JPH09296085A - Polypropylene composition and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polypropylene compsn. which has excellent mechanical strength and transparency, is less likely to become fragile upon radiation exposure and less likely to be colored and to provide a pharmaceutical for radiation sterilization and molding for medical applications comprising the polypropylene compsn. SOLUTION: This polypropylene compsn. comprises: 75 to 94wt.% polypropylene (A) having a content of an ethylene-derived unit of 2.5 to 6mol% and an MFR of 5 to 50g/10min; 5 to 15wt.% straight-chain, low-density polyethylene (B) having a density of 0.905 to 0.919g/cm<3> , a degree of crystallization of not less than 30%; 1 to 10wt.% ethylene/-1-butene copolymer (C) having a degree of crystallization of less than 30%; and, based on 100 pts.wt. in total of the components (A) to (C), 0.0001 to 0.05 polymer nucleating agent (D), 0.01 to 1.0 pts.wt. org. nucleating agent (E) having a mol.wt. of not more than 1,000, 0.01 to 1.0 pts.wt. org. phosphorus-based heat-resistant stabilizer (F), and 0.01 to 1.0 pts.wt. hindered amine photostabilizer (G).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION The present invention relates to a polypropylene composition suitable for use as a molding material used for irradiation such as sterilization by irradiation, and its use.

[0002]

BACKGROUND OF THE INVENTION Polypropylene has excellent transparency, heat resistance and mechanical properties, and has been conventionally used as various molding materials. For example, a molded product obtained by blending polypropylene with an organic nucleating agent such as a sorbitol compound is sterilized by radiation and used for pharmaceutical and medical applications.

However, the polypropylene molded body is
When it was irradiated with radiation, it became brittle, and in some cases, it was colored yellow due to irradiation. Therefore, when a known impact resistance improver is added to polypropylene to improve embrittlement due to radiation irradiation, for example, a rubber such as a conjugated diene rubber or ethylene / propylene random copolymer (EPR) is used as the impact resistance improver. When components are added, the composition becomes too soft and the mechanical strength becomes insufficient, and when soft polyethylene is added, the transparency tends to decrease.

[0004] Further, the one obtained by adding only the organic nucleating agent to polypropylene as described above is inferior in the mold releasability at the time of molding, the molding cycle (required time) becomes long, and the productivity cannot be said to be good. Further, polypropylene having no organic nucleating agent added, for example, a heat-resistant stabilizer such as a phenolic stabilizer has insufficient heat-resistant stability and may be colored yellow when irradiated with radiation to reduce the hue. there were.

Therefore, it is excellent in transparency and mechanical strength,
It has been desired to develop a polypropylene composition that is stable even when irradiated with radiation and is suitable for use as a molded product such as a syringe that is used after radiation sterilization.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and is a polypropylene composition which is excellent in mechanical strength and transparency and which is not easily brittle when exposed to radiation and is not easily colored. The object of the present invention is to provide a radiation-sterilized medicinal / medical molded article comprising the product and the polypropylene composition.

[0007]

SUMMARY OF THE INVENTION The polypropylene composition according to the present invention comprises:
(A) Contains units derived from ethylene in an amount of 2.5 to 6 mol% and is 230 in accordance with ASTM D1238.
Polypropylene having a melt flow rate MFR of 5 to 50 g / 10 minutes measured under a temperature of 2.16 kg and a temperature of 75;
~ 94% by weight, and (B) density is 0.905 to 0.9919g
/ Cm ³ and a crystallinity of 30% or more, a linear low-density polyethylene; 5 to 15% by weight, and (C) an ethylene / 1-butene copolymer having a crystallinity of less than 30%. 1-
10% by weight, and (D) 0.0001 to 0.05 part by weight of the polymer nucleating agent, and (E) 0.01 to 1 with respect to 100 parts by weight of the above (A) to (C). 0.0 parts by weight of an organic nucleating agent having a molecular weight of 1000 or less, (F) 0.01 to 1.0 parts by weight of an organic phosphorus heat stabilizer, and (G) of 0.01 to
It is characterized by comprising 1.0 part by weight of a hindered amine light stabilizer.

The (D) polymer nucleating agent is poly-3-methyl.
It is preferably -1-butene. The molded article formed from the polypropylene composition according to the present invention is suitable as a pharmaceutical / medical molded article for radiation sterilization.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The polypropylene composition according to the present invention and its use will be specifically described below.

In the present invention, the term "polymerization" means
The term "polymer" may be used to mean not only homopolymerization but also copolymerization, and the term "polymer" may be used to include not only homopolymer but also copolymer.

The polypropylene composition according to the present invention comprises
(A) Polypropylene, (B) Linear low-density polyethylene (L-LDPE), (C) Resin component containing ethylene / 1-butene copolymer, (D) Polymer nucleating agent and (E) Molecular weight An organic nucleating agent comprising a combination of 1,000 or less organic nucleating agents, and (F) an organophosphorus heat-resistant stabilizer,
(G) A hindered amine light stabilizer.

First, each of these components will be described. (A) Polypropylene In the present invention, as polypropylene (A), a unit derived from ethylene is 2.5 to 6 mol%, preferably 3 to 5
A propylene / ethylene copolymer containing in an amount of mol% is used.

This polypropylene has a melt flow rate MFR (according to ASTM D1238, 230 ° C.,
The value measured under a load of 2.16 kg) is 5 to 50 g / 10 minutes, preferably 10 to 30 g / 10 minutes.

In the present invention, a propylene / ethylene copolymer containing units derived from ethylene in the above amount is widely used, and the copolymer is preferably a random copolymer of propylene and ethylene.

The polypropylene (A) may contain a small amount of units derived from other copolymerizable monomers, such as α-olefin, as long as the object of the present invention is not impaired.

The polypropylene described above has a melting point Tm (temperature at the maximum peak position in the endothermic curve after once melting and solidifying) measured by a differential scanning calorimeter (DSC) of 100 ° C. or higher, preferably 125 to 170. It is desirable that the temperature is ° C.

In the present invention, polypropylene produced by various methods can be used, but it is desirable to use polypropylene produced by a catalyst for producing highly stereoregular polypropylene. Examples of such a catalyst for producing highly stereoregular polypropylene include titanium,
A solid titanium catalyst component containing magnesium, a halogen and, if necessary, an electron donor, a solid titanium catalyst formed from an organoaluminum compound and, if necessary, an electron donor, or a crosslinked metallocene compound and an organic compound; Metallocene-based catalysts using an aluminum oxy compound as a catalyst component are exemplified. A method for producing polypropylene using such a catalyst is described in, for example, JP-A-50-108385, which uses a solid titanium catalyst.
JP-A-50-126590, JP-A-51-20297
JP-A-51-28189, JP-A-52-1516
Details are described in publications such as No. 91. The techniques described therein can also be used in the present invention.

(B) Linear low-density polyethylene In the present invention, linear low-density polyethylene (L ) having a density of 0.905 to 0.919 g / cm ^{3 and} preferably 0.910 to 0.917 g / cm ^3. -LDPE) is used.

The crystallinity of the linear low-density polyethylene measured by the X-ray diffraction method is 30% or more, preferably 45.
５０50%. Linear low density polyethylene has a melting point (T
m), and has a melting point (Tm) measured by DSC of 100 to 130 ° C., preferably 105 to 12 ° C.
Desirably, the temperature is 5 ° C.

The present invention is not particularly limited except that the density and crystallinity are within the above ranges, and L-LDPE produced by a method known as linear low density polyethylene (B) is used. It can be widely used.

Linear low density polyethylene is a random copolymer of ethylene and a small amount of α-olefin,
Usually, the unit derived from the α-olefin is contained in an amount of 1 to 5 mol%, preferably 2 to 4 mol%.

As the α-olefin copolymerized with ethylene, for example, propylene, 1-butene, 1-pentene,
1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-
Pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene,
4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene and the like can be mentioned.

Of these, 4-methyl-1-pentene, 1-butene, 1-hexene and the like are preferable. These are 2
More than one kind may be copolymerized. The linear low-density polyethylene may contain a small amount of units derived from other copolymerizable monomers, for example, α-olefin, as long as the characteristics of the present invention are not impaired.

The linear low-density polyethylene as described above can be produced by a generally known medium / low pressure process using a titanium-based catalyst, a vanadium-based catalyst or a metallocene-based catalyst as a catalyst.

In the present invention, among the above as the linear low-density polyethylene (B), ethylene-4-methyl-1-
A pentene copolymer, an ethylene / 1-butene copolymer, and an ethylene / 1-hexene copolymer are particularly preferably used.

(C) Ethylene / 1-butene Copolymer In the present invention, the crystallinity measured by X-ray diffraction is 3
Less than 0%, preferably 20% or less, more preferably 15%
The following ethylene / 1-butene copolymer (EBR) is used. The ethylene / 1-butene copolymer is preferably amorphous or low crystalline, and is preferably an amorphous elastomeric material.

The ethylene / 1-butene copolymer used in the present invention desirably contains units derived from 1-butene in an amount of 5 to 25 mol%, preferably 7 to 22 mol%.

This ethylene / 1-butene copolymer is a DS
The glass transition temperature Tg measured at C is −55 ° C. or lower, preferably −60 ° C. or lower, or the melting point measured as the main peak by DSC is 90 ° C. or lower, preferably 80 ° C. or lower, particularly preferably 70 ° C. It is desirable that:

This ethylene / 1-butene copolymer is
A random copolymer of ethylene and 1-butene is desirable, and the parameter (B value) indicating the randomness of the ethylene / 1-butene chain distribution is 1.0 to 1.4. It is desirable to be excellent. The B value is
It is a random distribution index, and the molar fraction P _BE of ethylene / 1-butene alternating chains with respect to all dyad chains in the copolymer
Is divided by twice the product of the ethylene content (mole fraction) P _E and the 1-butene content (mole fraction) P _B.

B = P _BE / [2 (P _E · P _B )] Such P _E , P _B and P _BE values are specifically ¹³ C
By NMR (hexachlorobutadiene solvent), G.I.
J. Ray (Macromolecules, 10 , 773 (1977)); C.
Randall (Macromolecules, 15 , 353 (1982)); Poly
mer Science, Polymer Physics Ed., 11 , 275 (1973)),
K. It can be determined based on the report of Kimura (Polymer, 25 , 441 (1984)).

The B value is 2 when the ethylene / 1-butene random copolymer is a perfect alternating copolymer, and 0 when it is a perfect block copolymer. The ethylene / 1-butene copolymer may contain a unit derived from another monomer, for example, an α-olefin as long as the object of the present invention is not impaired.

The ethylene / 1-butene copolymer as described above can be produced by a known method, but it is preferably produced using a vanadium catalyst or a metallocene catalyst.

(D) Polymer Nucleating Agent The polymer nucleating agent used in the present invention has a melting point (Tm) of 2
Any polymer having a temperature of 50 ° C. or higher may be used, and examples thereof include polymers derived from branched olefins. Specifically, 3-methyl-1-butene, 3,3-dimethyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-
Pentene, 3-methyl-1-hexene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl- 1-hexene, 3,5,
Homopolymers or copolymers of 5-trimethyl-1-hexene, vinylcyclopentane, vinylcyclohexane, vinylcycloheptane, vinylnorbornane, allylnorbornane, styrene, dimethylstyrene, allylbenzene, allyltoluene, allylnaphthalene, vinylnaphthalene, etc. Is mentioned.

Among these, especially poly-3-methyl-1-
Butene and polyvinyl cyclohexane are preferably used. When forming a polypropylene composition, such a polymer nucleating agent may be used after forming a polymer mixture (masterbatch) containing the nucleating agent in a high concentration. For example, the polymer nucleating agent is used as a masterbatch. A polymer included as a prepolymer may be used. It may also be a kneaded product of a polymer nucleating agent and another polymer. The polymer (diluent) that forms the masterbatch together with the polymer nucleating agent may be the above-mentioned component such as (A), or may be a polymer other than (A), (B) and (C). This polymer (diluent) is preferably a crystalline polyolefin, especially a crystalline homopolypropylene.

(E) Organic Nucleating Agent Having a Molecular Weight of 1,000 or Less The polypropylene composition according to the present invention contains an organic nucleating agent (E) having a molecular weight of 1,000 or less as a nucleating agent together with the above-described polymer nucleating agent (D). . This organic nucleating agent (E)
As the organic compound, an organic compound having a molecular weight of 1,000 or less known as a nucleating agent is widely used.

Examples of such an organic nucleating agent include dibenzylidene sorbitols.
-p-Methyldibenzylidene sorbitol, 1,3,2,4-dibenzylidene sorbitol, 1,3-benzylidene-2,4-p-
Methylbenzylidene sorbitol, 1,3-benzylidene-
2,4-p-Ethylbenzylidene sorbitol, 1,3-p-Methylbenzylidene-2,4-benzylidene sorbitol, 1,3-p-
Ethylbenzylidene-2,4-benzylidene sorbitol,
1,3-p-methylbenzylidene-2,4-p-ethylbenzylidene sorbitol, 1,3-p-ethylbenzylidene-2,4-p-methylbenzylidene sorbitol, 1,3,2,4-di (p- Methylbenzylidene) sorbitol, 1,3,2,4-di (p-ethylbenzylidene) sorbitol, 1,3,2,4-di (pn-propylbenzylidene) sorbitol, 1,3,2,4-di (pi -Propylbenzylidene) sorbitol, 1,3,2,4-di (pn-butylbenzylidene) sorbitol, 1,3,2,4-di (ps-butylbenzylidene) sorbitol, 1,3,2,4-di ( pt-butylbenzylidene) sorbitol, 1,3,2,4-di (2 ', 4'-dimethylbenzylidene) sorbitol, 1,3,2,4-di (p-methoxybenzylidene) sorbitol, 1,3,2 1,4-di (p-ethoxybenzylidene) sorbitol, 1,3-benzylidene-2
-4-p-chlorobenzylidene sorbitol, 1,3-p-chlorobenzylidene-2,4-benzylidene sorbitol, 1,3-p-
Chlorbenzylidene-2,4-p-methylbenzylidene sorbitol, 1,3-p-chlorobenzylidene-2,4-p-ethylbenzylidene sorbitol, 1,3-p-methylbenzylidene-2,4
Examples thereof include -p-chlorobenzylidene sorbitol, 1,3-p-ethylbenzylidene-2,4-p-chlorobenzylidene sorbitol, and 1,3,2,4-di (p-chlorobenzylidene) sorbitol.

Among these, especially benzylidene sorbitol, 1,3,2,4-dibenzylidene sorbitol, 1,3,2,
4-di (p-methylbenzylidene) sorbitol, 1,3,2,4-
Di (p-ethylbenzylidene) sorbitol, 1,3-p-chlorobenzylidene-2,4-p-methylbenzylidenesorbitol, 1,3,2,4-di (p-chlorobenzylidene) sorbitol and the like are preferably used.

Examples of the organic nucleating agent (E) having a molecular weight of 1000 or less include aromatic benzoates such as aluminum benzoate, aluminum pt-butylbenzoate, sodium adipate, sodium thiophenecarboxylate, and sodium pyrrolecarboxylate. Metal salts of group carboxylic acids, inorganic compounds such as talc, and phosphate salts represented by the following formula can also be used.

[0039]

Embedded image

(In the formula, R ¹ is oxygen, sulfur or carbon number 1
A 10 hydrocarbon group, R ^2, R ³ is hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, R ^2, R ³ may be heterologous be homologous, R ² to each other , R ^{3 and} R ²
And R ³ may be bonded to form a ring, and M is 1 to 3
Is a valent metal atom, and n is an integer of 1 to 3. ) Specifically, sodium-2,2'-methylene-bis (4,6-di-
(t-butylphenyl) phosphate, sodium-2,2'-
Ethylidene-bis (4,6-di-t-butylphenyl) phosphate, lithium-2,2'-methylene-bis- (4,6-di-t-butylphenyl) phosphate, lithium-2,2 ' -Ethylidene-bis (4,6-di-t-butylphenyl) phosphate, sodium-2,2'-ethylidene-bis (4-i-propyl-
6-t-butylphenyl) phosphate, lithium-2,2'-
Methylene-bis (4-methyl-6-t-butylphenyl) phosphate, lithium-2,2'-methylene-bis (4-ethyl-6-
t-butylphenyl) phosphate, calcium-bis [2,2'-thiobis (4-methyl-6-t-butylphenyl) phosphate], calcium-bis [2,2'-thiobis (4-ethyl-6 -t-butylphenyl) phosphate], calcium-bis [2,2'-thiobis- (4,6-di-t-butylphenyl) phosphate], magnesium-bis [2,2'-thiobis (4, 6-di-t-butylphenyl) phosphate],
Magnesium-bis [2,2'-thiobis- (4-t-octylphenyl) phosphate], sodium-2,2'-butylidene-bis (4,6-di-methylphenyl) phosphate, sodium-2, 2'-butylidene-bis (4,6-di-t-butylphenyl) phosphate, sodium-2,2'-t-octylmethylene-bis (4,6-di-methylphenyl) phosphate, sodium-2 , 2'-t-octylmethylene-bis (4,6-
Di-t-butylphenyl) phosphate, calcium
Bis- (2,2'-methylene-bis (4,6-di-t-butylphenyl) phosphate), magnesium-bis [2,2'-methylene-bis (4,6-di-t-butylphenyl) ) Phosphate], barium-bis [2,2'-methylene-bis (4,6-di-t-
Butylphenyl) phosphate], sodium-2,2'-
Methylene-bis (4-methyl-6-t-butylphenyl) phosphate, sodium-2,2'-methylene-bis (4-ethyl-
6-t-butylphenyl) phosphate, sodium (4,
4'-dimethyl-5,6'-di-t-butyl-2,2'-biphenyl) phosphate, calcium-bis [(4,4'-dimethyl-6,6'-
Di-t-butyl-2,2'-biphenyl) phosphate], sodium-2,2'-ethylidene-bis (4-m-butyl-6-t-butylphenyl) phosphate, sodium-2,2 ' -Methylene-bis (4,6-di-methylphenyl) phosphate, sodium-2,2'-methylene-bis (4,6-di-ethylphenyl) phosphate, potassium-2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate, calcium-bis [2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate], magnesium-bis [2,2 ' -
Ethylidene-bis (4,6-di-t-butylphenyl) phosphate], barium-bis [2,2'-ethylidene-bis (4,6
-Di-t-butylphenyl) phosphate], aluminum-tris [2,2'-methylene-bis (4,6-di-t-butylfell) phosphate] and aluminum-tris [2,
2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate] and the like.

[0041]

Embedded image

(In the formula, R ⁴ is hydrogen or has 1 to 10 carbon atoms.
Wherein M is a monovalent to trivalent metal atom,
n is an integer of 1 to 3. ) Specifically, sodium-bis (4-t-butylphenyl)
Phosphate, sodium-bis (4-methylphenyl) phosphate, sodium-bis (4-ethylphenyl) phosphate, sodium-bis (4-i-propylphenyl) phosphate, sodium-bis (4-t-
Octylphenyl) phosphate, potassium-bis (4
-t-butylphenyl) phosphate, calcium-bis (4-t-butylphenyl) phosphate, magnesium
-Bis (4-t-butylphenyl) phosphate, lithium-bis (4-t-butylphenyl) phosphate, aluminum-bis (4-t-butylphenyl) phosphate and the like.

In the present invention, among the above organic nucleating agents, dibenzylidene sorbitols are preferable, and mono-p-methyldibenzylidene sorbitol, 1,3,2,4- is particularly preferable.
Dibenzylidene sorbitol, 1,3,2,4-di (p-methylbenzylidene) sorbitol and the like are preferably used.
Two or more kinds of organic nucleating agents (E) can be used.

When the polypropylene composition contains the nucleating agent as described above, the crystal grains can be made finer and the crystallization rate can be improved to enable high-speed molding. (F) Organic Phosphorus Heat-Resistant Stabilizer In the present invention, among the compounds known as heat-resist stabilizers, organophosphorus compounds are particularly used. Specifically, for example, trioctyl phosphite, trilauryl phosphite, tridecyl phosphite, octyl-diphenyl phosphite, tris (2,4-di-tert-butylphenyl)
Phosphite, triphenylphosphite, tris (butoxyethyl) phosphite, tris (nonylphenyl) phosphite, distearyl pentaerythritol diphosphite, tetra (tridecyl) -1,1,3-tris (2-methyl-5) -tert- butyl-4-hydroxyphenyl) butane diphosphite, tetra (C ₁₂ -C ₁₅ mixed alkyl) -4,4'-isopropylidene diphenyl diphosphite, tetra (tridecyl) -4,4'-butylidene bis ( 3-methyl-6-tert-butylphenol) diphosphite, tris (3,5-di-tert-butyl-4-hydroxyphenyl) phosphite, tris (mono / di mixed nonylphenyl) phosphite, hydrogenation-4,4 '-Isopropylidene diphenol polyphosphite, bis (octylphenyl) -bis [4,4'-butylidene bis (3-methyl-6-tert-butylpheno )] ・ 1,6-Hexanediol diphosphite, phenyl ・ 4,4'-isopropylidene diphenol pentaerythritol diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite ,
Bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, tris [4,4'-isopropylidene bis (2-tert-butylphenol)] phosphite, phenyl diisodecylphosphite, Di (nonylphenyl) pentaerythritol diphosphite), tris (1,3-di-stearoyloxyisopropyl) phosphite, 4,4'-isopropylidene bis (2-ter
t-Butylphenol) ・ di (nonylphenyl) phosphite, 9,10-di-hydro-9-oxa-10-phosphaphenanthrene-10-oxide, tetrakis (2,4-di-tert-butylphenyl) -4,4'-biphenylene diphosphonite and the like.

Two or more of these may be used in combination. Among these, tris (2,4-di-tert-butylphenyl) phosphite and tris (mono / di mixed nonylphenyl) phosphite are preferably used.

(G) Hindered Amine Light Stabilizer In the present invention, a hindered amine compound is used among known compounds as a light stabilizer, and all hydrogens bonded to carbons at the 2nd and 6th positions of piperidine are used. A hindered amine compound having a structure in which is substituted with a methyl group is used without particular limitation. Specifically, for example, bis (2,2,6,6-tetramethyl-4-piperidine) sebacate, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-succinate. Tetramethylpiperidine polycondensate, poly [[6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2-4-diyl] [(2,2,6,6 -Tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,
6,6-Tetramethyl-4-piperidyl) imino]], tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, 2,2, 6,6-tetramethyl-4
-Piperidyl benzoate, bis- (1,2,2,6,6-pentamethyl-4-piperidyl) -2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate , Bis- (N-methyl-2,
2,6,6-Tetramethyl-4-piperidyl) sebacate, 1,1'-
(1,2-ethanediyl) bis (3,3,5,5-tetramethylpiperazinone), (mixed 2,2,6,6-tetramethyl-4-piperidyl / tridecyl) -1,2,3 , 4-butanetetracarboxylate, (mixed 1,2,2,6,6-pentamethyl-4-piperidyl / tridecyl) -1,2,3,4-butanetetracarboxylate, mixed {2,2, 6,6-Tetramethyl-4-piperidyl / β, β, β ', β'-Tetramethyl-3,9- [2,4,8,10-
Tetraoxaspiro (5,5) undecane] diethyl} -1,
2,3,4-butane tetracarboxylate, mixed {1,
2,2,6,6-Pentamethyl-4-piperidyl / β, β, β ', β'-
Tetramethyl-3,9- [2,4,8,10-tetraoxaspiro (5,5)
Undecane] diethyl} -1,2,3,4-butanetetracarboxylate, N, N′-bis (3-aminopropyl) ethylenediamine-2-4-bis [N-butyl-N- (1,2,2 , 6,6-pentamethyl
-4-Piperidyl) amino] -6-chloro-1,3,5-triazine condensate, poly [[6-N-morpholyl-1,3,5-triazine-2-4-
Diyl] [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene [(2,2,6,6-tetramethyl-4-piperidyl) imino]], N, N'-bis (2,2,6,6-tetramethyl-4-
Piperidyl) hexamethylene diamine and 1,2-dibromoethane condensate, [N- (2,2,6,6-tetramethyl-4-piperidyl) -2-methyl-2- (2,2,6, 6-tetramethyl-4-piperidyl) imino] propionamide and the like.

Of these, bis (2,2,6,6-tetramethyl-4-piperidine) sebacate and the like are particularly preferably used. Polypropylene composition The polypropylene composition according to the present invention contains 75 to 94% by weight of (A) polypropylene as described above, preferably 8%.
5 to 15% by weight of linear low-density polyethylene (L-LDPE) (B) in an amount of 5 to 94% by weight, preferably 6 to 1
It contains 3% by weight of (C) ethylene / 1-butene copolymer (EBR) in an amount of 1 to 10% by weight, preferably 1 to 5% by weight, and further comprises (A) to (C ), And (D) polymer nucleating agent is added to 0.00
01-0.05 parts by weight, preferably 0.0002-0.00
In an amount of 5 parts by weight, (E) an organic nucleating agent having a molecular weight of 1000 or less is 0.01 to 1.0 parts by weight, preferably in an amount of 0.05 to 0.5 parts by weight, (F) an organophosphorus heat-resistant stabilizer The agent is 0.01-1.
0 parts by weight, preferably 0.05 to 0.5 parts by weight, and 0.01 to 1.0 parts by weight of the (G) hindered amine light stabilizer, preferably 0.05 to 0.5 parts by weight. Contained in.

As described above, in the present invention, a resin component containing a specific elastomeric EBR, a nucleating agent comprising a combination of a polymer nucleating agent and an organic nucleating agent having a molecular weight of 1000 or less, a heat stabilizer and a heat stabilizer selected in particular A polypropylene composition is formed by a specific combination with a light stabilizer, and thereby a polypropylene composition is obtained in which mechanical properties are unlikely to deteriorate even when irradiated with radiation and the hue is unlikely to change.

When polypropylene having an ethylene content of less than 2.5 mol% is used instead of polypropylene (A) among the resin components forming the polypropylene composition, the impact strength and the polypropylene composition May have poor transparency, or L-LDPE
The polypropylene composition containing no (B) is rigid (FM)
The polypropylene composition containing polyethylene having a density exceeding 0.919 g / cm ³ instead of L-LDPE (B) may have poor impact strength and transparency, and does not contain EBR (C). The polypropylene composition
Poor impact strength (IZ, drop strength) and transparency (HAZE).

Further, for example, a polypropylene composition containing no polymer nucleating agent (D) may be inferior in transparency (HAZE) and moldability, and as an additive, an organic phosphorus heat-resistant stabilizer (F) or a hindered amine light-stable stabilizer. The polypropylene composition not containing any of the agents (G) may deteriorate the resin during pelletizing or molding to increase the MFR, or may decrease the hue after γ-ray irradiation.

The polypropylene composition according to the present invention as described above may further contain other polymers, rubber components, other additives, etc., if necessary, as long as the objects of the present invention are not impaired. Also, for example, other polyethylene (HDPE, high pressure method LDPE), polymer nucleating agent diluent polymer, EPR, other heat stabilizers, hydrochloric acid absorbers, heat stabilizers, weather stabilizers, light stabilizers, UV absorbers. , Slip agent, anti-blocking agent, anti-fog agent, lubricant, antistatic agent, flame retardant, pigment, dye, inorganic filler, organic filler, dispersant, copper damage inhibitor, neutralizing agent, foaming agent, plasticizer , A bubble preventive agent, a cross-linking agent, a flowability improving agent such as peroxide, a weld strength improving agent, a natural oil, a synthetic oil, a wax and the like may be contained.

The polypropylene composition according to the present invention is a kneaded product of the above components, and can be obtained by a method of preparing (kneading) a conventionally known resin composition from the components. Specifically, each component is charged simultaneously or sequentially into, for example, a Henschel mixer, a V-type blender, a tumbler blender, a ribbon blender and the like, and after kneading, a single-screw extruder, a multi-screw extruder, a kneader, It is obtained by melt-kneading with a Banbury mixer or the like.
Among these, it is preferable to use a device having excellent kneading performance, such as a multi-screw extruder, a kneader, or a Banbury mixer, since a high-quality polypropylene composition in which each component is more uniformly dispersed can be obtained.

The above-mentioned components are compatible with each other and are excellent in kneading property, and easily form a homogeneously kneaded polypropylene composition. The polypropylene composition includes an injection molding method, an injection blow molding method, a direct blow molding method, a T die method, an inflation method,
A container-shaped, sheet-shaped or film-shaped molded product can be obtained by utilizing a molding method known per se such as a pressing method.

Particularly, the molded product comprising the polypropylene composition according to the present invention is suitable for use as a medical / medical molded product to be subjected to radiation sterilization treatment, for example, a vial bottle, a tablet bottle,
It can be suitably used in fields requiring sterilization by radiation, such as prefilled syringes, test tubes, drug containers such as petri dishes, dialyzers, waste blood tanks, and medical instruments such as syringes.

In the present invention, the radiation (including electron beam) is not particularly limited, but, for example, α-ray, β-ray, γ-ray, Van de Clark type electron accelerator, Cockcroft Walton type electron accelerator, insulation transformer type electron accelerator, transformer type gas (oil) insulation type accelerator, cold cathode shock voltage type electron accelerator,
An electron beam from a linear filament type electron accelerator or the like or radiation can be used. Further, X-rays can be mentioned.

The irradiation method is not particularly limited, and examples thereof include irradiation of a polypropylene composition molded body which has been molded into a predetermined shape in advance by a method such as injection molding, extrusion molding or compression molding. A so-called in-line method in which irradiation is performed at the same time as molding may be used. In the case of medical radiation sterilization treatment, it is preferable to give a predetermined shape to the polypropylene composition in advance and perform irradiation in a completely sealed state.

[0057]

The polypropylene composition according to the present invention comprises:
It has excellent radiation resistance, its mechanical strength does not easily decrease due to irradiation, and its hue does not change easily.

The polypropylene composition according to the present invention as described above is highly useful for applications such as pharmaceutical containers and medical instruments which are subjected to radiation sterilization. In particular, when the polypropylene composition according to the present invention is molded into a syringe by injection molding, even if sterilized by irradiation,
Since the mechanical strength, especially the impact resistance is not deteriorated and the transparency is maintained, it can be conveniently applied to visual inspection.

[0059]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to these examples.

The components used in Examples and Comparative Examples are shown below. (A) Polypropylene PP-1: Propylene / ethylene random copolymer (ethylene unit content 4 mol%) (MFR: 20 g / 10 min) PP-2: Propylene / ethylene random copolymer (ethylene unit content 2 mol%) (MFR: 20 g / 10 min) (B) L-LDPE (linear low-density polyethylene) PE-1: ethylene-4-methyl-1-pentene copolymer density 0.915 g / cm ³ MFR 15 g / 10 min ( Ethylene unit content 97 mol%) (Crystallinity 35%) PE-2: ethylene-4-methyl-1-pentene copolymer Density 0.920 g / cm ³ MFR 20 g / 10 min (Ethylene unit content 97.5 mol% ) (Crystallinity 40%) (C) Ethylene / 1-butene copolymer EBR: (Crystallinity 19%) (Ethylene unit content 89 mol%) (D) Polymer nucleating agent poly-3-methyl-1-butene To Homopolypropylene contained in an amount of 500 ppm (E) Organic nucleating agent having a molecular weight of 1,000 or less Mono-p-methyldibenzylidene sorbitol (F) Organic phosphorus heat stabilizer Tris (2,4-di-tert-butylphenyl) phosphite (G) Hindered amine light stabilizer Bis (2,2,6,6-tetramethyl-4-piperidine) sebacate Other ingredients Calcium stearate (hydrochloric acid absorbent) X: Tetrakis [methylene-3- (3,5-di) -tert-butyl-4-
Hydroxyphenyl) propionate] methane, Y: n-octadecyl-3- (4'-hydroxy-3 ', 5'-di-tert-
Butylphenyl) propionate

[0061]

Example 1 Polypropylene compositions were obtained by melt-kneading the components in the amounts shown in Table 1 at 230 ° C. The obtained polypropylene composition was tested as follows. The results of the tests (1) to (5) below are shown in Table 1, and the results of the tests (6) to (7) are shown in Table 2.

(1) Initial flexural modulus: FM (kg / cm ² ) Measured in accordance with ASTM D790. (2) Izod impact strength: IZ (kg · cm / cm) Measured in accordance with ASTM D256 (test temperature 23 ° C).

(3) Transparency: Haze (%) Test method ASTM D1003 Injection-molded square plate with a thickness of 2 mm (4) Moldability: 24 syringes under the conditions of resin temperature 230 ° C., mold temperature 40 ° C., 1 cycle 25 seconds It was evaluated by the releasability from the mold when injection molding was performed.

◯ ... No clinging of the product to the mold occurred, and good mold releasability was exhibited. X: The product was hugged by the mold, and the releasability was poor. (5) Drop strength After irradiating a syringe (injection-molded article) with a dose of 25 KGy of γ-ray, a metal weight weighing 45 g was dropped from a height of 195 cm onto the syringe at a temperature of 23 ° C. to test the syringe strength.
Tested with 20 syringes.

◯ ... No crack was found. × ... One or more cracks. (6) Yellowness after γ-ray irradiation: b value The polypropylene composition pellets thus obtained were exposed to γ-ray at 25K.
The yellowness after irradiation with the Gy dose was evaluated as the b value obtained by a spectral color difference meter (manufactured by Minolta). The larger the b value, the stronger the yellowness.

(7) Hue after γ-Ray Irradiation The polypropylene composition was injection molded into a square plate having a thickness of 2 mm, and the hue when the square plate was irradiated with 25 KGy of γ-ray was visually evaluated.

[0067]

[Comparative Examples 1-5] In Example 1, the resin component (A)
A composition was obtained in the same manner as in Example 1 except that (C) was replaced with each component shown in Table 1. The results of tests (1) to (5) are shown in Table 1.

[0068]

[Table 1]

[0069]

Comparative Examples 6 to 9 Compositions were obtained in the same manner as in Example 1 except that the additives shown in Table 2 were added to the same resin components as in Example 1. The results of tests (6) to (7) are shown in Table 2.

[0070]

[Table 2]

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Claims (3)

[Claims] (1) The unit derived from (A) ethylene is 2.5
230 ° C. 2.16 kg according to ASTM D1238
Melt flow rate MFR measured under load is 5-5
Polypropylene; 75-94% by weight, (B) density is 0.905-0.919 g / cm ³ , and crystallinity is 30.
% To 15% by weight; and (C) ethylene having a crystallinity of less than 30%.
1-butene copolymer; 1 to 10% by weight, and with respect to 100 parts by weight of the above (A) to (C) in total,
(D) 0.0001 to 0.05 part by weight of a polymer nucleating agent, and (E) 0.01 to 1.0 part by weight of a molecular weight of 1000.
The following organic nucleating agent, (F) 0.01 to 1.0 parts by weight of an organophosphorus heat stabilizer, and (G) 0.01 to 1.0 parts by weight of a hindered amine light stabilizer. A polypropylene composition comprising: 2. The polymer nucleating agent (D) is poly-3-methyl.
-The polypropylene composition according to claim 1, which is -1-butene. 3. A pharmaceutical / medical molding for radiation sterilization, which comprises the polypropylene composition according to claim 1 or 2.