JP2000006939A - Multi-layer extension blow molded container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light weight multi-layer extension blow molded container having a superior gas barrier characteristic which can be manufactured by an existing manufacturing facility. SOLUTION: There is provided an extension blow molded container 1 having a container wall with two kinds of material being laminated. Material quality of an inner layer 7 is polyester and material quality of an outer layer 6 is resin comprised of polyamide and polyester. An opening 2 of the container is made of material of the inner layer. The outer layer is formed continuously at a container wall having a thickness of 1/2 or less of that of a root 5 of the opening of the container. A ratio between a thickness of the inner layer and a thickness of the outer layer is in a range from 1:1 to 1:3 and there are provided protrusions 8 protruded at the outer layer toward the inner layer in such a way that the inner layer and the outer layer are hardly separated from each other at a part near the root part of that container opening of an interface between the outer layer and the inner layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer stretch blow-molded container having good protection of contents.

[0002]

2. Description of the Related Art Plastic containers made by stretch blow molding are used for beverages and seasonings because they are lightweight and hard to break. As a material for these containers, resins such as polyethylene terephthalate and polypropylene are generally used. However, these resins have poor gas barrier properties, and their uses are naturally limited. Further, in order to protect the contents, the container wall has been thickened, that is, the container weight has been increased. In recent years, content storage stability has been improved,
In other words, there has been an increasing demand for maintaining the quality at the time of manufacture for a long period of time, and a demand for a plastic container for contents requiring a container with higher barrier properties. In response to these demands, measures to improve the gas barrier properties of the container have been studied. For example, a material having excellent gas barrier properties has been applied to the container, and research into multi-layer containers has been conducted.

However, in the above-described measures for improving the gas barrier properties of the container, the application of the gas barrier material to the container is as follows.
Occasionally, the gas barrier properties are insufficient, and the technology of depositing oxide on a container is not yet practical and the technology has not yet been put on the market. In addition, a method of co-injection is generally used for multilayering containers, but there is no adhesion between the barrier material and the base material of the container. Therefore, versatility is poor.

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a multilayer stretch blow-molded container which can be manufactured with current manufacturing equipment, is lightweight and has excellent gas barrier properties. .

[0005]

That is, the first aspect of the present invention is as follows.
The invention relates to a stretch blow-molded container (1) having a container wall formed by laminating two types of materials, as shown in FIG.
The material of the inner layer (7) is polyester, the material of the outer layer (6) is made of a resin containing polyamide and polyester, the container mouth (2) is made of the material of the inner layer, and the container mouth (5).
The outer layer is continuously formed on the container wall having a thickness equal to or less than of the thickness of the outer layer, the ratio of the thickness of the inner layer to the thickness of the outer layer is between 1: 1 and 1: 3, A multilayer stretch blow-molded container (1), characterized in that a protrusion (8) in which the outer layer protrudes toward the inner layer side so that the inner layer and the outer layer are difficult to separate from each other at a portion near the container mouth side at the interface.

In a second aspect of the present invention, the material of the inner layer comprises polyethylene terephthalate, and the material of the outer layer comprises polyethylene terephthalate or polyethylene naphthalate or a copolymer thereof and MXD6 nylon. A multilayer stretch blow-molded container according to the first aspect, characterized in that:

A third invention of the present invention is the multilayer stretch blow molding according to the second invention, wherein the mixing ratio of the polyester to MXD6 nylon of the material of the outer layer is 5 to 30%. Container.

[0008]

The multilayer stretch blow-molded container of the present invention uses a material having a gas barrier property for the outer layer, and therefore has a higher gas barrier property than a single-layer container made of polyester alone. In addition, the outer layer is made by mixing a resin that has adhesiveness with the inner layer, and furthermore, the outer layer is provided with a protrusion at the interface between the outer layer and the inner layer, which makes separation difficult, so that the adhesion between the outer layer and the inner layer is improved. The outer layer and the inner layer are firmly adhered to each other.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The multilayer stretch blow-molded container of the present invention is prepared by first preparing a multilayer preform and then heating the preform to stretch blow molding. For example, in a mold for a preform, in which a cylindrical outer layer body (10) having a protrusion (8) on the upper inner surface is inserted in advance,
The molten inner layer material is injected to produce a multi-layer preform (11) shown in FIG. 2, and the preform is heated and stretch blow-molded to form a relatively thick mouth 2 and bottom 3; The multilayer stretch blow-molded container (1) of the present invention shown in FIG. 1 comprising a relatively thin body 4 and a mouth 5 is produced by the above-mentioned current production equipment.

As shown in FIG. 1, the structure of the multilayer stretch blow-molded container (1) of the present invention has a container wall formed by laminating two kinds of materials, and the material of the inner layer (7) is polyester. The material of the outer layer (6) is made of a resin having a gas barrier property containing polyamide and polyester, the container opening (2) is made of the material of the inner layer, and has a thickness of not more than 1/2 of the thickness of the container opening (5). Outer layer is continuously formed on the container wall,
The ratio of the thickness of the inner layer to the thickness of the outer layer is between 1: 1 and 1: 3, and at the interface between the outer layer and the inner layer near the mouth of the container, the protrusion (8) in which the outer layer projects toward the inner layer. ) Is provided.

The above-mentioned outer layer having gas barrier properties only needs to be located at a portion of 1/2 or less of the thickness of the mouth having the maximum thickness of the container, and the gas barrier properties of the container are improved. Although it is possible to form an outer layer on a thick portion of the container wall, the gas barrier property of the entire container is only slightly improved and is meaningless. The thickness of the outer layer is the same as the thickness of the outer layer, and the ratio of the thickness of the outer layer to the thickness of the inner layer is 1: 1 to 1:
It is desirable that the number be in the range of 3. If the thickness of the outer layer is too large, the gas barrier properties of the container are improved, but the impact strength of the container is deteriorated, and the molding of the container becomes difficult. Conversely, when the thickness of the outer layer is small, the moldability is good, but the gas barrier property is insufficient.

The material of the outer layer is preferably a material having good gas barrier properties and a material suitable for stretch forming properties. In addition, adhesiveness to the inner layer material is required. Further, depending on the contents, usable materials are limited in terms of safety. It is difficult at present to obtain materials meeting these requirements at low cost. Therefore, MXD6 nylon is used as a material having good gas barrier properties and good stretchability. However, this material has poor adhesion to the polyester of the inner layer material. Therefore, a polyester compatible with the inner layer material is added to the MXD6 nylon. The polyester added to the outer layer only needs to be compatible with the polyester of the inner layer material, and may contain the same polyester or polyethylene naphthalate as the inner layer material. Further, a material having an adhesive property between the polyester of the inner layer material and the MXD6 nylon of the outer layer material may be added. If there are many components other than the MXD6 nylon in the outer layer material, the gas barrier properties are undesirably reduced. If the polyester component is too large, nylon and polyester components are formed in a layer at the time of stretch molding, and the impact resistance is deteriorated and the function as a container is not satisfied. Therefore, the content of the outer layer material mainly composed of polyester other than nylon is preferably 5 to 30%, more preferably 1 to 30%.
0 to 20%. With such a mixing ratio, the adhesion between the outer layer and the inner layer is improved, and a container having good gas barrier properties can be provided.

Further, depending on the selection of the resin and the storage environment of the container, the adhesiveness between the outer layer and the inner layer may be insufficient. At that time, the outer layer and the inner layer need to be closely adhered in shape. At the end of the outer layer, that is, at the portion close to the mouth of the container, at the interface between the outer layer and the inner layer, a projection is provided in which the outer layer protrudes toward the inner layer so that the inner layer and the outer layer are difficult to separate. This projection may have any shape as long as it satisfies the functions described above. For example, those in which convex protrusions are arranged in a ring shape so as to surround the mouth, those in which the rings are arranged in a spiral shape, and those in which convex protrusions are scattered on the peripheral surface are arranged. But are not limited to these. The formation of these projections not only makes it difficult to mechanically separate the outer layer and the inner layer, but also increases the area of the interface between the outer layer and the inner layer, thereby improving the adhesiveness.

[0014]

EXAMPLES Examples of the present invention will be specifically described below. <Example 1> As an outer layer material, a copolymer of polyethylene terephthalate and polyethylene naphthalate in a ratio of 92 parts by weight to 8 parts by weight was used. , MXD6 nylon and 2
Materials mixed at a ratio of 8 were used. Using this outer layer material, a cylindrical outer layer body of a preform was prepared by an injection molding method. Next, the outer layer body was inserted into an injection mold for a preform, and a polyethylene terephthalate resin as an inner layer material was melt-injected to prepare a test tube preform having a weight of about 20 g. The preform 10 is heated and stretch blown by a stretch blow molding machine to have a capacity of about 50.
A 0 cc container of this example was molded. Note that a spiral projection (8) in which the outer layer protruded toward the inner layer was provided in a portion of the outer layer close to the container mouth side.

<Comparative Example> A preform having the same shape as in Example 1 was injection-molded using the polyethylene terephthalate material of the inner layer used in Example 1, and the preform was heated and stretch blow-molded. Thus, a container of the present comparative example having the same shape as in Example 1 was produced.

Next, the oxygen gas permeability of the containers produced in Example 1 and Comparative Example was comparatively evaluated. According to the evaluation results, the container of Example 1 was 0.010 CC / pkg / da.
y, whereas the container of the comparative example has 0.044 CC /
pkg / day, and the oxygen gas permeation amount was
Of the container of the comparative example was about 1/4 as compared with the container of the comparative example.

The drop impact strength of the container of Example 1 was evaluated. The evaluation method was as follows: a container was filled with 500 CC of water, stored at 5 ° C. for 24 hours, and dropped upright from a height of 1 m onto concrete 10 times. As a result of the evaluation, no damage was caused to the container by dropping, and no delamination between the outer layer and the inner layer was observed.

[0018]

The multilayer stretch blow-molded container of the present invention is a lightweight container having excellent gas barrier properties, dramatically improving the storage stability of the contents, and has been considered difficult with plastic containers. It can be applied to the contents, and by replacing the current plastic container, the shelf life of the contents can be extended.

Further, also in the manufacturing, the container can be manufactured without using expensive special equipment, the manufacturing can be performed with less environmental load, and the manufacturing cost of the container is relatively low.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view of a multilayer stretch blow-molded container of Example 1 of the present invention.

FIG. 2 is a front view in which a part of the preforming body of Example 1 is partially cut away.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Container 2 ... Mouth part 3 ... Bottom part 4 ... Body part 5 ... Mouth part 6 ... Outer layer 7 ... Inner layer 8 ... Projection part 10 ... Preformed body 11 ... Outer layer body

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) B29L 22:00 (72) Inventor Akitaka Iwasaki 1-5-1, Taito, Taito-ku, Tokyo Letterpress Printing Co., Ltd. F term (reference) 3E033 AA02 BA18 BA21 BB08 CA03 CA16 CA20 DB01 DD01 FA03 GA02 4F208 AA24 AA24E AA26 AA26E AA29 AG03 AG07 AG23 AG27 AH55 AR12 AR20 LA02 LA05 LB01 LB22 LG01 LG03 LG06 LG14 LG16 LG28 LG35 LG35

Claims (3)

[Claims] 1. A stretch blow-molded container having a container wall formed by laminating two kinds of materials, wherein the material of the inner layer is polyester, the material of the outer layer is a resin containing polyamide and polyester, and the mouth of the container is the inner layer. The outer layer is continuously formed on the container wall having a thickness equal to or less than 1/2 of the thickness of the container mouth portion, and the ratio of the thickness of the inner layer to the thickness of the outer layer is between 1: 1 and 1: 3. A multilayer stretch blow-molded container, characterized in that at the interface between the outer layer and the inner layer, near the container mouth side, there is a projection in which the outer layer projects toward the inner layer so that the inner layer and the outer layer are difficult to separate. 2. The multilayer according to claim 1, wherein the material of the inner layer comprises polyethylene terephthalate, and the material of the outer layer comprises polyethylene terephthalate or polyethylene naphthalate or a copolymer thereof and MXD6 nylon. Stretch blow molded containers. 3. The multilayer stretch blow-molded container according to claim 2, wherein the mixing ratio of polyester to MXD6 nylon of the material of the outer layer is 5 to 30%.