JP2004315680A - Polyolefin resin for radiation sterilization, and its molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyolefin resin for radiation sterilization, with controlled occurrence of an odor accompanying radiation sterilization treatment, and its molded article. <P>SOLUTION: The polyolefin resin for radiation sterilization is obtained by blending 100 pts.wt. of a polyolefin resin with 0.045 pt.wt. or less of a hydrochloric acid absorbent and 0.005 pt.wt. or less of an antioxidant. The polyolefin resin for radiation sterilization includes one wherein the polyolefin resin comprises an ethylene-α-olefin copolymer. A molded article and a film are provided which are made from the polyolefin resin for radiation sterilization. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a radiation-sterilized polyolefin resin and a molded product thereof. More specifically, the present invention relates to a polyolefin resin for radiation sterilization in which generation of odor due to radiation irradiation sterilization is suppressed, and a molded article thereof.
[0002]
[Prior art]
BACKGROUND ART Polyolefin resins are excellent in mechanical properties, thermal properties, moldability, etc., are lightweight and relatively inexpensive, and are therefore used as various molded articles, for example, films and fibers. In addition, polyolefin resins are excellent in hygiene and are therefore widely used especially for applications such as food containers and medical instruments. Many of food containers and medical instruments are sterilized by irradiation before use.
[0003]
As a molded body sterilized by irradiation, for example, Japanese Patent Application Laid-Open No. H11-255824 describes a food container for irradiation which does not generate odor even by irradiation, In the propylene-ethylene random copolymer, 0.05 parts by weight of calcium stearate as a neutralizing agent and 0.05 parts by weight of tris (2,4-di-tert-butylphenyl) phosphite as a phosphorus-based antioxidant are used. And a food storage container comprising a composition in which other additives are blended.
[0004]
Japanese Patent Application Laid-Open No. 2000-230056 discloses a lithium-aluminum composite hydroxide salt of ethylene-α-olefin copolymer containing 0.03% as a packaging film for radiation sterilization treatment with less generation of offensive odor due to irradiation of radiation. A packaging film for radiation sterilization treatment comprising a composition containing 1% by weight is described.
[0005]
However, the food container for irradiation described in Japanese Patent Application Laid-Open No. H11-255824 actually contains 0.05 parts by weight of calcium stearate as a neutralizing agent and tris (2,4- (T-butylphenyl) phosphite, 0.05 parts by weight, and the packaging film for radiation sterilization treatment described in JP-A-2000-230056 is a lithium aluminum composite hydroxide salt. Is contained in an amount of 0.03 to 1% by weight, so that further improvement has been desired for suppressing the generation of odor due to the radiation irradiation sterilization treatment.
[0006]
[Patent Document 1]
JP 11-255824 A [Patent Document 2]
JP 2000-230056 A
[Problems to be solved by the invention]
An object of the present invention is to provide a polyolefin resin for radiation sterilization in which generation of odor due to radiation sterilization treatment is suppressed, and a molded article thereof.
[0008]
[Means for Solving the Problems]
In view of such circumstances, the present inventors have conducted intensive studies and, as a result, have found that the present invention can solve the above problems, and have completed the present invention.
That is, the present invention
The present invention relates to a radiation-sterilized polyolefin resin having a compounding amount of a hydrochloric acid absorbent of not more than 0.045 parts by weight and a compounding amount of an antioxidant of not more than 0.005 parts by weight based on 100 parts by weight of a polyolefin resin and a molded article thereof. Things.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
The polyolefin resin used in the present invention is an olefin homopolymer or copolymer obtained by polymerizing an olefin by an ionic polymerization method or a radical polymerization method.
Examples of the olefin homopolymer include polyethylene, polypropylene, polybutene-1, and poly-4-methyl-pentene-1.
[0010]
Examples of the olefin copolymer include ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-4-methylpentene-1 copolymer, ethylene-hexene-1 copolymer, and ethylene-octene. -1 copolymer, ethylene-α-olefin copolymer such as ethylene-decene-1 copolymer, propylene-4-α such as propylene-4-methylpentene-1 copolymer and propylene-butene-1 copolymer And ethylene-propylene-α-olefin copolymers such as an olefin copolymer and an ethylene-propylene-butene-1 copolymer. Further, a copolymer of an α-olefin and a polyunsaturated compound such as a conjugated diene and a non-conjugated diene may be used. And, copolymers of ethylene with acrylic acid, methacrylic acid, unsaturated carboxylic acids such as maleic acid and their esterified products and acid anhydrides, and copolymers of ethylene with vinyl esters such as vinyl acetate, etc. Can be
[0011]
The above-mentioned polyolefin resins may be used alone or in combination of at least two kinds. The polyolefin resin is preferably an ethylene-α-olefin copolymer, more preferably an ethylene-hexene-1 copolymer.
[0012]
The density of the polyolefin resin used in the present invention is usually 880 to 970 Kg / m ³ , and preferably 890 to 940 Kg / m ³ from the viewpoint of the adhesiveness, handleability or impact strength of the molded article.
[0013]
The melt flow rate of the polyolefin resin used in the present invention measured at 190 ° C. is usually 0.1 to 50 g / 10 minutes, and from the viewpoint of moldability and strength, preferably 0.2 to 20 g / 10 minutes. is there.
[0014]
Examples of the method for producing the polyolefin resin used in the present invention include a production method using a known polymerization method using a known radical polymerization catalyst or ionic polymerization catalyst. Known catalysts include, for example, peroxide catalysts, Ziegler-Natta catalysts, metallocene catalysts, and the like, and known polymerization methods include, for example, solution polymerization, slurry polymerization, high-pressure ion polymerization, and high-pressure polymerization. Examples include a radical polymerization method and a gas phase polymerization method. Among them, a production method by a gas phase polymerization method using a metallocene catalyst is preferable.
[0015]
An ethylene-α-olefin copolymer produced by a gas phase polymerization method using a metallocene catalyst is preferable, and specifically, an ethylene-α-olefin copolymer described in JP-A-9-183816 is preferred. Polymers.
[0016]
The radiation-sterilizing polyolefin resin of the present invention contains 0.045 parts by weight or less of a hydrochloric acid absorbent and 0.005 parts by weight or less of an antioxidant with respect to 100 parts by weight of the polyolefin resin. It is. Preferably, it does not contain a hydrochloric acid absorbent and an antioxidant.
[0017]
Examples of the hydrochloric acid absorbent used in the present invention include higher fatty acid metal salts (so-called metal soaps) and inorganic hydrochloric acid absorbents. Examples of higher fatty acid metal salts (so-called metal soaps) include calcium stearate and magnesium stearate, and examples of the inorganic hydrochloric acid absorbent include hydrotalcites (DHT (Mg _4.5 manufactured by Kyowa Chemical Co., Ltd.) _{A l2 (OH) 18 CO 8} 3.5H 2 O)) and the like.
[0018]
Examples of the antioxidant used in the present invention include a phenolic antioxidant and a phosphorus-based antioxidant.
Examples of the phenolic antioxidant include 2,6-di-t-butyl-4-methylphenol (BHT) and n-octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl). Propionate (trade name Irganox 1076, manufactured by Ciba Specialty Chemicals), pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (trade name Irganox 1010, manufactured by Ciba Specialty Chemicals) 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate (trade name Irganox 3114, manufactured by Ciba Specialty Chemicals), 1,3,5-trimethyl-2,4, 6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) ) Benzene, 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10- Tetraoxaspiro [5.5] undecane (trade name Sumilizer GA80, manufactured by Sumitomo Chemical Co., Ltd.) and the like.
[0019]
Examples of the phosphorus-based antioxidant include distearyl pentaerythritol diphosphite (trade name Adekastab PEP8) and tris (2,4-di-t-butylphenyl) phosphite (trade name Irgafos 168, manufactured by Ciba Specialty Chemicals) , Bis (2,4-di-t-butylphenyl) pentaerythritol diphosphite, tetrakis (2,4-di-t-butylphenyl) 4,4′-biphenylenediphosphonite (trade name Sandostab P-EPQ) , Manufactured by Clariant Chapan), bis (2-t-butyl-4-methylphenyl) pentaerythritol diphosphite, and the like.
If necessary, additives such as an antiblocking agent, a lubricant, a pigment, and an antistatic agent may be added to the radiation-sterilized polyolefin resin and the molded article of the present invention. These additives may be used alone or in combination of at least two types.
[0021]
Examples of the antiblocking agent include an inorganic antiblocking agent and an organic antiblocking agent.Examples of the inorganic antiblocking agent include silica, diatomaceous earth, talc, aluminosilicate, kaolin, calcium carbonate, and the like. Examples of the antiblocking agent include Eposta-MA (manufactured by Nippon Shokubai Co., Ltd.).
[0022]
Examples of the lubricant include higher fatty acid amides and higher fatty acid esters. Examples of the pigment include a white pigment and carbon black. Examples of the antistatic agent include glycerin esters and sorbitanates of fatty acids having 8 to 22 carbon atoms, alkyl dialkanolamides of fatty acids having 8 to 22 carbon atoms, polyethylene glycol esters, and alkyl diethanolamine.
[0023]
The polyolefin molded article for radiation sterilization of the present invention is irradiated with radiation such as γ-ray or electron beam for the purpose of sterilization, and is used for radiation sterilization. The main uses include containers and films for packaging foods, medical instruments or packaging containers and films for medical instruments. Among them, preferred are food packaging containers and films for radiation sterilization for which low odor reduction is strongly desired, and more preferred are food packaging films for radiation sterilization.
[0024]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
The following polyolefin resins were used in Examples and Comparative Examples.
1. Polyolefin resin PO-1: an ethylene / hexene-1 copolymer produced by a gas phase polymerization method using a metallocene catalyst, MFR = 2 g / 10 min, density = 918 Kg / m ³
PO-2: an ethylene polymer produced by a high-pressure radical polymerization method, MFR = 2 g / 10 min, density = 923 Kg / m ³
PO-3: high-density polyethylene produced by a slurry polymerization method using a Ziegler-Natta catalyst, MFR = 1 g / 10 min, density = 946 Kg / m ³
[0025]
The odor was evaluated according to the following method.
About the sample of the Example and the comparative example, 1.00 g of the sample was put in a wide-mouthed bottle without odor, covered with aluminum foil, heated in an oven at 50 ° C. for 1 hour, and air-cooled in a room at 23 ° C. Panelists conducted a sensory test for odor. The evaluation of the odor intensity was performed by each panelist by giving a score by the following method, and the total score was given.
0 point: Odorless 1 point: Feel a weak odor.
2 points: A strong pungent odor is felt.
[0026]
Example 1
PO-1 pellets are formed by a 50 mmφ extruder, a 125 mmφ die and an inflation molding machine with a lip opening of 2.0 mm to form a 50 μm thick film at a processing temperature of 170 ° C., an extrusion rate of 25 kg / hour, and a blow ratio of 1.8. did.
The resulting film was irradiated with gamma rays using a cobalt 60 radiation source at a dose of 50 kilogray. The film samples after irradiation were evaluated for odor. The results are shown in Table 1.
[0027]
Example 2
Using a PO-2 pellet, a 50 mm-dia. Extruder, a die 125 mm.phi., And a lip opening 0.8 mm inflation molding machine, a film having a thickness of 50 .mu.m under the conditions of a processing temperature of 160.degree. Was molded.
The resulting film was irradiated with gamma rays using a cobalt 60 radiation source at a dose of 50 kilogray. The film samples after irradiation were evaluated for odor. The results are shown in Table 1.
[0028]
Example 3
Using a PO-3 pellet, a 50 mm diameter extruder, a die 125 mm diameter, and a lip opening 0.8 mm inflation molding machine, a film having a thickness of 50 µm under the conditions of a processing temperature of 190 ° C, an extrusion rate of 25 kg / hour, and a blow ratio of 1.8. Was molded.
The resulting film was irradiated with gamma rays using a cobalt 60 radiation source at a dose of 50 kilogray. The film samples after irradiation were evaluated for odor. The results are shown in Table 1.
[0029]
Comparative Example 1
In Example 1, instead of PO-1 pellets, 0.05 part by weight of calcium stearate (AH-1) as a hydrochloric acid absorbent and 1,3,3 as an antioxidant were added to 100 parts by weight of PO-1. 0.05 parts by weight of 5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate (AO-1) and tris (2,4-di-tert-butylphenyl) phosphite (AO- 2) The same procedure as in Example 1 was carried out except that pellets which were blended with 0.1 part by weight and melt-kneaded were used. The results are shown in Table 1.
[0030]
Comparative Example 2
In Example 2, instead of PO-2 pellets, 2,6-di-t-butyl-4-methylphenol (AO-3) 0.02 was used as an antioxidant per 100 parts by weight of PO-2. Example 2 was carried out in the same manner as in Example 2 except that a melt-kneaded pellet was prepared by blending with 0.1 part by weight of distearylpentaerythritol diphosphite (AO-4). The results are shown in Table 1.
[0031]
Comparative Example 3
In Example 3, instead of PO-3 pellets, 0.15 part by weight of calcium stearate (AH-1) as a hydrochloric acid absorbent and pentaerythrityl as an antioxidant were added to 100 parts by weight of PO-3. 0.06 parts by weight of tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (AO-5) and tris (2,4-di-t-butylphenyl) phosphite (AO-5) -2) The same procedure as in Example 3 was carried out, except that 0.1 parts by weight were blended and melt-kneaded pellets were used. The results are shown in Table 1.
[0032]
Examples 1 to 3 satisfying the requirements of the present invention show that generation of odor after γ-ray irradiation is suppressed to a low level. In particular, it can be seen that Example 1 using an ethylene / hexene-1 copolymer produced by a gas phase polymerization method using a metallocene catalyst was suppressed to an extremely low level.
In contrast, Comparative Examples 1 to 3, which do not satisfy the requirements of the present invention, show that the suppression of odor generation after γ-ray irradiation is insufficient.
[0033]
【The invention's effect】
As described above in detail, according to the present invention, a radiation-sterilizing polyolefin resin and a molded article thereof can be obtained in which generation of odor due to radiation irradiation sterilization treatment is suppressed.
[0034]
[Table 1]

Claims (4)

A polyolefin resin for radiation sterilization wherein the compounding amount of the hydrochloric acid absorbent is 0.045 parts by weight or less and the compounding amount of the antioxidant is 0.005 parts by weight or less based on 100 parts by weight of the polyolefin resin. The polyolefin resin for radiation sterilization according to claim 1, wherein the polyolefin resin is an ethylene-α-olefin copolymer. A molded article comprising the polyolefin resin for radiation sterilization according to claim 1. The molded article according to claim 3, wherein the molded article is a film.