JPH07267236A - Oxygen barrier type stretch blow-molded article and manufacture thereof - Google Patents

Abstract

PURPOSE:To provide a stretch blow-molded article with an excellent oxygen barrier property, wherein the oxygen barrier property of polyester has been improved, and a special design or special manufacturing processes are not required. CONSTITUTION:A resin composition containing PVDC (polyvinylidene), polyester and metallic compound is injection-molded, and then, stretch blow-molded to obtain a stretch blow-molded article with oxygen barrier property. As the manufacturing method, a pre-form is obtained by injection-molding the resin composition consisting of PVDC, polyester and metallic compound, and the temperature of the pre-form is adjusted to a specified drawing temperature, and a stretch blow-molding is done using a compressed gas. Otherwise, after being left to stand at an ordinary temperature, the pre-form is re-heated to a specified temperature, and the temperature of the pre-form is adjusted to a specified drawing temperature by cooling it, and a stretch blow-molding is done using a compressed gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxygen-barrier molded product provided as a packaging material. More specifically, the present invention relates to a stretch blow-molded article made of polyvinylidene chloride (hereinafter referred to as PVDC), polyester and a metal compound and having an excellent oxygen barrier property, and a method for producing the same.

[0002]

2. Description of the Related Art Polyester containers, especially polyethylene terephthalate (hereinafter referred to as PET) containers by stretch blow molding method are widely used as containers for beverages, seasonings, cosmetics, liquid detergents, etc. regardless of foods or non-foods at present. It is used.

However, such polyesters are still ignorable for permeation of gases, and particularly as a container for oxygen-insensitive contents, other resins having oxygen barrier properties such as saponified ethylene-vinyl acetate copolymer and PVDC are used. It was the actual situation that it was used by stacking with the above. In manufacturing these multi-layered containers, special equipment was required, and advanced technology was required in designing each layer thickness.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve this problem. The object of the present invention is to improve the oxygen barrier property of polyester, and
An object of the present invention is to provide a stretch blow-molded product excellent in oxygen barrier property that does not require a special design or manufacturing process.

[0005]

In order to solve this problem, the present invention is characterized in that a resin composition containing PVDC, polyester and a metal compound is injection molded and then stretch blow molded. A stretch-blow molded article is provided.

As a method for manufacturing the same, the PVD described above is used.
A resin composition composed of C, a polyester and a metal compound is injection-molded to obtain a preform, the temperature of which is adjusted to a predetermined stretching temperature, and stretch blow molding is performed using a compressed gas (hot parison method). The resin composition composed of PVDC, polyester and metal compound is injection-molded to obtain a preform, which is left at room temperature, reheated to a predetermined temperature with an infrared heater or the like, and cooled to a predetermined stretching temperature. Provided is a method for producing an oxygen-barrier stretch blow-molded product, which comprises adjusting and stretch-blowing using a compressed gas (cold parison method).

The present invention will be described in detail below. The above-mentioned PET is preferably used as the polyester used in the present invention, but in addition to this, polybutylene terephthalate and the like are also used. Specifically, (1) a co-condensation polymer of two or more dibasic acids containing mainly terephthalic acid and a dihydric alcohol, (2) a co-condensation polymer of terephthalic acid and two or more dihydric alcohols (3) Polyethylene terephthalate or a polymer alloy of the modified polyolefin with the cocondensation polymer of the above (1) or (2).

Other dibasic acids which can be contained as a comonomer component with terephthalic acid include aromatic compounds such as isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenyl ether dicarboxylic acid and diphenyl sulfone dicarboxylic acid. Dicarboxylic acids; alicyclic dicarboxylic acids such as hexahydroterephthalic acid and hexahydroisophthalic acid; adipic acid,
Aliphatic dicarboxylic acids such as sebacic acid and azelaic acid; p
Examples include oxyacids such as -β-hydroxyethoxybenzoic acid, p-oxybenzoic acid and ε-oxycaproic acid.

Examples of the dihydric alcohol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,4-dicyclohexanedimethanol,
Trimethylene glycol, tetramethylene glycol,
Hexamethylene glycol, decamethylene glycol,
Neopentylene glycol, diethylene glycol,
1,1-cyclohexanedimethylol, 1,4-cyclohexanedimethylol, 2,2-bis (4-β-hydroxyethoxyphenyl) sulfone cyclohexanediol, 1,4-bis (β-hydroxyethoxy) benzene, 1,3 Examples include glycols such as bis (β-hydroxyethoxy) benzene.

Examples of the modified polyolefin include a copolymer of ethylene and an unsaturated carboxylic acid or its ester, or an ionomer. Examples of unsaturated carboxylic acids or esters thereof include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate and the like. The copolymer of ethylene and unsaturated carboxylic acid or its ester is preferably one having an unsaturated carboxylic acid content of 3 to 20% by weight, and in the case of an ester, an ester component content of 1 to 20% by weight. Some are preferred.

In the present invention, polyester is a base resin, and is a material that forms the shape of a container such as a bottle. On the other hand, the oxygen barrier property develops when PVDC is oxidized by the action of a metal compound.

The metal compound used in the present invention is PV
It is an oxidation catalyst that can promote oxygen oxidation of DC to react oxygen that permeates and permeates PVDC with PVDC, resulting in improvement of oxygen barrier property. Such metal compounds include stearic acid, naphthenic acid, linoleic acid, dimethyldithiocarbamic acid, and the like.
Co, Ni, Fe, Al, Mg, Mn, Cu, V, Cr
An organic acid salt with a metal ion such as is used. Further, porphyrin, phthalocyanine, quinoline, ethylenediamine, pyridine, propylenediamine, diethylenetriamine, triethylenetetramine, 2,2'-bipyridine, 1,10-phenanthroline, ethylenediaminetetraacetate, dimethylglyoximate, glycinate, acetylacetonate, Schiff base. Organometallic complex salts using the above as a ligand are also preferably used. Further, inorganic salts such as iron chloride, aluminum chloride and cobalt blue can also be used. Further, these metal compounds can be used alone or as a mixture of two or more kinds.

These metal compounds may be contained in an amount of 1 to 2000 ppm, more preferably 1 to 500 ppm, in terms of metal atom concentration based on the whole resin.

As a method of adding the metal compound, it is possible to simply add and mix it to the resin during molding. But PVD
In order to improve the dispersibility of the metal compound in C and reduce the added amount of the metal compound to efficiently develop the oxygen barrier property, a PVDC masterbatch prepared by previously blending the metal compound using a twin-screw kneading extruder or the like is used. After making
The method of adding to polyester is preferably performed.

In the present invention, the polyester resin and PVDC resin may contain various additives. For example, antioxidant, nucleating agent, lubricant, anti-blocking agent,
It is a compatibilizing material such as a stabilizer, an antifogging agent, a colorant, and an adhesive resin. Of these, particularly with respect to the use of the antioxidant, it is desirable not to use it in the PVDC resin in which the oxidation reaction is carried out, or to use it in an amount of 1000 ppm or less so as not to hinder the oxidation reaction.

In the stretch blow molding method of the present invention, the molding temperature varies depending on the polyester to be used, but when PET is used as the polyester, for example, in the hot parison system, a preform is injection-molded to obtain a preform. It is preferable that the temperature is adjusted to the stretching temperature and the stretch blow molding is performed using compressed air.

In the cold parison system, a preform is obtained by injection molding. After leaving it at room temperature, reheat it to a temperature of 120-160 ° C with an infrared heater,
It is preferable to cool, adjust the temperature to a stretching temperature of 90 to 130 ° C., and perform stretch blow molding using a compressed gas.

In the present invention, in order to accelerate the oxidation reaction of PVDC, heat treatment, radiation irradiation treatment, corona discharge treatment or the like is preferably carried out after molding.

The heat treatment method is not particularly limited, and various known methods such as an oven and a high temperature bath can be used. It is left in these for a certain period of time and heated. The higher the heat treatment temperature and the longer the treatment time, the more the oxygen barrier property is promoted, but the temperature is preferably 30 ° C. or higher and 100 ° C. or lower without deformation of the container.

Radiation in the case of irradiation is α
Rays, β rays, γ rays, X rays, and electron rays are preferably used.
Irradiation of such radiation can be performed by various known methods.

The stretch blow molded product of the present invention is PVDC,
It is composed of polyester and a metal compound, and the mixing ratio of PVDC and polyester is preferably 1:10 by weight.
It is 0 to 25: 100. Even with a small PVDC ratio, high oxygen barrier properties can be exhibited by stretch blow molding. If PVDC is added in excess of this ratio, the surface properties of the single-layer molded product will be poor, which is not preferable in practice.

Although direct blow molding has some stretching effect, the degree of oxygen barrier property development is smaller than that of stretch blow molding.

The stretch blow-molded product obtained in the present invention has a single-layer structure and exerts its effect sufficiently.
For the purpose of modifying the surface properties to give cosmetic properties, a thermoplastic resin layer containing no metal compound may be provided on one or both surfaces of the resin to form a multilayer structure. As such a thermoplastic resin layer, polyolefin, polyester,
Examples thereof include polyamide, polycarbonate, polyacrylonitrile, and the like, and even if such a multilayer structure with other thermoplastic resin is taken, it does not hinder the oxygen barrier effect of the stretch blow-molded product in the present invention.

[0024]

In the PVDC containing the metal compound, the function of physically suppressing the permeation of oxygen due to so-called dissolution and diffusion, and the function of PVDC being oxidized by the catalytic action of the metal compound to trap oxygen in the layer. Oxygen barrier property is expressed by. In particular, the latter function has a function of trapping oxygen remaining inside the sealed package when dissolved inside the wall.

The PVDC according to the present invention easily forms radicals by light or heat during processing or storage in the presence of an oxidation catalyst, whereby polymer radicals are generated. This reacts with oxygen dissolved in the resin, absorbs oxygen,
As a result, it is presumed that the oxygen barrier property is improved.

The main feature of the present invention is that a resin composition comprising PVDC, polyester and a metal compound is injection molded and then stretch blow molded. As a result, PVDC is oriented in the polyester while forming a sea-island structure without being melted, and there is a high possibility that it will come into contact with oxygen molecules passing through the wall surface of the molded product.
A high oxygen barrier property can be expressed with the added amount.

[0027]

EXAMPLES The present invention will be specifically described below based on examples, but the present invention is not limited to the following examples.

Example 1 PVDC (MI (melt index) = 0.5 g / 10 min) and PET (IV
(Intrinsic viscosity) = 0.75 dl / g), mixing ratio, PVD
C: PET = 5: 95 (weight ratio) was mixed, and cobalt (II) stearate was added to the whole with a metal atom concentration of 200 p.
pm is added to obtain a resin composition according to the present invention. Then, by a cold parison method, injection molding was performed at a molding temperature of 280 ° C. to obtain a preform, which was then left at room temperature,
After reheating to 120 ° C., cooling and temperature adjustment to a stretching temperature of 95 ° C., stretch blow molding using compressed air and a volume of 50.
A bottle sample of 0 ml and a wall thickness of 500 μm was obtained.

Comparative Example 1 The resin composition of Example 1 was added to 2
Direct blow molding was performed at a molding temperature of 70 ° C. to obtain a bottle sample having a capacity of 500 ml and a wall thickness of 500 μm.

<Comparative Example 2> A bottle sample was molded in the same manner as in the production of the bottle sample 1 except that cobalt (II) stearate was not included.

<Comparative Example 3> PET (IV (intrinsic viscosity) =
Only 0.75 dl / g) was used as the resin composition, and a bottle sample was obtained in the same manner as in Example 1 below.

After molding the obtained bottle, it was stored at a temperature of 25 ° C. and a humidity of 65%, and the oxygen permeability was measured with time.
The measurement was performed at 25 ° C. with “Ox-TRAN100” (manufactured by Modern Control Co.). The results are shown in Table 1.

[0033]

[Table 1]

Example 2 PVDC (MI (melt index) = 0.5 g / 10 min)) and 200 ppm of cobalt stearate were mixed and extrusion molded at a temperature of 200 ° C. using a twin-screw kneading extruder. Then, resin compound pellets (masterbatch) were obtained. Then, PVDC resin compound pellets and PET (IV (intrinsic viscosity) = 0.
75 dl / g), PVDC: PET = 5: 95
(Weight ratio) was mixed to obtain a resin composition according to the present invention.
Injection molding is performed at a molding temperature of 280 ° C. by a hot parison method to obtain a preform, the temperature of which is adjusted to a stretching temperature of 95 ° C., and stretch blow molding is performed using compressed air to obtain a volume of 500 ml and a wall thickness of 500 μm. Bottle samples were obtained.

<Comparative Example 4> In the preparation of Sample 2 above,
Bottle samples were similarly molded except that cobalt stearate was not included.

<Comparative Example 5> PET (IV (intrinsic viscosity) =
Only 0.75 dl / g) was used as the resin composition, and a bottle sample was molded in the same manner as in Example 2 below.

Table 2 shows the results of evaluating the oxygen permeability of the obtained sample bottle in the same manner as in Example 1.

[0038]

[Table 2]

[0039]

As described in detail above, according to the present invention, it is possible to easily and efficiently produce and provide a stretch blow-molded article made of polyester and having a high oxygen barrier property.

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location D01F 6/48 B 6/92 301 LM 308 D (72) Inventor Keiko Nakamura 1-5 Taito, Taito-ku, Tokyo No. 1 Toppan Printing Co., Ltd. (72) Inventor Hiroshi Umeyama 1-5-1 Taito, Taito-ku, Tokyo Tokyo Toppan Printing Co., Ltd.

Claims (4)

[Claims] 1. A resin composition containing polyvinylidene chloride, a polyester and a metal compound is injection-molded,
An oxygen-barrier stretch blow-molded product characterized by being stretch blow-molded. 2. The mixing ratio of polyvinylidene chloride and polyester in the resin composition is 1: 100 to 25: by weight.
100. The oxygen-barrier stretch blow-molded product according to claim 1, which is 100. 3. The method for producing a stretch blow-molded product according to claim 1, wherein the resin composition is injection-molded to obtain a preform, and the preform is stretch-blow-molded using a compressed gas. 4. A resin composition is injection-molded to obtain a preform, which is allowed to stand at room temperature, reheated to a predetermined temperature, and stretch blow-molded using a compressed gas. A method for producing an oxygen barrier stretch blow-molded product according to any one of 1 and 2.