JP2006016600A - Propylene resin composition and outer cylinder for syringe and food container made of the composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive propylene resin composition which has balanced and improved transparency and impact resistance, hardly decreases its impact resistance after exposure to gamma ray and is excellent in performance suitable for application wherein emphasis is on rigidity or impact resistance, and an outer cylinder for a syringe and a chilled or frozen dessert container which are made of the resin composition. <P>SOLUTION: The outer cylinder for the syringe is formed from the propylene resin composition comprising (A) 80-99 wt.% ethylene/propylene random copolymer with an MFR (230°C) of 8-30 g/10 min and an ethylene content of 1.0-7.0 wt.% and (B) 1-20 wt.% ethylene/propylene/butene copolymer with an MFR (230°C) of 5-15 g/10 min, an ethylene content of 8.0-15.0 wt.% and a butene content of 3.0-20.0 wt.%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polypropylene resin composition excellent in transparency and impact resistance, and a medical instrument formed from the composition, in particular, a syringe barrel and a food container in which low temperature impact is important. Furthermore, it is related with the polypropylene-type resin composition which improves transparency, and can also endure conveyance and an unexpected fall.

  In general, polypropylene resins are used in a wide range of applications including food containers and pharmaceutical containers because they are excellent in chemical characteristics, physical characteristics, and moldability, and are inexpensive. However, since the polypropylene resin itself does not necessarily have sufficient transparency and mechanical strength characteristics, various nucleating agents are usually added to the polypropylene resin to improve transparency and mechanical strength characteristics, and a large amount of rubber component is used. Although the method of improving impact resistance by adding it is taken, usually transparency must be sacrificed.

  A method of adding a nucleating agent to improve transparency, a method of adding an amorphous ethylene / propylene copolymer to impart impact resistance, or a propylene / ethylene block copolymer as a polypropylene resin However, it is difficult to improve all of the performance at the same time, although it is possible to achieve the performance of transparency, rigidity, or impact resistance.

  In the prior art, impact resistance and rigidity are balanced simultaneously at the expense of transparency. Specifically, instead of adding impact resistance by adding an ethylene / propylene copolymer, transparency The decline was inevitable to some extent.

  In addition, as a commonly used polypropylene for medical devices, an ethylene-propylene random copolymer having a high ethylene content is used, and medical devices using this are used for unexpected drops and needles after γ-ray sterilization. There was a problem that the impact resistance was extremely lowered by γ-rays at the time of wearing, and cracking occurred particularly in winter.

In addition, drop strength in a chilled storage environment at 5 ° C. is regarded as important for dessert containers, and ethylene-propylene random copolymers commonly used lack chilled impact strength, causing unexpected fall and cracking especially in winter. There was a problem that occurred.
JP 2002-226649 A

  An object of the present invention is to provide a propylene-based resin composition that improves impact resistance and rigidity at the same time in a well-balanced manner, and further does not cause a decrease in transparency or improves transparency.

  The propylene-based resin composition of the present invention has a high ethylene content when emphasis is placed on impact resistance, while using an ethylene-propylene random copolymer with a low ethylene content when emphasis is placed on rigidity-impact balance, This is a propylene-based resin composition that can also achieve this goal.

  Another object of the present invention is to provide a syringe outer cylinder that can be molded from a resin composition by injection molding into a syringe outer cylinder and that can solve the cracking problem even after being sterilized by electron beams or γ rays.

  Furthermore, this invention aims at provision of the frozen dessert food container or dessert cup corresponding to chilled.

  In the present invention, (A) 80 to 99% by weight of an ethylene-propylene random copolymer having an MFR (230 ° C.) of 8 to 30 g / 10 minutes and an ethylene content of 1.0 to 7.0% by weight, (B) Ethylene-propylene-butene copolymer having an MFR (230 ° C.) of 5 to 15 g / 10 min, an ethylene content of 8.0 to 15.0 wt%, and a butene content of 3.0 to 20.0 wt% The present invention relates to a propylene-based resin composition (1) characterized by comprising 1 to 20% by weight of a coalescence.

  Further, the present invention provides a propylene-based resin composition (2) characterized in that the above-described resin composition (1) is controlled by a peroxide and the MFR (230 ° C.) is controlled to have a molecular weight of 25 to 40 g / 10 minutes. )

  In the present invention, 0.05 to 0.5 parts by weight of a nucleating agent containing an organophosphate metal salt as a main component per 100 parts by weight of the propylene-based resin composition (1) or (2). And a propylene resin composition (3).

  Moreover, this invention added the fatty-acid metal salt to the said propylene-type resin composition (1)-(3) as a dispersing agent of the organophosphate metal salt which is a nucleating agent, The propylene-type resin composition characterized by the above-mentioned. Regarding (4).

  Moreover, this invention relates to the propylene-type resin composition (5) formed by mix | blending 0.05-0.5 weight part of sorbitol nucleating agents with the said propylene-type resin composition (1) or (2).

  Furthermore, this invention relates to the syringe outer cylinder formed from either of the propylene-type resin compositions (1)-(5) of the said description.

  Furthermore, the syringe barrel relates to a syringe barrel that is sterilized by electron beam and γ-ray irradiation.

  Furthermore, this invention relates to the food container characterized by being formed from either of the propylene-based resin compositions (1) to (5) described above.

  Furthermore, the food container described above relates to a dessert cup or ice cream container.

  Conventionally, in order to impart impact resistance, an ethylene-α-olefin copolymer was added to balance physical properties at the expense of rigidity and transparency. However, the present invention sacrifices transparency. This unique performance was exhibited only in the composition range of the present invention.

  This is an unprecedented material, and this material is suitably used for dessert cups, ice cream containers, and inexpensive disposable syringe outer cylinders.

  The propylene-based resin composition according to the present invention, and the syringe outer cylinder used in the application for sterilization by γ-ray irradiation, which is required to have higher performance than food containers, are more specifically described. To do.

(A) Polypropylene (A) Polypropylene is a random copolymer of propylene and ethylene. The polypropylene has a melt flow rate value [MFR (230 ° C.)] of 8 to 30 g / 10 minutes, preferably 15 to 20 g / 10 minutes. The ethylene content measured by infrared absorption spectrum is 1.0 to 7.0% by weight, preferably 2.0 to 5.0% by weight, and more preferably 3.0 to 4.0% by weight.

  When the melt flow rate and the ethylene content are within the above ranges, the resin fluidity (moldability) and mechanical strength are well balanced, and a molded product having a good appearance can be obtained.

  Such polypropylene is produced in the required amount of propylene in the presence of a stereoregular olefin polymerization catalyst containing a transition metal compound component such as titanium or zirconium, an organoaluminum component, an electron donor, a carrier, etc. as required. It can be produced by polymerizing in the presence of the corresponding ethylene. Moreover, it is also possible to manufacture using the metallocene catalyst represented by the patent 3530143.

(B) Ethylene-propylene-butene copolymer (B) The ethylene-propylene-butene copolymer has an ethylene content of 8.0 to 15.0 wt%, preferably 10 to 12 wt%, and a butene content of 3. An ethylene-propylene-butene copolymer of 0 to 20.0 wt%, preferably 12.0 to 20.0 wt%, more preferably 15.0 to 18.0 wt%. The compatibility is improved, the transparency is improved, and the copolymer exhibits a rubber property with good low temperature impact resistance.

  The melt flow rate value [MFR (230 ° C.)] of this copolymer (B) is 5 to 15 g / 10 minutes, preferably 6 to 10 g / 10 minutes. When it is within this MFR range, the copolymer is finely dispersed in polypropylene and excellent in transparency.

  Such an ethylene-propylene-butene copolymer is a stereoregular polymerization such as a metallocene catalyst comprising a metallocene compound in which a compound having a cyclopentadiene skeleton is coordinated to a transition metal such as zirconium metal and an organoaluminum oxy compound. It can be produced by copolymerizing ethylene, propylene and 1-butene in the presence of a catalyst. In particular, an ethylene-propylene-butene copolymer produced using a metallocene-based catalyst has a narrow molecular weight distribution and composition distribution, and therefore has good extraction resistance by an internal solution, and is a resin composition for containers and syringes. Suitable as a raw material resin.

( C) Nucleating Agent ( C) The nucleating agent in the present invention is preferably an organic phosphate metal salt due to the balance of physical properties and transparency. As the trade name, NA-21 and NA-11 manufactured by Asahi Denka are exemplified, but NA-21 is most preferable from the viewpoint of transparency.

  For products in which odor is not a problem, it is also preferable to use a sorbitol nucleating agent.

Examples of the product name include Gerol MD manufactured by Shin Nippon Rika, Millard 3988 manufactured by Milliken, NC-4 manufactured by Mitsui Chemicals, and the like.

  Specifically, (a) carboxylic acid metal salts such as aluminum p-tert-butylbenzoate, (b) polyhydric alcohol derivatives such as dibenzylidene sorbitol and bis (4-methylbenzylidene) sorbitol, (c) sodium-2 Organophosphate metal salts such as 1,2-methylenebis (4,6-di-tert-butylphenyl) phosphate, (d) branched olefins such as 3-methyl-1-butene, 3,3-dimethyl-1- Polymer nucleating agents such as homopolymers or copolymers such as butene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 3-methyl-1-pentene can be given.

  Among these, an organophosphate metal salt is preferable, and by adding the metal salt, a good balance between rigidity and impact resistance of the propylene resin composition can be achieved, and excellent odor characteristics can be obtained. As an organic phosphate metal salt, sodium-2,2-methylenebis (4,6-di-tert-butylphenyl) phosphate represented by the following formula (1), an aluminum compound represented by the following formula (2), etc. Can be illustrated. In particular, the effect of the compound represented by the following formula (1) is high.

ここで、t-Buは、tert-ブチル基を示す。

Here, t-Bu represents a tert-butyl group.

In the above formula (2), 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 Furthermore, compounds in which X is a methylene group and R ₁ and R ₂ are tert-amyl groups can be exemplified.

  The polypropylene resin composition of the present invention may be subjected to molecular weight control with (D) peroxide described later, if necessary. In this case, tert-butanol is produced as a by-product. This tert-butanol can be controlled to 100 ppm or less by pellet drying at 110 ° C. for 12 hours to meet US Food and Drug Administration (FDA) standards.

Moreover, the aspect which is a composition containing a phosphorus antioxidant and / or an amine antioxidant at the time of the production of the propylene resin composition of the present invention is suitable.
An embodiment in which an amine is added for medical use and an amine is not added for food is suitable.

  When added, phosphorus antioxidant 0.05-0.2% by weight, preferably 0.1-0.15% by weight, amine antioxidant (E) 01-0.1% by weight, preferably 0 0.03 to 0.06% by weight, calcium stearate and hydrotalcite as a neutralizing agent are 0.02 to 0.2% by weight, preferably 0.3 to 0.7% by weight. In order to reduce certain voids, molecular weight control by peroxide, especially 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and molecular weight control by an extruder, total MFR (230 ° C) The molecular weight is controlled at 25 to 40 g / 10 min.

  When each component is within the above-mentioned blending range, it is possible to bring out unprecedented characteristics such as improvement of transparency while keeping the fluidity, rigidity and impact resistance of the resin composition at a high level.

  The melt flow rate MFR (230 ° C.) of the propylene-based resin composition of the present invention is preferably 25 to 40 g / 10 minutes, more preferably 25 to 35 g / 10 minutes. If it is less than this, molding defects such as short shots and burning due to the need to raise the resin temperature occur in multi-cavity molding. Further, in the case of more than this, molding defects such as burrs and voids due to gas entrainment and impact resistance decrease are caused.

Phosphorus Antioxidant The phosphorus antioxidant used in the present invention is not particularly limited, and conventionally known phosphorus antioxidants can be used. In addition, it is preferable to use only one type of phosphorus-based antioxidant because the content contamination due to bleeding is small.

  The phosphorus-based antioxidant preferably used in the present invention is a trivalent organic phosphorus compound, specifically, tris (2,4-di-t-butylphenyl) phosphite, 2,2-methylenebis (4,6 -Di-t-butylphenyl) octyl phosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, and the like.

Amine-based antioxidant Examples of the amine-based antioxidant used in the present invention include compounds having a piperidine ring. Specifically, dimethyl succinate / 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, bis (2,2,6,6-tetramethyl- 4-piperidyl) sebacate and the like are used. When this antioxidant is used as a food container, it is preferable not to add it from the viewpoint of taste.

Peroxide As the peroxide used in the present invention, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane is exemplified. Other examples include 1,3-bis (t-butylperoxy-isopropyl) benzene, but 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, especially for food and medical use Is preferred.

Syringe outer cylinder The propylene-based resin composition of the present invention maintains excellent rigidity and impact resistance at the same time, and at the same time has excellent properties for improving transparency, and even after γ-ray sterilization. Since it has high impact resistance, it can be used particularly as a syringe outer cylinder. In addition to this, the polypropylene resin composition of the present invention has productivity that cannot be achieved with conventional polypropylene, in which the impact resistance is hardly reduced even when treated with γ rays at low cost.

  In addition, since this syringe outer tube is highly reduced in tert-butanol which is a by-product in the polypropylene resin composition, t-butanol can also be produced in the syringe outer tube at 10 ppm or less and is very safe. .

  The polypropylene resin composition of the present invention can be blended with additives such as a lubricant, if necessary, within a range not departing from the object of the present invention. In addition, when using as an electron beam or a gamma ray, for example, as a medical instrument, it is not recommended to add a phenolic antioxidant because it may turn yellow.

  If necessary, other additives and the like are mixed with the above components using a Henschel mixer, V-type blender, tumbler blender, ribbon blender, etc., and then a single screw extruder, a multi-screw extruder, a kneader, a Banbury mixer, etc. By melting and kneading using the above, it is possible to obtain a high-quality resin composition in which each component and additive are uniformly dispersed and mixed.

  A syringe outer cylinder according to the present invention is a syringe outer cylinder manufactured from a resin composition containing the above-described components by means of injection molding and having excellent rigidity, transparency, and impact resistance, and an electron beam or γ Even if the sterilization process is performed by wire, the impact resistance is small and the cost is low. This makes it particularly suitable for disposable syringes that pursue high quality.

Food container A food container according to the present invention is a food container manufactured from a resin composition containing the above-described components by means of injection molding and having excellent rigidity, transparency, and impact resistance. It possesses characteristics that cannot be achieved with conventional polypropylenes that possess impact resistance at 5 ° C. chilled storage and are extremely excellent in transparency. This makes it particularly suitable for dessert cups that pursue visibility.

  EXAMPLES Next, the present invention will be described through examples, but the present invention is not limited to the examples.

The raw materials used in the examples are as follows.
(A-1) Ethylene-propylene random copolymer:
MFR (230 ° C.); 12 g / 10 minutes Ethylene content; 4.0% by weight
(A-2) Ethylene-propylene random copolymer MFR (230 ° C.); 12 g / 10 minutes Ethylene content; 2.6% by weight
(B-1) Ethylene-propylene-butene copolymer:
MFR (230 ° C.); 8 g / 10 minutes Ethylene content 12.0 wt%, butene content 18.0 wt%
(B-2) Ethylene / 1-octene copolymer:
MFR (230 ° C.); 8 g / 10 minutes Density; 0.870 g / cm 3
Product Name: Engage 8200 (made by DuPont Dow Elastomer)
(B-3) Ethylene-propylene-butene copolymer:
MFR (230 ° C.); 8 g / 10 minutes Ethylene content 25.0 wt%, butene content 13.3 wt%
(B-4) Ethylene-propylene-butene copolymer:
MFR (230 ° C.); 8 g / 10 minutes Ethylene content 5.0 wt%, butene content 16 wt%
(C) a nucleating agent;
Hydroxyaluminum-bis [2,2-methylene-bis (4,6-di-t-butylphenyl) phosphate] (main component) Product name NA-21 (Asahi Denka)

The production example of (B-1) is shown below.
[Synthesis Example 1]
Synthesis of diphenylmethylene (3-tert-butyl-5-methyl-cyclopentadienyl) (2,7-di-tert-butyl-fluorenyl) zirconium dichloride (1) (3-tert-butyl-5-methyl-cyclo Synthesis of pentadienyl) (2,7-di-tert-butyl-fluorenyl) diphenylmethane A 200 ml three-necked flask equipped with a magnetic stirrer tip and a three-way cock was thoroughly purged with nitrogen, and 2.53 g of 2 , 7-di-tert-butylfluorene (9.10 mmol) was dissolved in 70 ml of dehydrated diethyl ether. To this solution, 6.4 ml of n-butyllithium / hexane solution (1.56M: 9.98 mmol) was gradually added dropwise in an ice bath, and the mixture was stirred overnight at room temperature. A solution prepared by dissolving 3.01 g of 3-tert-butyl-1-methyl-6,6-diphenylfulvene (10.0 mmol) in 40 ml of dehydrated diethyl ether was added to the reaction solution, and the mixture was stirred under reflux for 7 days. The reaction mixture was added to 100 ml of hydrochloric acid aqueous solution (1N), diethyl ether was added, the organic layer was separated, and washed with saturated aqueous sodium hydrogen carbonate solution and saturated brine. After drying over anhydrous magnesium sulfate, the desiccant was filtered, and the solvent was removed from the filtrate under reduced pressure to obtain a reddish brown liquid. Purification by column chromatography using 180 g of silica gel (developing solvent: n-hexane), the developing solvent was distilled off under reduced pressure, recrystallized from methanol, and dried under reduced pressure to obtain 1.65 g (2.85 mmol). The target compound was obtained as a pale yellow solid (yield: 31%).

(2) Synthesis of diphenylmethylene (3-tert-butyl-5-methyl-cyclopentadienyl) (2,7-di-tert-butyl-fluorenyl) zirconium dichloride 50 ml with a magnetic stirrer tip and a three-way cock The Schlenk flask was thoroughly purged with nitrogen, and 0.502 g of (3-tert-butyl-5-methyl-cyclopentadienyl) (2,7-di-tert-butyl-fluorenyl) diphenylmethane (0. 868 mmol) was dissolved in 30 ml of dehydrated diethyl ether. To this solution, 1.40 ml of an n-butyllithium / hexane solution (1.56M: 2.18 mmol) was gradually added dropwise in an ice bath, and the mixture was stirred overnight at room temperature. The orange solid obtained by distilling off the solvent under reduced pressure was washed with dehydrated pentane and dried under reduced pressure to obtain an orange solid. 30 ml of dehydrated diethyl ether was added to this solid, and after sufficiently cooling with a dry ice / methanol bath, 0.206 g of zirconium tetrachloride (0.882 mmol) was added. After stirring for 2 days while gradually returning to room temperature, the solvent was distilled off under reduced pressure. The reaction mixture was introduced into a glove box, reslurried with dehydrated hexane, and filtered through a glass filter filled with diatomaceous earth. The solid obtained by concentrating the filtrate was washed with a small amount of dehydrated toluene, and dried under reduced pressure to obtain 140 mg (0.189 mmol) as a pink solid (yield: 22%). The identification was performed by ¹ H-NMR spectrum and FD-mass spectrometry spectrum. The measurement results are shown below.

¹ H-NMR spectrum (CDCl3, TMS standard): δ / ppm 0.99 (s, 9H), 1.09 (s, 9H), 1.12 (s, 9H), 1.91 (s, 3H) , 5.65 (d, 1H), 6.14 (d, 1H), 6.23 (m, 1H), 7.03 (m, 1H), 7.18-7.46 (m, 6H), 7.54-7.69 (m, 2H), 7.80-7.83 (m, 1H), 7.95-8.02 (m, 5H)
FD-mass spectrometry spectrum: M / z = 738 (M ⁺ )

[Polymerization Example 1]
(Synthesis of propylene / ethylene / butene copolymer) (B-1)
After charging 1834 ml of dry hexane, 120 g of 1-butene and triisobutylaluminum (1.0 mmol) into a 4000 ml polymerization apparatus sufficiently purged with nitrogen at room temperature, the temperature inside the polymerization apparatus was raised to 65 ° C. After pressurizing the system pressure to 0.55 MPa, the system pressure was adjusted to 0.75 MPa with ethylene. Subsequently, diphenylmethylene (3-tert-butyl-5-methylcyclopentadienyl) 2,7-di-tert-butylfluorenylzirconium dichloride 0.001 mmol synthesized in Synthesis Example 1 and 0.3 mmol in terms of aluminum Toluene solution in contact with methylaluminoxane (manufactured by Tosoh Finechem) was added to the polymerization vessel, polymerized for 20 minutes while maintaining the internal temperature at 65 ° C. and the internal pressure at 0.75 MPa with ethylene, and 20 ml of methanol was added. The polymerization was stopped by addition. After depressurization, the polymer was precipitated from the polymerization solution in 4 L of methanol and dried under vacuum at 130 ° C. for 12 hours. The obtained polymer was 197.3 g, and was a propylene / ethylene / butene copolymer having an MFR of 8 (g / 10 min), ethylene of 12.0 wt% and butene of 18 wt%.

B-3 and B-4 were produced by changing the amount of propylene, ethylene and butene added under the above conditions.

(Examples 1-2)
In a Henschel mixer, 100 parts by weight of a mixture having a ratio shown in Table 1 consisting of ethylene-propylene random copolymer (A-1) or (A-2) and ethylene / 1-octene copolymer (B1) is supplied. Further, 0.1 parts by weight of a phosphorus antioxidant [tris (2,4-di-t-butylphenyl) phosphite], 0, 25 parts by weight of the nucleating agent (C), 0.1 parts by weight of calcium stearate, 2 , 5-Dimethyl-2,5-di- (tert-butylperoxy) hexane was added in an amount of 0.03 part and mixed with stirring.

  The mixture was melt-kneaded at a resin temperature of 220 ° C. using a twin screw extruder (40 mmφ), and the kneaded product was extruded, cooled in water and cut to obtain a polypropylene resin composition pellet. The pellet was dried at 110 ° C. for 8 hours.

  Then, using the pellets, a sheet-shaped test piece having a thickness of 1 mm at 180 ° C. and a mold temperature of 40 ° C. by injection molding, a test piece for bending strength test (ASTM D790, thickness 3.2 mm, length 127 mm, width 12) , 7 mm), and test pieces for a high-speed surface impact test (length 130 mm × width 120 mm × thickness 2 mm). These test pieces were irradiated with γ-rays of 15 kGy, and using this test piece, the haze, bending elastic modulus, and high-speed surface impact test absorbed energy were measured, and the results are shown in Table 1.

In the present invention, a detailed physical property measuring method is shown below.
(I) Haze: Measured using a 1 mm sheet in accordance with ASTM D1003.
(B) Bending elastic modulus: A bending test was performed according to ASTM D790, and the bending elastic modulus was calculated from the result.
(C) High-speed surface impact test: A striker with a load cell having a tip diameter of 1/2 inch is made to collide with a sample in a 5 ° C. atmosphere of a 2 mm thick square plate at a speed of 3 m / s. A base having a tip diameter (receiving diameter) of 3 inches was used as a receiving base on the back surface of the sample. As a value, the total absorbed energy from yielding to destruction was obtained.
(D) Melt flow rate (MFR): Measured at 230 ° C. under a load of 2.16 kg according to ASTM D-1238.

(Comparative Examples 1-2)
In Examples 1 and 2, Examples 1 to 2 were used except that (B-2) an ethylene / 1-octene copolymer was replaced with an octene copolymer instead of (B-1) an ethylene-propylene-butene copolymer. Same as 2. The physical property measurement results are also shown in Table 1.

(Comparative Example 3)
Example 1 is the same as Example 1 except that (B-3) ethylene-propylene-butene copolymer was used instead of (B-1) ethylene-propylene-butene copolymer.

(Comparative Example 4)
Example 1 is the same as Example 1 except that (B-4) ethylene-propylene-butene copolymer was used instead of (B-1) ethylene-propylene-butene copolymer.

(Comparative Example 5)
In Example 1, only the (A-1) ethylene-propylene random copolymer was used.

(Comparative Example 6)
In Example 2, only (A-2) ethylene-propylene random copolymer was used.

The comparative example was injection-molded in the same manner as in the example, measured for physical properties, and listed in Table 1.

  From the physical property measurement results shown in Table 1, it can be seen that the polypropylene resin composition according to the present invention maintains or improves transparency and further improves impact resistance. In the case of this resin composition, the amount of rubber added is small and the cost increase is very small. Almost no deterioration in impact resistance after γ-ray irradiation was observed, and the properties of the polypropylene resin composition that could not be achieved with conventional cost and resin compositions were shown, which is very useful.

  It is possible to develop an unprecedented material that can maintain high good impact resistance and rigidity even after γ-ray irradiation and is low in cost while maintaining such good transparency without impairing only in the composition range of the present invention. It was. The impact resistance can be dramatically improved even at 5 ° C. after γ-irradiation, which can solve the problem of cracking in winter and the problem of breaking when a needle is attached. This material is suitable for an inexpensive disposable syringe outer cylinder.

The present invention has such excellent physical properties even when γ-ray irradiation is performed, and the physical properties of food containers that do not irradiate γ-rays are even better, and are suitable for frozen dessert containers and dessert containers.

Claims (9)

(A) 80 to 99% by weight of an ethylene-propylene random copolymer having an MFR (230 ° C.) of 8 to 30 g / 10 minutes and an ethylene content of 1.0 to 7.0% by weight;
(B) Ethylene-propylene having an MFR (230 ° C.) of 5 to 15 g / 10 min, an ethylene content of 8.0 to 15.0 wt%, and a butene content of 3.0 to 20.0 wt% 1-20% by weight of butene copolymer,
A propylene-based resin composition (1), comprising:   A propylene-based resin composition (2), wherein the molecular weight of the resin composition according to claim 1 is controlled with a peroxide, and the MFR (230 ° C) is controlled to 25 to 40 g / 10 minutes.   A propylene-based resin comprising 0.05 to 0.5 parts by weight of a nucleating agent (C) mainly composed of an organophosphate metal salt per 100 parts by weight of the propylene-based resin composition according to claim 1 or 2. Resin composition (3).   A propylene-based resin composition comprising a fatty acid metal salt added to the resin composition according to any one of claims 1 to 3 as a dispersant for an organic phosphate metal salt that is a nucleating agent ( 4).   A propylene-based resin composition (5) comprising 0.05 to 0.5 parts by weight of a sorbitol nucleating agent per 100 parts by weight of the propylene-based resin composition according to claim 1 or 2.   A syringe outer cylinder comprising a composition formed from the propylene-based resin composition according to any one of claims 1 to 5 and formed by injection molding.   7. The medical disposable syringe outer cylinder according to claim 6, wherein the syringe outer cylinder is sterilized by electron beam irradiation, particularly γ-ray irradiation.   A food container comprising a composition formed from the propylene-based resin composition according to claim 1, wherein the composition is formed by injection molding. The food container according to claim 8, which is a dessert cup or an ice cream container.