JP2006045257A - Thermoplastic resin composition and molded article thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin composition capable of obtaining a molded article excellent in flowability and moldability, as well as excellent in balance between impact resistance and rigidity, and to provide the molded article thereof. <P>SOLUTION: The thermoplastic resin composition comprises 30-50 parts mass of a rubber-containing graft copolymer (A) and 50-70 parts mass of a hard polymer (B), wherein (A)+(B)=100 parts mass. The rubber-containing graft copolymer (A) is prepared by allowing a rubbery polymer (a), which has a gel content of 50-70 mass%, an amount of swelling of 10-50 times and a mass average particle size of 100-600 nm, to occlude an aromatic vinyl monomer and a vinyl cyanide monomer and by graft polymerization of the monomers in the range of a graft density of 6-15%. The hard polymer (B) has aromatic vinyl monomer units and vinyl cyanide monomer units, has a ratio (Mw/Mn) of mass average molecular weight Mw to number average molecular weight Mn of acetone solubles of 4.0 or more, and has a proportion of the polymer having a molecular weight of 50,000 or more of 35-65 mass%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermoplastic resin composition suitable for injection molding of a large molded product, which is excellent in fluidity and moldability, the molded product obtained is excellent in impact resistance and does not generate a silver phenomenon, and the molded product.

  ABS resin has excellent mechanical properties such as moldability and impact resistance, and chemical resistance, so it is used as a molding material for various components in a wide range of fields such as the vehicle field and the home appliance field. Yes. In recent years, there is an increasing demand for cost reduction and weight reduction of vehicle equipment and other various devices, and in response to such requests, housing materials for OA devices tend to be made thinner.

  However, when the molded product is thinned, there is a problem that impact resistance, particularly low-temperature impact resistance is lowered. In other words, various physical properties of rubber-containing styrenic resins such as ABS resin are generally influenced by factors such as the composition of the rubber phase used, gel content, particle size, particle size distribution, rubber content, etc. When the resin viscosity is reduced and the rubber content in the resin is reduced in order to improve the moldability and formability, machines such as impact resistance, especially low temperature impact resistance, are important characteristics. Characteristics are degraded. Accordingly, when such a resin is used, the quality is deteriorated.

  In this way, when molding large molded products with excellent moldability (silver generation) and fluidity, it is very difficult to obtain an ABS resin that does not generate silver, has excellent surface appearance, and excellent impact resistance. It was difficult.

Therefore, various things have been tried in the past in order to improve both the fluidity and moldability characteristics. For example, Patent Document 1 discloses a thermoplastic resin composition having a specific melt viscosity and improved molding processability and impact resistance.
However, when the present inventors evaluated the thermoplastic resin composition of Patent Document 1 with a comparatively large and complex molded product as an actual product, silver was generated in the molded product. Thus, conventionally, a thermoplastic resin composition that has been improved to such a degree that both fluidity and moldability are sufficiently satisfied has not been obtained.
JP-A-6-145467

  The present invention has been made in view of the above circumstances, and is capable of obtaining a molded product having excellent balance between impact resistance and rigidity, as well as excellent fluidity and moldability, and injection molding of a large molded product. It is an object of the present invention to provide a thermoplastic resin composition suitable for the above and a molded product in which the generation of silver is suppressed and the balance between impact resistance and rigidity is excellent.

  As a result of detailed studies based on the knowledge about the above-mentioned defects, the present inventors have found that a rubber-containing styrene-based resin obtained by graft polymerization of styrene and acrylonitrile at a specific graft density to a polybutadiene having a specific gel content, and a specific molecular weight. In combination with a hard styrene-acrylonitrile copolymer having a molecular weight distribution, an ABS resin has an unprecedented effect of improving impact resistance, fluidity and moldability. A thermoplastic resin composition suitable for injection molding has been invented.

  That is, the thermoplastic resin composition of the present invention has a gel content of 50 to 70% by mass, a swelling amount of 10 to 50 times, and a mass average particle diameter in the range of 100 to 600 nm. A rubber-containing graft copolymer obtained by impregnating (a) a part or all of a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer and graft-polymerizing it in a graft density range of 6 to 15%. Polymer (A) 30-50 parts by mass, aromatic vinyl monomer unit and vinyl cyanide monomer unit, ratio of mass average molecular weight Mw and number average molecular weight Mn of acetone-soluble matter (Mw / Mn) is 4.0 or more, and the ratio of those having a molecular weight of 50,000 or more is 35 to 65% by mass of a hard polymer (B) containing 50 to 70 parts by mass [rubber-containing graft copolymer ( Of A) and the rigid polymer (B) Meter is characterized in that it is 100 parts by weight.

Here, it is desirable that the graft polymer (A) is further graft-polymerized with another monomer copolymerizable with the aromatic vinyl monomer and the vinyl cyanide monomer.
Moreover, the molded article of the present invention is obtained by molding the thermoplastic resin composition of the present invention.

The thermoplastic resin composition of the present invention is excellent in both fluidity and moldability (silver), and according to this thermoplastic resin composition, it has impact resistance, particularly low temperature impact resistance and rigidity. A molded product having an excellent balance can be obtained. Such a thermoplastic resin composition is suitable for injection molding of a large molded product.
In addition, the molded product of the present invention is excellent in the balance between impact resistance and rigidity because generation of silver is suppressed.

Hereinafter, the present invention will be described in detail <Rubber-containing graft copolymer (A)>
The rubber-containing graft copolymer (A) in the present invention impregnates the rubbery polymer (a) with a part or all of a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer. And graft polymerization.

  The rubbery polymer (a) is composed of a polymer obtained by polymerizing a diene monomer. For example, polybutadiene, poly (butadiene-styrene), poly (butadiene-acrylonitrile), polyisoprene, polycyclopentadiene, Examples include poly 2,3-dimethyl butadiene. Of these, polybutadiene is preferred.

  The rubbery polymer (a) has a gel content of 50 to 70% by mass and a swelling amount of 10 to 50 times. When the gel content of the rubbery polymer (a) is 50 to 70% by mass and the swelling amount is 10 to 50 times, the moldability of the thermoplastic resin composition is greatly improved, and thereby molding is performed. Deterioration of the surface appearance of the product and residual strain can be suppressed.

Here, the gel content is calculated as follows.
After the latex containing the rubber polymer (a) is coagulated and dried, a sample Wc (g) of the rubber polymer (a) is dissolved in toluene at room temperature (23 ° C.) for 20 hours, and then 100 The insoluble matter is fractionated with a mesh wire mesh, the insoluble matter is dried at 60 ° C. for 24 hours, the dry insoluble matter amount Wg (g) is measured, and the following formula is calculated.
Gel content (mass%) = Wg / Wc × 100

The amount of swelling is calculated as follows.
After the latex containing the rubber polymer (a) is coagulated and dried, the rubber polymer (a) is dissolved in toluene at room temperature (23 ° C.) for 20 hours, and then the insoluble matter is separated with a 100 mesh wire mesh. Immediately after the measurement, the insoluble matter amount Ws (g) in the swollen state is measured, then the insoluble matter is dried at 60 ° C. for 24 hours, the dry insoluble matter amount Wg (g) is measured, and the following formula is calculated.
Swelling amount (times) = Ws / Wg

  The mass average particle diameter of the rubber polymer (a) needs to be in the range of 100 to 600 nm in order to improve the fluidity of the thermoplastic resin composition and the impact resistance of the obtained molded product. Preferably it is 150-500 nm, Most preferably, it is 200-400 nm. When the mass average particle diameter is less than 100 nm, the impact resistance of the obtained molded product is inferior. When the mass average particle diameter exceeds 600 nm, the surface gloss of the obtained molded product is deteriorated.

  In the rubber-containing graft copolymer (A), a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer in the presence of the rubbery polymer (a) has a graft density of 6 to 15. %, Preferably 7 to 10%. When the graft density is 6 to 15%, the balance between the fluidity of the thermoplastic resin composition and the impact resistance of the resulting molded product, particularly the low temperature impact resistance, is improved.

The graft density here is a value determined as follows.
That is, a sample of the rubber-containing graft copolymer (A) is dissolved in acetone, separated into a soluble component and an insoluble component using a centrifugal separator, and the obtained insoluble component X (g) is ozonolyzed. . And methanol insoluble matter m (g) is isolate | separated. About the obtained methanol insoluble matter, the mass average molecular weight Mw was calculated | required with GPC (gel permeation chromatography), and it is the value computed by the following formula based on these results.
Graft density (%) = Graft rate / (Mw / 10 ⁴ )
Graft rate (mass%) = {m / (X−m)} × 100

Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, paramethylstyrene, bromostyrene, and the like. Among these, styrene is particularly preferable.
Examples of the vinyl cyanide monomer include acrylonitrile and methacrylonitrile. Among these, acrylonitrile is particularly preferable.
About these monomers, 1 type can be used individually or in combination of 2 or more types.

  Moreover, you may use the other monomer copolymerizable with an aromatic vinyl monomer and a vinyl cyanide monomer as needed. Examples of such other monomers include methacrylic acid or acrylic acid esters such as methyl methacrylate and methyl acrylate, maleimide compounds such as N-phenylmaleimide and N-cyclohexylmaleimide, acrylic acid, methacrylic acid, and itacon. Examples thereof include unsaturated carboxylic acid compounds such as acid and fumaric acid. These can be used alone or in combination of two or more.

  Any known polymerization method can be adopted as the graft polymerization method for synthesizing the rubber-containing graft copolymer (A). In particular, a monomer-impregnated rubber obtained by impregnating the rubber polymer (a) with the monomer mixture by mixing and leaving the rubber polymer (a) and a part or the whole of the monomer mixture in advance. It is preferable to polymerize all the monomers after preparing the polymer and then adding the remaining monomer mixture. If this polymerization method is adopted, the moldability of the thermoplastic resin composition and the physical properties such as the impact resistance of the resulting molded article are improved.

  The specific method of graft polymerization described above is, for example, firstly charging a rubbery polymer (a) produced by emulsion polymerization into a reactor equipped with a stirring blade and a jacket, Part or the whole amount is added all at once or continuously dropped, and the mixture is allowed to stand at 40 to 70 ° C. for 5 to 60 minutes while stirring, and then the remaining monomer mixture and initiator are added. The monomer added before the initiator is added impregnates the rubbery polymer (a) and polymerizes in the rubbery polymer (a) to become a polymer. Thus, the structure in which the polymer is formed in the rubbery polymer (a) is referred to as an occluded structure.

  Here, a monomer constituting the polymer in the rubber polymer (a) (hereinafter referred to as “occluded monomer”), that is, a single amount impregnated and polymerized in the rubber polymer (a). As the body, the same kind as the monomer newly added after impregnation can be used. As the occluded monomer, an aromatic vinyl monomer or a vinyl cyanide monomer is preferably used, and an aromatic vinyl monomer is particularly preferably used. In particular, if an aromatic vinyl monomer is used, the fluidity becomes better.

  Thus, when the rubbery polymer (a) in the rubber-containing graft copolymer (A) has an occluded structure, that is, the rubbery polymer (a) is impregnated with an occluded monomer in advance. 10 to 60% by mass, more preferably 30 to 50% by mass, based on all monomer components polymerized into the rubbery polymer (a). If the amount of occluded monomer is less than 10% by mass, the effect of improving the fluidity by adopting the occluded structure is not sufficiently exhibited. If the amount of occluded monomer exceeds 60% by mass, the balance of physical properties, particularly sufficient impact resistance is achieved. It becomes difficult to obtain.

<Hard polymer (B)>
The hard polymer (B) in the present invention has an aromatic vinyl monomer unit and a vinyl cyanide monomer unit as constituent components, and if necessary, an aromatic vinyl monomer and vinyl cyanide. Another monomer copolymerizable with the monomer may be copolymerized.
Here, the aromatic vinyl monomer, the vinyl cyanide monomer, and other monomers copolymerizable therewith are the same as those used in the rubber-containing graft copolymer (A) described above. Can be used.

  The hard polymer (B) needs to have a ratio (Mw / Mn) of mass-average molecular weight Mw and number-average molecular weight Mn of acetone-soluble content to 4.0 or more. Mw / Mn is preferably 5.0 or more. When Mw / Mn is less than 4.0, the fluidity of the thermoplastic resin composition is lowered and the moldability is deteriorated.

  The ratio of the polymer having a molecular weight of 50,000 or more needs to be 35 to 65% by mass, preferably 40 to 60% by mass, in the hard polymer (B) (100% by mass). is there. If the proportion of the polymer having a molecular weight of 50,000 or more exceeds 65% by mass, the moldability deteriorates with a decrease in the fluidity of the thermoplastic resin composition. The impact resistance of the is reduced.

  About the manufacturing method of a hard polymer (B), the well-known polymerization method which emulsified, suspended, the block shape, or these were compounded is employable. At this time, a chain transfer agent may be used. Examples of the chain transfer agent include octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-hexyl mercaptan, and α-styrene dimer. These chain transfer agents can be used individually by 1 type or in combination of 2 or more types.

<Thermoplastic resin composition>
The thermoplastic resin composition of the present invention contains 30 to 50 parts by mass of a rubber-containing graft copolymer (A) and 50 to 70 parts by mass of a hard polymer (B) [rubber-containing graft copolymer (A ) And the hard polymer (B) is 100 parts by mass].

  When the rubber-containing graft copolymer (A) is less than 30 parts by mass (when the hard polymer (B) exceeds 70 parts by mass), the balance between the impact resistance and the rigidity of the obtained molded product is deteriorated. On the other hand, when the rubber-containing graft copolymer (A) exceeds 50 parts by mass (when the hard polymer (B) is less than 50 parts by mass), the fluidity and moldability deteriorate.

  In addition, the thermoplastic resin composition may further contain various additives such as pigments, dyes, lubricants, antioxidants, ultraviolet absorbers, antistatic agents, reinforcing agents, fillers, etc. as necessary. It can mix | blend within the range.

  Although there is no restriction | limiting in particular as a method of obtaining a thermoplastic resin composition, It is preferable to melt-knead, after mixing a rubber-containing graft copolymer (A) and a hard polymer (B). Melt kneading can be performed using, for example, an extruder, a Banbury mixer, or the like.

<Molded product>
The molded article of the present invention is obtained by molding the above-described thermoplastic resin composition.
As the molding method, known molding methods such as injection molding, extrusion molding, vacuum molding, pressure molding, blow molding, and profile extrusion molding can be used.
The molded article of the present invention is composed of a thermoplastic resin composition that is excellent in fluidity and moldability, and that has an excellent balance between impact resistance and rigidity of the obtained molded article, and is suitable for large molded articles. .

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to synthesis examples, examples, and comparative examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In the following, “part” means “part by mass”.
Further, the gel content, swelling amount and mass average particle diameter of the rubber-like polymer (a); the graft density and the amount of occluded monomer of the rubber-containing graft copolymer (A); styrene in the hard polymer (B) The content of units and acrylonitrile units, the Mw / Mn of the hard polymer (B), and the proportion of those having a molecular weight of 50,000 or more were measured as follows.

[Gel content]
The rubber polymer (a) sample Wc (g) was dissolved in toluene at room temperature (23 ° C.) for 20 hours, and then the insoluble matter was fractionated with a 100 mesh wire mesh. After drying for a while, the dry insoluble content Wg (g) was measured and calculated by the following formula.
Gel content (mass%) = Wg / Wc × 100

[Swelling amount]
The rubber-like polymer (a) was dissolved in toluene at room temperature (23 ° C.) for 20 hours, and then the insoluble matter amount Ws in the swollen state was measured immediately after separating the insoluble matter with a 100 mesh wire net, and then insoluble. The minute was dried at 60 ° C. for 24 hours, the dry insoluble content Wg (g) was measured, and calculated by the following formula.
Swelling amount (times) = Ws / Wg

[Mass average particle diameter]
The mass average particle diameter of the rubber polymer (a) was determined by a dynamic light scattering method using Micro track Model: 9230UPA manufactured by Nikkiso Co., Ltd.

[Graft density]
A sample of the rubber-containing graft copolymer (A) was dissolved in acetone and separated into a soluble part and an insoluble part using a centrifugal separator, and the obtained insoluble part X (g) was subjected to ozonolysis. Insoluble matter was dissolved in methanol, and methanol insoluble matter m (g) was separated. About the obtained methanol insoluble matter, mass average molecular weight Mw was calculated | required by GPC, and it computed with the following formula based on these results.
Graft density (%) = Graft rate / (Mw / 10 ⁴ )
Graft rate (mass%) = {m / (X−m)} × 100

  Here, the mass average molecular weight Mw was measured using “GPC (Gel Permeation Chromatography)” manufactured by Tosoh Corporation and calculated by a standard polystyrene conversion method. Further, ozonolysis of insoluble matter was carried out by dispersing acetone-insoluble matter in chloroform and allowing it to stand for 12 hours or more, and then bubbling ozone through the solution for 2 hours to cause butadiene to decompose. The completion of the decomposition reaction was confirmed by measuring the liquid permeability. After the decomposition, the liquid was concentrated and methanol was added to precipitate the polymer component, which was filtered and dried to obtain a methanol-insoluble matter.

[Occluded monomer amount]
The amount of occluded monomer is the amount of monomer component polymer located inside the rubbery polymer. The particle size of the rubbery polymer before impregnation and the rubbery polymer after graft polymerization. The amount of occluded monomer can be calculated from the volume increase rate. Specifically, each of the rubbery polymers before and after the graft polymerization was stained with osmic acid, the particle diameter was measured by observation with a transmission electron microscope (TEM), and the amount of occluded monomer was calculated from the average volume increase. .

[Monomer unit content]
The styrene unit and acrylonitrile unit in the hard polymer (B) were determined by infrared spectrum.
[Molecular weight]
The ratio of Mw / Mn and molecular weight of 50,000 or more of the hard polymer (B) is that the sample of the hard polymer (B) is dissolved in acetone. ).

<Synthesis Example 1: Production of rubber-containing graft copolymer (A-1)>
In autoclave, raw materials in Table 1 excluding ferrous sulfate, sodium pyrophosphate, crystalline glucose and cumene hydroperoxide (the gel content of polybutadiene (a-1) is 60% by mass, the amount of swelling is 30 times, the mass average particle The diameter was 300 nm) and heated to 60 ° C. to impregnate the polybutadiene (a-1) with the monomer mixture. Then, after being left at 60 ° C. for 45 minutes, ferrous sulfate, sodium pyrophosphate, crystalline glucose and cumene hydroperoxide are continuously added over 150 minutes, and then the temperature is raised to 70 ° C. This was maintained for 1 hour to complete the reaction to obtain a polymer latex.
Next, an antioxidant was added to the polymer latex, and then the sulfuric acid was added to solidify the polymer. After sufficiently washing with water, the polymer latex was dried to obtain a rubber-containing graft copolymer (A-1).
And the mass average molecular weight of the grafted polymer in the obtained rubber-containing graft copolymer (A-1) and the graft ratio were measured, and the graft density was determined. Further, the amount of occluded monomer was determined.

<Synthesis Example 2: Production of rubber-containing graft copolymer (A-2)>
A rubber-containing graft copolymer was used in the same manner as in Synthesis Example 1 except that a polybutadiene (a-2) latex having a gel content of 98% by mass, a swelling amount of 20 times, and a mass average particle size of 300 nm was used as the polybutadiene latex. The union (A-2) was obtained. The mass average molecular weight and graft ratio of the grafted polymer in the obtained rubber-containing graft copolymer (A-2) were measured, and the graft density was determined. Further, the amount of occluded monomer was determined.

<Synthesis Example 3: Production of rubber-containing graft copolymer (A-3)>
A rubber-containing graft copolymer (A-3) was obtained in the same manner as in Synthesis Example 2 except that the amount charged into the autoclave was changed to the amount shown in Table 1 and the impregnation time was changed. The mass average molecular weight and graft ratio of the grafted polymer in the obtained rubber-containing graft copolymer (A-3) were measured to determine the graft density. Further, the amount of occluded monomer was determined.

<Synthesis Example 4: Production of Rigid Polymer (B-1)>
A monomer mixture consisting of the components shown in Table 2 was charged into a reactor purged with nitrogen, heated to 60 ° C. for 5 hours, heated to 120 ° C., and then reacted for 4 hours to complete the polymerization. . The final conversion rate at that time was 96%, the Mw / Mn of the obtained hard polymer (B-1) was 4.0, the proportion of the polymer having a molecular weight of 50,000 or more was 55% by mass, and the content of acrylonitrile units The amount was 28.4% by mass.

<Synthesis Example 5: Production of hard polymer (B-2)>
A hard polymer (B-2) was obtained in the same manner as in Synthesis Example 4 except that 0.1 part of t-dodecyl mercaptan and 0.6 part of normal octyl mercaptan were used. The final conversion rate at that time was 98%, Mw / Mn of the obtained hard polymer (B-2) was 4.6, the proportion of the polymer having a molecular weight of 50,000 or more was 52% by mass, and the content of acrylonitrile units. Was 28.3 mass%.

<Synthesis Example 6: Production of hard polymer (B-3)>
A hard polymer (B-3) was obtained in the same manner as in Synthesis Example 4 except that 0 part of t-dodecyl mercaptan and 1.0 part of normal octyl mercaptan were used. The final conversion rate at that time was 98%, Mw / Mn of the obtained hard polymer (B-3) was 9.7, the proportion of the polymer having a molecular weight of 50,000 or more was 47% by mass, and the content of acrylonitrile units. Was 27.0% by mass.

<Synthesis Example 7: Production of hard polymer (B-4)>
A hard polymer (B-4) was obtained in the same manner as in Synthesis Example 4, except that 0.4 part of t-dodecyl mercaptan and 0 part of normal octyl mercaptan were used. The final conversion rate at that time was 98%, Mw / Mn of the obtained hard polymer (B-4) was 1.7, the proportion of the polymer having a molecular weight of 50,000 or more was 65% by mass, and the content of acrylonitrile units. Was 26.7% by mass.

<Examples 1-3, Comparative Examples 1-4>
Each polymer obtained in the above synthesis example was blended in the ratio shown in Table 3, and hescheled together with 0.5 parts by mass of a lubricant (“PRN-208” manufactured by Nippon Oil & Fats Co., Ltd.). Next, the mixture was melt-mixed at 220 ° C. with a twin-screw extruder (manufactured by Nippon Steel Works: TEX-44) and pelletized to obtain a thermoplastic resin composition. The pellets were molded at 240 ° C. with a 4 ounce injection molding machine (manufactured by Nippon Steel Works), and necessary test pieces were prepared and evaluated as follows. The results are shown in Table 3.

(Izod impact strength)
Using a test piece having a thickness of 1/8 inch, Izod impact strength was measured at 23 ° C. and −30 ° C. in accordance with ASTM-D256.
(Melt flow index)
The melt flow index (MI) was measured at 220 ° C. and a load of 98 N in accordance with ASTM-D1238.

(Tensile strength)
Tensile strength was measured at 23 ° C. according to ASTM-D790.
(Growth rate)
The elongation was measured at 23 ° C. according to ASTM-D790.

(Bending strength)
The bending strength was measured at 23 ° C. according to ASTM-D790.
(Flexural modulus)
The flexural modulus was measured at 23 ° C. according to ASTM-D790.

(Surface appearance)
A test piece of 50 × 200 × 2 (mm) was prepared and judged based on the following evaluation criteria.
A: Extremely uniform gloss was shown.
○: Gloss unevenness is slight and practical.
(Triangle | delta): There exists a partial gloss unevenness and it cannot endure practical use.
X: Gloss unevenness is remarkable.
XX: Gloss unevenness is extremely remarkable.

(Spiral flow)
Using a spiral mold having a thickness of 2 mm, the thermoplastic resin composition was injected from a 4 ounce injection molding machine at an injection temperature of 220 ° C., a mold temperature of 50 ° C. and an injection pressure of 7 Mpa, and the flow length (mm) was measured.

(Silver test)
Using a lid mold (automobile meter panel mold), the thermoplastic resin composition was injected from an 8 ounce injection molding machine at an injection temperature of 250 ° C. and a mold temperature of 50 ° C. to obtain a molded product. The injection speed was increased stepwise and injection molding was repeated. The surface of the molded product was visually observed, and the injection speed when silver was generated was defined as the silver generation injection speed.

  The thermoplastic resin compositions of Examples 1 to 3 were improved in moldability due to improved silver properties and fluidity, and had a good balance between impact resistance and rigidity.

  The thermoplastic resin composition of Comparative Example 1 had a Mw / Mn of the hard polymer (B) of 1.7, which was outside the scope of the present invention, and thus was poor in fluidity and moldability.

  In the thermoplastic resin composition of Comparative Example 2, the rubber-containing graft copolymer (A) has a gel content of 98% by mass, which is outside the scope of the present invention, and the Mw / Mn of the hard polymer (B). 1.7, which was outside the scope of the present invention, was inferior in fluidity and moldability, and inferior in surface appearance.

  The thermoplastic resin composition of Comparative Example 3 has a rubber-containing graft copolymer (A) having a gel content of 98% by mass and a graft density of 5%, which is outside the scope of the present invention. Since Mw / Mn of B) was 1.7, which was outside the scope of the present invention, the fluidity and formability of the surface appearance were inferior, and the impact resistance was also inferior.

  The thermoplastic resin composition of Comparative Example 4 had a rubber content of the graft copolymer (A) having a gel content of 98% by mass and a graft density of 5%, which was outside the scope of the present invention. It was inferior.

  From the above results, according to the present invention, the thermoplastic resin composition in which the rubber-containing graft copolymer (A) and the hard polymer (B) are blended at a specific resin composition ratio is fluid and moldable (silver). It has been found that the molded product can be made thin without reducing the impact resistance, since both are excellent in both, and the balance between impact resistance and rigidity is also good.

The thermoplastic resin composition of the present invention is an epoch-making high-performance molding material in which the conventional defects of rubber-containing styrenic resins represented by ABS resin are improved. Therefore, the thermoplastic resin composition of the present invention has a very large industrial practical value as a molding material for large molded articles such as home appliances.

Claims (3)

An aromatic vinyl monomer and a rubber polymer (a) having a gel content of 50 to 70% by mass, a swelling amount of 10 to 50 times, and a mass average particle diameter in the range of 100 to 600 nm 30 to 50 parts by mass of a rubber-containing graft copolymer (A) impregnated with a part or all of a monomer mixture containing a vinyl cyanide monomer and graft-polymerized in a range of a graft density of 6 to 15%;
It has an aromatic vinyl monomer unit and a vinyl cyanide monomer unit, has a ratio (Mw / Mn) of mass average molecular weight Mw to number average molecular weight Mn of acetone-soluble matter of 4.0 or more, and has a molecular weight And 50 to 70 parts by mass of the hard polymer (B) having a ratio of 35 to 65% by mass of [the total of the rubber-containing graft copolymer (A) and the hard polymer (B) It is 100 parts by mass].   The graft polymer (A) is further graft-polymerized with another monomer copolymerizable with an aromatic vinyl monomer and a vinyl cyanide monomer. Thermoplastic resin composition. A molded article obtained by molding the thermoplastic resin composition according to claim 1.