide (BP○”) is used as a polymerization initiator.
) After adding 0.01 parts by weight, the volume 3. is equipped with a screw-type stirring tank with a full liquid draft. Continuously 1. It was fed at a rate of i/hour (p+).

In the first reaction tank, polymerization was carried out at a reaction temperature of 127° C., a rotation speed of a PA stirring blade of 4, and 0 rps to cause phase transition of the rubbery polymer and generate rubber particles. The conversion rate of monomer to polymer in the first reaction solution was 27.2 wt%.The rubber particles produced in the reaction solution averaged about 1. It was Oa Chron.

The first reaction liquid is continuously taken out from the first reaction tank, and the capacity is 24.
．． The reaction was continued by continuously supplying it to a 9f second reaction tank. At the same time, the bound styrene content of 8 parts by weight is 40 wt%,
A second raw material solution consisting of styrene-butadiene block copolymer rubber with a block styrene content of 30 wt%, 77.0 parts by weight of styrene, and 15.0 parts by weight of ethylbenzene as a solvent was added with 2. 6-
0.1 parts by weight of ditertiary butylphenol and benzoyl peroxide (BPO) as a polymerization initiator.
After adding 0.005 parts by weight, 1 part by weight was continuously added to the second reaction tank.
2.0/! /hour (F2). In the second reaction tank, the reaction temperature was 140'C, and the rotation speed of the stirring blade was 3.5 rps.
The rubber component in the second raw material solution was also made into particles by polymerization.

The conversion rate of total monomers to polymer in the second reactor was 33
．． The rubber particles produced from the rubber component in the second raw material solution had an average size of about 0.3 microns. Approximately 0
．． The second reaction liquid having rubber particles with a bimodal particle size distribution of 2 microns and about 1.0 microns is continuously removed from the second reaction tank, and the outlet temperature of each formal reaction tank is 140°. C, 150°C 1160°C third,
Polymerization was continued by continuously supplying the polymer to the fourth and fifth reaction vessels.

The reaction solution continuously taken out from the fifth reaction tank had a conversion rate of all monomers to polymer of 81.6%.

After the reaction liquid from the fifth reaction tank is continuously sent to a conventionally known devolatilization device to separate unreacted monomers and solvent from the polymer containing the rubber component under high temperature and reduced pressure. , and pelletized using an extruder to obtain high impact polystyrene resin. At that time, the rubbery polymer containing the rubber component was pelletized at a temperature of 250"C in the devolatilization equipment. The obtained high impact polystyrene resin contained 11.1% of the rubber component in the resin. , the rubber component has a bimodal particle size of rubber particles having a single occlusion structure of about 10% rubber particles with an average particle size of 1.0 microns and about 90% rubber particles with an average particle size of 0.3 microns. Consists of distributed rubber particles.

Further, the crosslinking degree index of the rubber component in the dispersed phase was 15.2, and the molecular weight distribution index of the polystyrene in the continuous phase was 2.7. In addition, when the obtained product was shaped into a bottom shape and the Izot impact value and surface gloss of the molded product were measured, they were 8.3 kg・Cl.
It showed a well-balanced performance of gloss and impact with l1/Cl of 11.93.1%.

Similar evaluations were made in the following Examples and Comparative Examples,
They are shown in Tables 1 and 2, respectively.

Example 2 The amount of polybutadiene in the first raw material solution was 8.0 parts by weight, the amount of styrene-butadiene block copolymer rubber in the second raw material solution was 9.0 parts by weight, and the monomer at the outlet of the final reaction tank was The operation was carried out in the same manner as in Example 1, except that the operation was carried out so that the conversion rate to polymer was 74.9%.

Example 3 The operation was carried out in the same manner as in Example 2 except that the supply rate of the first raw material solution was changed to 32/hour and the supply rate of the second raw material solution was changed to llf/hour. The proportion of small particles was about 80%, and the proportion of large particles was about 20%.

Example 4 As the styrene-butadiene block copolymer rubber in the second raw material solution, a complete block type containing 140 wt% of bound styrene and 40 wt% of blocked styrene was used, and the other conditions were the same as in Example 3. I drove.

Comparative Example 1 The operation was carried out in the same manner as in Example 1 except that the amount of polybutadiene in the first raw material solution was 13.0 parts by weight and the amount of styrene was 72.0 parts by weight. As a result, rubber particles were not produced in the first reaction tank, and rubber particles were produced in the second reaction tank at the same time as the rubber component in the second raw material solution, but the rubber particles produced at that time were clearly It did not show a bimodal particle size distribution.

Comparative Example 2 The operation was carried out in the same manner as in Example 1, except that birch whose conversion rate of monomer to polymer in the first reaction tank exceeded 30% was used. The rubber particles on the large particle side generated in the first reaction tank are 2.
It was as large as 7μ, and the surface gloss of the obtained product was low.

Comparative Example 3 The operation was carried out in the same manner as in Example 1, except that the conversion rate of monomer to polymer in the first reaction tank was controlled to be 10% or less. In the first reaction tank, rubber particles were not produced, but in the second reaction tank, rubber particles were produced at the same time as the rubber component in the second raw material solution. It did not show a peaked particle distribution.

Comparative Example 4 The amount of styrene-butadiene Pronk copolymer rubber in the second raw material solution was 21.0 parts by weight, and the amount of styrene was 64.0 parts by weight.
The operation was carried out in the same manner as in Example 1 except that the amount was 0 parts by weight. The rubber particles produced in the second reaction tank were large, and no rubber particles smaller than 0.5 microns were observed.

Comparative Example 5 The operation was carried out in the same manner as in Example 1 except that the conversion rate of all monomers into polymer in the second reaction tank was 15% or less. As a result, the rubber particles produced in the first reaction tank become enlarged in the second reaction tank, and the second raw material? The rubber particles produced from the styrene-butadiene block copolymer rubber in tM are also 0.
．． The particles were larger than 5 microns.

Comparative Example 6 The operation was carried out in the same manner as in Example 1 except that the conversion rate of all monomers into polymer in the second reaction tank was set to be 50% or more. The rubber particles generated in the second reaction tank are large and 0.5
Rubber particles smaller than microns were not observed.

Comparative Example 7.8.9 As a rubber component in the second raw material solution, bound styrene-containing 1
The operation was carried out in the same manner as in Example 1, except that a 9 wt % styrene-butadiene block copolymer rubber, a styrene-butadiene random copolymer rubber having a bound styrene content of 2511 t %, and a polypucdiene rubber were used. The rubber particles produced in the second reaction tank do not have a single occlusion structure,
Furthermore, the particle size was 0.5 microns or more.

Comparative Example 10 The operation was carried out in the same manner as in Example 1 except that the supply rate of the first raw material solution was 0.51/hour. The proportion of large particles is small,
The resulting product had low impact strength.

Comparative Example 11 The supply amount of the first raw material solution was 6.017 hours, and the supply amount of the second raw material solution was 7.1 hours! The operation was carried out in the same manner as in Example 1 except that the time was changed to /hour. The rubber particles generated in the second reaction tank are 0.
Most of the particles were 5 microns or larger.

Comparative Example 12 Operation was carried out by changing the amount of rubber component in the raw material solution so that the rubber content in the final product was 711 t%. Although the resulting molded product had excellent gloss, its impact strength was low.

Comparative Example 13 The operation was carried out in the same manner as in Example 1, except that the treatment temperature in the devolatilization device was lowered so that the resulting resin had a crosslinking index of 20 or more. As a result, the gloss of the resin molded product was lowered.

Comparative Example 14 The operation was carried out in the same manner as in Example 1, except that the treatment temperature in the devolatilization device was increased so that the crosslinking index was 10 or less.

As a result, the impact strength of the resulting resin decreased.

Comparative Example 15 The temperature of the final reaction tank was raised, and the operation was carried out so that the conversion rate of monomer to polymer in the final reaction tank was 90% or more. The molecular weight distribution index of the resin obtained in the continuous tank polystyrene was as high as 3.4.

Comparative Example 16 In Example 1, the second reaction tank was not used, and the first reaction solution and the second raw material solution were directly supplied to the third reaction tank, which was a formal reaction tank, for polymerization. Rubber particles were generated in the third reaction tank from the rubber component in the second raw material solution, but the rubber particle size was larger than 0.5 microns and did not exhibit a clear bimodal particle size distribution.

〔Effect of the invention〕

By the continuous production method of styrenic resin according to the present invention, it is possible to continuously produce a resin that has excellent molded product appearance and impact resistance.

Claims (3)

[Claims] (1) In the continuous production of impact-resistant styrenic resins having rubber particles with a bimodal particle size distribution as a dispersed phase, (A) a vinyl aromatic resin containing 2 to 12 wt% of a rubbery polymer; A first raw material solution consisting of a monomer is continuously supplied to the first reaction tank at a rate of F_1l/hour to carry out polymerization, converting 10 to 30 wt% of the monomer into a polymer, and ．．
a first reaction liquid having rubber particles with an average particle diameter of 5 to 2.0 microns; (B) the first reaction liquid is continuously supplied to a second reaction tank of a complete mixing tank type; Content is 20wt%
A second raw material solution made of a vinyl aromatic monomer containing 5 to 20 parts by weight of a styrene-butadiene block copolymer rubber whose block styrene content is 60% or more of the total bound styrene content is also 50 wt % or less. (C) In the second reaction tank, the first reaction liquid and the second raw material solution are continuously supplied to the second reaction tank in an amount of 15 to 50 wt% of the total monomer. Polymerization is carried out to a conversion rate, and the rubber component in the second raw material solution is also made into particles, so that rubber particles with an average particle diameter of 0.5 to 2.0 microns are 5 to 35 wt%, and 0.1 to 0. a second reaction solution having rubber particles with a bimodal particle size distribution of 95 to 65 wt % rubber particles with an average particle diameter of .5 microns; (D) the second reaction solution is transferred to a third reaction tank; , and further, if necessary, continuously supplying the reaction solution to subsequent reaction tanks to carry out polymerization until the monomer conversion rate reaches 60 to 90 wt%, (E) Continuously supplying the reaction solution in the final reaction tank The polymer containing the rubber component is separated from the unreacted monomer by sending it to a devolatilization unit, which has rubber particles with a bimodal particle size distribution as a dispersed phase, and the rubbery polymer is separated from the unreacted monomer. The ratio is 8w
impact resistant styrenic resin in which the molecular weight distribution index of the vinyl aromatic polymer in the continuous phase is in the range of 1.9 to 3.0 and the crosslinking degree index in the dispersed phase is in the range of 10 to 20. A continuous manufacturing method characterized by obtaining. (2) A patent characterized in that in the above manufacturing method, 90 wt% or more of the small particle portion of the rubber particles in the resulting impact-resistant styrenic resin with a bimodal particle size distribution has a single occlusion structure. The method according to claim 1. (3) In the above manufacturing method, the ratio F_1/F_2 of the supply amount of the first raw material solution and the supply amount of the second raw material solution is 5/95.
~40/60, and if the proportion of the rubbery polymer in the first raw material solution is x_1wt% and the proportion of the styrene-butadiene block copolymer in the second raw material solution is x_2wt%, then F_1×x_1/F_2 ×x_2 is 5/95~30/
70. The method according to claims 1 and 2, characterized in that: