JP2004176061A - Producing method of propylene resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a producing method of a propylene resin composition which is excellent in rigidity, impact resistance, and particularly appearance of a molded product while transparency is maintained, and to provide an injection-molded product made from the propylene resin composition. <P>SOLUTION: The producing method of the propylene resin composition comprises adding (D) 0.0001-0.03 pt.wt. of an organic peroxide, to 100 pts.wt. of a mixture of (A) 45-96 pts.wt. of a propylene-ethylene randam copolymer having a melt flow rate (hereafter referred to as MFR) of 0.5-50 g/10 min and an ethylene content of 2.0-5.0 wt.%, (B) 2-15 pts.wt. of an ethylene-α-olefin copolymer having an MFR of 5-70 g/10 min and a density of 0.860-0.913 g/cm<SP>3</SP>, and being made by a metallocene catalyst, (C) 2-40 pts.wt. of a propylene single polymer having an MFR of 0.5-30 g/10 min, a ratio of the (D)/the (B) being ≤1/100, making a serial melt kneading or a segmentation melt kneading, and obtaining the resin composition having an MFR being by 1.2-3 times that of the (A). <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a method for producing a polypropylene resin composition and a molded article comprising the resin composition. More specifically, the present invention relates to a molded article made of the resin composition. The present invention relates to a method for producing a polypropylene resin composition having excellent heat resistance and an injection-molded article comprising the resin composition.

BACKGROUND ART Injection molded products such as food containers and medical instruments using a polypropylene-based resin have been reduced in manufacturing cost as compared with the related art due to the achievement of thinning and the like. However, in practical use, the injection-molded article is often kept cool in a state filled with food, beverage, drug, or drug solution, and there is a possibility that an impact is applied in that state. Therefore, the demand for improving the impact resistance of food containers and medical instruments is becoming very large.
Generally, as a method for imparting impact resistance to a polypropylene resin, a propylene / ethylene random copolymer or a propylene / ethylene block copolymer having an increased ethylene content is used as a base material for a thin injection molded product. It is possible to improve the impact resistance by using as. However, a thin injection molded product using a propylene / ethylene random copolymer having a high ethylene content as a base material may have a remarkably reduced rigidity and may impair workability in actual use. A thin-walled injection-molded article using a propylene / ethylene block copolymer having a low content as a base material has extremely poor transparency, which may cause a problem in the visibility of the contents.

As a method for solving such problems, for example, (a) a propylene homopolymer or an ethylene / propylene random copolymer having an ethylene content of 3% by weight or less, and (b) an ethylene content of 4 to 15% by weight. A mixture comprising an ethylene / propylene random copolymer and (c) an organic peroxide, wherein the ethylene content in the total amount of these resins is 1.5 to 4.5% by weight, and the total amount of the resins is 100% by weight. There is disclosed a technique relating to a propylene-based polymer composition in which a mixing ratio of an organic peroxide to parts by weight is 0.001 to 0.25 parts by weight, and a melt flow index is 15 g / 10 minutes or more (for example, Patent Document 1). However, the composition according to this technique has insufficient tensile elasticity after γ-ray irradiation, impact resistance, and the like, which are not sufficient with respect to recent demand levels in the application field.
A propylene homopolymer block in which a melt flow rate (hereinafter, may be abbreviated as “MFR”) is reduced from 0.05 to 10 g / 10 min to 10 to 100 g / 10 min in the presence of a radical generator. 100 parts by weight of a propylene block copolymer containing 95 to 5% by weight of a propylene / ethylene random copolymer block having 5 to 95% by weight and an ethylene content of 2 to 15% by weight, and 0.05 to 0.1% of a sorbitol compound. A polypropylene composition comprising 5 parts by weight is disclosed (for example, see Patent Document 2). However, since this polypropylene composition uses a block copolymer of a propylene homopolymer and a propylene / ethylene random copolymer, there is a problem that the polypropylene composition does not have sufficient transparency to be used for a thin injection molded product. is there.

Furthermore, in these thin and transparent injection-molded products, the superiority of the molded appearance is conspicuous, and even if jet lines or white spots occur even a little, the molded appearance becomes poor, and it is difficult to obtain excellent molded appearance quality. . For the purpose of improving impact resistance, a resin composition containing a dispersed phase may be used.However, due to resin flow during molding and stress generated at the mold interface, the resin composition at the interface with the dispersed phase or inside the dispersed phase is used. A peeling phenomenon may occur, causing a significant defect in appearance.
Therefore, there has been a strong demand for the development of a thin-walled injection-molded product which is more excellent in rigidity and impact resistance than conventional products, and which is significantly excellent in appearance of the molded product, while maintaining transparency.
JP-A-61-159439 JP-A-60-215047

  An object of the present invention is to provide a method for producing a polypropylene resin composition which is excellent in rigidity and impact resistance while maintaining transparency, and which is particularly excellent in appearance of a molded article, and an injection molded article comprising the polypropylene resin composition. Is to do.

  The present inventors have conducted intensive studies in order to solve the above problems, and found that the cause of poor appearance of molded articles such as jet lines and white spots in a resin composition having excellent transparency, rigidity and impact resistance is ethylene.・ By elucidating the cross-linking state and dispersion state of the dispersed phase mainly composed of α-olefin copolymer, by appropriately controlling the cross-linking state at the interface of the dispersed phase, and controlling the dispersion state to a fine dispersion state. It was found that the appearance defect of the molded article was improved. That is, an organic polymer is used for a mixture containing a specific propylene / ethylene random copolymer, an ethylene / α-olefin copolymer polymerized using a specific metallocene catalyst, and a specific propylene homopolymer at a specific ratio. The present inventors have found that this problem can be solved by a method for producing a propylene resin composition by adding an oxide at a specific ratio and sequentially melting and kneading or split melting and kneading, thereby completing the present invention.

That is, according to the first aspect of the present invention, (A) the melt flow rate (230 ° C., 21.18 N load) is 0.5 to 50 g / 10 min, and the ethylene content is 2.0 to 5 g. 0.0% by weight of a propylene / ethylene random copolymer: 45 to 96 parts by weight;
(B) Ethylene / α polymerized using a metallocene catalyst having a melt flow rate (190 ° C., 21.18 N load) of 5 to 70 g / 10 min and a density of 0.860 to 0.913 g / cm ³ -An olefin copolymer: 2 to 15 parts by weight, and (C) a propylene homopolymer having a melt flow rate (230 ° C, 21.18 N load) of 0.5 to 30 g / 10 min: 2 to 40 parts by weight. (D) 0.0001 to 0.03 parts by weight of the organic peroxide and 100 parts by weight of the total amount of the components (A) to (C) of the mixture, A method for producing a propylene resin composition which is added so that the amount ratio becomes 1/100 or less, and is sequentially melt-kneaded or dividedly melt-kneaded, wherein the melt flow rate of the propylene resin composition (230 ° C., 21.18N load) ) (A) the production method of the polypropylene resin composition, which is a 1.2 to 3.5 times the component melt flow rate is provided.
(However, the melt flow rate of the component (A), the component (C) and the polypropylene resin composition is a value measured according to JIS K6758, and the melt flow rate of the component (B) is a value measured according to JIS K6760. , Density is a value measured according to JIS K6760.)

  Further, according to the second invention of the present invention, in the first invention, the sequential melt-kneading is performed by melting and kneading the components (B) and (C), and then melt-kneading the component (A). A method for producing a propylene resin composition is provided.

  Further, according to the third invention of the present invention, in the first invention, in the split melting and kneading, the components (B) and (C) are supplied and melt-kneaded in the first stage, and the component (A) is supplied in the second stage. A method for producing a propylene resin composition is provided, which is a method of melt-kneading.

  Further, according to the fourth invention of the present invention, in the first invention, in the split melting and kneading, the components (A) and (C) are supplied and melt-kneaded in the first stage, and the component (B) is supplied in the second stage. A method for producing a propylene resin composition is provided, which is a method of melt-kneading.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the resin temperature in the sequential melt-kneading or the split melt-kneading is 200 to 230 ° C. Is provided.

  According to a sixth aspect of the present invention, there is provided an injection-molded article comprising the propylene resin composition produced in any one of the first to fifth aspects.

  According to a seventh aspect of the present invention, there is provided the injection-molded article according to the sixth aspect, wherein the maximum particle size of the dispersed phase in the cut-out cross section of the molded article is 1 μm or less.

  The propylene resin composition obtained by the production method of the present invention is excellent in rigidity and impact resistance while maintaining transparency, and is particularly excellent in appearance of a molded product. In addition, an injection-molded article obtained by using the polypropylene resin composition is excellent in transparency, rigidity and impact resistance, and significantly improves the appearance of the molded article.

Hereinafter, the production method of the propylene resin composition of the present invention, the resin composition obtained by the production method, its features, and applications will be described in detail.
1. Constituents of propylene resin composition (1) Propylene / ethylene random copolymer ((A) component)
The melt flow rate of the (A) propylene / ethylene random copolymer used in the present invention (a value measured at 230 ° C. under a load of 21.18 N, sometimes abbreviated as MFR hereinafter) is 0.5 to 50 g. / 10 minutes, preferably 2.5 to 40 g / 10 minutes, more preferably 4.5 to 35 g / 10 minutes. When the MFR is less than 0.5 g / 10 minutes, even if the predetermined amount of (D) organic peroxide is added, MFR suitable for thin-wall molding cannot be obtained, and a problem occurs during injection molding. In order to obtain an MFR suitable for thin-wall molding using a material having an MFR of less than 0.5 g / 10 minutes, a large amount of an organic peroxide must be added to carry out molecular weight reduction. In some cases, the odor of the molded product is deteriorated, causing a problem in practical use, or leading to poor appearance of the molded product. Conversely, when the MFR exceeds 50 g / 10 min, mechanical properties such as impact resistance after irradiation tend to be insufficient particularly in a field requiring hygiene such as radiation sterilization.
Here, the MFR of the component (A) is measured according to the MFR (conditions: 230 ° C., load: 21.18 N) of the JIS K6758 polypropylene test method.
The MFR of the component (A) can be adjusted according to the polymerization temperature and the hydrogen concentration in the polymerization stage. Further, after polymerization, MFR can be increased by molecular weight reduction using an organic peroxide or radiation irradiation treatment. The MFR of the component (A) used in the present invention is preferably prepared in the polymerization stage.

  The ethylene content in the component (A) used in the present invention is 2.0 to 5.0% by weight, preferably 3.0 to 4.5% by weight. If the ethylene content in the propylene / ethylene random copolymer is less than 2.0% by weight, sufficient impact resistance cannot be obtained. On the other hand, if the ethylene content exceeds 5.0% by weight, sufficient rigidity is not obtained. Can not be obtained.

  The component (A) is produced by, for example, slurry polymerization, gas phase polymerization, or bulk polymerization using a highly stereoregular catalyst. As the polymerization method, any of a batch polymerization method and a continuous polymerization method can be adopted, but the continuous polymerization method is preferred from the viewpoint of productivity. As the above-mentioned highly stereoregular catalyst, for example, a catalyst obtained by combining an organic aluminum compound component with a solid component formed by contacting titanium tetrachloride, an organic acid halide and an organic silicon compound with magnesium chloride can be used.

(2) Ethylene / α-olefin copolymer polymerized using metallocene catalyst (component (B))
The ethylene / α-olefin copolymer polymerized using the metallocene catalyst (B) used in the present invention has a function of imparting impact resistance while maintaining the transparency of the polypropylene resin composition.
The component (B) is a copolymer of ethylene and an α-olefin having 3 to 12 carbon atoms, for example, propylene, butene-1, 4-methyl-pentene-1, hexene-1, octene-1, and the like. The α-olefin having 3 to 12 carbon atoms may be one kind or two or more kinds.
The MFR of the component (B) measured at 190 ° C. and a load of 21.18 N is 5 to 70 g / 10 min, preferably 6 to 60 g / 10 min, and more preferably 8 to 50 g / 10 min. When the MFR is less than 5 g / 10 minutes, dispersion in the polypropylene component becomes difficult, and it is difficult to improve transparency. Conversely, when the MFR exceeds 70 g / 10 minutes, the difference in melt viscosity from the polypropylene component becomes too large, which makes it difficult to uniformly disperse the granules, and also causes the granules to stay in the granulator or the molding machine. , The effect of improving the impact resistance may not be obtained or may be impaired, and the appearance of the color tone may be deteriorated due to stagnation, which is not preferable.
Here, the MFR of the component (B) is measured at 190 ° C. under a load of 21.18 N in accordance with JIS K6760.
The MFR of the component (B) can be adjusted according to the polymerization temperature and the hydrogen concentration in the polymerization stage. Further, after polymerization, the molecular weight can be increased by an organic peroxide or irradiation treatment. The MFR of the component (B) used in the present invention is preferably prepared in the polymerization stage.

The density of the component (B) is 0.860 to 0.913 g / cm ³ , preferably 0.870 to 0.910 g / cm ³ , and more preferably 0.880 to 0.905 g / cm ³ .
An ethylene / α-olefin copolymer polymerized using a metallocene catalyst having a density of less than 0.860 g / cm ³ significantly deteriorates transparency and rigidity. On the other hand, an ethylene / α-olefin copolymer polymerized by using a metallocene catalyst having a density exceeding 0.913 g / cm ³ has no sufficient effect of improving impact resistance in the resin composition of the present invention, and has a high transparency. Even spoil.
Here, the density is a value measured according to JIS K6760.
The density of the component (B) can be adjusted by the composition ratio of ethylene and α-olefin.

Further, the component (B) used in the present invention is one in which two or more crystallization peak temperatures (Tc) are observed in a temperature-lowering thermogram at 10 ° C./min by a differential scanning calorimeter (DSC). Is preferred.
The difference between the high temperature side (Tc2: high temperature crystallization peak temperature) and the low temperature side (Tcl: low temperature crystallization peak temperature) of the crystallization peak temperature (Tc) is preferably 5 ° C. or more, more preferably 8 ° C. or more. is there.
Further, Tc2 is preferably 110 ° C. or lower, more preferably 100 ° C. or lower, and desirably 90 ° C. or lower, and Tcl is preferably 70 ° C. or lower, more preferably 60 ° C. or lower, and desirably 50 ° C. or lower.

The component (B) used in the present invention has a temperature rise of not less than the temperature T2 obtained from the following equation with respect to the temperature T1 obtained from the following equation from the carbon number (c) and the density (d) of the α-olefin. The total elution amount by melt separation (TREF) is preferably at least 5% by weight of the total elution.
Tl (° C.) = − 1097 + c × 2.3 + d × 1270
T2 (° C.) = (Tl + 30)

The measurement by temperature rising elution fractionation (TREF: Temperature Rising Fraction) is described in “Journal of Applied Polymer Science, Vol. 26, pp. 4217-4231 (1981)”, and “Polymer Journal 2PIC09 (1981)” (1985). Is performed as follows on the basis of the principle described in "1.
First, a polymer to be measured is completely dissolved in a solvent. Thereafter, cooling is performed to form a thin polymer layer on the surface of the inert carrier. Such a polymer layer is formed such that an easily crystallizable material is formed on the inner side (closer to the surface of the inert carrier), and a hardly crystallizable material is formed on the outer side. Next, when the temperature is increased continuously or stepwise, in the low temperature stage, the polymer is eluted from the amorphous portion in the target polymer composition, that is, the polymer having a high degree of short-chain branching, and the temperature increases. The one with a low degree of branching gradually elutes, and finally the linear part without branching elutes, and the measurement is completed. The concentration of the eluted component at such a temperature is detected, and the composition distribution of the polymer can be seen from a graph drawn by the amount of the eluted and the elution temperature.

(3) Propylene homopolymer (component (C))
The propylene homopolymer (C) used in the present invention has a function of imparting rigidity and molding cycle properties to the polypropylene resin composition.
The MFR of the component (C) measured at 230 ° C. and a load of 21.18 N is 0.5 to 30 g / 10 min, preferably 1.0 to 25 g / 10 min, more preferably 2.0 to 20 g / 10 min. is there. If the MFR is less than 0.5 g / 10 minutes, a significant reduction in molecular weight is required to obtain good moldability, which also impairs economic efficiency. Conversely, those having an MFR of more than 30 g / 10 minutes impair the impact resistance of molded articles, especially after radiation sterilization.
Here, the MFR of the component (C) is measured according to the MFR of the JIS K6758 polypropylene test method (condition: 230 ° C., load: 21.18 N).
The MFR of the component (C) can be adjusted according to the polymerization temperature and the hydrogen concentration in the polymerization stage. Further, after polymerization, MFR can be increased by molecular weight reduction using an organic peroxide or radiation irradiation treatment. The MFR of the component (C) used in the present invention is preferably prepared in the polymerization stage.

(4) Raw Material Resin Mixing Ratio In the raw material resin mixture of the present invention, the component (A) is 45 to 96 parts by weight, preferably 57 to 92 parts by weight, based on 100 parts by weight of the total of the components (A) to (C). More preferably 64 to 88 parts by weight, the component (B) 2 to 15 parts by weight, preferably 2 to 12 parts by weight, more preferably 3 to 10 parts by weight, and the component (C) 2 to 40 parts by weight, The content is preferably 5 to 35 parts by weight, more preferably 10 to 30 parts by weight.
When the content of the component (A) is less than 45 parts by weight, impact resistance and transparency may be insufficient, and a problem may occur in moldability. On the other hand, when the content of the component (A) exceeds 96 parts by weight, it becomes difficult to sufficiently improve the impact resistance that can be achieved by blending the component (B), or Good molding cycle properties that can be achieved by blending cannot be obtained.
If the content of the component (B) exceeds 15 parts by weight, the rigidity is insufficient, and the resin and the dispersed phase composed of an ethylene / α-olefin copolymer are mixed with each other due to the resin flow during molding and the stress generated at the mold interface. A peeling phenomenon occurs at the interface or inside the dispersed phase, and a remarkable defect tends to occur in the appearance, which may cause a problem in the moldability, particularly in the appearance. On the other hand, when the content of the component (B) is less than 2 parts by weight, it becomes impossible to sufficiently improve the impact resistance.
When the content of the component (C) is less than 2 parts by weight, the effect of improving rigidity and molding cycleability is not recognized, while when the content of the component (C) exceeds 40 parts by weight, impact resistance and In many cases, transparency is not suitable in practical use, which is not preferable.

(5) Organic peroxide ((D) component)
In the polypropylene resin composition of the present invention, (D) an organic peroxide is added in an amount of 0.0001 to 0.03 parts by weight to a total of 100 parts by weight of the raw material resin mixture (A) to (C) during the production thereof. Parts, preferably 0.001 to 0.028 parts by weight, more preferably 0.005 to 0.025 parts by weight, and the amount ratio to the component (B) is 1/100 or less, preferably 0.5 / 100 to 1 / 100, more preferably 0.6 / 100 to 0.9 / 100.
If the component (D) is less than 0.0001 part by weight based on 100 parts by weight of the total of the raw material resin mixture (A) to (C), flow characteristics suitable for thin-wall molding cannot be obtained. If the amount exceeds 0.03 parts by weight, the odor of the molded product deteriorates, causing problems in practical use, and crosslinking of the component (B). The degree may be higher than necessary, which may lead to poor appearance of the molded product.
Further, when the amount ratio of the component (D) to the component (B) exceeds 1/100, the degree of crosslinking of the component (B) becomes unnecessarily high, leading to poor appearance of a molded article.

  Specific examples of the component (D) include, for example, methyl ethyl ketone peroxide, t-butyl peroxyisopropyl carbonate, dicumyl peroxide, cumene hydroperoxide, 2,5-dimethyl-2,5-di (t-butyl peroxide). Oxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexine-3, di-t-butylperoxyphthalate, and the like. Preferred are 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 2,5-dimethyl-2,5-di (t-butylperoxy) hexine-3.

(6) Optional Components The raw resin used in the present invention may optionally contain other additional components as long as the effects of the present invention are not significantly impaired.
Examples of the optional component include a resin component such as polyethylene and an ethylene / α-olefin copolymer other than the component (B), and various additives.
Polyethylene that can be optionally used in the present invention is a homopolymer of ethylene or a copolymer containing an α-olefin having 3 to 12 carbon atoms as a copolymer component, and is heated at 190 ° C. and a load of 21.18 N. The measured MFR is preferably 10 to 50 g / 10 minutes, more preferably 13 to 40 g / 10 minutes, and still more preferably 15 to 30 g / 10 minutes. If the MFR is less than 10 g / 10 minutes, transparency may be deteriorated due to poor dispersion or the like. Conversely, those having an MFR of more than 50 g / 10 minutes are not preferred because they do not contribute much to the improvement of the desired physical properties in the present system and tend to impair moldability and appearance.
The preferred density of polyethylene is 0.940 to 0.980 g / cm ³ , more preferably 0.947 to 0.969 g / cm ³ , and still more preferably 0.951 to 0.963 g / cm ³ . Polyethylene having a density of less than 0.940 g / cm ³ is not preferred because nucleating agent properties tend to be insufficient and the effect of improving physical properties tends to be insufficient. On the other hand, polyethylene having a density of more than 0.980 g / cm ³ is not preferred because impact resistance may be impaired.
Other optional components include resin additives used in ordinary polyolefin resins, for example, phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, neutralizing agents, light stabilizers, ultraviolet absorbers, Examples include nucleating agents, transparent nucleating agents, lubricants, slip agents, antistatic agents, flame retardants, metal deactivators, and fillers. The amount of these additional components is generally about 0.001 to 2 parts by weight, preferably about 0.01 to 0.8 parts by weight, based on 100 parts by weight of the raw resin mixture.

2. Production of Polypropylene Resin Composition (1) Production Method In the production method of the polypropylene resin composition of the present invention, the above-mentioned components and, if necessary, additives are blended in the above-mentioned proportions, mixed by stirring, and kneaded. At the time of granulation, the component (B) is manufactured by a method of sequential melt-kneading or split melt-kneading so that the size at the stage where the component (B) becomes fine particles as a result of kneading and the contact of the organic peroxide in that state are minimized. There is a need.
When kneading and granulating by batch injection instead of the production method (granulation method) by sequential melt-kneading or split melt-kneading, a dispersed phase is generated by crosslinking of the finely divided component (B) after crosslinking treatment, resulting in a huge molded product. Agglomerates tend to occur, resulting in problems such as transparency and appearance of molded articles.

A preferred form of granulation by sequential melt-kneading is to produce a propylene resin composition produced by sequential melt-kneading, in which the components (B) and (C) are first melt-kneaded, and then the component (A) is melt-kneaded. Is the way. Here, the organic peroxide of the component (D) is preferably added at a later stage together with the component (A).
After melt-kneading the components (B) and (C), the granulated product is used as a master batch, and separately prepared organic peroxides of the components (A) and (D) are added and melt-kneaded. Is also preferred.

One of the preferred forms of granulation by split melt-kneading is to first melt-knead the components (B) and (C) and supply the component (A) to the first stage and melt-knead the components. Is a method for producing a propylene resin composition produced by the method described above. Here, the organic peroxide of the component (D) is preferably added at a later stage together with the component (A).
One preferred form of granulation by split melt-kneading is to first supply components (A) and (C) and melt-knead them in the first stage, and then feed and melt-knead component (B) in the second stage. This is a method for producing a propylene resin composition produced by melt-kneading. Here, it is preferable that the organic peroxide of the component (D) is added (main charging) in the former stage together with the components (A) and (C). It is preferable to supply the component (B) from the feed hole at the stage after the decomposition of the organic peroxide of the component (D) has advanced.

  In the above method for producing a propylene resin composition, the resin temperature in the sequential melt-kneading or the split melt-kneading is preferably from 200 to 230 ° C, more preferably from 220 to 230 ° C. If the resin temperature is lower than 200 ° C., the required amount of the organic peroxide increases, or it becomes difficult to adjust the MFR to a value suitable for thin-wall molding, or the component (D) remaining undecomposed remains. The organic peroxide tends to lead to the crosslinking treatment of the component (B) at the molding stage, and the appearance of the molded product tends to be poor. This is not preferred because the odor tends to worsen, the degree of crosslinking of the component (B) becomes more than necessary, and the dispersion state tends to be poor.

  The kneader used for sequential melt kneading or split melt kneading of the propylene resin composition is kneaded using a usual kneader such as a single screw extruder, a twin screw extruder, a Banbury mixer, a roll mixer, a Brabender plastograph, and a kneader.・ It can be granulated. In the case of manufacturing by sequential melt-kneading, it is preferable to use a twin-screw extruder from the viewpoint of easiness of feeding a raw material resin at a later stage.

(2) Propylene resin composition The polypropylene resin composition produced according to the method for producing a propylene resin composition of the present invention has higher rigidity and impact resistance than conventional products while maintaining transparency, and appearance of molded products. Is much better.
The MFR (at 230 ° C., 21.18 N load) of the propylene resin composition produced based on any of the above-mentioned methods for producing a propylene resin composition is 1.2 to 3.5 times the MFR of the component (A), Preferably it is 1.4 to 3.2 times, more preferably 2.0 to 3.0 times. When the MFR of the propylene resin composition is less than 1.2 times the MFR of the component (A), the molding fluidity of the thin-walled molded product is insufficient, or the mechanical properties after radiation sterilization treatment with time. In some cases, there is a problem in terms of maintenance, and when the ratio exceeds 3 times, the amount of the organic peroxide of the component (D) is large, which leads to poor appearance of the molded article derived from the component (B).
In particular, the preferred MFR range of the propylene resin composition for thin injection molded articles is about 10 to 100 g / 10 minutes. Generally, if the MFR is less than 10 g / 10 minutes, the high-speed moldability is not sufficient. On the other hand, when it exceeds 100 g / 10 minutes, problems such as a decrease in impact resistance and a decrease in rigidity due to a decrease in skin layer thickness occur.
Here, the MFR of the propylene resin composition is measured in accordance with the MFR of the JIS K6758 polypropylene test method (conditions: 230 ° C., load: 21.18 N), similarly to the MFR of the component (A).

Further, the Q value of the propylene resin composition is preferably from 2.2 to 5, more preferably from 2.5 to 4.2, and particularly preferably from 2.9 to 3.8. When the Q value of the propylene resin composition is less than 2.2, the flowability of the resin in thin-wall molding is inferior and the shape following property is poor, so that a good molded product cannot be obtained. If the amount exceeds the above range, the amount of low molecular weight components derived from the raw materials to be blended becomes large, which is not preferable from the viewpoint of solvent extraction resistance.
Here, the Q value is a ratio (Mw / Mn) between the weight average molecular weight Mw and the number average molecular weight Mw measured by GPC, and is measured under the following conditions.
Apparatus: Waters HLC / GPC 150C
Column temperature: 135 ° C
Solvent: o-dichlorobenzene Flow rate: 1.0 ml / min
Column: Tosoh Corporation GMH _HR- H (S) HT 60 cm x 1
Injection volume: 0.15 ml (no filtration treatment)
Solution concentration: 5 mg / 3.4 ml
Sample preparation: Adjust to a solution of 5 mg / 3.4 ml using o-dichlorobenzene and dissolve at 140 ° C. for 1 to 3 hours.
Calibration curve: Use a polystyrene standard sample.
Calibration curve order: 1st order PP molecular weight: PS × 0.639

3. Injection molded article comprising propylene resin composition An injection molded article can be obtained using the polypropylene resin composition of the present invention. The thin and transparent injection molded article of the present invention is produced by molding the propylene resin composition pellets by an injection molding method (including a gas injection molding method) or an injection compression molding method (injection press). I do.

The injection-molded article comprising the polypropylene resin composition of the present invention obtained as described above has a maximum particle diameter of the dispersed phase in the cut cross section of preferably 1 μm or less, more preferably 0.1 to 1.0 μm, and still more preferably. Has a characteristic of 0.2 to 0.8 μm, particularly preferably 0.2 to 0.6 μm.
If the maximum particle size of the dispersed phase exceeds 1 μm, transparency tends to be impaired, and defects such as poor appearance as a result of coarse interfacial peeling due to flow stress during molding tend to easily occur, which is not preferable.
Here, the maximum particle diameter of the dispersed phase is the maximum value of the length in the longitudinal direction of the largest dispersed phase observed by morphological observation. That is, when the largest dispersed phase is elliptical, the major axis is the largest particle diameter, and when the largest dispersed phase is a long oriented dispersed phase, the length in the longitudinal direction of the dispersed phase is taken.
The method for measuring the maximum particle size of the dispersed phase is as follows. A portion of the injection molded article having a thickness of 1 ± 0.2 mm is cut out, and the center in the thickness direction is dyed with ruthenium tetroxide and deposited with gold or platinum. A pre-process was performed, a morphological observation of 10,000 times was performed using a scanning electron microscope (SEM), and two different photographs of 10 μm × 12 μm with different visual fields were taken. Among the dispersed particles in the visual field, The largest dispersed phase is specified, and the length in the longitudinal direction is defined as the maximum particle size.

The injection-molded article of the present invention is excellent in transparency, rigidity and impact resistance, and greatly improves the appearance of the molded article.
Therefore, the injection-molded article comprising the polypropylene resin composition of the present invention is a one-hand cup type typically represented by food containers such as margarine containers, jelly containers, pudding containers, containers for mizuyokan, coffee drinks, milk drinks and the like. It can be suitably used for containers for various beverages, beverage containers such as baby bottles, and medical containers such as drug containers.

  The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The methods for measuring and evaluating the properties of the polypropylene resin composition and the injection-molded article are as follows.

(1) MFR: The MFR of (A) propylene / ethylene random copolymer and (C) propylene homopolymer was measured according to JIS K6758 polypropylene test method MFR (conditions: 230 ° C, load: 21.18N). The MFR of the ethylene / α-olefin copolymer (B) polymerized using a metallocene catalyst was measured at 190 ° C. and a load of 21.18 N in accordance with JIS K6760.
(2) Density: The density of the (B) ethylene / α-olefin copolymer was measured according to JIS K6760.
(3) Q value: measured by the method described above.
(4) Haze: Measured at 23 ° C. in accordance with JIS K7105 using a flat injection-molded product of 120 mm × 80 mm × 2 mm as a sample.
(5) Flat plate falling weight impact: Measured at 0 ° C. according to JIS K7214 using a flat injection molded product of 120 mm × 80 mm × 2 mm as a sample.
(6) The particle size of the dispersed phase: using a flat injection molded product of 100 mm x 100 mm x 1 mm as a sample, confirming that the thickness at a position of 25 mm x 25 mm from the gate side corner is a predetermined value, and then performing the above-described method. Was measured.
(7) Appearance evaluation of molded article: The cup-shaped molded article was observed for the presence or absence of white unevenness and white turbidity, and the appearance of the molded article was visually evaluated.
：: No abnormal appearance is present in the entire cup. △: Minor appearance abnormality is observed in a part of the cup. ×: Abnormal appearance is observed in half or more area of the cup.

The resin (A), the resin (B), and the resin (C) used in this example were commercially available grades manufactured by Nippon Polychem Co., Ltd., or those manufactured by the following manufacturing examples.
(Production Example 1 (Production of Resin A1))
(I) Production of Prepolymerization Catalyst Component In a 5 liter reaction vessel equipped with a reflux condenser, 40 g of chip-shaped metallic magnesium (purity 99.5%, average particle size 1.6 mm) and n were placed under a nitrogen gas atmosphere. After adding 1250 ml of -hexane and stirring at 68 ° C for 1 hour, the metallic magnesium was taken out and dried at 65 ° C under reduced pressure to obtain preactivated metallic magnesium.
To this metallic magnesium, 700 ml of n-butyl ether and 2.5 ml of an n-butyl ether solution of n-butylmagnesium chloride (1.75 mol / l) were added, and the resulting suspension was kept at 55 ° C. and further added to 250 ml of n-butyl ether. A solution in which 192.5 ml of n-butyl chloride was dissolved was added dropwise over 50 minutes. After performing the reaction at 70 ° C. for 4 hours with stirring, the reaction solution was kept at 25 ° C.
278.5 ml of HC (OC ₂ H ₅ ) _{3 was} added dropwise to the reaction solution over 1 hour. After the completion of the dropwise addition, the reaction was carried out at 60 ° C. for 15 minutes, and the solid produced by the reaction was washed six times with 1500 ml each of n-hexane, and dried under reduced pressure at room temperature for 1 hour, containing 19.0% of magnesium and 28.9% of chlorine. 158 g of a magnesium-containing solid were recovered.
Under a nitrogen gas atmosphere, 31.5 g of a magnesium-containing solid and 250 ml of n-heptane were put into a 1500 ml reaction vessel equipped with a reflux condenser, a stirrer and a dropping funnel to form a suspension. A mixed solution of 100 ml (0.02 mmol) of 2-trichloroethanol and 55 ml of n-heptane was dropped from the dropping funnel over 30 minutes, and further stirred at 80 ° C. for 1 hour. The resulting solid was filtered, washed four times with 500 ml each of n-hexane at room temperature, and twice with 500 ml each of toluene to obtain a solid component.
200 ml of toluene was added to the solid component, and titanium tetrachloride was further added so that the volume ratio of titanium tetrachloride / toluene was 3/2, and the temperature was raised to 90 ° C. Under stirring, a mixed solution of 10 ml of di-n-butyl phthalate and 25 ml of toluene was added dropwise over 5 minutes, followed by stirring at 120 ° C. for 2 hours. The obtained solid substance was separated by filtration at 90 ° C., and washed at 90 ° C. twice with each 500 ml of toluene. Further, titanium tetrachloride was newly added so that the volume ratio of titanium tetrachloride / toluene became 3/2, and the mixture was stirred at 120 ° C. for 2 hours. The obtained solid substance was separated by filtration at 110 ° C., and washed seven times with 500 ml of n-hexane at room temperature. Thus, a solid catalyst component in which the titanium compound was supported on the magnesium compound was obtained. A portion of the solid catalyst component was dried under a nitrogen atmosphere and subjected to elemental analysis. As a result, the content of titanium was 1.6% by weight.
After replacing the metal container with an internal volume of 10 L equipped with a stirrer with nitrogen, 6000 ml of n-hexane and an n-hexane solution containing 200 g of the solid catalyst component were added, and the content was kept at 20 ° C. Subsequently, 70 g of triethylaluminum was added, and 400 g of propylene was supplied with stirring at 120 ° C. over 120 minutes while maintaining the system at 20 ° C. After the supply of propylene was stopped, stirring was continued for another 20 minutes to complete the reaction. After allowing to settle for 20 minutes, the supernatant was removed by a decantation method, 6000 ml of n-hexane was further added, and the mixture was stirred at 25 ° C., then allowed to settle, and the operation of removing the supernatant was repeated 5 times. A polymerization catalyst component was obtained.

(Ii) Production of Propylene-Ethylene Copolymer 100 kg / hr of liquefied propylene and 0.2 g / hr of the prepolymerized catalyst component obtained in (1) above (hereinafter referred to as “preliminary The amount was converted to the catalyst solid amount excluding the polymerized polymer.), 7.3 g / hr of triethylaluminum, and 2.2 g / hr of cyclohexylmethyldimethoxysilane were continuously supplied. In addition, hydrogen was continuously supplied as a molecular weight adjuster so that the concentration in the propylene liquid became 0.21 mol%, and ethylene as a comonomer became 0.75 mol% in the propylene liquid. The polymerization temperature was kept at 70 ° C. and the average residence time was kept at 1 hour.
The slurry continuously withdrawn from the reaction tank is led to a countercurrent washing tower, washed with a new liquid propylene of the same volume as the slurry, and then unreacted propylene is volatilized and dried to obtain a propylene-ethylene copolymer. The combined powder (resin A1) was obtained at a production rate of 6.4 kg / hr. The MFR of the obtained powder was 5.0 g / 10 minutes, and the ethylene content was 4.0 wt%.

(Production Examples 2 to 4 (Production of Resins A2, A3, A4))
A propylene-ethylene copolymer powder was obtained in the same manner as in Production Example 1 except that the supply amount of the prepolymerization catalyst component, the hydrogen concentration in the liquid, and the ethylene concentration in the liquid were as shown in Table 1. Table 1 shows the properties of the obtained powder.

(Example 1)
(A) MFR of 5.0 g / 10 min, ethylene content of 4.0 wt% propylene / ethylene random copolymer powder (resin A1) 75 wt%, (B) MFR of 35 g / 10 min, density Propylene / 1-hexene copolymer (kernel KJ650T: manufactured by Nippon Polychem Co., Ltd.) polymerized using a metallocene catalyst having a MFR of 0.885 g / cm ³ , and (C) an MFR of 5.0 g / 10 And a phosphorus-based antioxidant (tris- (2,4-di-t-butyl) as an additive to 100 parts by weight of a resin material composed of 20% by weight of a propylene homopolymer powder (MA4A: manufactured by Nippon Polychem Co., Ltd.). Phenyl) phosphite) 0.10 part by weight, neutralizing agent (calcium stearate) 0.05 part by weight, sorbitol nucleating agent (1,3,2,4-di-p-methyl) -Benzylidene-sorbitol) 0.20 part by weight, a light stabilizer (polyester of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidineethanol and succinic acid) 0.05 part by weight and a slip agent ( 0.03 parts by weight of polysiloxane oil) and 230 of (D) 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as organic peroxide (Perhexa 25B: manufactured by NOF CORPORATION) The weight ppm was weighed.
Among the above, the components (B), (C) and the additives are mixed by stirring, and the first-stage melting is performed at a granulation temperature of 220 ° C. using a twin-screw extruder (PCM30 manufactured by Ikegai Iron Works Co., Ltd.). The mixture was kneaded and granulated. The pellets obtained by the first-stage melt-kneading, the components (A) and (D) the organic peroxide were stirred and mixed, and the mixture was granulated at a granulation temperature of 230 ° C. using a twin-screw extruder (same as above). The second stage of melt kneading and granulation was performed to obtain pellets of the polypropylene resin composition. The physical properties of the obtained polypropylene resin composition were measured.
Next, a 100 mm × 100 mm × 1 mm flat plate (Nippon Steel Corporation) was obtained using the obtained polypropylene resin composition pellets, using an injection molding machine described after each molded product shape, at a resin temperature of 220 ° C. J100SA manufactured by Shosho Co., Ltd., a flat plate of 120 mm x 80 mm x 2 mm (EC100-2B manufactured by Toshiba Machine Co., Ltd.), a cup-shaped molded product having a bottom diameter of 50 mm, a top surface diameter of 60 mm, and a wall thickness of 0.7 mm (Toshiba Machine Co., IS220F-10A) Was injection molded, and the molded product was evaluated.
Table 2 shows the evaluation results of the obtained polypropylene resin composition and injection molded articles using the same.

(Example 2)
(D) The same weighed material consisting of the raw resin (A) component, the (B) component, the (C) component, and the additive was used, except that the amount of the organic peroxide was 250 ppm by weight. The production and evaluation of the polypropylene resin composition were carried out in the same manner as in Example 1 except that the melt-kneading was performed by the following method.
The raw resin (A) component, (C) component, additive, and (D) 250 ppm by weight of organic peroxide are mixed with stirring, and a weight feeder is fed to a main feed hole of a twin screw extruder (KTX44 manufactured by Kobe Steel). The raw material resin (B) is fed into the sub-feed hole at the subsequent stage by using a weight feeder to supply the raw material resin (B) to the predetermined mixing ratio. And the subsequent granulation temperature was set at 200 ° C., melt-kneaded and granulated to obtain pellets of the polypropylene resin composition. Table 2 shows the results.

(Example 3)
(D) Except that the amount of the organic peroxide was changed to 240 ppm by weight, the same weighed material comprising the raw resin (A) component, the (B) component, the (C) component, and the additive was used. The production and evaluation of the polypropylene resin composition were carried out in the same manner as in Example 1 except that the melt-kneading was performed by the following method.
The raw resin (B) component, the (C) component, and the additives are stirred and mixed, and the mixture is fed into a main feed hole of a twin-screw & single-screw tandem type extruder (KCM50 + KE60 manufactured by Kobe Steel) using a weight feeder to a predetermined amount. The mixture is supplied at the mixing ratio, the former granulation temperature is set to 220 ° C., and the mixture of the raw material resin (A) component and (D) organic peroxide 240 wt ppm is used in the latter sub-feed hole using a weight feeder. Then, the mixture was supplied so as to have a predetermined mixing ratio, and the granulation temperature in the subsequent stage was set to 230 ° C., and the mixture was melt-kneaded and granulated to obtain pellets of a polypropylene resin composition. Table 2 shows the results.

(Example 4)
Example 1 except that a propylene / ethylene random copolymer powder (F409CE: manufactured by Nippon Polychem Co., Ltd.) having an MFR of 10.0 g / 10 min and an ethylene content of 4.0% by weight was used as the component (A). Similarly, a polypropylene resin composition was produced by successive melt-kneading and granulation, and evaluated. Table 2 shows the results.

(Example 5)
Example 2 was the same as Example 2 except that as the component (A), a propylene / ethylene random copolymer powder (F409CE: manufactured by Nippon Polychem Co., Ltd.) having an MFR of 10.0 g / 10 min and an ethylene content of 4.0% by weight was used. Similarly, a polypropylene resin composition was produced by split-melt kneading and granulation, and evaluated. Table 2 shows the results.

(Example 6)
Example 3 was the same as Example 3 except that as the component (A), a propylene / ethylene random copolymer powder (F409CE: manufactured by Nippon Polychem Co., Ltd.) having an MFR of 10.0 g / 10 min and an ethylene content of 4.0% by weight was used. Similarly, a polypropylene resin composition was produced by split-melt kneading and granulation, and evaluated. Table 2 shows the results.

(Example 7)
In Example 1, 73% by weight of (A) a propylene / ethylene random copolymer powder (MG3: manufactured by Nippon Polychem Co., Ltd.) having an MFR of 10.0 g / 10 minutes and an ethylene content of 3.0% by weight, B) 7% by weight of an ethylene / propylene / 1-hexene copolymer (kernel KJ650T: manufactured by Nippon Polychem Co., Ltd.) polymerized using a metallocene catalyst having an MFR of 35 g / 10 min and a density of 0.885 g / cm ³ ; And (D) a polypropylene resin composition was produced by successive melt-kneading and granulation in the same manner as in Example 1 except that the amount of the organic peroxide was changed to 270 ppm by weight, and evaluated. Table 2 shows the results.

(Example 8)
As the component (B), an ethylene / propylene / 1-hexene copolymer (kernel KS560T: manufactured by Nippon Polychem Co., Ltd.) polymerized using a metallocene catalyst having an MFR of 15 g / 10 min and a density of 0.898 g / cm ³ is used. A polypropylene resin composition was produced by successive melt-kneading and granulating in the same manner as in Example 4 except for using, and evaluated. Table 1 shows the results.

(Example 9)
In Example 1, (A) 70% by weight of a propylene / ethylene random copolymer powder (resin A2) having an MFR of 20.0 g / 10 min and an ethylene content of 3.0% by weight, and (B) an MFR of 10% by weight of an ethylene / propylene / 1-hexene copolymer (kernel KJ740T: manufactured by Nippon Polychem Co., Ltd.) polymerized using a metallocene catalyst having a density of 50 g / 10 min and a density of 0.880 g / cm ³ , and (C) The polypropylene resin composition was successively melt-kneaded and granulated in the same manner as in Example 1 except that the propylene homopolymer powder (MA3: manufactured by Nippon Polychem) having an MFR of 10 g / 10 min was changed to 20% by weight. Manufactured and evaluated. Table 2 shows the results.

(Comparative Example 1)
(A) 75% by weight of a propylene / ethylene random copolymer powder (resin A3) having an MFR of 3.0 g / 10 minutes and an ethylene content of 4.0% by weight, and (D) an amount of an organic peroxide of 400%. Except for the weight ppm, the same weighed material consisting of the raw resin (B) component, the (C) component, and the additives was used as in Example 1, and was subjected to batch melt kneading and granulation by the following method.
A raw resin (A), a component (B), a component (C), an additive, and a weighed substance comprising (D) an organic peroxide of 400 ppm by weight are mixed and stirred, and a twin-screw extruder (PCM30 manufactured by Ikegai Iron Works) And the mixture was melt-kneaded and granulated at a granulation temperature of 215 ° C to obtain pellets of the polypropylene resin composition. Table 3 shows the results.

(Comparative Example 2)
As the component (A), a propylene / ethylene random copolymer powder (resin A4) having an MFR of 2.5 g / 10 min and an ethylene content of 3.5% by weight was used. Was changed to 450 ppm by weight, and batch melting, kneading and granulating were performed in the same manner as in Comparative Example 1 to produce and evaluate a polypropylene resin composition. Table 3 shows the results.

(Comparative Example 3)
(A) The same procedure as in Comparative Example 1 was carried out except that a propylene / ethylene random copolymer powder (resin A1) having an MFR of 5.0 g / 10 min and an ethylene content of 4.0% by weight was used as the component (A). Batch melt kneading and granulation were performed to produce and evaluate a polypropylene resin composition. Table 3 shows the results.

(Comparative Example 4)
The same procedure as in Comparative Example 2 was carried out, except that a propylene / ethylene random copolymer powder (resin A1) having an MFR of 5.0 g / 10 min and an ethylene content of 4.0% by weight was used as the component (A). Batch melt kneading and granulation were performed to produce and evaluate a polypropylene resin composition. Table 3 shows the results.

(Comparative Example 5)
(D) Except that the amount of the organic peroxide was changed to 450 ppm by weight, the same weighed material comprising the raw material resins (A), (B), (C) and additives was used as in Example 1. In the same manner as in Example 1, except that the resin temperature of the first stage in the sequential melt-kneading was set at 195 ° C. and the resin temperature of the second stage was set at 195 ° C., the polypropylene resin composition was sequentially melt-kneaded and granulated. Then, the production and evaluation of the polypropylene resin composition were performed. Table 3 shows the results.

(Comparative Example 6)
(D) The same components as in Example 7 were used except that 380 ppm by weight of the organic peroxide was used. The resin temperature of the first stage in the split melting and kneading was 220 ° C., and the resin temperature of the second stage was 200 ° C. Except for the above, the polypropylene resin composition was subjected to split melt-kneading and granulation in the same manner as in Example 2 to produce and evaluate the polypropylene resin composition. Table 3 shows the results.

(Comparative Example 7)
(A) 72% by weight of a propylene / ethylene random copolymer powder (MG3: manufactured by Nippon Polychem Co., Ltd.) having an MFR of 10.0 g / 10 min and an ethylene content of 3.0% by weight, and (B) an MFR of 15 g / 10 minutes, 8% by weight of an ethylene / propylene / 1-hexene copolymer (kernel KS560T: manufactured by Nippon Polychem Co., Ltd.) polymerized using a metallocene catalyst having a density of 0.898 g / cm ³ , and (C) an MFR of 5 g / cm ³ The same components as in Example 1 were used except that the propylene homopolymer powder (MA4A: manufactured by Nippon Polychem Co., Ltd.) was 20% by weight for 10 minutes and the amount of the organic peroxide (D) was 250 ppm by weight. Batch melting kneading and granulation were performed by the following method.
The raw materials (A) component, (B) component, (C), additives and (D) a weighed material composed of an organic peroxide are stirred and mixed, and the main feed of a twin-screw extruder (PCM30 manufactured by Ikegai Iron Works Co., Ltd.) The mixture was supplied to the holes, melt-kneaded and granulated all at a granulation temperature of 230 ° C., and pellets of a polypropylene resin composition were obtained. Table 4 shows the results.

(Comparative Example 8)
(A) 75% by weight of a propylene / ethylene random copolymer powder (FG4: manufactured by Nippon Polychem Co., Ltd.) having an MFR of 8.0 g / 10 minutes and an ethylene content of 4.0% by weight, and (B) an MFR of 35 g / 10 minutes, 5% by weight of an ethylene / propylene / 1-hexene copolymer (kernel KJ650T: manufactured by Nippon Polychem Co., Ltd.) polymerized using a metallocene catalyst having a density of 0.885 g / cm ³ , and (C) an MFR of 5 g / A polypropylene resin was prepared in the same manner as in Comparative Example 7 except that the amount of propylene homopolymer powder (MA4A: manufactured by Nippon Polychem Co., Ltd.) was 20% by weight and the amount of (D) the organic peroxide was 310 ppm by weight. The composition was subjected to collective melt kneading and granulation to produce and evaluate a polypropylene resin composition. Table 4 shows the results.

(Comparative Example 9)
(A) A propylene / ethylene random copolymer powder having an MFR of 10.0 g / 10 min and an ethylene content of 3.0% by weight (MG3: manufactured by Nippon Polychem) 73% by weight, (B) an MFR of 35 g / 10 minutes, 7% by weight of an ethylene / propylene / 1-hexene copolymer (kernel KJ650T: manufactured by Nippon Polychem Co., Ltd.) polymerized using a metallocene catalyst having a density of 0.885 g / cm ³ , and (C) an MFR of 10 g / cm ³ A polypropylene resin was prepared in the same manner as in Example 1 except that the amount of the propylene homopolymer powder (MA3: manufactured by Nippon Polychem Co., Ltd.) was 10% by weight and the amount of the organic peroxide (D) was 400 ppm by weight. The composition was sequentially melt-kneaded and granulated to produce and evaluate a polypropylene resin composition. Table 4 shows the results.

(Comparative Example 10)
(A) MFR is 5.0 g / 10 min, ethylene content is 4.0 wt%, propylene / ethylene random copolymer powder (resin A1) 78 wt%, (B) MFR is 35 g / 10 min, density 2% by weight of an ethylene / propylene / 1-hexene copolymer (kernel KJ650T: manufactured by Nippon Polychem Co., Ltd.) polymerized using a metallocene catalyst having a MFR of 0.885 g / cm ³ , and (C) an MFR of 5 g / 10 min. Propylene homopolymer powder (MA4A: manufactured by Nippon Polychem Co., Ltd.) was 20% by weight and (D) the amount of the organic peroxide was 250 ppm by weight, except that the polypropylene resin composition was successively prepared in the same manner as in Example 1. Melt kneading and granulation were performed to produce and evaluate a polypropylene resin composition. Table 4 shows the results.

(Comparative Example 11)
(A) a propylene / ethylene random copolymer powder having an MFR of 10.0 g / 10 min and an ethylene content of 4.0% by weight (F409CE: manufactured by Nippon Polychem Co., Ltd.); 78% by weight; (B) an MFR of 35 g / 10 minutes, 2% by weight of an ethylene / propylene / 1-hexene copolymer (kernel KJ650T: manufactured by Nippon Polychem Co., Ltd.) polymerized using a metallocene catalyst having a density of 0.885 g / cm ³ , and (C) an MFR of 5 g / A polypropylene resin was prepared in the same manner as in Example 1 except that the propylene homopolymer powder (MA4A: manufactured by Nippon Polychem Co., Ltd.), which was 10 minutes, was 20% by weight, and the amount of the organic peroxide (D) was 250 ppm by weight. The composition was sequentially melt-kneaded and granulated to produce and evaluate a polypropylene resin composition. Table 4 shows the results.

(Comparative Example 12)
(A) 70% by weight of a propylene / ethylene random copolymer powder (MG3: manufactured by Nippon Polychem Co., Ltd.) having an MFR of 10.0 g / 10 min and an ethylene content of 3.0% by weight, and (B) an MFR of 50 g / 10 minutes, 10% by weight of an ethylene / propylene / 1-hexene copolymer (kernel KJ740T: manufactured by Nippon Polychem Co., Ltd.) polymerized using a metallocene catalyst having a density of 0.880 g / cm ³ , and (C) an MFR of 10 g / cm ³ A polypropylene resin was prepared in the same manner as in Comparative Example 7 except that the amount of the propylene homopolymer powder (MA3: manufactured by Nippon Polychem Co., Ltd.) was 20% by weight and the amount of the organic peroxide (D) was 480 ppm by weight. The composition was subjected to collective melt kneading and granulation to produce and evaluate a polypropylene resin composition. Table 4 shows the results.

  As is clear from Tables 2 to 4, injection molded articles from the polypropylene resin composition obtained by the production method of the present invention were excellent in molded appearance, transparency, and impact resistance (Examples 1 to 9). . On the other hand, an injection-molded product from a resin composition obtained by batch melt kneading other than sequential melt kneading or split melt kneading is inferior in molding appearance (Comparative Examples 1 to 4, 7, 8, and 12). If the amount of the organic peroxide is too large, the appearance of the molded product is also inferior (Comparative Examples 5, 6, and 9). At the composition ratio where the ratio becomes high, the required level of impact resistance cannot be exhibited (Comparative Examples 10 and 11).

  The propylene resin composition obtained by the production method of the present invention is excellent in rigidity and impact resistance while maintaining transparency, and is particularly excellent in appearance of a molded product. In addition, injection molded products obtained using the polypropylene resin composition are excellent in transparency, rigidity, impact resistance, and the appearance of the molded product is greatly improved. It can be used for containers, medical containers, etc., and has great industrial value.

Claims (7)

(A) A propylene / ethylene random copolymer having a melt flow rate (230 ° C., 21.18 N load) of 0.5 to 50 g / 10 min and an ethylene content of 2.0 to 5.0% by weight. : 45 to 96 parts by weight,
(B) Ethylene / α polymerized using a metallocene catalyst having a melt flow rate (190 ° C., 21.18 N load) of 5 to 70 g / 10 min and a density of 0.860 to 0.913 g / cm ³ -An olefin copolymer: 2 to 15 parts by weight, and (C) a propylene homopolymer having a melt flow rate (230 ° C, 21.18 N load) of 0.5 to 30 g / 10 min: 2 to 40 parts by weight. (D) 0.0001 to 0.03 parts by weight of the organic peroxide and 100 parts by weight of the total amount of the components (A) to (C) of the mixture, A method for producing a propylene resin composition which is added so that the amount ratio becomes 1/100 or less, and is sequentially melt-kneaded or dividedly melt-kneaded, wherein the melt flow rate of the propylene resin composition (230 ° C., 21.18N load) ) (A) the production method of the polypropylene resin composition, which is a 1.2 to 3.5 times the component melt flow rate.
(However, the melt flow rate of the component (A), the component (C) and the polypropylene resin composition is a value measured according to JIS K6758, and the melt flow rate of the component (B) is a value measured according to JIS K6760. , Density is a value measured according to JIS K6760.)   2. The method for producing a propylene resin composition according to claim 1, wherein the successive melt kneading is a method in which the component (B) and the component (C) are melt kneaded, and then the component (A) is melt kneaded. Method.   2. The split melting and kneading method according to claim 1, wherein the component (B) and the component (C) are supplied and melt kneaded in the first stage, and the component (A) is supplied and melt kneaded in the second stage. A method for producing a propylene resin composition.   2. The split melting and kneading method according to claim 1, wherein the components (A) and (C) are supplied and melt kneaded in the first stage, and the component (B) is supplied and melt kneaded in the second stage. A method for producing a propylene resin composition.   The method for producing a propylene resin composition according to any one of claims 1 to 4, wherein a resin temperature in the sequential melt-kneading or the split melt-kneading is 200 to 230 ° C.   An injection molded article comprising the propylene resin composition obtained by the method for producing a propylene resin composition according to claim 1.   The injection-molded article according to claim 6, wherein the maximum particle size of the dispersed phase in the cut section of the molded article is 1 µm or less.