JP3339129B2 - Oxygen barrier resin molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molded article such as a film having excellent oxygen barrier properties and a laminate.

[0002]

2. Description of the Related Art The functions required for packaging are diverse,
Mechanical protection, safety, hygiene, workability, merchantability (transparency, printability, heat sealability), convenience, economical efficiency, etc., but various gas barrier properties as content protection are food It is an important property that affects the storage stability of food products, and the necessity is increasing due to the diversification of distribution forms, packaging technology, additives, and changes in tastes. And
It was also a weak point of general plastic materials. Deterioration factors of food are oxygen, light, heat, and moisture, and oxygen is a particular causative substance. The barrier material is an indispensable material for effectively blocking this and at the same time as a means for controlling the deterioration of food such as gas filling and vacuum packaging.
In addition, not only oxygen gas but also various gases, organic solvent vapor,
Due to its barrier function such as aroma, it is very effectively used in carbon dioxide beverage containers, rust prevention, odor prevention, sublimation prevention, cosmetics, agricultural chemicals, and medical fields.

[0003] Among the films made of thermoplastic resin, oriented films such as polypropylene, polyester and polyamide have excellent mechanical properties, heat resistance and transparency and are widely used as packaging materials. I have. However, when these films are used for food packaging, their gas permeability is too large and their oxygen barrier properties are insufficient, resulting in deterioration of the contents such as due to oxidative degradation or aerobic microorganisms. In many cases, a method of easily stacking another film layer having good oxygen barrier properties is often employed. As the most representative means, a method of laminating a metal foil such as aluminum or a method of evaporating those metals on the surface of a thermoplastic resin film is used, and excellent gas barrier properties, particularly oxygen barrier properties are effectively utilized. I have. However, these aluminum laminates and vapor-deposited films become opaque and the contents cannot be seen when food is packaged using them. Due to such disadvantages, films having excellent transparency and excellent oxygen barrier properties are increasingly desired.

Conventionally, various types of transparent plastic materials having low oxygen permeability are also known. For example, there are films made of polyvinyl alcohol, polyethylene vinyl alcohol copolymer and polyvinylidene chloride-based resin. It is known that metal and glass materials used have an oxygen permeability of almost zero, whereas these plastic materials still transmit a considerable amount of oxygen.

[0005] Japanese Patent Application Laid-Open No. Hei 4-351542 and Japanese Patent Application Laid-Open
In Japanese Patent Application Laid-Open No. 2-207338, an extremely excellent oxygen barrier property is realized by irradiating a radiation to an ethylene-vinyl alcohol copolymer film or a laminate comprising the same.

[0006]

However, the ethylene-vinyl alcohol copolymer films disclosed in JP-A-4-351542, JP-A-02-258257, and JP-A-62-207338, and laminates made thereof, On the other hand, the method of irradiating radiation has a problem that the resin is originally limited to an ethylene-vinyl alcohol copolymer having excellent oxygen barrier properties.

An object of the present invention is to solve the above-mentioned problems, and to provide a technique for imparting a high level of oxygen barrier properties to any resin composition, molded article, film, laminate, or the like. It is in.

[0008]

The present inventors have been studying oxygen barrier materials for many years. As a result, it was found that when a molded article comprising a resin composition containing a triphenylmethyl compound was irradiated with radiation, remarkably excellent oxygen barrier properties were exhibited, and the present invention was completed.

That is, the present invention relates to an oxygen-barrier resin molded article and a laminate obtained by irradiating a molded article made of a resin composition containing a triphenylmethyl compound with radiation.

[0010] The type of radiation used in the present invention is not particularly limited, but gamma rays, alpha rays, electron beams and the like are preferably used. In particular, an electron beam is an industrially advantageous radiation such as improvement in production speed and high safety.

The electron beam source has an acceleration voltage of 100 kV.
An electron beam accelerator of not less than 3000 kV is preferably used. If the acceleration voltage is smaller than 100 kV, the penetration depth of the electron beam is not sufficient, and if it is larger than 3000 kV, the device becomes too large. Examples of the electron beam irradiation device include an electron beam scanning type device such as a Van de Graaff type, and an electron beam fixing / conveyor moving type device such as an electron curtain type.

The absorbed dose of radiation used in the present invention is:
The absorbed dose is 0.1 Mrad or more and 100 Mrad or less, more preferably 0.5 Mrad or more and 30 Mrad or less. When the absorbed dose is smaller than 0.1 Mrad, the oxygen barrier property is not sufficiently improved, and when the absorbed dose is larger than 100 Mrad, mechanical properties are deteriorated, which is not preferable.

The radiation irradiation conditions used in the present invention are not particularly limited, and various conditions are possible. The irradiation atmosphere is preferably an inert gas atmosphere such as under nitrogen, but there is no particular problem in air. The irradiation speed and time are not particularly limited as long as a predetermined absorbed dose is irradiated.

The triphenylmethyl compound used in the present invention is a compound capable of generating a free radical represented by the following general formula by irradiation. (Wherein, R ¹ , R ² and R ³ each represent a hydrogen atom, a hydroxyl group, an amino group, a nitro group, a halogen atom, an alkyl group, an alkoxy group or a carboxyl group;
Represents a hydrogen atom, a halogen atom, a hydroxyl group, an amino group or an ether residue. )

Specifically, triphenylmethane, triphenylmethylcarbinol, triphenylmethyl chloride,
And triphenylmethyl bromide.

The amount of the triphenylmethyl compound used in the present invention is not particularly limited, but is preferably 0.1% to 30% by weight in the resin composition. 0.1%
If less than 30%, the effect of improving oxygen barrier properties is small, and
If used in excess of the above, mechanical properties such as tensile strength of the resin composition may be impaired, which is not preferred.

The resin used in the present invention is not particularly limited. Generally, all resins used for packaging materials can be used. Specifically, polyester resins such as polyethylene terephthalate, polyamide resins such as nylon-6, nylon-6,6, and polyolefins such as polyethylene, polypropylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, etc. Resins, polyvinyl alcohol resins such as polyvinyl alcohol and ethylene-vinyl alcohol copolymer, polyvinylidene chloride, polyvinyl chloride, polyacrylonitrile, polystyrene, polymethyl methacrylate, polycarbonate, and many others.

Further, the resin molded article of the present invention may be used as a laminate as required. The lamination form is not particularly limited, such as a film, a sheet, and a container. Further, the base resin of the laminate is not particularly limited, but polyolefin-based, polyester-based, polyether-based, polyamide-based, vinyl-based,
Examples include polycarbonate-based and cellulose-based films. Among these, polypropylene biaxially stretched,
Stretched films such as polyethylene terephthalate and nylon are preferred from the viewpoint of strength, elongation, water resistance and heat resistance.

Further, within a range that does not impair the effects of the present invention,
Various additives such as an ultraviolet absorber, a coloring agent, and an antioxidant may be mixed in the resin composition and the molded article.

[0020]

The oxygen barrier properties in the present invention are presumed to be due to the oxygen scavenging effect of the triphenylmethyl compound reacting with the permeated oxygen through the free radicals generated by irradiation. Therefore, it is considered that the laminate in which another oxygen-barrier resin is disposed in the outer layer can be used not only for the oxygen-barrier property but also for deoxygenation packaging for absorbing oxygen in the system. Of course, it is widely used for general packaging materials having oxygen barrier properties.

[0021]

EXAMPLES The present invention will be described in detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. [Measuring equipment] Oxygen permeability measuring device (OX-TRAN10
/ 50A, manufactured by MOCON) at a temperature of 30 ° C. (humidity controlled thermostat 21 ° C.).

[Example 1] Polyethylene terephthalate resin (PETG6763: manufactured by Eastman Kodak Company)
90 parts by weight and 10 parts by weight of triphenylmethane (manufactured by Nacalai Tesque) as a triphenylmethyl compound are kneaded with a Banbury kneader (Laboplast mill: manufactured by Toyo Seiki Seisakusho) at 160 ° C., 60 rpm for 5 minutes under a nitrogen purge. It was press-formed at a temperature of 160 ° C. and a pressure of 50 kg / cm ² to a thickness of 100 μm. The obtained film is treated with an electron beam irradiation device Curetron EBC-20 manufactured by Nissin High Voltage Co., Ltd.
0-20-15, acceleration voltage 200 kV, electron flow 5
Electron beam irradiation (absorbed dose: 10 Mrad) was performed under conditions of mV, conveyor speed of 6 m / min, and nitrogen. When an oxygen permeability test was performed on the obtained sample, the oxygen permeability was 0.96 cc.
/ m ² · day · atm (irradiation 1 day), showing excellent oxygen barrier properties.

Example 2 An oxygen permeability test was performed in the same manner as in Example 1 except that triphenylmethyl chloride (manufactured by Nacalai Tesque) was used as the triphenylmethyl compound. The oxygen permeability was 5.4 cc. / m ² · day · atm (irradiation 1 day), showing excellent oxygen barrier properties.

Comparative Example 1 An oxygen permeability test was carried out in the same manner as in Example 1 except that no triphenylmethyl compound was used and no electron beam was irradiated.
The oxygen barrier property was inferior at 7 cc / m ² · day · atm.

Comparative Example 2 An oxygen permeability test was performed in the same manner as in Example 1 except that no triphenylmethyl compound was used. The oxygen permeability was 75 cc / m ² · day · at.
m (1 day of irradiation) and the oxygen barrier property was poor.

[Comparative Example 3] An oxygen permeability test was performed in the same manner as in Example 1 except that no electron beam was irradiated. The oxygen permeability was 61 cc / m ² · day · atm, which was an oxygen barrier property. It was inferior.

Comparative Example 4 An oxygen permeability test was conducted in the same manner as in Example 1 except that triphenylmethyl chloride (manufactured by Nacalai Tesque) was used as a triphenylmethyl compound and no electron beam was irradiated. However, the oxygen permeability is 5
The oxygen barrier property was inferior to 4 cc / m ² · day · atm.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Tatsuma Kuroda 2-10-1 Tsukahara, Takatsuki City, Osaka Prefecture Inside Sumitomo Chemical Co., Ltd. (56) References JP-A-7-102089 (JP, A) 1953-36549 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J ⁷ /00-7/18 C08L 1/00-101/18

Claims (3)

(57) [Claims] 1. An oxygen barrier resin molded article obtained by irradiating a molded article comprising a resin composition containing a triphenylmethyl compound with radiation. 2. A compound represented by the general formula: (Wherein, R ¹ , R ² and R ³ each represent a hydrogen atom, a hydroxyl group, an amino group, a nitro group, a halogen atom, an alkyl group, an alkoxy group or a carboxyl group;
Represents a hydrogen atom, a halogen atom, a hydroxyl group, an amino group or an ether residue. The oxygen-barrier resin molded article according to claim 1, which is a compound represented by the formula: 3. A laminate having at least one layer of the oxygen-barrier resin molded article according to claim 1.