JPH0355507B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a thermoplastic resin composition for molding. More specifically, the present invention relates to a thermoplastic resin composition for molding that, when molded, has excellent properties in terms of adhesiveness, appearance, mechanical strength, and solvent resistance of the molded product. [Prior art and problems] In recent years, plastics have been increasingly used as materials for parts for automobiles and parts for home appliances, especially from the viewpoint of weight reduction and economic efficiency. Polypropylene, which has excellent properties, is preferably used. However, since polypropylene is a nonpolar compound, in the form of a molded product, polypropylene has extremely poor adhesion to each other or to other polar substances. For this reason, in the adhesion process for adhering polypropylene molded products to each other or for surface decoration of the molded products, a surface treatment process such as plasma treatment or primer coating of the products is indispensable. There are disadvantages involved. In addition, in the adhesion process related to the article, conventionally,
Solvent-based adhesives such as chloroprene-based, urethane-based, and acrylonitrile-butadiene rubber-based adhesives have been mainly used. However, solvent-based adhesives have problems from the viewpoint of safety, health, and disaster prevention because the solvent scatters or evaporates during work, and in recent years, solvent-free adhesives have been used.
Water-based emulsion type adhesives have been used. Since this adhesive is water-based, it is difficult to wet the surface of a polypropylene molded article compared to a solvent-based adhesive, making it even less suitable for adhesion to the molded article. On the other hand, attempts have been made to improve the adhesive properties of polypropylene, such as adding polystyrene to a polypropylene composition. However, since polystyrene has poor compatibility with polypropylene, delamination of the molded product may occur. In order to improve this drawback, as a compatibilizing resin,
Compositions using hydrogenated styrene-butadiene block copolymers or hydrogenated styrene-isoprene block copolymers are disclosed in U.S. Pat.
It is disclosed in JP-A-4188432, JP-A-54-53159, JP-A-56-38338, and the like. When the present inventors conducted additional test molding of these disclosed compositions, the molded products did not exhibit delamination, and
Although an improvement in adhesion was observed, there were still problems in terms of the characteristics necessary for molded products. That is, the composition described in US Pat. No. 4,188,432 had a problem in weather resistance because it used a polystyrene-polybutadiene graft copolymer as the polystyrene component. In addition, during molding, the weld portion, which is formed when two or more flows of resin meet, has a poor appearance due to linear unevenness, and is also insufficient in rigidity and solvent resistance. On the other hand, the composition disclosed in JP-A-54-53159 was insufficient in terms of weld part appearance, impact resistance, and solvent resistance. Furthermore, the composition disclosed in JP-A-56-38338 also had the drawbacks of poor balance between rigidity and impact resistance, and insufficient adhesion. The present inventors have conducted extensive research into compositions containing polypropylene and polystyrene that satisfy all of mechanical strength, weld appearance, solvent resistance, and adhesive properties. As a result, a specific highly crystalline propylene-ethylene block copolymer was used as the polypropylene, and an amorphous ethylene-propylene copolymer was used as the polypropylene, and a hydrogenated styrene-butadiene block copolymer or a styrene-butadiene block copolymer was used as the compatibilizing resin. A composition that uses a hydrogenated isoprene block copolymer and further contains a styrene homopolymer in a specific proportion has significantly improved adhesion, appearance, mechanical strength, and solvent resistance compared to conventional compositions. The present invention was completed based on this finding. As is clear from the above description, the object of the present invention is to create a thermoplastic resin composition for molding that has excellent adhesiveness, rigidity, impact resistance, weld area appearance, and solvent resistance when using an aqueous emulsion type adhesive. It is about providing something. [Means for solving the problems] The present invention has the following configuration. The total amount of (A) to (D) below is 100% by weight, (A) One or more stages of propylene homopolymer production process in which 70 to 95% by weight of the total polymerization amount is polymerized, followed by 30% of the total polymerization amount. Ethylene produced by polymerizing propylene and ethylene using a stereoregular catalyst by a polymerization method consisting of a multi-stage polymerization process with one or more stages of producing an ethylene-propylene copolymer to polymerize ~5% by weight. A propylene-ethylene block copolymer having a content of 3 to 20% by weight of the total polymerized amount, the melt flow rate (MFR) of the propylene homopolymer portion and the absorbance ratio (IR-τ, Infrared wave number 997cm ^-1
The absorbance ratio at 973 cm ^-1 (A ₉₉₇ /A ₉₇₃ ) is
2 to 3% by weight of the precipitate that satisfies the following formula IR−τ≧0.0203logMFR+0.950 and that first precipitates when a dilute solution of xylene in which the propylene homopolymer portion is dissolved is slowly cooled with stirring. The IR-τ of the component is 0.97 or more, and the ratio (M _w1 /M _w0 ) of the weight average molecular weight (M _w1 ) of the precipitated component to the weight average molecular weight (M _w0 ) of the propylene homopolymer portion is 3. Propylene which is more than -
Ethylene block copolymer 30-70% by weight, (B) Amorphous ethylene-propylene copolymer 2-
(C) 2-15% by weight of hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-isoprene block copolymer, and (D) 20-50% by weight of styrene homopolymer. thermoplastic resin composition for use. The propylene-ethylene block copolymer used in the present invention is a highly viscous crystalline propylene-ethylene block copolymer (hereinafter sometimes referred to as the propylene-ethylene block copolymer according to the present invention) having a specific composition and physical properties. ). The well-known propylene-ethylene block copolymer is produced by a polymerization process that includes two or more polymerization steps each comprising a propylene homopolymer portion and an ethylene homopolymer portion or an ethylene-propylene copolymer portion. Although it is produced legally and has better impact resistance than propylene homopolymer, it has the disadvantage of reduced rigidity. As described above, there is generally an incompatible relationship between the rigidity and impact resistance of plastic materials, and it is often extremely difficult to simultaneously improve the former and the latter. However, in the propylene-ethylene block copolymer according to the present invention, the melt flow rate (MFR) of the propylene homopolymer portion, which accounts for 70 to 95% by weight of the whole, and the absorbance ratio (IR-τ, infrared Fractions of 997cm ^-1 and 973cm ^-1
The absorbance ratio (A ₉₉₇ /A ₉₇₃ ) satisfies the following formula: IR−τ≧0.0203logMFR+0.950, and when the dilute solution of xylene in which the propylene homopolymer portion is dissolved is slowly cooled while stirring. The IR-τ of 2 to 3% by weight of the precipitated component that first precipitates is 0.97 or more, and the weight average molecular weight (M _w1 ) of the precipitated component and the weight average molecular weight (M _{w0 )} of the propylene homopolymer portion are ) is a specific highly crystalline polypropylene having a ratio (M _w1 /M _w0 ) of 3 or more, and the ethylene content in the remaining ethylene-propylene copolymer portion is 3 to 20% of the total amount of the polymer. % by weight.
Such a copolymer and its production method are described in the specification of Japanese Patent Application No. 62-23889 previously filed by the present applicant, and are as follows. The propylene-ethylene block copolymer according to the present invention is composed of, for example, a titanium-containing solid component (a solid compound mainly composed of titanium trichloride or a solid compound in which titanium tetrachloride is supported on a carrier such as magnesium chloride) and an organic aluminum Slurry polymerization carried out in an inert solvent using a so-called Tieghu-Natsuta type catalyst, in which a combination of compounds and, in some cases, an electron donor component is combined as the third component of the catalyst; bulk polymerization in propylene itself as a solvent; Polymerization or gas phase polymerization mainly using propylene gas to produce propylene under specific conditions, i.e. at a relatively low polymerization temperature (room temperature to about 60℃)
and including a step of polymerizing in the substantial absence of a molecular weight modifier (usually hydrogen gas).
In the propylene homopolymer production process of stages or higher, 70 to 95% by weight of the total polymerization amount is polymerized. Also, aromatic carboxylic acid esters (e.g. p-
When a large amount of methyl toluate, methyl p-anisate, etc.) is used as the third component of the catalyst, polymerization occurs at a relatively high polymerization temperature (60°C to 75°C) and in the presence of a certain amount of molecular weight regulator. It can be produced by using a polymerization method including the steps of: It can be obtained by a method in which, following the above propylene homopolymer production process, ethylene-propylene copolymerization is carried out in an amount of 30 to 5% by weight of the total polymerization amount. However, the ethylene content in the total polymer must be within the range of 3 to 20% by weight. When the ratio of the propylene homopolymer portion to the ethylene-propylene copolymer portion and the ethylene content are outside the range, it becomes difficult to achieve both rigidity and impact resistance. The propylene-ethylene block copolymer according to the present invention obtained as described above has significantly higher mechanical strength than conventionally known propylene homopolymers or propylene-ethylene block copolymers. In the composition of the present invention, the content of the propylene-ethylene block copolymer is 30 to 70% by weight,
Preferably it is 35 to 70% by weight. If the blending amount is less than 30% by weight, the appearance of the weld part and solvent resistance of the molded product will be poor, and if the amount is less than 70% by weight,
Exceeding this is not preferable because the adhesiveness becomes insufficient. The amorphous ethylene-propylene copolymer used in the present invention as the above-mentioned component (B) is preferably ethylene-propylene having an ethylene content of 40 to 80% by weight and a Mooney viscosity of M100°C and 1+4 of 20 to 70. Use rubber. If a composition with an ethylene content outside the above-mentioned range or a Mooney viscosity of less than 20 is used, the impact resistance of the molded product will decrease when such a composition is made, and if the Mooney viscosity exceeds 70. If it is used in excess of this amount, the appearance of the molded product will deteriorate, such as flow marks appearing on the surface of the molded product, which is not preferable. The amount of the amorphous ethylene-propylene copolymer used is 2 to 15% by weight, preferably 5 to 15% by weight. The amount used is 2% by weight
If it is less than 15%, the adhesion and impact resistance of the molded product will decrease when such a composition is made into a molded product, and
If it exceeds % by weight, the rigidity decreases, which is not preferable. The hydrogenated styrene-butadiene block copolymer or the hydrogenated styrene-isoprene copolymer, which is the above-mentioned component (C) used in the present invention, is a combination of a styrene block and a butadiene block, or a styrene block and an isoprene block. 80% of the butadiene portion or isoprene portion of the block copolymer having one or more of each
It is a hydrogenated block copolymer as described above, and preferably contains 10 to 60% by weight of styrene.
The amount of hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-isoprene copolymer used is 2 to 15% by weight, preferably 5 to 15% by weight. If the amount used is less than 2% by weight, when such a composition is made into a molded article, the impact resistance of the molded article will be poor and the molded article will cause delamination. Moreover, if it exceeds 15% by weight, the rigidity decreases, which is not preferable. The hydrogenated styrene-butadiene block copolymer or styrene-isoprene block copolymer hydrogenated product (C) used in the present invention is available under the trade name Kraton G1650 or Kraton G1650.
It is easily available under names such as G1652, Kraton G1657, and Kraton G1701 (all manufactured by Ciel Chemical Co., Ltd.). Further, these hydrogenated block copolymers may be used alone or in combination. In addition, the above-mentioned styrene homopolymer (D) used in the present invention is a styrene homopolymer obtained by a known polymerization method, and may be appropriately selected from those commercially available as general polystyrene. It is easily available under names such as Styron 666, Styron 679, and Styron 691 (all manufactured by Asahi Kasei Corporation). The amount of the styrene homopolymer used is 20 to 50% by weight, preferably 30 to 50% by weight. If the amount used is less than 20% by weight, adhesiveness and rigidity will decrease, and if it exceeds 50% by weight, impact resistance, weld appearance, and solvent resistance will decrease, which is not preferable. The composition of the present invention may contain various additives normally added to polypropylene, such as antioxidants, antistatic agents, ultraviolet absorbers, copper inhibitors,
Pigments and the like may be used in combination as appropriate. Furthermore, the composition of the present invention may contain any filler as long as it does not significantly impair the purpose of the present invention. Examples of the filler include inorganic or organic fillers such as glass fiber, talc, mica, wood flour, and synthetic fibers. In producing the thermoplastic resin composition for molding of the present invention, predetermined amounts of the above (A) to (D) may be mixed and then sufficiently kneaded. As a mixing device, a high-speed stirring device such as a Hensel mixer (trade name) or a super mixer may be used, and as a kneading device, a Banbury mixer, roll, co-kneader, etc.
A single-screw or twin-screw extruder may be used.
Mixing conditions are not limited, but are from room temperature to 100°C, preferably from room temperature to 60°C, for 1 to 1 hour, preferably 3 to 30 minutes. Although the kneading conditions are not limited, the residence time in the extruder is 10 seconds to 5 seconds.
minutes, preferably 20 seconds to 2 minutes. The kneading temperature is 180 to 300°C, preferably 200 to 280°C. The thermoplastic resin composition for molding of the present invention thus obtained is used to produce molded articles by a molding method such as injection molding or extrusion molding, depending on the purpose. [Effects of the Invention] When the thermoplastic resin composition for molding of the present invention is made into a molded product, the molded product has excellent rigidity, impact resistance, welded part appearance, solvent resistance, and adhesiveness, and
It has these excellent properties in a well-balanced manner. In particular, since the composition of the present invention uses a specific high-rigidity propylene-ethylene block copolymer, it has better impact resistance than when a normal propylene-ethylene block copolymer is used (Comparative Example 1). A significant increase in stiffness is seen without any loss. Similarly, compositions lacking essential components of the present invention (Comparative Examples 2 and 3), polypropylene (Comparative Example 4), and styrene homopolymer (Comparative Example 5) all lack a balance of properties. Furthermore, even when each essential component of the present invention is used, when a composition (Comparative Examples 6 and 7) having a composition that deviates from the usage ratio of the present invention is used, the properties are unbalanced. As is clear from the above description, the composition consisting of the essential components and specific compounded components of the present invention has an excellent balance of properties and is useful in various molding fields, especially in terms of rigidity, impact resistance, and appearance. It can be suitably used in fields where solvent resistance and adhesiveness are required, for example, fields such as automobile parts and home appliances. [Examples] The present invention will be explained below with reference to Examples and Comparative Examples. The production of propylene-ethylene block copolymers used in Examples and Comparative Examples and the evaluation of molded articles were carried out by the following methods. 1) Production of propylene-ethylene buturoc copolymer according to the present invention Preparation of solid catalyst component 600 ml of n-hexane, 0.50 mol of diethylaluminum monochloride (DEAC), and 1.30 mol of diisoamyl ether were mixed at 25°C for 1 minute. , react at the same temperature for 5 minutes to form the reaction product solution (diisoamyl ether/DEAC).
A molar ratio of 2.6) was obtained. Put 4.5 mol of titanium tetrachloride into a reactor purged with nitrogen, heat it to 35°C, and add the entire amount of the reaction product solution () to it.
After dropping for 300 minutes, keep at the same temperature for 60 minutes,
After that, the temperature was raised to 85℃ and the reaction was continued for another hour, cooled to room temperature, the supernatant liquid was removed, and n-
Add 4000 ml of hexane and remove the supernatant liquid by decantation. This washing operation was repeated four times to obtain 190 g of a solid product (2). The whole of this () was suspended in 3000 ml of n-hexane and diisoamyl ether was added at 20°C.
290 g of titanium tetrachloride and 350 g of titanium tetrachloride were added over about 1 hour at room temperature, and the mixture was reacted at 75°C for 1 hour. After the reaction is complete, cool to room temperature (20℃), remove the supernatant liquid by decantation, add 4000ml of n-hexane, stir for 10 minutes, leave to stand, and remove the supernatant. Repeat this process 5 times. After that, it was dried under reduced pressure to obtain a solid product (). Preparation of pre-activated catalyst After purging a stainless steel reaction vessel with internal volume 20 with inclined blades with nitrogen gas, 15 n-hexane and diethyl aluminum monochloride were added.
After adding 42 g of solid product () at room temperature, 30 g of propylene was fed at 0.5 g/min over 60 minutes and stirring was continued for a further 8 hours, after which unreacted propylene and n-hexane were removed under reduced pressure. , a preactivated catalyst () was obtained (about 1 g of propylene reacted per 1 g of solid product ()). Block copolymerization of propylene and ethylene In a nitrogen-substituted stainless steel polymerization vessel with an internal volume of 250 and a turbine-type stirring blade, 100 g of n-hexane was added, followed by 20 g of diethylaluminium monochloride, and the preactivated catalyst ()
40g, p- as aromatic carboxylic acid ester
20.0 g of methyl toluate was charged, and then the temperature was raised to 40° C., propylene was supplied, and the total pressure was raised to 10 Kg/cm ² G. 40℃, 10Kg/ ^cm2
Polymerize for 15 minutes while maintaining the temperature at
Add 1100N of hydrogen as a stage polymerization and lower the temperature.
The temperature was raised to 50° C. for 3 hours and 45 minutes, the total pressure was maintained at 10 Kg/cm ² G, and after polymerization was continued, the supply of propylene was stopped. Next, unreacted propylene is released,
A portion of the slurry in the polymerization vessel was collected, filtered, washed, and dried to obtain a propylene homopolymer powder. This polymer has a melt flow rate (MFR) of 71, an IR-τ value of 1.003, and an initial 2.5 wt%
The IR-τ value of the precipitate was 1.060. Also,
The ratio M _w1 /M _w0 of the weight average molecular weight (M w1 ) of the precipitated component to the weight average molecular weight (M _{w0 )} of the propylene homopolymer was 9.90. After releasing unreacted propylene, the interior of the polymerization vessel was
℃, and after adding 1600N of hydrogen, the third
Ethylene and propylene were continuously supplied as monomers for the stage polymerization for 2 hours so that the supply ratio of ethylene was 30% by weight. The total supply of ethylene was 3.1Kg. After the polymerization was completed, the supply of ethylene and propylene was stopped, and unreacted ethylene and propylene were discharged. Then, 25 methanol was supplied into the polymerization vessel, and the temperature was raised to 90°C. 30 minutes later, more
Add 100g of 20% by weight caustic soda water,
After stirring for a minute and adding 50% pure water, the remaining propylene was discharged. After removing the aqueous layer, add 50% pure water and wash with water for 10 minutes.After removing the aqueous layer, add 50% pure water again and wash for 10 minutes.
The mixture was stirred and washed with water, and the aqueous layer was extracted. Then, polypropylene-n-hexane
The slurry is extracted, filtered, and dried, and the propylene homopolymer portion is 86.7% by weight of the total polymer, and the ethylene content is 8.0% by weight of the total polymer.
and the melt flow rate (MFR) is 28
31.1 kg of propylene-ethylene block copolymer powder according to the present invention was obtained. 2) Production of ordinary propylene-ethylene block copolymer In the production of the propylene-ethylene block copolymer according to the present invention, methyl p-toluate was not used and the amount of preactivated catalyst was 20 g. A propylene homopolymer portion was produced in the same manner as above, except that the first stage polymerization was omitted and the amount of hydrogen added was 600N. When a part of the slurry was extracted and its physical properties were measured, the melt flow rate (MFR) was 76, and the IR-τ value was
0.964, the IR−τ value of the initial xylene precipitate is
0.966, and the ratio _{M w1 /} M _w0 of the weight average molecular weight (M w1 ) of the precipitated component to the weight average molecular weight (M _w0 ) of the propylene homopolymer was 1.33. Subsequently, ethylene-propylene copolymerization was carried out in the same manner as described above, but the amount of hydrogen added was
It was set to 800N. After completing the polymerization and performing the same post-treatment, the melt flow rate (MFR)
30, the propylene homopolymer portion was 86.7% by weight of the total polymer amount, and the ethylene content was 8.0% by weight. 33.2 kg of normal propylene-ethylene block copolymer powder was obtained. 3) Melt flow rate (MFR): 230℃, 2.16Kg according to ASTM D-1238
Measured under load conditions (unit: g/10 minutes) 4) Mechanical strength measurement method for injection molded products Rigidity: Flexural modulus at 23℃ in accordance with JIS K7203
Measured at a temperature of 80°C (Unit: Kg)
f/cm ² ). Impact resistance: Izot impact strength is measured at 23℃ in accordance with JIS K7110 (unit: Kg・cm/
cm). 5) Appearance of the weld part: Gates were provided at both ends of a mold for making a flat plate measuring 150 mm in length, 30 mm in width, and 3 mm in thickness, and molten resin was injected from both ends using the injection molding method, with a weld part in the center. A flat plate was prepared and its appearance was observed.
Items with noticeable linear unevenness in the weld part
Those that are slightly visible are marked as △, and those that are not marked as ○. 6) Solvent resistance: A flat plate with a length of 50 mm, a width of 50 mm, and a thickness of 3 mm was made by injection molding and used as a test piece. The obtained test piece was immersed in kerosene kept at 30°C for 3 hours, taken out, and left in the air at room temperature for 1 day. After standing, the test pieces were observed, and those with cracks on the entire surface were evaluated as ×, those with partial cracks as △, and those with no cracks as ○. 7) Adhesion: Preparation of test piece A flat plate measuring 100 mm in length, 20 mm in width, and 3 mm in thickness was molded by injection molding and used as a test piece. Adhesion After applying a water-based emulsion type adhesive (manufactured by Kanebo NSC, trade name: Yodozol AA57) to the 2 cm square edge of each set of two test pieces with a brush, overlap the coated surfaces. Glued. followed by 80℃ for 30 minutes
After drying, it was left at room temperature for 24 hours. Measurement of adhesive strength Using a Tensilon type tensile tester at room temperature, both ends of the bonded specimen were pulled at a shear rate of 20 mm/min to measure the shear strength (Kg
f/cm ² ). Example 1 4.5 kg of propylene-ethylene block copolymer according to the present invention obtained by the method described above and Mooney viscosity ML100 were placed in a Hensel mixer (trade name) having an internal volume of 50.
Styrene with a temperature of 1+4 of 25, an ethylene content of 75% by weight, an amorphous ethylene-propylene copolymer (manufactured by Nippon Gosei Co., Ltd., trade name EP02P), 0.6 kg, and a styrene/butadiene hydrogenation ratio of 29/71. -Butadiene block copolymer hydrogenated product (Ciel Chemical Co., Ltd.)
(product name: Kraton G1652) 0.9Kg, styrene homopolymer with melt flow rate (MFR) 20 (product name: Styron 679, manufactured by Asahi Kasei Corporation) 4.0Kg, 2.
5 g of 6-di-t-butyl-p-cresol and 5 g of calcium stearate were added and mixed with stirring for 5 minutes. Subsequently, the mixture was extruded using a single-screw extruder with an inner diameter of 40 mm at a melt-kneading temperature of 230°C.
A pellet-shaped thermoplastic resin composition for molding was obtained.
The resulting composition was evaluated for mechanical strength, weld appearance, solvent resistance, and adhesiveness by the methods described above. The results are shown in Table 1. Comparative Example 1 In Example 1, propylene according to the present invention
A pellet-like composition was obtained in the same manner except that 4.5 kg of the usual propylene-ethylene block copolymer obtained by the method described above was used instead of the ethylene block copolymer. The obtained composition was evaluated in the same manner as in Example 1, and the results are shown in Table 1. Comparative Example 2 A pellet-like composition was obtained in the same manner as in Example 1 except that the hydrogenated styrene-butadiene block copolymer was not used. Table 1 shows the evaluation results for the obtained compositions. Comparative Example 3 A pellet-like composition was obtained in the same manner as in Example 1, except that the amorphous ethylene-propylene copolymer was not used. Table 1 shows the evaluation results for the obtained compositions. Comparative Example 4 10 kg of the propylene-ethylene block copolymer according to the present invention obtained by the method described above and 10 g of 2,6-di-t-butyl-p-cresol were added to the Hensel mixer (trade name) used in Example 1. , and 10 g of calcium stearate were added and stirred and mixed for 5 minutes. Subsequently, a pellet-like composition was obtained in the same manner as in Example 1. The evaluation results are shown in Table 1. Comparative Example 5 A styrene homopolymer (manufactured by Asahi Kasei Corporation, trade name Styron 679) was evaluated in the same manner as in Example 1. The results are shown in Table 1. Example 2 In Example 1, styrene/butadiene block copolymer hydrogenated material was replaced with styrene/butadiene block copolymer hydrogenated material.
0.9 kg of a hydrogenated styrene-isoprene block copolymer with an isoprene hydrogenation ratio of 37/63 (manufactured by Ciel Chemical Co., Ltd., trade name Kraton G1701)
A pellet-like composition was obtained in the same manner except that the following procedure was used. Table 1 shows the evaluation results for the obtained composition.
It was shown to. Example 3 In Example 1, talc with an average particle size of 2 μm was added.
A pellet-like composition was obtained in the same manner except that 1.0 kg was added. The evaluation results are shown in Table 1. Examples 4 to 6, Comparative Examples 6 to 7 Pellet-like compositions were obtained in the same manner as in Example 1, except that the proportions of each component used were changed as shown in the table. Table 2 shows the results of evaluating each of the obtained compositions.

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Claims (1)

[Scope of Claims] 1. A propylene homopolymer production process of one or more stages in which (A) 70 to 95% by weight of the total polymerization amount is polymerized, assuming that the total amount of (A) to (D) below is 100% by weight; Polymerization of propylene and ethylene using a stereoregular catalyst by a polymerization method consisting of a multi-step polymerization process including one or more steps of producing an ethylene-propylene copolymer in which 30 to 5% by weight of the total polymerization amount is subsequently polymerized. A propylene-ethylene block copolymer having an ethylene content of 3 to 20% by weight based on the total polymerization amount, which is produced by measuring the melt flow rate (MFR) of the propylene homopolymer portion and infrared absorption spectroscopy. Absorbance ratio (IR-τ, infrared wave number 997 cm ^-1 and
The absorbance ratio at 973 cm ^-1 (A ₉₉₇ /A ₉₇₃ ) is
2 to 3% by weight of the precipitate that satisfies the following formula IR−τ≧0.0203logMFR+0.950 and that first precipitates when a dilute solution of xylene in which the propylene homopolymer portion is dissolved is slowly cooled with stirring. The IR-τ of the component is 0.97 or more, and the ratio (M _w1 /M _w0 ) of the weight average molecular weight (M _w1 ) of the precipitated component to the weight average molecular weight (M _w0 ) of the propylene homopolymer portion is 3. Propylene which is more than -
Ethylene block copolymer 30-70% by weight, (B) Amorphous ethylene-propylene copolymer 2-
(C) 2-15% by weight of hydrogenated styrene-butadiene block copolymer or hydrogenated styrene-isoprene block copolymer, and (D) 20-50% by weight of styrene homopolymer. thermoplastic resin composition for use.