KR20030056061A - High Gloss Thermoplastic Resin Composition Having High Flowability and Method of Preparing the Same - Google Patents

Abstract

PURPOSE: A thermoplastic resin composition and its preparation method are provided, to obtain a thermoplastic resin having high fluidity and excellent gloss, mold cycle time and impact resistance with a low cost. CONSTITUTION: The method comprises the steps of continuous bulk polymerizing a styrene monomer rubbery solution where a polybutadiene rubber is dissolved in a styrene monomer in a first reactor under the condition of V1/F = 3.04 and 1.2 <= V1/V2 <= 1.6, wherein F is the total flux of the source solution injected into a first reactor, V1 is the internal volume of a first reactor, and V2 is the internal volume occupied by the reaction solution; and sending the obtained polymer into a second reactor and adding polydimethylsiloxane to the second reactor to continuous bulk polymerize the reaction mixture to allow the solid component to be 55-80 wt%. The polybutadiene rubber is dissolved in a styrene monomer in the concentration of 7-20 wt%, and contains 10-98 % of a cis-form; and the polydimethylsiloxane is added in the amount of 0.01-0.80 wt% based on the amount of the reaction mixture of the second reactor, and has a viscosity of 10-10,000 cps.

Description

High Gloss Thermoplastic Resin Composition Having High Flowability and Method of Preparing the Same

Field of invention

The present invention relates to a rubber modified styrene resin composition having high flow and high gloss. More specifically, the present invention performs a continuous block polymerization of the styrene rubber solution in which the polybutadiene rubber is dissolved in the first reactor to complete phase inversion, and adds polydimethylsiloxane in the second reactor to increase the solid content of 55-80%. The present invention relates to a rubber-modified styrene resin composition and a method for producing the same, which are subjected to continuous bulk polymerization so that the average particle diameter of the rubber particles in the final resin composition is in the range of 0.2-1.1 µm.

Background of the Invention

Rubber modified styrenic resins are excellent in fluidity and gloss compared to other resins. It is widely used for molded articles such as office equipment and flame retardant base resins. In particular, when the rubber-modified styrene resin is applied as a flame-retardant base resin, it is also excellent in workability such as injection molding, extrusion sheet molding, extrusion vacuum molding, etc., and has a merit of obtaining not only a beautiful appearance but also a high molding cycle time.

Rubber-modified styrene-based resins are generally polybutadiene rubber and styrene butadiene-polymer polymer rubber. In order to give high fluidity and high gloss of rubber-modified styrene-based resins, the problem of controlling the rubber particle diameter to optimum value and narrowing the particle diameter distribution The problem of this is becoming an important task to be solved.

In the case of using polybutadiene rubber, it is very difficult to control the rubber particle size to an optimum value. When styrene / butadiene interpolymer rubber is used, it is easy to control the rubber particle size to an optimum value, but it is difficult to obtain good impact resistance.

The rubber-modified styrene resin has a structure in which spherical rubber particles are distributed in various sizes on a polystyrene matrix, and the rubber particle sizes generally range from 1.5 to 6.0 μm. The resin having such a structure exhibits the effect that the rubber particles absorb the impact when an impact is applied from the outside.

In addition, the size of the rubber particles also affects the glossiness of the resin molded article. In general, the smaller the size of the rubber particles, the better the gloss. On the other hand, when the size of the rubber particles is reduced in consideration of the glossiness, the impact strength is lowered.

U.S. Patent No. 4,146,589 discloses (A) continuous mass polymerization of a styrene monomer first solution in which 2-15% by weight of polybutadiene rubber is dissolved in a first reactor so as to have a rubber particle size of about 0.5-1.0 µm, and (B) Continuous mass polymerization of the second styrene monomer solution in which 2-15% by weight of polybutadiene rubber is dissolved in a second reactor to obtain a rubber particle size of about 2-3 μm, (C) the first polymerization solution and the second polymerization solution Styrene-based rubber modified with (D) continuous bulk polymerization of the mixed solution in a third reactor, (E) heating the solution, and (F) separating the polymer from the solution A method for producing a resin is disclosed.

US Pat. No. 4,493,922 consists of polystyrene as a matrix and two elastomers or copolymers uniformly dispersed in the matrix, one of which has a particle size of 0.2-0.6 μm and 60-95% by weight relative to polybutadiene. The other discloses an impact resistant thermoplastic molding having a particle size of 2-8 μm and 40-5% by weight relative to polybutadiene. However, the above-mentioned 4,146,589 and 4,493,922 have the disadvantage that the effective impact strength and glossiness cannot be obtained and the surface appearance of the molded article is not uniform when molded at low temperature.

Japanese Patent Application Laid-Open No. 57-170950 discloses rubber modifications comprising (a) a polybutadiene solution with an average rubber particle size of 0.5-2.5 μm and a rubbery polymer of 1-15% by weight, (b) methanol and (c) organic polysiloxane. A styrene resin composition is disclosed.

Japanese Patent Laid-Open No. 2-34615 discloses a resin composition composed of (a) butadiene rubber polymer, (b) toluene and (c) organic polysiloxane.

The above-mentioned 57-170950 and 2-34615 contain polydimethylsiloxane, but there is a problem in that the average rubber particle size, the ratio of the gel component to the rubber component are not constant, and thus do not exhibit good impact properties.

Therefore, in order to solve the above problems, the present inventors appropriately control the average rubber particle size as well as the ratio of the gel component to the rubber component in the resin composition, so that the thermoplastic resin composition has not only high flowability and high glossiness but also good impact strength. And developing a method for producing the same.

An object of the present invention is to provide a rubber-modified styrene resin composition having an average rubber particle size of 0.2-1.1 µm and a gel component to rubber component ratio in the range of 1.9-3.4, and a method of manufacturing the same.

Another object of the present invention is to provide a rubber-modified styrene resin composition excellent in fluidity and molding cycle time, and a method for producing the same.

Still another object of the present invention is to provide a rubber-modified styrene resin composition having high glossiness and a method of manufacturing the same.

Still another object of the present invention is to provide a rubber-modified styrene-based resin composition excellent in impact strength and a method of manufacturing the same.

The above and other objects of the present invention can be achieved by the present invention described below.

1 is a process chart of the continuous block polymerization according to the present invention.

The method for producing a thermoplastic resin composition of the present invention comprises (1) a styrene monomer rubbery solution in which polybutadiene rubber is dissolved in a styrene monomer as a raw material solution, and V ₁ / F = 3.04 (V ₁ : Content of the first reactor, F : Flow rate of the raw material solution introduced into the first reactor), 1.2 ≤ V ₁ / V ₂ ≤ 1.6 (V ₁ : the volume of the first reactor, V ₂ : volume of the reaction solution) to maintain the conditions The first step of continuous bulk polymerization in the reactor and (2) the polymer discharged from the first reactor is sent to the second reactor to add 0.01-0.80% by weight of poly dimethylsiloxane so that the solid component is 55-80% by weight. It consists of a second step of bulk polymerization. The ratio of the gel component to the rubber component of the final pellet prepared by the above production method is in the range of 1.9 to 3.4, and the average rubber particle size is in the range of 0.2 to 1.1 μm. The thermoplastic resin composition of the present invention is produced by continuous bulk polymerization, and the process according to the present invention is approximately disclosed in FIG.

Hereinafter, the details of the present invention will be described below.

(1) First step

The raw material solution supplied to the first reactor is a styrene monomer rubbery solution in which polybutadiene rubber is dissolved in styrene monomer, and the raw material solution is continuously supplied from the storage tank to the first reactor.

As the polybutadiene rubber dissolved in the solution of the styrene monomer, various polybutadiene rubbers can be used, but polybutadiene rubber having a content of 10 to 98% of the cis form solution polymerized by a lithium-based catalyst is preferable.

The rubber component dissolved in the solution of the styrene monomer is preferably in the range of 7 to 20% by weight based on the rubbery solution. When the concentration of the polybutadiene rubber is outside the range of 7 to 20% by weight, the styrene monomer in the rubber solution and the additionally supplied styrene monomer do not mix well due to phase unevenness, and the power loss is supplied when feeding into the first reactor. Occurs. In a preferred embodiment of the present invention, the rubber component concentration is adjusted to 12% by weight to ensure the safety of the process operation, and the styrene monomer is further added to maintain the rubber component concentration of the first reactor at 9.0% by weight.

The rubbery solution of styrene monomer in which 7-20% polybutadiene rubber is dissolved preferably has a viscosity of 25-110 cps at 25 ° C., more preferably in the range of 25-70 cps. . The viscosity of the rubbery solution of the styrene monomer is an important factor because it affects the average rubber particle size after the polymerization reaction and the rotation speed of the average shear rate regulator during the polymerization reaction.

The first reactor may be further supplied with a styrene monomer to ensure the stability of the process. Styrene monomers that can be used in the present invention include styrene, α-ethylstyrene and α-methylstyrene. Further necessary styrene monomers are fed to the first polymerizer separately from the rubbery solution.

In order to supply the rubber-like solution and the styrene monomer to the first reactor at a predetermined ratio, a flow controller is used, which can be easily performed by those skilled in the art.

In the first reactor, polymerization was performed when V ₁ / F = 3.04, 1.2 ≤ when the internal volume of the first reactor was V ₁ , the volume of the reaction solution was V ₂ , and the flow rate at which the raw material solution was fed to the first reactor was F. The reaction is carried out under the condition of V ₁ / V ₂ ≤ 1.6, and the rotation speed of the average shear rate regulator of the first reactor is maintained at 16 to 52 revolutions per minute. If the ratio of V ₁ / V ₂ exceeds 1.6 (V ₁ / V ₂ > 1.6), there is a problem that the rubber particles are unstable because the phase inversion is not completed and the rubber particles are too small, the impact strength falls, V _If the ratio of ₁ / V ₂ is smaller than 1.2 (V ₁ / V ₂ <1.2), there is a problem that rubber gloss becomes large and good gloss and fluidity cannot be obtained. Therefore, in order to improve mixing and control the average rubber particle size in the first reactor, the range of 1.2 ≦ V ₁ / V ₂ ≦ 1.6 is maintained.

The average shear rate regulator of the first reactor is maintained at 16-52 revolutions per minute. If the rotation speed of the average shear rate controller is less than 16 times / minute, uniform mixing is difficult, and there is a risk of runaway reaction, and the average rubber particle size is increased to reduce the glossiness of the resin. On the other hand, when the rotation speed of the average shear rate regulator is 52 times / minute or more, the load of the regulator increases, making it difficult to operate, and the average rubber particle size decreases, thereby reducing the impact resistance of the resin. The polymerized product in the first reactor is continuously supplied to the second reactor, and continuous bulk polymerization is continued.

(2) second stage

The polymer discharged from the first reactor is continuously supplied to the second reactor and continuously bulk polymerized so that the average rubber particle size is in the range of 0.2-1.1 μm.

In the second reactor, polydimethylsiloxane is added in an amount of 0.01-0.80% by weight based on the total reaction solution. Polydimethylsiloxane is located between polystyrene molecules or between polybutadiene rubber particles and polystyrene molecules to buffer shocks to alleviate external impacts within the resin, or dispersed between polybutadiene rubber components and polystyrene molecules to mitigate impacts. It seems to bring about an effect. In addition, the polydimethylsiloxane dispersed in the resin is partially bleeded between the polystyrene molecules to cover the surface of the resin, thereby reducing the stress of the molding when it is released from the mold during injection molding, thereby reducing the physical properties It is thought to reduce change.

The polydimethylsiloxane introduced into the second reactor preferably has a viscosity of 50-9,000 cps. When the viscosity of the polydimethylsiloxane is less than 50 cps, the dispersion effect in the resin is reduced and the impact strength is lowered. When the viscosity of the polydimethylsiloxane is 9,000 cps or more, a mechanical problem occurs due to the high viscosity when introduced into the second reactor.

The polydimethylsiloxane is dissolved after being dissolved in a separate tank at a ratio of 1: 1 with the styrene monomer.

In the second reactor, the continuous bulk polymerization is preferably performed so that the content of the polymerized solid component is 55-80% by weight. If the content of the solid component exceeds 80% by weight, there is a problem that the impact strength is lowered.

In the first reactor or the second reactor, other additives such as a chain transfer agent may be added, which can be easily carried out by those skilled in the art. For example, a releasing agent, an antistatic agent, a flow agent, an ultraviolet absorber, an antioxidant, and the like may be appropriately added according to the respective uses.

In the second reactor, the reaction product after completion of the polymerization reaction is sent to a devolatilization process, an unreacted monomer is separated while passing through an evaporator, a temperature riser, and the like, and cut into pellets. It is preferable that the ratio of the gel component to the rubber component of the final resin composition in the form of the pearllet is in the range of 1.9 to 3.4. The "gel component" refers to a portion obtained by graft polymerization of a styrene monomer to polybutadiene rubber, and the ratio of the gel component to the rubber component affects physical properties such as high impact and gloss. When the ratio of the gel component to the rubber component is in the range of 1.9 to 3.4, the average rubber particle size is in the range of 0.2 to 1.1 mu m.

The present invention will be further illustrated by the following examples, which are only described for the purpose of illustrating the present invention and are not intended to limit the protection scope of the present invention.

Example

Example 1

86 wt% of styrene monomer and 14 wt% of polybutadiene rubber were added to the polymerization raw material storage tank and dissolved for 3 hours. The viscosity of this rubbery solution was 30 cps. The rubbery solution of the styrene monomer and the styrene monomer were introduced into the first reactor, and the polymerization was carried out by maintaining the polymerization temperature at 135 ° C using peroxyester as an initiator. First when the flow volume of the V _2, the raw material solution to the first reactor, the contents less V _1, the reaction solution of the reactor points in the input into the first reaction vessel with the _{F, V 1 / F = 3.04} , V 1 / V 2 = 1.4 was adjusted. The rotation speed of the shear rate regulator at this time was 45 times / minute. The rubber phase concentration was maintained at 12.0% by weight. The polymer of the first reactor was continuously supplied to the second reactor in the same manner as the first reactor feed flow rate, and 0.015% by weight of polydimethylsiloxane was added to the second reactor. The viscosity of dimethyl polysiloxane was 200 cps, and this polydimethylsiloxane was dissolved in styrene monomer and added. Antioxidants and mold release agents were fed to 1000 ppm and 8000 ppm in the final pellets, respectively. The solid component content of the polymer obtained in the second reactor was 70% by weight. The final polymerization solution was sent to a devolatilization step, and the temperature was raised to 240 ° C. to remove volatile components such as unreacted monomers and to prepare a pellet.

Example 2

The same procedure as in Example 1 was conducted except that the viscosity of the rubbery solution was maintained at 90 cps.

Example 3

The same procedure as in Example 1 was carried out except that the rotation speed of the shear rate controller of the first reactor was adjusted to 50 times / minute.

Example 4

The same procedure as in Example 1 was conducted except that the volume (V ₁ / V ₂ ) of the reactor volume / reaction liquid was 1.55 by adjusting the residence time in the first reactor.

Example 5

The same procedure as in Example 1 was carried out except that the rotation speed of the shear rate controller of the first reactor was 40 times / minute.

Example 6

The same procedure as in Example 1 was carried out except that the solid component content in the second reactor was adjusted to 60 wt% by adjusting the residence time.

Example 7

The retention time was adjusted in the same manner as in Example 1 except that the content of the solid component in the second reactor was 75% by weight.

Example 8

The same procedure as in Example 1 was conducted except that 0.400 wt% of dimethyl polysiloxane was added.

Example 9

The same procedure as in Example 1 was conducted except that 0.65 wt% of polydimethylsiloxane was added.

Example 10

The same procedure as in Example 1 was carried out except that the viscosity of the polydimethylsiloxane was 800 cps.

Example 11

The same procedure as in Example 1 was conducted except that the viscosity of the polydimethylsiloxane was 7000 cps.

Comparative Example 1

The viscosity of the rubbery solution was 125 cps, and the rotation speed of the shear rate controller in the first reactor was 45, except that the procedure was carried out in the same manner as in Example 1.

Comparative Example 2

The residence time was adjusted in the same manner as in Example 1 except that the volume (V ₁ / V ₂ ) of the reactor contents / reaction liquid in the first reactor was set to 1.1.

Comparative Example 3

The same procedure as in Example 1 was carried out except that the solid component content of the second reactor was adjusted to 86 wt% by adjusting the residence time.

Comparative Example 4

The same procedure as in Example 1 was conducted except that the polydimethylsiloxane was added at 0.005% by weight.

Comparative Example 5

The same procedure as in Example 1 was conducted except that the viscosity of the polydimethylsiloxane was 14,000 cps.

Comparative Example 6

The residence time was adjusted in the same manner as in Example 1 except that the volume (V ₁ / V ₂ ) of the reactor volume / reaction liquid in the first reactor was adjusted to 1.8.

The working conditions for the above Examples 1-11 and Comparative Examples 1-6 are shown in Table I.

First reactor Second reactor Rubber solution viscosity (cps) Shear speed controller rotation speed (times / minute) Inner volume / Reaction volume (V ₁ / V ₂ ) Solid component (wt%) Polydimethylsiloxane (% by weight) Polydimethylsiloxane viscosity (cps) Example One 30 45 1.40 70 0.015 200 2 90 45 1.40 71 0.015 200 3 30 50 1.40 70 0.015 200 4 30 44 1.55 69 0.015 200 5 30 40 1.40 71 0.015 200 6 30 45 1.40 60 0.015 200 7 30 45 1.40 75 0.015 200 8 30 45 1.40 72 0.400 200 9 30 45 1.40 71 0.650 200 10 30 45 1.40 70 0.015 800 11 30 45 1.40 72 0.015 7000 Comparative Example One 125 45 1.40 72 0.015 200 2 30 45 1.10 70 0.015 200 3 30 45 1.40 86 0.015 200 4 30 45 1.40 71 0.005 200 5 30 45 1.40 69 0.015 14000 6 30 45 1.80 72 0.015 200

Physical properties of the specimens of Example 1-11 and Comparative Example 1-6 were measured by the following method.

(1) Gloss: It measured according to JIS K 7150 (60 °).

(2) Izod impact strength was measured according to ASTM D256 (1/8 ＂notched).

(3) Flowability: measured by ASTM D1238 (200 ℃, 5 Kg)

(4) Average rubber particle size: 0.3 g of the sample was dissolved in 10 ml of solvent (DMF), and then measured by a Marlburn, England.

(5) Gel content: 1 g of a sample was accurately weighed and recorded in a Erlenmeyer flask (1), and it was dissolved in 20 ml methyl ethyl ketone (MEK). The dissolved sample was transferred to a correctly weighed SUS tube (②). To reduce analytical error, 20 ml of MEK was added to an Erlenmeyer flask to transfer the remaining sample. Separation was carried out by a centrifuge (condition: at least 15,000 rpm at 30 ° C., at least 30 minutes). After separation, the supernatant was discarded and 10 ml of MEK was added to the precipitate, which was then crushed with a grinder. 30 ml of MEK was further added and centrifuged. After separation, the supernatant was discarded and dried in a 105 ° C convection oven for 4 hours, and allowed to cool in a desiccator for 20 minutes. Accurately weigh the SUS tube after cooling to cool (③) to calculate the gel content by the following formula.

Gel component content (%) = [(③-②) ÷ ①] × 100

(6) Rubber content: 0.4 g of the sample was placed in a 50 ml Volumetric flask and weighed. The sample was dissolved by adding 30 ml of chloroform to an extra flask for blank. After dissolution, 10 ml of ICI-CCI ₄ mixture was added and 50 ml was added with chloroform. After leaving for 30 minutes, 20 ml of the flask was collected and mixed with about 60 ml of KI solution. After dropping 3-4 drops of starch, the titration was performed by titration with 0.04 N Na ₂ S ₂ O ₃ . The rubber component content was calculated | required by the following formula.

The results of the physical property measurement for Examples 1-11 and Comparative Examples 1-6 are shown in Table 2.

Resin composition Properties Average Rubber Particle Size (㎛) Gel / Rubber Ingredients Glossiness (%) Fluidity (g / 10 min) Izod impact strength (kgcm / cm) Example One 0.28 2.4 96 9.5 17.0 2 0.50 2.5 84 9.6 22.0 3 0.27 2.6 99 9.4 15.5 4 0.28 2.7 96 10.5 17.0 5 0.30 2.5 97 9.5 17.4 6 0.28 2.3 94 9.3 17.1 7 0.27 2.6 96 9.6 16.3 8 0.29 2.6 95 9.5 17.3 9 0.29 2.4 97 9.7 17.8 10 0.27 2.5 94 9.3 17.1 11 0.28 2.7 96 9.6 17.4 Comparative Example One 1.4 2.7 38 9.4 9.1 2 1.2 2.3 43 7.0 10.2 3 0.26 2.4 96 9.5 12.1 4 0.27 2.1 93 9.7 8.3 5 0.29 2.5 97 9.6 8.7 6 0.17 2.5 99 14.0 7.1

In the results of Table 2, in Comparative Example 1 in which the viscosity of the rubber supernatant introduced into the first reactor exceeded 110 cps, the average rubber particle size was very large as 1.4 μm, and not only glossiness but also impact strength were reduced. Appeared. Glossiness, fluidity, and impact strength were also reduced in Comparative Example 2 having a V ₁ / V ₂ ratio of 1.1, and Impact Strength was also decreased in Comparative Example 3 having a solid content of 86% by weight in the second reactor. Appeared to be. In Comparative Examples 4 and 5, the impact strength was also lowered. In Comparative Example 6, in which the ratio of V ₁ / V ₂ was 1.8, the gloss was excellent, but the impact strength was lowest. there was.

In the present invention, a continuous mass polymerization is performed by introducing a styrene rubber solution having a constant viscosity range into a first reactor at a constant speed, and adding a polydimethylsiloxane in the second reactor so that the solid component content is 55-80%. By polymerizing to appropriately adjust the rubber particle average diameter and the ratio of the gel component to the rubber component of the final resin composition, there is provided a rubber-modified styrene resin composition having not only high fluidity and high glossiness but also good impact strength and a method of producing the same. Has the effect.

Simple modifications and variations of the present invention can be easily made 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 (4)

(1) V ₁ / F = 3.04 (V ₁ : content of the first reactor, F: content of the raw material solution to be added to the first reactor using a styrene monomer rubber-like solution in which polybutadiene rubber is dissolved in the styrene monomer as a raw material solution. Flow rate), a first step of continuous bulk polymerization in the first reactor to maintain conditions of 1.2 ≦ V ₁ / V ₂ ≦ 1.6 (V ₁ : volume of the first reactor, V ₂ : volume of the reaction solution); And (2) a second step of continuously bulk polymerizing the polymer discharged from the first reactor to a second reactor to add polydimethylsiloxane so that the solid component is 55-80% by weight; The polybutadiene rubber, which is dissolved in a solution of the styrene monomer, has a cis form content of 10-98%, is dissolved in a solution of styrene monomer at a concentration of 7-20% by weight, and the polydimethylsiloxane is a second In an amount of 0.01-0.80 wt% based on the reactants of the reactor, the polydimethylsiloxane has a viscosity range of 10-10,000 cps. The method of claim 1, wherein the rubber solution is 25-110 cps at 25 ℃ manufacturing method of the thermoplastic resin composition. The method of claim 1, wherein the number of revolutions of the average shear rate controller of the first reactor is maintained at 16-52 times / minute. The thermoplastic resin composition according to any one of claims 1 to 3, wherein the average particle diameter of the rubber particles is in the range of 0.2 to 1.1 µm, and the ratio of the gel component to the rubber component is in the range of 1.9 to 3.4.