KR101555085B1 - Method for producing a Rubber Modified Styrene Resin Using Styrene-Butadiene Copolymer - Google Patents

Abstract

The present invention relates to a process for producing a rubber-modified styrenic resin, and more particularly to a process for continuously producing a rubber-modified styrenic resin for high gloss and high impact.
The present invention is characterized in that a rubber-modified styrene resin is prepared by melt-kneading a low-sheath polybutadiene rubber and a styrene-butadiene rubber, which is widely used for blend for impact modification, in a styrene-based monomer.
The rubber-modified styrenic resin produced by the present invention has high gloss and excellent impact strength and drop impact strength.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a method for continuously producing a rubber-modified styrenic resin using a styrene-butadiene rubber,

The present invention relates to a process for producing a rubber-modified styrenic resin, and more particularly, to a continuous process for producing a styrene-based resin having high impact properties and high impact properties by mixing low sheath polybutadiene and styrene-butadiene rubber .

In order to improve the luster and high impact properties of the resin composition, the styrene resin may be prepared by blending a rubber polymer in a styrene resin or by graft copolymerizing a styrene monomer in the presence of a rubber polymer to prepare a food container, a housing for electric and electronic products, Extruded sheets have been used in various fields where impact resistance is required.

Especially, recently, as consumers tend to prefer products with large products and beautiful appearance, consumer electronics companies are increasing production of large products, and attempts have been made to reduce the thickness of products.

However, when the thickness of the product is reduced, a practical impact strength such as a falling impact is lowered, so that there is a problem that a crack occurs in the appearance of the molded product even in a small impact. Accordingly, resin manufacturers are focusing on research and development of products with excellent impact strength while reducing manufacturing material costs.

Conventional techniques for increasing the practical impact strength include a method of dispersing the particle size of a rubber phase, which is a dispersed phase of a rubber-modified styrenic resin, in a bimodal or trimodal form so that rubber-modified styrene The system is preliminarily polymerized, and thereafter, the system is mixed in the reactor after the phase transition. However, in order to produce different particle distributions, not only reactors having different polymer raw material ratios are required before the phase transition, but also have a disadvantage in that the control for polymerization is complicated and the practical impact strength is not sufficiently improved. Moreover, It is difficult to obtain a product having a glossiness.

Another conventional technique for increasing the practical impact strength is to increase the grafting ratio and to increase the bonding strength between the rubber phase, which is a dispersion phase, and the polystyrene phase, which is a continuous phase. However, the method of increasing the grafting ratio of the rubber phase and the polystyrene phase by using an 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 deteriorates.

        Conventionally, low-viscosity low-sheath polybutadiene (1,4-cis content 25-40%) rubber has been used to obtain a rubber-modified styrene resin having excellent surface gloss. However, when low-viscosity low-sheath polybutadiene rubber is used alone, it is difficult to sufficiently reduce the size of rubber particles in the product. Occlusion of polystyrene in rubber particles is mainly formed by a salami structure, And there is a drawback that the practical impact strength is low because the grafting efficiency is low. Korean Patent Laid-Open Publication No. 10-2011-0061734 discloses a method for producing a styrenic resin in which gloss and impact are drastically improved by using a low sheath polybutadiene rubber and a rubber including a high sheath polybutadiene rubber, The manufacturing cost of raw materials is high.

A problem to be solved by the present invention is to provide a novel rubber-modified polystyrene which not only has a high gloss appearance but also has a practical impact strength.

Another problem to be solved by the present invention is to provide a continuous production process of a novel rubber-modified polystyrene having a high gloss appearance as well as a practical impact strength and a high gloss.

In order to solve the above-mentioned problems, the process for producing a rubber-modified styrenic block copolymer according to the present invention is characterized in that a rubber comprising a rosewise polybutadiene rubber and a styrene-butadiene rubber is dissolved in a styrene-based monomer and polymerized.

In the present invention, the low sheath polybutadiene rubber is a polybutadiene rubber having a content of 1,4-cis (sheath) of 20-50 wt%, more preferably 30-40 wt%.

In a preferred embodiment of the present invention, the low sheath polybutadiene rubber has a 1,4-cyclohexane content of 20-50 wt%, a vinyl content of 10-20 wt%, preferably 13-16 wt% , And the viscosity of the rubber solution prepared by dissolving it in the styrene monomer at 5 wt % is 150-180 centipoise. Here, the vinyl content refers to the content of vinyl groups capable of graft bonding with the polystyrene matrix among the microstructures of the rubber composed of Vinyl, Cis, and Trans structures. The vinyl content is not limited theoretically. However, as the content of the vinyl group increases, The efficiency is increased and finally the mechanical strength of HIPS is influenced. If the content of vinyl is too high, the graft rate may become excessively high to lower the impact of the rubber or deteriorate the fluidity. If the vinyl content is too low, the HIPS property may be lowered.

In the present invention, the butadiene content of the styrene-butadiene rubber is preferably 50-90 wt%, more preferably 55-80 wt%, and most preferably 60-70 wt%.

In the practice of the present invention, the styrene-butadiene rubber has a viscosity of 1,000 to 1,500 centipoise and a melt index (Melt Flow, ASTM D1238, 200 캜 5 kg) of 25 % by weight in toluene, -9.

In the present invention, the total content of the rubber is preferably 5-12 wt%, more preferably 6-10 wt%, and most preferably 7-8 wt%.

Among the rubbers, the low sheath polybutadiene rubber and the styrene-butadiene rubber preferably have a higher rubber content of the low sheath polybutadiene. In the present invention, when the content of the low sheath polybutadiene is high, physical properties such as impact, gloss, and drop impact are excellent. More preferably, the content of the low sheath polybutadiene rubber is 51-99 wt%, more preferably 60-95 wt%, and most preferably 70-90 wt%. However, when the content of low-sheath polybutadiene is high, the effect of the styrene-butadiene rubber mixture does not appear.

In the present invention, in order to produce the high-gloss and ultra-high impact rubber-modified styrenic resin, a rubber solution prepared by dissolving 5 % by weight of styrene monomer and having a viscosity of 150 to 180 centipoise, 4-cis content of 30 to 40% by weight and vinyl content of 13 to 16% by weight) and 25 % by weight of toluene dissolved in a styrene-butadiene rubber having a viscosity of 1,000 to 1,500 centipoise %), And it is more preferable to add mineral oil and silicone oil during the polymerization process.

A continuous process for producing a rubber-modified styrene resin excellent in high gloss and ultrahigh impact resistance according to the present invention

(A) A styrene-based monomer, a low sheath polybutadiene rubber (1,4-cis content 30 to 40% by weight, vinyl content 13 to 16% by weight) and styrene-butadiene rubber (butadiene content 60 To 70% by weight), and a rubber compounding solution is prepared by adding additives such as a molecular weight regulator and mineral oil. The rubber compounding solution is continuously introduced into the first reactor and continuously introduced into the first reactor, Reacting at 120 ° C for 3 to 7 hours until the time after the phase transition to prepare a first polymer having a monomer conversion of 20 to 35% by weight;

 (B) continuously adding the first polymer to a second reactor and polymerizing at 110 to 130 ° C for 1 to 2 hours to prepare a second polymer having a monomer conversion of 35 to 50% by weight;

 (C) continuously introducing the second polymer into a third reactor and reacting at 120 to 140 ° C for 0.5 to 1.5 hours to prepare a third polymer having a monomer conversion of 50 to 70% by weight;

 (D) continuously adding the third polymer to a fourth reactor and reacting the polymer at 140 to 160 ° C for 0.5 to 1.0 hour to prepare a fourth polymer having a monomer conversion of 70 to 90% by weight;

(E) introducing the fourth polymer into a volatile fraction eliminator to remove unreacted monomers and residual volatile components

.

More specifically,

Preparation of first polymer

In the process for producing a rubber-modified styrene resin according to the present invention, the low-sheath polybutadiene rubber and the styrene-butadiene rubber are first dissolved in the styrene-based monomer and ethylbenzene in a dissolving tank. Preferably, the rubber mixture solution contains 73 to 94 parts by weight of a styrene monomer, 5 to 12 parts by weight of a rubber component, and 0 to 15 parts by weight of ethylbenzene, and then a molecular weight modifier and mineral oil are added as an additive.

The rubber mixed solution is continuously introduced into a first reactor to prepare a first polymer having a monomer conversion of 20 to 35% by weight . In the first reactor, the reaction is carried out at 90 to 120 ° C for 3 to 7 hours, and the polymerization proceeds until the post-phase transition.

The polybutadiene rubber is polybutadiene and styrene-butadiene copolymer produced by using butadiene. The low sheath polybutadiene rubber has a 1,4-content of 30-40 wt% and a vinyl content of 13-16 wt%. The styrene monomer , The viscosity of the rubber solution prepared from the 5 wt% solution is preferably 150 to 180 centipoise. The styrene-butadiene rubber is a rubber solution prepared by dissolving 60% to 70% of butadiene in toluene and 25% Is preferably 1,000 to 1,500 centipoise. When the viscosity of the styrene solution is out of the above range, the glossiness and rigidity are not balanced.

The content of the two kinds of polybutadiene rubber components is preferably 5 to 12% by weight. When the total amount of the rubber components is 5% by weight or less, the impact resistance is remarkably lowered, and when it is 12% by weight or more, gloss and rigidity are lowered.

The styrene-based monomer may be at least one selected from the group consisting of styrene,? -Methylstyrene,? -Ethylstyrene, o-methylstyrene, p-styrene, m-methylstyrene,? -Methylstyrene vinyltoluene, , 1,3-dimethylstyrene, 2,4-dimethylstyrene, and the like, and mixtures thereof.

In the present invention, the polymerization solvent may be used in order to lower the viscosity of the polymerization solution. The polymerization solvent may be used in an amount of 0 to 15 parts by weight based on 100 parts by weight of the monomer mixture, and aromatic compounds such as toluene, ethylbenzene, benzene, Methyl ethyl ketone, and the like.

In the present invention, the rubber mixture solution may contain a molecular weight modifier to adjust the molecular weight. Examples of the molecular weight regulator include n-dodecylmercaptan, n-amyl mercaptan, t-butyl mercaptan, t-dodecylmercaptan, n-hexylmercaptan, n-octylmercaptan, And 0 to 1000 ppm of a molecular weight modifier is preferably used relative to 100 parts by weight of the monomer mixture.

Mineral oil and silicone oil are used as the additive of the present invention, and it is preferable to use 1 to 5 parts by weight of mineral oil having a low viscosity of 10 to 20 centipoise with respect to 100 parts by weight of the monomer mixture, It is preferable to use 0 to 2 parts by weight of the monomer mixture having a viscosity of 5,000 to 10,000 centipoise per 100 parts by weight of the monomer mixture.

Preparation of Second Polymer

The first polymerizate is continuously introduced into the second reactor to prepare a second polymer having a monomer conversion of 35 to 50% by weight. The reaction temperature of the second reactor is 1 to 2 hours at 110 to 130 ° C, and the monomer conversion is 35 to 50% by weight.

Preparation of the Third Polymer

The second polymer is continuously added to a third reactor and reacted at 120 to 140 ° C for 0.5 to 1.5 hours to prepare a third polymer having a monomer conversion of 55 to 65% by weight.

Preparation of the fourth polymer

The third polymer is continuously added to the fourth reactor and reacted at a temperature in the range of 140 to 160 ° C to prepare a fourth polymer having a monomer conversion of 70 to 90% by weight.

The polymerized product having a conversion rate of 70 to 90% by weight through the fourth reactor is transferred to a devolatilizer to remove unreacted monomers and residual volatile components, and finally a rubber-modified styrene resin is produced.

In the production process of the present invention, a rubber-modified styrenic resin can be prepared by adding a lubricant, a solvent, a plasticizer, an antioxidant or an ultraviolet absorber used in conventional polymer polymerization.

In the present invention, in the bulk polymerization, the monomer mixture is polymerized in a polymerization tank at a constant conversion rate, and then unreacted monomers are recovered from the polymer polymerized in the devolatilizer to produce a polymer, and the recovered unreacted monomers are introduced into the polymerization reactor And a continuous polymerization process is used.

In the present invention, the polymerization tank can be used by connecting one or plural stirring tank reactors. In addition, additives or monomer feeding lines may be additionally connected to each of the stirring tank reactors to control the viscosity or the composition of the final product .

In the present invention, the polymerization baths can be operated under pressure or reduced pressure, and the temperature of the inner polymer and monomer mixture in each polymerization reactor during the polymerization is maintained at 90-160 Lt; 0 > C.

In order to solve the above problems, the present invention provides a low-sheath polybutadiene rubber having a sheath content of 20-50 wt.% Relative to the weight of low-sheath polybutadiene rubber, a styrene-butadiene rubber having a butadiene content of 50-90 wt. Butadiene rubber in an amount of 5 to 12 wt% based on the mass of the polystyrene, wherein the mixing ratio of the rubber is greater than the content of the low-sheath polybutadiene rubber is greater than the content of the styrene-butadiene rubber .

In the practice of the present invention, the low sheath polybutadiene rubber has a viscosity of 150 to 180 centipoise and a vinyl content of 10 to 20 % by weight in a rubber solution prepared by dissolving it in a styrene monomer at 5 wt % The butadiene rubber preferably has a viscosity of 1,000 to 1,500 centipoise in a rubber solution prepared by dissolving it in toluene at 25 wt % .

In the present invention, the polybutadiene rubber preferably has a graft ratio of 8 to 15% so that a large amount of styrene is grafted to improve impact strength and gloss.

The present invention will be further illustrated by the following examples, which are to be construed as illustrative examples only and are not intended to limit or limit the scope of protection of the present invention.

INDUSTRIAL APPLICABILITY As described above, the present invention has the effect of providing a continuous process for producing a rubber-modified styrenic resin in which high gloss and impact resistance are improved by using a low sheath polybutadiene rubber and a styrene-butadiene rubber.

1 is a process diagram of a polymerization process according to an embodiment of the present invention.
2 is a flow chart of a polymerization process according to a comparative example of the present invention.
Fig. 3 is a view showing the microstructure of the polybutadiene rubber, and is (a) seas, (b) trans, and (c) vinyl structure.

The present invention will be described in more detail by way of the following examples. The following examples illustrate the invention in detail, but are for the purpose of illustrating the invention and are in no way to be construed as limiting thereof.

Example 1

A rubber solution prepared by dissolving a styrene monomer in a styrene monomer and having a vinyl content of 14 wt% and a styrene monomer in a 5 wt% solution to have a viscosity of 34.5 wt%, a 1,4-cyclohexanone content of 34.5 wt%, and a viscosity of 175 centipoise 6.75 parts by weight of rubber and 68.5% by weight of rubber. A rubber solution prepared by dissolving in 25% by weight of toluene and having a viscosity of 1,200 centipoise and having a melt index (Melt Flow, ASTM D1238, 200 DEG C, 5 kg) 0.75 parts by weight of butadiene (rubber content 68.5%) was dissolved in 87.5 parts by weight of styrene monomer and 5.0 parts by weight of ethylbenzene to prepare a raw rubber solution. 0.1 part by weight of tertiary dodecyl mercaptan as a molecular weight modifier, 1.5 parts by weight of mineral oil and 0.5 part by weight of silicone oil were added as an additive. The rubber mixed solution was continuously introduced into the first reactor and reacted at 120 ° C. for 6 hours with respect to the entire flow rate of the first reactor. The reactant passed through the first reactor was introduced into the second reactor. The first polymer was reacted in a second reactor at 140 ° C for 1 hour, and then charged into a third reactor. The reaction was carried out in a third reactor at 150 ° C for 0.5 hour, then charged into a fourth reactor and reacted at 160 ° C for 0.5 hour. After passing through the four reactors, the unreacted monomer, residual volatile matter and solvent were removed through a volatilization tank and then pelletized to prepare the final polymerized product. Analysis of the resin properties and the analysis of properties of the injection molded articles were carried out for the final polymerized product.

Example 2

Except that the content of the low sheath polybutadiene rubber was changed to 6.0 parts by weight and the content of the styrene-butadiene rubber was changed to 1.5 parts by weight.

Example 3

Except that the content of low-sheath polybutadiene rubber was changed to 5.25 parts by weight and the content of styrene-butadiene rubber was changed to 2.25 parts by weight.

Comparative Example 1

Except that the content of the low-sheath polybutadiene rubber was changed to 3.75 parts by weight, and the content of styrene-butadiene rubber was changed to 3.75 parts by weight.

Comparative Example 2

The procedure of Example 1 was repeated, except that 3.0 parts by weight of low-sheath polybutadiene rubber and 4.5 parts by weight of styrene-butadiene rubber were used.

Comparative Example 3

Except that the content of the low-sheath polybutadiene rubber was changed to 7.5 parts by weight and the content of the styrene-butadiene rubber was changed to 0 part by weight.

Comparative Example 4

Except that the content of the low-sheath polybutadiene rubber was changed to 0 parts by weight and the content of styrene-butadiene rubber was changed to 7.5 parts by weight.

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

(1) Impact strength: Measured by ASTM D-256.

(2) Melt Flow: Measured according to ASTM D-1238.

(3) Graft rate: The graft rate was obtained by the following equation (1).

(4) Polishing degree: Measured according to ASTM D-523.

(5) Drop impact strength: Measured according to ASTM D-3029.

[Equation 1]

Graft ratio (%) = 100 x {toluene solvent insoluble matter (%) - polybutadiene amount (%)} / [100-polybutadiene amount

Example Comparative Example One 2 3 One 2 3 4 Raw material
Furtherance
(Parts by weight) Styrene monomer content 87.5 87.5 87.5 87.5 87.5 87.5 87.5 Polybutadiene rubber + styrene-butadiene rubber content 7.5 7.5 7.5 7.5 7.5 7.5 7.5 Ethylbenzene 5 5 5 5 5 5 5 Rubber type
And composition ratio
(weight%) Low sheath polybutadiene rubber (viscosity 150 ~ 180 centipoise) 90 80 70 50 40 100 - Styrene-butadiene rubber
(Rubber content 60 ~ 70%) 10 20 30 50 60 - 100 Part fee
Furtherance
(Parts by weight) Molecular weight regulator 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Mineral oil 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Silicone oil 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Item Example Comparative Example One 2 3 One 2 3 4 Impact strength (Kg. Cm / cm) 9.3 10.2 11.1 10.4 11.5 9.1 4.5 The melt index (g / 10 min, 200 DEG C, 5 Kg) 5.6 5.2 5.1 5.8 5.0 6.2 6.8 Graft rate (%) 12.7 10.7 8.1 6.2 6.5 20.4 3.4 Glossiness (%, 60 °) 85.6 83.7 82.6 58.4 45.1 31.3 89.5 Drop impact strength (J) 20.8 23.7 15.6 18.6 12.3 22.3 5.9

Claims (10)

Styrene-butadiene rubber and a low sheath polybutadiene rubber having a silicon content of 20-50 wt% are dissolved in a styrene-based monomer,
Here, the styrene-butadiene rubber has a viscosity of 1,000 to 1,500 centipoise and a melt index (Melt Flow, ASTM D1238, 200 ° C, 5 kg) of 2-9 in a rubber solution prepared by dissolving it in toluene at 25 wt %
Wherein the low sheath polybutadiene rubber has a viscosity of 150-180 centipoise and a vinyl content of 13-16 weight% in a rubber solution prepared by dissolving it in a styrene monomer in an amount of 5 weight % Gt; The styrene-butadiene rubber according to claim 1, wherein the styrene-butadiene rubber has a butadiene content of 50-90 wt%. The method of claim 1, wherein the low sheath polybutadiene rubber has a 1,4-cis content of 30-40 wt%. delete The method for producing a rubber-modified styrenic block copolymer according to claim 1, wherein the content of rosewise polybutadiene rubber is higher than that of styrene-butadiene rubber. delete delete delete delete delete

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