JP3599072B2 - Vinyl aromatic polymer-containing resin composition - Google Patents

Description

【００３９】
表１で明かなようにアニオン重合により合成した星型分岐ポリスチレンはリニアーなポリスチレンと同一分子量で比較して格段に流動性にすぐれており、また分岐数の多いものほど流動性が大であることもわかる。
【００４０】
実施例１〜６および比較例１〜４
参考例で調整した（Ａ）成分及び（Ｂ）成分を表２に記載の割合で配合し、４０ｍｍシート押出機を用いて０．７ｍｍ厚さのシート成形し、試験片としてシートの押出し方向及び垂直方向につき測定した引張り弾性率、２３℃における面衝撃強さ、組成物のメルトフローを評価した（表２）。なお、各種評価の方法は以下の通りである。
引張り弾性率：ＪＩＳＫ−６８７２に準拠して、シートの押出し方向及び垂直方向につき測定した。（単位Ｋｇ／ｃｍ^２ ）
面衝撃強さ：重錘形状が１／２インチのものを用いてＡＳＴＭＤ１７０９に準拠して測定した（単位Ｋｇ・ｃｍ）
メルトフローレート：ＩＳＯ−Ｒ１１３３に準拠（２００℃、５Ｋｇ荷重）
【００４１】
【表２】

【００４２】
結果は表２に記載するように、成分（Ａ）としてアニオン重合の分岐状ポリスチレンを用いたスチレン系樹脂組成物は、ほぼ同一分子量のアニオン重合リニアーポリスチレンを用いたスチレン系樹脂組成物に比較して、著しく流動性が大であり、また、引張り弾性率の値で押出し方向と垂直方向の値の差が少ないという特徴を示している。
更に、ラジカル重合のポリスチレンを用いたスチレン系樹脂組成物に比較して弾性率及び面衝撃強さ共に格段に優れた効果を示している。
【００４３】
【発明の効果】
ゴム変性ビニル芳香族重合体にアニオン重合の星型分岐構造を有するビニル芳香族重合体を配合することにより、得られたビニル芳香族重合体樹脂組成物は、良好な流動性を有し、かつ耐面衝撃性と剛性のバランスに優れた効果を有し、家電製品、事務機器、工業部品、日用雑貨など多岐にわたる分野で利用可能である。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention provides a vinyl aromatic polymer resin composition having good fluidity despite having a high molecular weight vinyl aromatic polymer in the matrix component, and having excellent mechanical strength. About. The composition of the present invention is particularly excellent in sheet moldability, is excellent in balance between surface impact resistance and rigidity, and can provide a sheet having a good appearance. Furthermore, a high rigidity and high impact resistance grade can be obtained for injection molding from good fluidity.
[0002]
[Prior art]
Rubber-modified polystyrene represented by HIPS is inexpensive, has excellent processability, and has excellent impact strength and electrical insulation properties, and is therefore used in a wide variety of fields such as home appliances, office equipment, industrial parts, and daily necessities. There has been some rule of thumb in the past regarding resin substitution in the resin industry, where resin applications start with relatively high-end, expensive resins and, as the product becomes more widespread, move to lower-grade resins. It is to do.
[0003]
This tendency also applies to polystyrene-based resins. For example, when HIPS is used in applications where ABS resins have been used in the past, higher impact resistance and higher stiffness can be achieved while maintaining the easy moldability, which is an advantage of polystyrene-based resins. Is required. However, HIPS resins have a trade-off relationship in that those having excellent impact resistance have low rigidity, whereas those having high rigidity have low impact resistance, and in particular, satisfy both the surface impact resistance and the rigidity at the same time. At present, HIPS has not been obtained.
[0004]
Generally, the rubber-modified polystyrene is obtained by polymerizing styrene in the presence of a rubber-like polymer, and the rubber-modified polystyrene thus obtained is a resin composed of linear (linear) polystyrene. In the continuous phase, the rubbery polymer is present as a dispersed phase.
[0005]
As is well known, to increase the impact resistance of rubber-modified polystyrene, it is effective to increase the content of the rubber-like polymer in the resin composition, but on the other hand, there is a problem that rigidity and fluidity decrease. is there. For this reason, in order to improve the balance between the impact resistance and rigidity of rubber-modified polystyrene and the fluidity, it is important to impart high impact resistance using as little of the rubber-like polymer as possible. There is a need for a method for further improving the balance between impact resistance and fluidity under the combined content. In addition, various techniques for controlling the molecular weight and molecular weight distribution of the polystyrene portion of the continuous phase in order to enhance the balance between impact resistance and fluidity have been studied, but no satisfactory effect has been obtained yet.
[0006]
[Problems to be solved by the invention]
The present invention is intended to provide a vinyl aromatic polymer resin composition which can be substituted for applications in which a higher-order resin than the vinyl aromatic polymer resin has been used, and has an improved balance between impact resistance and fluidity. is there.
[0007]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that a vinyl aromatic polymer having an ultrahigh molecular weight star-branched structure having a weight average molecular weight of 500,000 or more and formed by anionic polymerization (hereinafter referred to as a star) Resin or a star-branched polymer) is blended with a rubber-modified vinyl aromatic polymer produced by ordinary radical polymerization. The resin composition contains an ultrahigh molecular weight vinyl aromatic polymer as a matrix component. Nevertheless, it shows good fluidity, and its mechanical properties such as impact resistance and rigidity and thermal properties such as heat resistance are much better than ordinary radical polymerized rubber-modified vinyl aromatic polymer. And completed the present invention.
[0008]
The present invention is characterized in that a continuous phase of a rubber-modified vinyl aromatic polymer contains an ultra-high molecular weight vinyl aromatic polymer which is a star polymer having a specific structure formed by anionic polymerization in a continuous phase. In the case of the vinyl aromatic polymer of, for example, an ultra-high molecular weight linear anionic vinyl aromatic polymer or a linear radically polymerized vinyl aromatic polymer, the fluidity of the resin composition is greatly reduced, and the effect of the present invention cannot be achieved.
[0009]
The star polymer having a specific structure synthesized by anionic polymerization referred to in the present invention is a prepolymer in a living state having a uniform linear molecular weight by anionic polymerization, a low molecular weight polyfunctional compound (coupling agent) or a small amount of divinylbenzene. It is obtained by reacting with polyfunctional monomers such as. Furthermore, it can also be synthesized using a polyfunctional anionic polymerization initiation catalyst synthesized from a polyfunctional vinyl monomer.
[0010]
The star polymer in the present invention refers to a star polymer defined in New Edition Dictionary of Polymers (Asakura Shoten) p432. In the case of the present invention, it is a radial-type polymer in which n vinyl aromatic polymers are bonded around a polyfunctional low molecular weight compound residue or a polyvinyl aromatic residue. Here, the base compound of the polyfunctional compound residue or the polyvinyl compound residue is a low molecular weight compound having a molecular weight of about 2,000 or less. The number of branched polymers is 3 to 8.
The star polymer may be, for example, a mixture of a three-branched and a four-branched polymer.
[0011]
The molecular weight of the star-branched polymer which is the component (A) of the present invention is in a range of 500,000 to 5,000,000 as a weight average molecular weight (Mw). Normally, in the anionic polymerization, the molecular weight is adjusted by the amount of organolithium used as a catalyst with respect to the charged monomer amount, but in the star-shaped branched polymer of the present invention, the molecular weight jumps according to the number of branches due to a coupling reaction. In the case of the present invention, the weight average molecular weight (Mw) of the star-branched polymer after the coupling reaction is in the range of 500,000 to 5,000,000, more preferably 500,000 to 2,000,000, further preferably 500,000 to 1,500,000. is there.
[0012]
When the weight average molecular weight of the star-shaped branched polymer is 500,000 or less, the fluidity of the composition becomes high. However, as a composition for sheet use, the fluidity becomes too high and adversely affects the extrusion stability. Is also unfavorable because the stiffness and surface impact strength tend to decrease. The star-shaped branched polymer can be obtained by a coupling reaction described below. The branched polymer before coupling has a molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of 1.5 or less and has a uniform chain length of vinyl aromatic. A group polymer is preferable, and the molecular weight distribution of the obtained star-shaped branched polymer may be in the range of 1.0 to 3.0, preferably 1.0 to 2.0. The synthesis of the star-shaped branched polymer by the anionic polymerization method used in the present invention is carried out by reducing the active one-terminal vinyl aromatic polymer obtained by polymerizing a vinyl aromatic monomer in a hydrocarbon solvent using an organolithium compound. It is obtained by performing a coupling reaction with a polyfunctional compound having a molecular weight.
[0013]
In the above method, examples of the organic lithium compound include n-propyl lithium, iso-propyl lithium, n-butyl lithium, iso-butyl lithium, sec-butyl lithium, tert-butyl lithium, phenyl lithium and the like.
[0014]
The polyfunctional compound used for the coupling reaction is a low molecular weight compound having 3 to 8 functional groups capable of forming a bond by reacting with an active lithium terminal. Examples of these low molecular weight compounds include polyhalogen compounds, polyepoxy compounds, polycarboxylic acid ester compounds, polyketone compounds, polycarboxylic anhydrides, and the like. Specific examples include silicon tetrachloride, di (trichlorosilicone). Ryl) ethane, 1,3,5-tribromobenzene, methyltrichlorotin, epoxidized soybean oil, tetraglycidyl 1,3-bisaminomethylcyclohexane, dimethyl oxalate, tri-2-ethylhexyl trimellitate, pyromellitic acid Dianhydride, diethyl carbonate and the like.
[0015]
In carrying out the anionic polymerization method, the lithium compound is added in an amount of 0.05 to 0.5 parts by weight based on 100 parts by weight of the vinyl aromatic monomer. Further, the above polyfunctional compound is added and reacted in an amount of 0.5 to 1.5 times equivalent to the organic lithium. The reaction proceeds very quickly and is usually completed in minutes to tens of minutes. As a solvent for the above reaction, cyclohexane, n-hexane, benzene, toluene, ethylbenzene and the like are used. The reaction temperature of the above-mentioned anionic polymerization method is carried out in the range of -30 to 150 ° C, and the polymerization time is usually several seconds to several hours, depending on the concentration of the hydrocarbon solvent and the polymerization temperature. These reactions can be performed in either a batch system or a continuous system, but a batch system having a narrower molecular weight distribution can be obtained.
[0016]
Separately from the above coupling reaction, a vinyl aromatic monomer is polymerized in a hydrocarbon solvent using an organolithium compound as an initiator, and the one-terminal active vinyl aromatic polymer present in the living room after completion of the polymerization is used as an initiator. By adding a small amount of a polyfunctional vinyl aromatic monomer (for example, divinyl benzene) and polymerizing it, it is possible to synthesize a multi-branched vinyl aromatic polymer. The ratio of the polyfunctional vinyl aromatic monomer to be added to the organolithium compound used as the polymerization initiator in the present method is in the range of 0.1 to 1.0 in molar ratio. According to this method, it is possible to synthesize a multibranched branched polymer having a somewhat broad molecular weight distribution and substantially similar to a star polymer.
[0017]
By blending the star-branched polymer as the component (A) obtained by the above polymerization method with a known rubber-modified vinyl aromatic polymer as the component (B) described below, the vinyl aromatic polymer of the present invention is obtained. A united resin composition is obtained. What is necessary is to increase the content of the rubbery polymer in the rubber-modified vinyl aromatic polymer because the rubbery polymer in the rubber-modified vinyl aromatic polymer is to be diluted by the star-shaped branched polymer. It is important to keep it. Although it depends on the impact strength and rigidity of the target vinyl aromatic polymer resin composition, the content of the rubbery polymer in the rubber-modified vinyl aromatic polymer to be blended generally ranges from 6 to 30% by weight. It is suitable.
[0018]
The known rubber-modified vinyl aromatic polymer which is the component (B) of the present invention can be prepared from styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, ethylstyrene, P-tert in the presence of a rubbery polymer. And a mixture of two or more kinds of α-alkyl-substituted styrenes such as α-methylstyrene and the like. A polymer in which a rubbery polymer is present as dispersed particles in a continuous phase formed by coalescence.
[0019]
Typical examples include a rubber-modified polystyrene known as HIPS, and a rubber-modified styrene-based resin composition in which the styrene unit of the polystyrene phase is replaced with a vinyl aromatic monomer unit other than the above styrene. I can do it. For the purpose of the present invention, the branched vinyl aromatic polymer of the component (A) and the rubber-modified vinyl aromatic polymer of the component (B) are preferably composed of the same vinyl aromatic monomer.
[0020]
The rubbery polymer in the component (B) refers to a polymer having a glass transition temperature of -30 ° C or lower. Specific examples include polybutadiene, styrene-butadiene rubber (SBR), diene rubbers such as acrylonitrile-butadiene rubber (NBR), ethylene-propylene-diene rubber (EPDM), and acrylic rubber. As the polybutadiene rubber, both high cis rubber and low cis rubber can be suitably used. Further, as the above-mentioned polybutadiene rubber, SBR and NBR, those obtained by hydrogenating a part or all of unsaturated double bonds thereof can be suitably used.
[0021]
The component (B) is generally prepared by subjecting a vinyl aromatic monomer to bulk, bulk / suspension, or emulsion polymerization in the presence of the rubbery polymer. The method is economically superior. In the case of bulk polymerization, a small amount of an inert solvent such as ethylbenzene or toluene may be added.
[0022]
By the above method, by polymerizing the vinyl aromatic monomer in the presence of the rubber-like polymer, the vinyl aromatic polymer is partially grafted around the rubber-like polymer particles, and the rubber-like polymer particles Forms a dispersed phase having a structure in which some vinyl aromatic polymer particles are included inside. Since the graft component and the encapsulated vinyl aromatic polymer particles are contained in the dispersed phase, the weight of the dispersed phase of the rubber-modified vinyl aromatic polymer becomes higher than the weight of the rubbery polymer.
[0023]
The ratio of the weight of the dispersed phase to the weight of the rubbery polymer is in the range of about 1.5 to 3.5 for bulk, bulk / suspension polymerization. The dispersed phase can be separated and collected by dissolving it in a good solvent for the vinyl aromatic polymer constituting the continuous phase of the rubber-modified vinyl aromatic resin composition, for example, methyl ethyl ketone, and centrifuging.
The weight average molecular weight of the vinyl aromatic polymer constituting the continuous phase of the component (B) may be in the range of 150,000 to 300,000 according to a conventional method, but from 200,000 to 300000 for the purpose of the present invention. Thousands are preferred. Further, the average particle size of the dispersed phase formed by the rubbery polymer as the component (B) is adjusted to the range of 0.1 to 4.0 μm. A more preferable range of the particle diameter is 0.4 to 3 μm. The swelling index (Swelling Index) for toluene, which is a measure of the degree of crosslinking of the dispersed phase particles, is adjusted to a range of 6 to 14.
[0024]
The vinyl aromatic polymer resin composition of the present invention can be obtained by mixing the star-shaped branched vinyl aromatic polymer (A) and the rubber-modified vinyl aromatic polymer (B). In this case, the component (A) The proportion of the component (A) to the continuous phase in the finally obtained vinyl aromatic polymer resin composition is such that the proportion of the component (A) is 5% by weight or more, more preferably 10% by weight or more. Is preferred.
[0025]
The components (A) and (B) may be mixed by melt-kneading with a known device such as a kneader, a Banbury mixer, a single-screw or twin-screw extruder, or the like. More preferably, anionic polymerization is carried out, and a polymerization liquid containing a star-shaped branched polymer synthesized by deactivating living anions by a coupling reaction and a polymerization liquid of the component (B) in the course of bulk polymerization are mixed. After the polymerization of the component (B) is continued for a desired period of time and the polymerization is completed, the residual monomer and an inert solvent such as ethylbenzene are removed by a devolatilizer to obtain the vinyl aromatic polymer resin composition of the present invention. .
[0026]
The vinyl aromatic polymer resin composition of the present invention optionally contains additives such as higher fatty acids, higher fatty acid metal salts, stabilizers such as polydimethylsiloxane and hindered phenol, pigments, plasticizers, and antistatic agents. Can be added.
[0027]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, specific embodiments of the present invention will be described, but the scope of the present invention is not limited to these embodiments.
[0028]
Reference Example 1 (adjustment of rubber-modified polystyrene B1)
Polybutadiene (Nihon Zeon Co., Ltd., Nipol 1220SL) was dissolved in styrene, and then small amounts of ethylbenzene and t-butylperoxyisopropyl carbonate were added to prepare a polymerization stock solution having the following composition. (Unit weight parts)
・ Polybutadiene 9.8
・ Styrene 76.8
・ Ethylbenzene 13.0
T-butyl peroxyisopropyl carbonate 0.04
.Alpha.-methylstyrene dimer 0.02
・ Polydimethylsiloxane 0.10
[0029]
The polymerization stock solution was continuously fed at 2.2 liter / hr to a 6.2-liter three-tank reactor equipped with a stirrer. The reactor internal temperature was controlled so that the solid content concentration at the outlet of the first tank reactor was 38% by weight. At the same time, the temperature inside the reactor was adjusted so that the solid content concentration at the outlet of the reactor in the final tank was 80% by weight. Next, the mixture was fed to a devolatilizer under a vacuum at 230 ° C. to remove unreacted styrene and ethylbenzene, and the mixture was granulated with an extruder to obtain pellet-shaped rubber-modified polystyrene B1. The proportion of polybutadiene in B1 was 12.3% by weight. The weight average molecular weight and the number average molecular weight of the continuous phase determined by gel permeation chromatography (hereinafter abbreviated as GPC) of the methyl ethyl ketone soluble portion of B1 were 254,000 and 92,000, respectively. The average particle size of the dispersed phase was 1.5 μm, and the swelling index for toluene was 9.8.
[0030]
Reference Example 2 (adjustment of branched polystyrene A1 and A2)
An autoclave was charged with 14.0 kg of styrene and 60 kg of cyclohexane, and the internal temperature was controlled at 50 ° C. Next, a 10% cyclohexane solution containing 7.6 g of n-butyllithium was injected to start the reaction. Four minutes later, the internal temperature rose to 75 ° C. The reaction solution was sampled, and the molecular weight was measured by GPC. As a result, the weight average molecular weight at this point was 179,000, and the number average molecular weight was 170,000. Then, the autoclave was heated to 80 ° C., and a 20% cyclohexane solution containing 10.0 g of tetraglycidyl 1,3-bisaminomethylcyclohexane (hereinafter abbreviated as TED) was added in two portions to carry out the coupling reaction. Carried out. After stirring for 20 minutes, the polymer was precipitated with methanol to recover a branched polymer A1.
[0031]
Its GPC chart was a mixture of 3- and 4-branched polystyrene containing 15.2% of uncoupled low molecular weight. This had a weight average molecular weight of 5280,000 and a number average molecular weight of 350,000. TED is a tetrafunctional coupling agent, but the formation of a slightly more than 60% of a three-branched polymer is considered to be due to steric hindrance that the active terminal styryllithium hardly reacts with the fourth epoxy group.
The synthesis conditions of A1 in Reference Example 2 were partially changed and the same treatment was carried out to obtain a star-shaped branched polymer containing 80% of a 3-branched polymer and having a weight average molecular weight of 706,000 and a number average molecular weight of 53.50000. A2 was synthesized. Table 1 shows the analysis results and the melt flow rates.
[0032]
Reference Example 3 (adjustment of 4-branched polystyrene A3, A4)
An autoclave was charged with 60 kg of cyclohexane and 10.0 kg of a styrene monomer, and the internal temperature was controlled at 50 ° C. Then, a 10% cyclohexane solution containing 5.2 g of n-butyllithium was injected to initiate polymerization. After 5 minutes, the internal temperature rose to 80 ° C. A part of the reaction solution was sampled and subjected to GPC analysis. As a result, it was found that the polymer was a polymer having a weight average molecular weight of 182.2 million and a number average molecular weight of 176.000. Thereafter, the internal temperature of the autoclave was raised to 80 ° C., and a 10% cyclohexane solution containing 2.8 g of di (trichlorosilyl) ethane was added as a coupling agent. The reaction was carried out with stirring for 20 minutes. The reaction solution was treated in methanol to recover the branched polymer A3.
[0033]
It had a weight average molecular weight of 704,000 and a number average molecular weight of 612,000, and 90% or more were 4-branched polymers. The di (trichlorosilyl) ethane used as the coupling agent was a hexafunctional coupling agent, but acted only on the basis of steric hindrance or tetrafunctional as in the case of TED. The same treatment was performed by adjusting the amounts of the catalyst and the coupling agent to obtain a star-shaped branched polymer A4 having a weight average molecular weight of 1,730,000 and a number average molecular weight of 1,230,000.
[0034]
Reference Example 4 (adjustment of 6-branched polystyrene, 8-branched polystyrene A5, A6)
In an autoclave, 60 kg of cyclohexane and 10.0 kg of styrene monomer were charged, and a catalyst of a 10% cyclohexane solution containing 8.0 g of n-butyllithium was added at an internal temperature of 50 ° C. to carry out polymerization. At this time, a polymer having a weight average molecular weight of 121,000 and a number average molecular weight of 112,000 was prepared, and a 10% cyclohexane solution containing 35 g of p-divinylbenzene was added thereto. After reacting for 20 minutes, the reaction solution was poured into a large amount of methanol, and the polymer was precipitated to obtain a branched polymer A5. The result of GPC analysis of this product was a branched polymer having a weight-average molecular weight of 7380,000 and a number-average molecular weight of 447,000, having an average of 6 branches and almost a star shape.
[0035]
In the same manner as in the present reference example, the average eight-branched polymer A6 having a weight average molecular weight of 63,000 and a number average molecular weight of 3,470,000 was obtained by changing the amounts of n-butyllithium and divinylbenzene. When a branched polymer is obtained using divinylbenzene, the number of branches is adjusted by the amount of added divinylbenzene, but the polymer has a molecular weight distribution broader than that of a coupling agent and has a structure substantially similar to a star-shaped polymer. Is obtained.
[0036]
Reference Example 5 (adjustment of linear monodisperse polystyrene L1, L2)
60 kg of cyclohexane and 10.0 kg of styrene monomer were charged into an autoclave, and a cyclohexane solution containing 2.5 g of n-butyllithium was injected at an initial reaction temperature of 50 ° C. to perform a polymerization reaction. The mixture was reacted for 20 minutes, and the polymer was precipitated in methanol to obtain a linear monodispersed polymer L1. This was a nearly monodisperse polymer having a weight average molecular weight of 5340,000 and a number average molecular weight of 51,840,000. Similarly, a linear polymer L2 having a weight average molecular weight of 735,000 and a number average molecular weight of 68.050,000 was obtained.
[0037]
Reference Example 6 (adjustment of low molecular weight 3-branched polystyrene A7 for comparative example)
10 kg of styrene and 60 kg of cyclohexane were charged into an autoclave, and the internal temperature was adjusted to 50 ° C. A 10% cyclohexane solution containing 4.8 g of n-butyllithium was injected and allowed to react for 20 minutes. At this time, the weight average molecular weight of the prepolymer was 15,000. Next, the internal temperature was raised to 80 ° C., and a cyclohexane solution containing 0.95 moles of TED per styryl living polymer was added, followed by coupling for 20 minutes to obtain polymer A7. This was a predominantly three-branched polystyrene containing 15.8% uncoupled and having a weight average molecular weight of 385,000.
Table 1 shows the properties of the samples prepared in the reference examples and the sample properties used in the examples and comparative examples.
[0038]
[Table 1]

[0039]
As is clear from Table 1, star-branched polystyrene synthesized by anionic polymerization has much better fluidity than linear polystyrene at the same molecular weight, and the greater the number of branches, the greater the fluidity. I understand.
[0040]
Examples 1 to 6 and Comparative Examples 1 to 4
The components (A) and (B) adjusted in the reference example were blended at the ratios shown in Table 2 and formed into a sheet having a thickness of 0.7 mm using a 40 mm sheet extruder. The tensile modulus measured in the vertical direction, the surface impact strength at 23 ° C., and the melt flow of the composition were evaluated (Table 2). In addition, various evaluation methods are as follows.
Tensile modulus: Measured in the extrusion direction and the vertical direction of the sheet according to JIS K-6872. (Unit Kg / cm ² )
Surface impact strength: Measured according to ASTM D1709 using a weight having a shape of 1/2 inch (unit: Kg · cm)
Melt flow rate: conforms to ISO-R1133 (200 ° C, 5kg load)
[0041]
[Table 2]

[0042]
The results are shown in Table 2. As shown in Table 2, the styrenic resin composition using an anionically polymerized branched polystyrene as the component (A) was compared with a styrenic resin composition using an anionically polymerized linear polystyrene having almost the same molecular weight. This shows that the fluidity is remarkably large, and that the difference between the value in the tensile direction and the value in the vertical direction is small.
Furthermore, compared to a styrene resin composition using radically polymerized polystyrene, the elastic modulus and surface impact strength are far superior.
[0043]
【The invention's effect】
By blending the rubber-modified vinyl aromatic polymer with a vinyl aromatic polymer having a star-shaped branched structure of anionic polymerization, the obtained vinyl aromatic polymer resin composition has good fluidity, and It has an excellent effect on the balance between surface impact resistance and rigidity, and can be used in a wide variety of fields such as home appliances, office equipment, industrial parts, and daily necessities.

Claims (5)

Component (A) 1 to 50% by weight of a vinyl aromatic polymer having a star-shaped branched structure obtained by anionic polymerization having a weight average molecular weight (Mw) of 500,000 to 5,000,000, and rubber obtained by component (B) radical polymerization A vinyl aromatic polymer resin composition comprising 99 to 50% by weight of a modified vinyl aromatic polymer. The vinyl aromatic polymer resin composition according to claim 1, wherein the component (A) is 10 to 50% by weight and the component (B) is 90 to 50% by weight. The vinyl aromatic polymer resin composition according to claim 1 or 2, wherein the component (A) has a weight average molecular weight (Mw) of 500,000 to 2,000,000, and a molecular weight distribution of 1.0 to 3.0. Component (A) is a branched aromatic polymer having a molecular weight distribution (weight average molecular weight Mw / number average molecular weight Mn) of 1.5 or less as a branched polymer around a polyfunctional low molecular weight compound residue. A branched vinyl aromatic polymer having a star-shaped branched structure having eight bonds, a weight average molecular weight (Mw) of 500,000 to 5,000,000, and a molecular weight distribution of 1.0 or more and 3.0 or less. The vinyl aromatic polymer resin composition according to any one of claims 1 to 3. The weight average molecular weight (Mw) of the vinyl aromatic polymer constituting the continuous phase of the component (B) is 150,000 to 300,000, and the average particle diameter of the dispersed phase formed by the rubbery polymer is 0.1 to 4.0 μm. The vinyl aromatic polymer resin composition according to any one of claims 1 to 4, comprising a rubber-modified vinyl aromatic polymer having a rubber-like polymer content of 6 to 30% by weight.