JPH03281647A - Radiation-resistant polypropylene composition - Google Patents

Abstract

PURPOSE:To prepare the title compsn. excellent in impact resistance, transparency, and high-speed moldability after the exposure to a radiation by compounding a specific propylene resin mixture having a specified ethylene content and a specific clarifier and degrading the resulting compsn. so as to give the compsn. a specified melt flow rate. CONSTITUTION:A propylene homopolymer with a melt flow rate of 0.5-15g/10min or an ethylene-propylene random copolymer contg. 1wt.% or lower ethylene is mixed with an ethylene-propylene random copolymer with a melt flow rate of 0.5-15g/10min and contg. 2.5-5.0wt.% ethylene to give a resin mixture contg. 2.3-3.5wt.% ethylene. 100 pts.wt. said mixture and 0.15-0.35 pts.wt. clarifier comprising a sorbitol compd. [e.g. (1,3)2,4-di(p-methylbenzylidene)sorbitol] are compounded and the resulting compsn. is degraded so as to give the compsn. a melt flow rate of 25-100g/10min.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a radiation-resistant polypropylene composition, in particular, which prevents deterioration of impact resistance etc. and discoloration due to irradiation with radiation such as T-rays and electron beams, The present invention relates to a radiation-resistant polypropylene composition suitable for medical devices, etc., which has good transparency and high-speed moldability.

[Conventional technology]

In recent years, when molded products made of polyolefins such as polypropylene are used for medical devices, food packaging, etc., in addition to sterilization by boiling or gas, sterilization is also performed by irradiation with radiation such as T-rays or electron beams. It's starting to look like this.

However, due to its molecular structure, the molecular chains of polyolefins are easily cleaved by radiation, and irradiation of about 2.5 megarads, which is usually used as a guideline for sterilizing doses, significantly progresses decomposition and deterioration, resulting in loss of impact resistance, etc. Mechanical properties may deteriorate or low molecular weight eluted components may increase.

Further, there is also the problem that various stabilizers, modifiers, etc., which are generally added for the purpose of preventing oxidation, deteriorate in quality and cause significant discoloration.

In an attempt to solve the problems caused by such radiation irradiation, various polyolefin compositions as described below have been proposed.

JP-A No. 60-55005 has a random ethylene content of 2
A radiation resistant polypropylene composition comprising 8 to 7.0% by weight of an ethylene-propylene random copolymer resin is disclosed.

JP-A No. 60-99147 discloses polypropylene resin 10
0 parts by weight, 0.01 to 4 parts by weight of sorbitol derivative 1) IJs (2,4-di-t-butylphenyl)
phosphite) and 0.01 to 4 parts by weight of dimethylsuccinate 2-(4-hydroxy-2,2,6,6-tetramethyl-1-piperidyl)ethanol condensate. discloses a polypropylene resin composition that has good stability against radiation irradiation and excellent transparency.

JP-A-60-168740 discloses a blend of (A) polypropylene or an ethylene-propylene random copolymer having an ethylene content of 2% by weight or less, and (B) an ethylene-propylene random copolymer having an ethylene content of 4% by weight or more. 0.01 to 4% by weight of ethylene-propylene random copolymer mixture with an ethylene content of 2 to 4% by weight.
A radiation-resistant polypropylene resin composition containing 0.5% by weight of diallyl (iso)phthalate or triallyl (iso)cyanurate is disclosed.

JP-A No. 60-215047 discloses a propylene homopolymer block of 5 to 95% by weight in which the melt flow rate is reduced from 0.05 to 10 g/10 minutes to 10 to 100 g/10 minutes in the presence of a radical generator. and 100 parts by weight of a propylene-based block copolymer consisting of 95-5% by weight of a propylene/ethylene random copolymer block with an ethylene content of 2-15% by weight, and 0.05-0.5 parts by weight of a sorbitol-based compound. Discloses a polypropylene composition characterized by:

JP-A-60-215048 discloses a propylene homopolymer block of 5 to 95 parts by weight and an ethylene content of 2 to 15 parts by weight.
100 parts by weight of a propylene block copolymer consisting of 95 to 5 parts by weight of propylene/ethylene random copolymer blocks, and 0.05 parts by weight of a sorbitol compound
Discloses a polypropylene resin composition characterized in that it consists of 0.5 parts by weight.

Unexamined Japanese Patent Publication 1986. No.-73711 contains 100 parts by weight of polypropylene or ethylene-propylene random copolymer, 5 to 0.2 parts by weight of organic peroxide o, oo, and 0.01 to 0.5 parts by weight of triallyl(iso)cyanurate or diallyl(iso)phthalate. Discloses a radiation-resistant polypropylene resin composition containing parts by weight.

JP-A-61-159437 discloses that (A) the content of propylene homopolymer or ethylene is at most 3.0% by weight;
An ethylene-propylene random copolymer, (B)
A mixture consisting of an ethylene-propylene random copolymer with an ethylene content of 4.0 to 15.0% by weight, and (C) an organic peroxide, the total amount of these homopolymers and copolymers. The content of ethylene in it is 1.5-4
．． 5% by weight, and the mixing ratio of organic peroxide with respect to the total amount of 100% by weight of the homopolymer and copolymer is 0.
．． 001 to 0.25 parts by weight and a melt flow index of 15 g/10 minutes or more is disclosed.

[Problem to be solved by the invention]

However, JP-A-60-55005, JP-A-60-
No. 99147, JP-A-60-168740, JP-A-6
The radiation-resistant polypropylene compositions of No. 1-159437 and JP-A No. 61-73711 do not have sufficient transparency;
There is also a problem that the effect of suppressing deterioration of tensile modulus, impact resistance, etc. after T-ray irradiation is not sufficient.

Also, JP-A-60-215047 and JP-A-60-21
The polypropylene composition of No. 5048 uses a block copolymer of propylene homopolymer and propylene/ethylene random copolymer, so it does not have sufficient transparency to be used in medical devices such as syringes. There's a problem.

Therefore, an object of the present invention is to provide a radiation-resistant polypropylene composition that is excellent in transparency and high-speed moldability, and in which deterioration of impact resistance after T-ray irradiation is suppressed.

[Means to solve the problem]

As a result of intensive research in view of the above objectives, the present inventors have determined that the deterioration of impact resistance etc. after T-ray irradiation is due to an increase in the amount of peroxy radicals generated during T-ray irradiation, and that the specific ethylene content A propylene-ethylene random copolymer with The composition in which the melt flow rate is adjusted by adding and degrading the peroxy radicals has a small increase in the amount of peroxy radicals even after irradiation with T-rays, thereby suppressing the decrease in impact resistance. It was discovered that it has excellent transparency and high-speed moldability, and the present invention was conceived.

That is, the radiation-resistant polypropylene composition of the present invention is
(a) (i) Melt flow rate is 0.5 to 15 g/
10 min propylene homopolymer or ethylene content 1
Gi) a propylene-ethylene random copolymer with a melt flow rate of 0.5-15 g 710 min and an ethylene content of 2.5-5.0 wt% and (b) a sorbitol compound as a clarifying agent in an amount of 0.15 to 0.35 parts by weight based on 100 parts by weight of the resin mixture, and the ethylene content in the resin mixture is 2°. 3～
3.5% by weight, and the melt flow rate of the composition adjusted by degradation is 25 to 100 g/10 min.

The present invention will be explained in detail below.

The resin mixture (a) used in the present invention consists of (1) a propylene homopolymer or a propylene-ethylene random copolymer containing a trace amount of ethylene, and Gi) a propylene-ethylene random copolymer.

The above (i> propylene homopolymer or propylene-ethylene random copolymer containing a trace amount of ethylene is 0
．． Melt flow rate (MFR) of 5-15g/10min
1230°C, 2.16kg load).

If the melt flow rate of the propylene homopolymer or propylene-ethylene random copolymer containing a trace amount of ethylene is less than 0.5, sufficient transparency cannot be obtained, and if it exceeds 15, T-ray irradiation Later impact resistance decreases. A preferred melt flow rate is 1 to 9 g/10 minutes. Further, the ethylene content of the propylene-ethylene random copolymer is 1% by weight or less, preferably 0.5% by weight or less.

The propylene-ethylene random copolymer (11) has a melt flow rate of 0.5 to 15 g/10 minutes and an ethylene content of 2.5 to 5.0% by weight. If the melt flow rate of the propylene-ethylene random copolymer is less than 0.5, sufficient transparency and impact resistance cannot be obtained, and if it exceeds 15, the impact resistance after T-ray irradiation may decrease. growing. The preferred melt flow rate is 1~
It is 9g/10 minutes.

Furthermore, if the ethylene content of the propylene-ethylene random copolymer is less than 2.5% by weight, the impact resistance of the resulting composition after irradiation with gamma rays will decrease. On the other hand, if it exceeds 5.0% by weight, transparency and high-speed moldability will decrease.

In the present invention, a resin mixture of such a propylene homopolymer or a propylene-ethylene random copolymer containing a trace amount of ethylene and a propylene-ethylene random copolymer is used. However, it is necessary to set the blending ratio of the two so that the content of ethylene in the mixture is 2.3 to 3.5% by weight. If the ethylene content in the mixture is less than 2.3% by weight, the impact resistance after irradiation with gamma rays decreases. Moreover, if it exceeds 3.5% by weight, transparency and high-speed moldability will decrease.

The composition of the present invention contains (b) a sorbitol compound as a clarifying agent.

In the present invention, the sorbitol compound is defined by the general formula: %formula% (wherein, R is an alkyl group having 1 to 5 carbon atoms, an alkoxy group, a halogen atom, or a hydroxyl group, and m and n are O to 3). is an integer.R may also represent the same compound,
m and n may be the same in the same compound. ) is a compound represented by Examples of the sorbitol compounds include dibenzylidene sorbitol, (1,
3) 2.4-di(p-methylbenzylidene) sorbitol, (1,3) 2.4-di(p-chlorobenzylidene) sorbitol, (1,3) 2.4-di(p-methoxybenzylidene) sorbitol Examples include. Especially (1,3) 2゜4-di(p-methylbenzylidene)
Sorbitol is preferred.

The amount of the sorbitol compound added is determined by combining the above-mentioned (i) propylene homopolymer or propylene-ethylene random copolymer containing a trace amount of ethylene with 0D propylene-
Total with ethylene random copolymer (resin mixture) 1
0.00 parts by weight, the amount is 0.15 to 0.35 parts by weight. If the amount of the sorbitol compound added is less than 0.15 parts by weight, the effect of improving transparency and high-speed moldability will not be sufficient, and if it exceeds 0.35 parts by weight, it will cause coloring.

Note that a commonly used method may be used to add the sorbitol compound to the propylene resin.

For example, a suitable method is to add a sorbitol compound to a propylene resin and then knead it in an extruder.

In the present invention, a composition comprising such a mixture of propylene resins and a sorbitol compound is degraded in the presence of a radical generator to give a melt flow rate of 25 to 100 g/10 minutes. Note that the object of the present invention can be achieved whether the degradation is performed either before or after blending the sorbitol compound. If the melt flow rate is less than 25 g and 710 minutes, high-speed moldability is insufficient and impact resistance after γ-ray irradiation is also insufficient. On the other hand, if it exceeds 100 g/10 minutes, the impact resistance of the composition itself will decrease. The preferred melt flow rate is 30-8
0g 710 minutes.

Incidentally, the molecular weight reduction by a radical generator can be achieved by a normal method, for example, by melt-kneading the above mixture in an extruder in the presence of a radical generator such as a peroxide at 200 to 280°C for 1 to 3 minutes. This can be done by

As the radical generator, it is preferable to use an organic peroxide. Specific examples include methyl ethyl ketone peroxide, t-butylperoxyisopropyl carbonate, dicumyl peroxide, cumene hydroperoxide, 2.5-dimethyl-2°5-di(t-butylperoxy)hexane, 2. .5-dimethyl-2,5-di(t
-butylperoxy)hexyne-3, di-t-butylperoxyphthalate, and the like. These organic peroxides are used depending on the desired melt flow rate, but
Usually 0.01 to 0.0% per 100 parts by weight of the resin mixture.
It is used in a proportion of 1 part by weight.

The composition of the present invention consists of the above-mentioned (a) propylene-based resin mixture and (b) sorbitol-based compound, but may also contain a hindered amine-based compound, a phosphorus-based antioxidant, and a neutralizing agent as necessary. be able to.

In the present invention, the hindered amine compounds include:
For example, di(2,2,6,6-tetramethyl-4piperidyl)sebacate, 4-benzoyloxy-2゜2,
6.6. -tetramethylpiperidine, succinic acid and N(2
-hydroxyethyl) -condensate with 2,2,6,6-tetramethyl4-hydroxypiperidine, 1.2.3.
4-tetra(2,2,6,6-tetramethyl-4-piperidyl)-butanetetracarboxylate, 1,4-di(2,2,6°6-tetramethyl-4-piperidyl)
-2,3-butanedione, tris-(2,2,6,6-
Tetramethyl-4-piperidyl) trimellitate, 1.
2.2.6.6-bentamethyl-4-piperidyl stearate, 1.2.2.6.6-bentamethyl-4-piperidyl-n-octoate, bis-(1,2°2,6.
6-bentamethyl-4-piperidyl) sebacate, tris-(2,2,6,6-tetramethyl-4-piperidyl)nitrile acetate, 4-hydroxy-2,2,6,
6-tetramethylpiperidine, 4-hydroxy-1,2
,2,6,6pentamethylbiperidine, N,N'-bis(3-aminopropyl)ethylenediamine-2,4-
Bis(N-butyl-N-(1,2,2,6,6-bentamethyl-4-piperidyl)aminoco-6-chloro-1,
3,5-) riazine condensate, poly[((1,1,3,
3-Tetramethylbutyl)imino-1,3,5-)riazine-2,4-diyl) ((2,2,6゜6-tetramethyl-4-piperidyl)imino)hexamethylene(
(2,2,6,6-tetramethyl-4-piperidyl)imino)], poly[(6-morpholino-1,3,5triazine-2,4-diyl) ((2,2,6,6- Tetramethyl-4-piperidyl)imino)hexamethylene (
(2,2,6,6-tetramethyl-4-piperidyl)imino)],]N,N'-bis2.2.6.6-tetramethyl-4-piperidyl)hexamethylenediamine and 1.
Examples include polycondensates with 2-dibromoethane.

The amount of the hindered amine compound added is 0.01 to 1.5 parts by weight per 100 parts by weight of the propylene resin mixture.
Parts by weight are preferred, particularly 0.03 to 1.0 parts by weight. If the amount of the hindered amine compound added is less than 0.01 parts by weight, the effect of suppressing yellowing and deterioration of mechanical strength due to its addition will not be sufficient, and if it exceeds 1.5 parts by weight, the effect will not improve commensurately. I can't get it.

In addition, examples of the phosphorus antioxidant added to the polyolefin in the present invention include alkyl phosphites, alkylaryl phosphites, allyl phosphites, alkyl phosphonites, etc., and specifically distearyl pentaeryth IJ) -rudiphosphite, tris(2,
4-di-t-butylphenyl) phosphite, tetrakis(2,4-di-t-butylphenyl)-4,4'-biphenylene phosphite, cyclic neopentanetetrayl bis(2,4-di t- butylphenyl phosphite), bis(2,6-t-phthyl-4-methylphenyl)pentaerythritol-diphosphite, tetrakis(2,4-di-butylphenyl)-4,4'-piphenylene diphosphonite, 2 , 2'-ethylidenebis(4,6-di-t-butylphenyl)fluorophosphite, and the like.

The amount of the phosphorus antioxidant added is preferably 0.01 to 0.5 parts by weight, particularly preferably 0.01 to 0.2 parts by weight, per 100 parts by weight of the propylene resin mixture.

If the amount of phosphorus antioxidant added is less than 0.01 part by weight,
The effect of its addition is not sufficient, and even if it exceeds 0.5 parts by weight, no commensurate improvement in effect can be obtained.

Furthermore, a neutralizing agent can be added to the polyolefin composition of the present invention. As the neutralizing agent, metal soaps, hydrotalcites, aluminum calcium silicate, oxides and hydroxides of metals of group Ⅰ of the periodic table, etc. can be used.

Examples of the metal soap include calcium stearate, magnesium stearate, barium stearate, and the like. The above-mentioned hydrotalcites include hydrous basic carbonates such as magnesium, calcium, zinc, aluminum, bismuth, etc., or those free from crystallization water, and include natural products and synthetic products. As a natural product, M
g6Aj? 2 (OH) 16C03 and 4H20. In addition, as synthetic products, Mgo,
7 Mo, 3 (Kano) 2 (CO-) 0.15 ・0
．． 54HzO, Mg<, su2(01DI3co3
・3.5H,0, Mg4.1AC (Oll), 2.
,CD,,Zn6Aj! 2(OH)+acL ・4H
20, Ca a jl! 2 (OH), 6CO,・
4H20, Mg+<day 1□ (DH) 29.6 ・
4.2) 1.0 etc. are mentioned. As the above-mentioned metal of Group Ⅰ of the periodic table, magnesium, calcium, zinc, etc. are preferable.

The amount of the neutralizing agent added is preferably 0.01 to 0.5 parts by weight, particularly 0.02 parts by weight, based on 100 parts by weight of the resin mixture.
~0.1 part by weight is preferred. Neutralizing agent content is 0°01
If it is less than 0.5 parts by weight, the effect of reducing yellowing etc. by its addition will not be sufficient, and if it exceeds 0.5 parts by weight, no corresponding improvement in effect will be obtained.

In addition, hindered amine compounds, phosphorus compounds,
To add the neutralizing agent to the propylene resin, the same method as in the case of the sorbitol compound described above may be used.

In addition to the above-mentioned additives, the polypropylene composition may contain other additives as necessary, such as inorganic fillers such as talc, mica, and wollastonite, heat stabilizers, plasticizers, antistatic agents, A mold release agent etc. can be added.

[For production]

The radiation-resistant polypropylene composition of the present invention has excellent impact resistance after T-ray irradiation, transparency, and high-speed moldability.

The reason why such an effect is obtained is not necessarily clear, but it is speculated as follows.

In a mixture of a propylene-ethylene random copolymer and a propylene homopolymer, the melt flow rate of the propylene homopolymer, the ethylene content and melt flow rate of the propylene-ethylene random copolymer,
By setting the ethylene content in these mixtures and the melt flow rate after degradation of the composition within predetermined ranges, the amount of crystals, amount of amorphous, and properties of the crystalline portion in the polymer can be changed, and T It is possible to suppress the production of peroxy radicals, which are a deterioration factor caused by wires, and also to achieve the high rigidity and high crystallization temperature necessary for high-speed moldability. This is thought to be because the above mixture is limited to a range that is optimal in terms of transparency.

〔Example〕

The present invention will be explained in further detail by the following specific examples.

In addition, in each example and comparative example, as an additive,
The following were used.

(a) Sorbitol compound So: (1,3)2,4-di(p-methylbenzylidene) sorbitol [trade name Nigerol MO manufactured by Shinnihon Rika ■] (b) Hindered amine compound Uv, dimethyl succinate-1- (2-hydroxyethyl)-4-hydroxy-2,2,6,6-titramethylpiveridine polycondensate, [trade name Cotinuvin 622LD manufactured by Ciba Geigy] (C) Phosphorous antioxidant PI Nidris (2, 4-di-t-butylphenyl) phosphite [Product name: Mark 2112 (manufactured by Adeka Argus)] (d) Neutralizing agent 5t-Ca Calcium nistearate (manufactured by Nitto Kasei) Examples 1 to 24 and Comparative Example 1 ~11 A propylene-ethylene random copolymer, a propylene homopolymer, a sorgol compound in an amount shown in Table 1 based on a total of 100 parts by weight of the above resin components, a hindered amine compound, and an oxidized An inhibitor and a neutralizing agent are combined, and peroxide (2,5-dimethyl-2,5-di(tertiary-butylperoxy)hexane, Perhekiza 2 manufactured by NOF ■) is added for degradation. .5B> to the melt flow rate shown in Table 1, from 600 to 1500.
They were blended within a ppm range and premixed using a Henschel mixer. This mixture was then heated in an extruder at 230°C (50°C
The mixture was melted and kneaded using a turbulent φ, single screw, L/ml = 28) to degrade and pelletize.

The ethylene content and melt flow rate of the propylene-ethylene random copolymer, the ethylene content in the mixture of the brobylene-ethylene random copolymer and the propylene homopolymer, and the melt flow rate after degradation are set according to Table 1. Shown. In this example, the melt flow rate of the propylene homopolymer was set to be the same as that of the copolymer in order to efficiently knead it with the propylene-ethylene random copolymer.

Furthermore, in each of the above Examples and Comparative Examples, the amount of the hindered amine compound added was 0 to 100 parts by weight of the resin component.
The amount of the antioxidant was 0.1 part by weight, and the amount of the neutralizing agent was 0.05 part by weight.

Next, samples were made from the pellets using an 8-ounce injection molding machine manufactured by Jujuki Co., Ltd. under the following conditions.

Cylinder temperature・・250℃ or 200℃Injection pressure・・
...900kg/Cfft holding pressure...250
kg/CrI holding time...15 seconds Cooling time...10 seconds or 20 seconds Mold...80mm x 80mm x 3mm, 2 film gates Mold temperature...60 ℃ or 30℃ For the test piece thus obtained, 0.2Mra
After T-rays were irradiated at a dose of 2.5 Mrad at d/hr, the impact resistance after T-ray irradiation was measured.

The impact resistance after T-ray irradiation was measured by the DuPont Innoreito method. This method is in accordance with JIS K7211 (general rules for falling weight impact testing methods for hard plastics), using a weight of 100 g.
This is a method of measuring 50% fracture energy under the conditions of a test temperature of 0°C.

Next, /<-oxyl radicals were quantified by the following method on the test piece after the T-ray irradiation.

For quantitative determination of peroxy radicals, a Chemiluminescence Analyzer Model XX-7 manufactured by Tohoku Denshi Sangyo ■ was used. The measurement sample was 0.2g from the test piece after T-ray irradiation.
I used the one cut out. Measurement conditions are temperature 120℃
, the gate time was 10 seconds, and the number of measurements was 50 times, and the total number of measured light emission times was taken as the amount of non-oxy radicals.

Next, we evaluated transparency.

Transparency was determined by measuring haze (haze value) in accordance with JIS 7105 using a color computer model 5M-4-2 manufactured by Suga Test Instruments.

In addition, in the above-mentioned transparency measurement, 250
Injection molded at ℃ 80mmX 80mmX 1 +r+
+n flat plate was used.

Furthermore, high-speed moldability was evaluated.

High-speed moldability was determined by using an 8-ounce injection molding machine made by Jujuki Co., Ltd. to produce a molded product under the following two conditions: A% B.
At this time, the following evaluation was performed depending on the situation when the molded product was released from the mold.

■Molding conditions Mold: 80 mm x 80 x 3 circles,
Cylinder temperature with two film gates...A + 250℃ B: 200℃ Mold...A: 60℃ B: 30℃ Injection pressure... - Next pressure 900kg/cTl secondary Pressure 2
50kg/arj Cycle...Injection + holding pressure 15 seconds, cooling 10 seconds ■Evaluation criteria ○: Actual height under both conditions A and B, no deformation, warping, or poor transparency due to the bottle, and good separation. Indicates type.

Δ: Under either condition A or B, deformation due to the protruding bottle, warping, and poor transparency are observed.

x: Under both conditions A and B, the molded product was not sufficiently solidified and was not released from the mold.

The results are also shown in Table 1.

As is clear from Table 1, the radiation-resistant polypropylene composition of the present invention has good impact resistance after T-ray irradiation, transparency, and high-speed moldability.

On the other hand, the compositions of each comparative example were insufficient in at least one of impact resistance, transparency, and high-speed moldability after T-ray irradiation.

〔Effect of the invention〕

As detailed above, the radiation-resistant polypropylene composition of the present invention comprises (a) (i) a propylene homopolymer having a predetermined melt flow rate or a propylene-ethylene random copolymer containing a trace amount of ethylene; a resin mixture with a propylene-ethylene random copolymer having a predetermined melt flow rate and ethylene content;
The resin mixture contains a sorbitol compound, and the ethylene content in the resin mixture and melt flow rate after degradation are set within a specific range, so impact resistance after radiation irradiation, transparency, and high-speed moldability are all good. It is.

Such a radiation-resistant polypropylene composition of the present invention is suitable for medical instruments, particularly microsyringes.

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Claims (5)

[Claims] (1) (a) (i) Melt flow rate is 0.5 to 15
g/10 min of propylene homopolymer or propylene-ethylene random copolymer with an ethylene content of 1% by weight or less, and (ii) a melt flow rate of 0.5 to 15 g/10 g/10 min.
A resin mixture with a propylene-ethylene random copolymer having an ethylene content of 2.5 to 5.0% by weight in 10 minutes; (b) 0.0% as a clarifying agent per 100 parts by weight of the resin mixture; 15 to 0.35 parts by weight of a sorbitol compound, and the ethylene content in the resin mixture is 2.3 to 0.35 parts by weight.
3.5% by weight, and a melt flow rate of the composition adjusted by degradation is 25 to 100 g/10 minutes. (2) The radiation-resistant polypropylene composition according to claim 1, wherein the sorbitol compound is (1,3)2
, 4-di(p-methylbenzylidene) sorbitol. (3) The radiation-resistant polypropylene composition according to claim 1 or 2, wherein the composition further comprises a resin mixture 1
A radiation-resistant polypropylene composition containing 0.01 to 1.5 parts by weight of a hindered amine compound per 00 parts by weight. (4) The radiation-resistant polypropylene composition according to any one of claims 1 to 3, wherein the composition further contains 0.01 to 0.5 parts by weight of a phosphorous antioxidant per 100 parts by weight of the resin mixture. A radiation-resistant polypropylene composition comprising: (5) The radiation-resistant polypropylene composition according to any one of claims 1 to 4, wherein the composition further contains 0.01 to 0.5 parts by weight of a neutralizing agent per 100 parts by weight of the resin mixture. A radiation-resistant polypropylene composition characterized by: