JP2008255319A - Propylene resin composition and its molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a propylene resin composition excellent in whitening resistance, high rigidity, low temperature impact resistance and heat resistance, to provide a molded article using the same, and to provide a resin cap for a container. <P>SOLUTION: The propylene resin composition comprises (A) 60 to 99 pts.wt. of an ethylene-propylene block copolymer having a melt flow rate of 2 to 80 g/10 min at 230°C, homo portion stereoregularity of ≥0.960 and a total ethylene content of 2 to 12 wt.%, and (B) 1 to 40 pts.wt. of polyethylene having a melt flow rate of 1 to 60 g/10 min at 190°C and a density of 0.860 to 0.940 g/cm<SP>3</SP>. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a propylene resin composition and a molded article comprising the composition, and more specifically, a propylene resin composition having an excellent balance of whitening resistance, rigidity and impact resistance, and high productivity, and a composition thereof. The present invention relates to a molded article made of a product and a resin cap for containers.

  In general, propylene resins are widely used in the manufacture of molded products such as food containers, medical containers, caps, and automobile parts because they are excellent in chemical and physical properties and have excellent moldability. In these applications, it is desirable that the resin has high rigidity, impact resistance, moldability, etc., but it is difficult to match all the performances uniformly to the target level.

  The method of forming caps with the highest productivity using propylene resin is compression molding (compression molding). When molding caps by compression molding, forcibly removing cap screw parts on the production line (screws) There is a step of forcibly pulling out the part instead of rotating the part, and depending on the shape and color of the cap, the conventional ethylene-propylene block copolymer was whitened and could not be used. Some caps (bottles, tubes, etc.) filled in the actual use of caps may be distributed, stored, or consumed at low temperatures (around 5 ° C). In order to prevent damage, impact resistance at low temperatures is required.

In order to prevent whitening, it is conceivable to use a polypropylene homopolymer or an ethylene-propylene random copolymer (see, for example, Patent Document 1), but these systems cannot provide impact resistance at low temperatures. . In addition, when a cap formed of a material having low rigidity is used, carbonated beverages and the like have high internal pressure, and there is a risk of the cap top surface becoming convex or the cap coming off. In addition, depending on the contents, there is a cap that fills the contents at a high temperature, which may require heat resistance. Polypropylene resin compositions have high heat resistance, but polyethylene resin compositions have low heat resistance, which is a concern. To date, there is no cap that satisfies all of these.
Japanese Patent No. 3853924

  In view of the above problems, an object of the present invention is to provide a propylene resin composition excellent in whitening resistance, high rigidity, low temperature impact resistance, and heat resistance, and a molded body and a container resin cap using the same. is there.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a propylene resin composition containing a specific amount of a specific ethylene-propylene block copolymer and a specific polyethylene has difficulty whitening and high rigidity. The inventors have found that the resin composition can be excellent in low-temperature impact resistance and heat resistance, and have completed the present invention.

That is, according to the first invention of the present invention, (A) the melt flow rate at 230 ° C. is 2 to 80 g / 10 min, the homo part stereoregularity is 0.960 or more, and the total ethylene content is 3 to 12. 60-99 parts by weight of ethylene-propylene block copolymer in weight%, (B) polyethylene having a melt flow rate at 190 ° C. of 1-60 g / 10 min and a density of 0.860-0.940 g / cm ³ A propylene resin composition comprising 1 to 40 parts by weight is provided.

  According to the second invention of the present invention, in the first invention, a nucleating agent is further blended at a ratio of 0.05 to 0.3 parts by weight with respect to 100 parts by weight of the composition. A propylene resin composition is provided.

  According to a third aspect of the present invention, there is provided a propylene resin composition according to the second aspect, wherein the nucleating agent is an organophosphate metal salt.

  According to the fourth invention of the present invention, in the second invention, the nucleating agent is a nucleating agent mainly comprising a component represented by the following general formula (I). Propylene resin compositions are provided.

（式（Ｉ）中、Ｍｅｔａｌは１価又は３価の金属を示す。）

(In the formula (I), Metal represents a monovalent or trivalent metal.)

  According to a fifth invention of the present invention, in any one of the first to fourth inventions, erucic acid amide or oleic acid amide is further added in an amount of 0.01 to 2 with respect to 100 parts by weight of the composition. Propylene resin composition characterized by mix | blending in the ratio of a weight part is provided.

According to a sixth aspect of the present invention, there is provided a molded article formed by compression molding or injection molding from the propylene resin composition according to any one of the first to fifth aspects.
Furthermore, according to the seventh invention of the present invention, in the sixth invention, a molded product characterized in that it is a resin cap for containers is provided.

  In the polypropylene resin composition of the present invention, the resin composition is less likely to be whitened while maintaining low-temperature impact properties by changing the morphology of the material by blending a specific low-density polyethylene with a specific ethylene-propylene block copolymer. It becomes. In addition, a nucleating agent can be blended to further increase the rigidity and obtain a well-balanced resin composition. Therefore, the cap obtained from the propylene resin composition is suitable for beverage cap applications that require whitening resistance, rigidity, low-temperature impact resistance, heat resistance, etc., and all caps currently required for caps. Satisfy the request.

  The present invention comprises (A) an ethylene-propylene block copolymer and (B) polyethylene, and, if necessary, a propylene resin composition further containing a nucleating agent, erucic acid amide or oleic acid amide, and the like, and It is a resin cap molded from the resin composition. Hereinafter, the component which comprises a propylene resin composition, the manufacturing method of a resin composition, and a molded article are demonstrated in detail.

1. Propylene resin composition (1) Ethylene-propylene block copolymer (A)
The (A) ethylene-propylene block copolymer used in the propylene resin composition of the present invention is basically composed of a polypropylene segment (hereinafter sometimes referred to as a homo part) and an ethylene / propylene copolymer segment. It is a polymer, and a polyethylene segment may coexist if necessary. The polypropylene segment is crystalline, and mainly contributes to imparting mechanical strength such as rigidity of the block copolymer. The ethylene / propylene copolymer segment has rubber properties and forms a rubber portion of the block copolymer, which contributes to imparting impact resistance.

  The polypropylene segment in the block copolymer is preferably 70 to 95% by weight, more preferably 86 to 93% by weight, and the ethylene / propylene copolymer segment is preferably 5 to 30% by weight, more preferably. 7 to 14% by weight. Within this range, it is suitable for improving various mechanical properties of the resin composition.

The melt flow rate (MFR) at 230 ° C. of the block copolymer is 2 to 80 g / 10 minutes, preferably 7 to 13 g / 10 minutes. Within this range, a resin composition suitable for a high production rate derived from the rigidity and impact resistance of the resin composition and the molding temperature is provided. When the MFR is less than 2 g / 10 min, molding becomes difficult, and 80 g / 10 min. If it exceeds 1, good impact resistance cannot be obtained.
Here, MFR at 230 ° C. is a value measured at 230 ° C. under a 2.16 kg load in accordance with ASTM D-1238.

The stereoregularity of the homo part (polypropylene segment) is 0.960 or more, preferably 0.965 or more. If the stereoregularity is less than 0.960, the molded product is easily deformed during molding.
Here, the stereoregularity is a value measured by a ¹³ C-NMR method.

Furthermore, the total ethylene content in the block copolymer is 2 to 12% by weight, preferably 4 to 9% by weight. Within this range, it is suitable for the impact resistance of the resin composition. If the total ethylene content is less than 2% by weight, the impact resistance is insufficient, and if it exceeds 12% by weight, the rigidity becomes insufficient.
Here, the ethylene content is a value measured by the IR method.

  Such an ethylene-propylene block copolymer is a so-called propylene homopolymerization in the presence of an olefin stereoregular polymerization catalyst, followed by a copolymerization of propylene and ethylene, and if necessary, a homopolymerization of ethylene. It can manufacture by employ | adopting a multistage polymerization method. Further, it can also be produced by mechanically melt-kneading a propylene homopolymer, a copolymer of propylene and ethylene, and if necessary, an ethylene homopolymer.

  The catalyst used for obtaining the ethylene-propylene block copolymer used in the present invention is not particularly limited, and a known catalyst can be used. For example, a so-called Ziegler-Natta catalyst or a metallocene catalyst (for example, described in JP-A-5-295022) in which a titanium compound and organoaluminum are combined can be used. In the present invention, since a propylene block copolymer having a good balance between rigidity and impact resistance is particularly preferable, a Ziegler-Natta catalyst having high stereoregularity is generally more preferable. Further, the ethylene-propylene block copolymer produced using a metallocene catalyst is more preferable because the compatibility is good when the component (B) is a low density polyethylene produced using a metallocene catalyst.

(2) Polyethylene (B)
The polyethylene (B) used in the propylene resin composition of the present invention is a polyethylene having a density of 0.860 to 0.940 g / cm ³ and may be an ethylene homopolymer, but 30 wt% or less of the polyethylene (B), Preferably, when a polymer obtained by copolymerization with 15 to 25 wt% of another α-olefin is used, the impact resistance becomes good. Examples of other α-olefins include propane, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-octene, 1-octene, Decene etc. can be mentioned.
Further, the value of (weight average molecular weight) / (number average molecular weight), which is an index of the width of the molecular weight distribution, should be less than 7, preferably less than 3.5, and more preferably less than 3, the physical properties of rigidity and impact resistance. Balance becomes good. The value of (weight average molecular weight) / (number average molecular weight) can be measured by general GPC.

The melt flow rate (MFR) of polyethylene at 190 ° C. is 1 to 60 g / 10 minutes, preferably 3 to 40 g / 10 minutes. Within this range, the (A) component and (B) component of the resin composition are well mixed, and a well-balanced resin composition excellent in whitening resistance can be obtained. When the MFR is less than 1 g / 10 minutes or exceeds 60 g / 10 minutes, dispersion in the component (A) is deteriorated and a stable composition cannot be obtained.
Here, MFR at 190 ° C. is a value measured at 190 ° C. under a load of 2.16 kg in accordance with ASTM D-1238.

The density of the polyethylene is 0.860~0.940g / cm ^3, preferably 0.880~0.920g / cm ^3. If the density is less than 0.860 g / cm ³ , the rigidity is insufficient, and if it exceeds 0.940 g / cm ³ , whitening tends to be noticeable.
Here, the density is a value measured according to ASTM D1505.

  Such (B) polyethylene can be produced by using an olefin stereoregular polymerization catalyst and polymerizing in the presence of ethylene and, if necessary, other α-olefins while adjusting the molecular weight.

(3) Nucleating Agent A nucleating agent (also simply referred to as a nucleating agent in the following description) can be added to the propylene resin composition of the present invention as necessary. Examples of nucleating agents that can be used include (a) metal carboxylates such as aluminum p-tert-butylbenzoate, (b) polyhydric alcohol derivatives such as dibenzylidene sorbitol and bis (4-methylbenzylidene) sorbitol, (c ) Organophosphate metal salts such as sodium-2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate, (d) branched olefins such as 3-methyl-1-butene, 3,3- Polymer nucleating agents such as homopolymers or copolymers such as dimethyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3-methyl-1-pentene, etc. can be mentioned. .

  Among these, organophosphate metal salts are preferable, and they are not only suitable for food applications with little odor, but also add to achieve a good balance between the rigidity and impact resistance of the propylene resin composition and have excellent whitening resistance. Can be granted. Examples of the organic phosphate metal salt include sodium-2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate represented by the structural formula (II) and an aluminum compound represented by the general formula (III). Etc. can be illustrated. In particular, the effect of the compound represented by the formula (II) is high.

（式（ＩＩ）中、ｔ−Ｂｕはｔｅｒｔ−ブチル基を示す。）

(In formula (II), t-Bu represents a tert-butyl group.)

In the above formula (III), R ₁ and R ₂ are each independently a hydrogen atom or an alkyl group. Examples of the alkyl group include groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, amyl, tert-amyl, hexyl, heptyl, octyl, nonyl, 2-ethylhexyl and the like. X is an alkylene group, and examples thereof include methylene, ethylene, and propylene groups.

Specifically, a compound in which X is a methylene group, R ₁ is a tert-butyl group, R ₂ is a methyl group, and X is a methylene group, and R ₁ and R ₂ are tert-butyl groups In addition, compounds in which X is a methylene group and R ₁ and R ₂ are tert-amyl groups can be exemplified.

  In addition, when the production rate of the cap is particularly important, a nucleating agent mainly composed of a component represented by the following general formula (I) in a beverage system in which the nucleating agent is not extracted by the beverage in contact with the cap. It is preferable to use it. The “main component” in the present invention indicates that the content is 50% by weight or more. The content is preferably 70% by weight or more, particularly preferably 80% by weight or more.

  In the above formula (I), Metal refers to a monovalent or trivalent metal, among which monovalent is preferable. A particularly preferred Metal is sodium. In the case of a trivalent metal, an aluminum metal containing a hydroxyl group is also possible.

(4) Other additives The propylene resin composition of the present invention may further include a phenol-based, phosphorus-based, or thioether-based antioxidant, a neutralizer, a light stabilizer, a weathering stabilizer, if necessary. Additives such as pigments, dyes, lubricants such as stearylamide, erucic acid amide, and oleic acid amide, and fillers such as talc can be blended within a range that does not impair the object of the present invention.
In particular, the addition of a lubricant improves the effect of preventing whitening that occurs when the cap is forcibly removed. When erucic acid amide or oleic acid amide is blended, it is preferably blended at a ratio of 0.01 to 2 parts by weight with respect to 100 parts by weight of the composition.

(5) Blending ratio of each component The blending ratio of the (A) ethylene-propylene block copolymer and (B) polyethylene in the propylene resin composition of the present invention is 60 (A) ethylene-propylene block copolymer. It is -99 weight part, Preferably it is 80-95 weight part, (B) polyethylene is 1-40 weight part, Preferably it is 5-20 weight part. Within this range, the product cap is hard to be whitened and becomes a resin composition having excellent impact resistance at low temperatures.

  In the propylene resin composition of the present invention, when a nucleating agent is added, the nucleating agent is preferably 0.05 to 0.30 parts by weight, more preferably 0.07 to 100 parts by weight. It is blended in a proportion of 0.30 parts by weight, more preferably 0.07 to 0.20 parts by weight. When the blending ratio is within this range, a composition excellent in all balances such as rigidity, further heat resistance, and improvement in crystallization speed of the propylene resin composition can be obtained.

2. Production of Propylene Resin Composition The propylene resin composition of the present invention comprises (A) an ethylene-propylene block copolymer, and (B) polyethylene, and if necessary, a nucleating agent and other additives in the above-mentioned blending amount range. Then, after mixing using a mixer such as a Henschel mixer, V-blender, ribbon blender, tumbler blender, etc., the mixture is melt kneaded with a single screw extruder, twin screw extruder, kneader, Banbury mixer, etc. A composition can be obtained.

3. Molded body If necessary, the propylene resin composition may be blended with a pigment master batch, and compression molded or injection molded to produce various molded products such as caps.
As the pigment master batch used above, either an inorganic pigment or an organic pigment master batch can be used. Examples of the former include oxides, sulfides and sulfates of various metals, and examples of the latter include phthalocyanine, quinacridone, benzidine, chromophthal, and perylene compounds.

When producing a resin cap as a molded product, compression molding with the highest productivity is particularly preferable. The cap of the present invention can be used in a wide range of industrial fields as a cap in the food field, the medical field, and the like.
In particular, it is suitable for use in food containers and caps thereof, specifically PET bottle caps, and since it has high whitening resistance and impact resistance, caps and liners with carbonated beverage liners (However, there are two types of PET bolt caps: one with a liner on the inner top surface of the cap and one with a shape that does not use a liner to maintain the sealing property. Yes, the liner material is soft and different from the material of the cap body.)

  The present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. In addition, the measurement method, evaluation method, resin, and additive of physical property values used in Examples and Comparative Examples are as follows.

1. Physical property measurement method and evaluation method (1) Melt flow rate (MFR): In accordance with ASTM D-1238, a propylene resin is measured at 230 ° C. and a load of 2.16 kg, an ethylene resin is 190 ° C., and 2. Measurement was carried out under a load of 16 kg (unit: g / 10 minutes).
(2) Flexural modulus: measured at 23 ° C. according to ASTM D-790 (unit: MPa).
(3) Izod impact strength: measured using a test piece with a notch at 5 ° C. or 0 ° C. according to ASTM D-256 (unit: J / m).

(4) Whitening property:
Part 1:
Using a DuPont impact tester, using a 12.7 mm cradle, a semicircular strike tip with a radius of 8 mm, and a 1 kg load, place a cap on the cradle and place the strike core in the center of the top of the cap. The load was dropped from the height, the degree of whitening was confirmed, and judgment was made according to the following criteria.
◎: Very good ○: Good △: Conspicuous whitening ×: Conspicuous whitening

Part 2:
Using a DuPont impact test device in the same way as Part 1, using a 12.7 mm cradle and a semi-circular hitch tip with a radius of 8 mm, hit the hitch on a flat plate of 100 mm x 100 mm x 1 mm thick and load from a height of 30 cm The degree of whitening when dropped was confirmed. The load was dropped by shifting the position of the flat plate every 100 g from 100 g to 1000 g, the degree of whitening was confirmed, and the same judgment criterion as that No. 1 was used. Moreover, the flat plate after the test was photographed.

(5) Moldability: The molding condition when the cap was injection-molded was observed and judged according to the following criteria.
○: A good molded product is obtained.
X: The molded product is deformed.
(6) Haze: Haze (%) with a thickness of 2 mm or 1 mm was measured according to JIS K7105.
(7) Tensile yield strength and tensile elongation at break (tensile test): Yield strength and elongation were measured according to JIS K7113.

2. Each component (resin, additive)
I. PP component (A-1) ethylene-propylene block copolymer: ethylene content 5 wt%, ethylene / propylene copolymer segment 10 wt%, MFR (ASTM D-1238, 230 ° C., 2.16 kg load) 10 g / 10 min , Homo part stereoregularity 0.970 (measured by ¹³ C-NMR)
(A-2) Ethylene-propylene block copolymer: ethylene content 5 wt%, ethylene / propylene copolymer segment 10 wt%, MFR (ASTM D-1238, 230 ° C., 2.16 kg load) 10 g / 10 min, homo Stereoregularity 0.950 (measured by ¹³ C-NMR)
(A-3) ethylene-propylene random copolymer: ethylene content 2 wt%, MFR (ASTM D-1238, 230 ° C., 2.16 kg load) 10 g / 10 minutes,
(A-4) Propylene homopolymer: MFR (ASTM D-1238, 230 ° C., 2.16 kg load) 10 g / 10 min, stereoregularity 0.970 (measured by ¹³ C-NMR)
(A-5) Ethylene-propylene block copolymer: ethylene content 3.5 wt%, ethylene / propylene copolymer segment 7 wt%, MFR (ASTM D-1238, 230 ° C., 2.16 kg load) 10 g / 10 min , Homo part stereoregularity 0.960 (measured by ¹³ C-NMR)

B. PE component (B-1) low-density polyethylene: density (ASTM D1505) 0.907 g / cm ³ , MFR (ASTM D-1238, 190 ° C., 2.16 kg load) 12 g / 10 min. Nippon Polyethylene Corporation Kernel KS571.
(B-2) High density polyethylene: Density (ASTM D-1505) 0.963 g / cm ³ , MFR (ASTM D-1238, 190 ° C., 2.16 kg load) 3.5 g / 10 min.
(B-3) Low density polyethylene: Density (ASTM D-1505) 0.905 g / cm ³ , MFR (ASTM D-1238, 190 ° C., 2.16 kg load) 3.5 g / 10 min. Nippon Polyethylene Corporation Kernel KF370.
(B-4) Low density polyethylene: Density (ASTM D-1505) 0.898 g / cm ³ , MFR (ASTM D-1238, 190 ° C., 2.16 kg load) 38 g / 10 min. Nippon Polyethylene Corporation Kernel KJ650T.
(B-5) High density polyethylene: Density (ASTM D-1505) 0.964 g / cm ³ , MFR (ASTMD-1238, 190 ° C., 2.16 kg load) 7.0 g / 10 min. Nippon Polyethylene Corporation Novatec HD HJ560.

C. Additive component (C) Phenolic antioxidant: Tetrakis [methylene-3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] Methane (D) Phosphorous antioxidant: Tris (2,4 -Di-tert-butylphenol) phosphite (E) Neutralizing agent: Calcium stearate (F-1) Nucleating agent: 2,2-methylenebis (4,6-di-tert-butylphenyl) sodium phosphate (F- 2) Nucleating agent: CAS No. represented by the general formula (I). 351870-33-2; 80 wt%, CAS No. 7631-86-9; 10 wt%, CAS No. 112-84-5; trade name HPN-68L (made by Milliken Japan) consisting of 10 wt%
(G) Lubricant: Erucamide (H) Filler: Talc (Talc High Filler P7 from Matsumura Sangyo Co., Ltd.)

(Examples 1-3)
Resins and additives were prepared at the blending ratios (parts by weight) shown in Table 1, and then uniformly mixed in a Henschel mixer. Next, using a high-speed twin screw extruder, melt kneading was performed at a resin temperature of 200 ° C., and the kneaded product was extruded to obtain pellets. A test piece was prepared by injection molding using this pellet, and a bending test and an Izod test were conducted. In addition, a cap was molded by injection molding to confirm moldability, and the degree of whitening when a 1 kg load was dropped from a position of 30 cm height on the top surface of the cap was confirmed. The results are shown in Table 1.

(Comparative Examples 1-5)
Except having used the resin and additive described in Table 1, it carried out similarly to Example 1 and obtained the pellet and the test piece. Thereafter, physical property tests were conducted, and the results are shown in Table 1.

(Examples 4 to 12)
Resins and additives were prepared at the blending ratios (parts by weight) shown in Table 2, and then uniformly mixed in a Henschel mixer. Next, using a high-speed twin screw extruder, melt kneading was performed at a resin temperature of 200 ° C., and the kneaded product was extruded to obtain pellets. A test piece was prepared by injection molding using this pellet, and a bending test, an Izod test, a haze measurement, a tensile test, and a whitening test (part 2) were performed. Moreover, the cap was shape | molded by injection molding and the moldability was confirmed. The results are shown in Table 2.

(Comparative Examples 6-8)
Except having used the resin and additive described in Table 2, it carried out similarly to Example 4 and obtained the pellet and the test piece. Thereafter, physical property tests were conducted, and the results are shown in Table 2.

As is clear from Tables 1 and 2, Examples 1 to 12 have good whitening resistance, high rigidity, and excellent low-temperature impact properties. On the other hand, whitening is remarkable in Comparative Examples 1, 6, and 8, and whitening is also conspicuous in Comparative Examples 2 and 7. Further, in Comparative Example 3, there was a problem that the product was deformed when taken out at the time of injection molding. Comparative Examples 4 and 5 have good whitening resistance but low impact at low temperatures.
Further, from Table 2, even if the talc as a filler is added to the extent shown in Example 8 within the range of the present invention, a molded product having good whitening resistance and excellent balance between rigidity and impact can be obtained. You can see that
As mentioned above, it turns out that the resin composition obtained in Examples 1-12 is a composition excellent in whitening resistance, high rigidity, low temperature impact property, and moldability compared with Comparative Examples 1-8.

  Since the polypropylene resin composition of the present invention is a resin composition that does not easily whiten while maintaining low-temperature impact properties, the cap obtained from the resin composition has difficulty whitening, rigidity, low-temperature impact resistance, and heat resistance. It is suitable for the use of beverage caps that are required, and meets all requirements currently required for caps. Therefore, it can be used in a wide range of industrial fields as caps in the food field, medical field, and the like.

Claims (7)

(A) An ethylene-propylene block copolymer 60 having a melt flow rate at 230 ° C. of 2 to 80 g / 10 min, a homo-part stereoregularity of 0.960 or more, and a total ethylene content of 2 to 12% by weight. 99 parts by weight and (B) 1 to 40 parts by weight of polyethylene having a melt flow rate at 190 ° C. of 1 to 60 g / 10 minutes and a density of 0.860 to 0.940 g / cm ^3. Propylene resin composition.   Furthermore, a nucleating agent is mix | blended in the ratio of 0.05-0.3 weight part with respect to 100 weight part of this composition, The propylene resin composition of Claim 1 characterized by the above-mentioned.   The propylene resin composition according to claim 2, wherein the nucleating agent is an organophosphate metal salt. The propylene resin composition according to claim 2, wherein the nucleating agent is a nucleating agent mainly comprising a component represented by the following general formula (I).

(In the formula (I), Metal represents a monovalent or trivalent metal.)   Furthermore, erucic acid amide or oleic acid amide is mix | blended in the ratio of 0.01-2 weight part with respect to 100 weight part of this composition, The any one of Claims 1-4 characterized by the above-mentioned. Propylene resin composition.   A molded article obtained by compression molding or injection molding from the propylene resin composition according to any one of claims 1 to 5.   It is a resin cap for containers, The molded article of Claim 6 characterized by the above-mentioned.