JPS60158045A - Multilayer blow molding vessel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to multilayer blow molded containers. More detailsK+'
! , relates to a polyethylene terephthalate container with excellent barrier properties.

Containers made by melt extrusion blow molding of thermoplastic plastic chaff such as polyolefinone are lighter than glass pins and have excellent impact resistance.

- Used in many dues instead of glass bottles. This is because the blow-molded container vh using ゛%&C polyethylene tetanium tarley) tree 111k has significantly better transparency, gloss, and barrier properties than containers made of polyolefinone.

It is attracting attention as an alternative container to glass. Moreover.

□As biaxial stretch blow molding technology for crystalline resins such as polyethylene terephthalate resins has developed in recent years, its use has increased. However, even if polyethylene terephthalate resin is stretch-molded, it still has insufficient barrier properties, so its range of use is limited.

For example, in the case of carbonated beverages, the change in flavor is noticeable, with 4 volumes of carbon dioxide permeating through a 1.5 liter bottle over a 12 week period, resulting in a decrease in flavor by 15%. . In addition, in fruit juice and pulp drinks, vitamin C is destroyed due to the permeation of oxygen gas, etc.
There are still problems with long-term distribution.

By the way, in order to improve the barrier properties of a container made of blow-molded polyethylene terephthalate resin, it is conceivable to make the container multi-layered with a material having higher barrier properties. For example, cover the surface with polyvinyl alcohol or polyvinylidene chloride. However, polyvinyl alcohol and polyvinylidene chloride.

It has no adhesive properties with polyethylene terephthalate, so even if it can be made into multiple layers, gas and contents that permeate between the layers will accumulate.
There was a problem of peeling.

The present inventor has solved the above problem by making the following invention. That is, it is a multilayer blow molded polyethylene terephthalate container having at least one surface layer mainly composed of a vinylidene chloride-acrylonitrile copolymer consisting of 98 to 65 mol% vinylidene chloride and 2 to 55 mol% acrylonitrile. .

The present invention - 11! A house with an inner or outer surface layer based on polyethylene terephthalate! In the above blow-molded containers, on the surface thereof.

It is a container provided with a resin layer containing at least 11 or more vinylidene chloride-acrylonitrile copolymer as the main component.This multi-layering is achieved by coating a resin dissolved in a polar solvent and drying it to form a film. It is a container that has become a container. Vinylidene chloride-acrylonitrile copolymers tend to crystallize, but when the ratio of acrylonitrile is increased, crystallization does not occur and film formability is obtained, but barrier properties are degraded. The limit is 35 mol% acrylonitrile, which must be less than this. On the other hand, if the amount of acrylonitrile is too small, the film forming properties will be lowered and the barrier properties will be lowered, so the limit is 2 mol %. Therefore, the mol% of acrylonitrile is preferably 2 to 35 mol%. or,
The decrease in acrylonitrile also affects the adhesive strength with polyethylene terephthalate, and preferably the mol% of acrylonitrile is 5 to 15 mol%.

By the way, vinylidene chloride-acrylonitrile copolymer is
Dissolve it in a highly polar solvent such as tetrahydrofuran, dimethylformamide, or ethylene methyl ketone.
This solution is applied to the surface of a container containing polyethylene terephthalate (4) as the main component. At this time, it was found that the surface of the container, which was not stretched and formed, turned white and lost its transparency. Moreover, it has been found that the density of the stretched polyethylene terephthalate must be at least 135 or higher. This may be because the stretching ratio is low.

When the stretching temperature is high and the density of polyethylene terephthalate is low, the molecular chains on the surface of the container are not sufficiently crystalline and form single-molecule gaps, which the polar solvent acts on. This is considered to occur. On the other hand, if a polyethylene terephthalate container is stretch-molded to have a density of 1.36 or more per surface, the molecules will be aligned without any gaps, and it is thought that whitening will not occur. This can also be considered in terms of plane orientation, and in one plane orientation it is 70
Good results have been obtained if the value is X10-' or more.

<Example I> Unipet as a polyethylene terephthalate resin
RT-543 (manufactured by Nippon Unibet) ASB -
Stretch blow molding was carried out using a stretch blow molding machine 1so (manufactured by Nisshin ASB Kikai ■). (Stretching temperature 87c) The mold is a round bottom 12 bottle with a density of 1.567 and a plane orientation of 127X.
A polyethylene terephthalate container having a body length of 10-' was made. As a coating solution.

A vinylidene chloride-acrylonitrile copolymer containing 10 mole percent of acrylonitrile was dissolved in a mixed solvent of tetrahydrofuran and acetone (2:1) at 10 weight percent. The polyethylene terephthalate container was dripped in the coating solution, and immediately after being lifted from the coating solution, it was placed in a glass container such as the coating container, and the solvent was volatilized from the coated surface by infrared heating from outside the glass container. Using an infrared heating lamp of 10 W/cWL, the coating container was heated for about 30 seconds with the coating container placed 10 crrL from the center of the lamp. Apply and solvent? The volatilized container was further aged at 60'C for 1 minute and at 4°C.
Aging was performed for 1 day. The thickness of the coating layer of the produced multilayer blow molded container was 5 micrometers.

<Comparative Example> In the same manner as in the examples, polyethylene terephthalate resin was stretch blow molded using a stretch blow molding machine for UNIPET@RT-545f and ASB-150.

The same mold was used, but the temperature during stretching was increased to 11 oc to create a polyethylene terephthalate container with a body having a density of t551 plane orientation of 56 x 10-'. The same coating solution as in the example was used. However, the areas where the solution had adhered, such as the body, turned white, and the original glass-like transparency of 1 was lost.

Next, the oxygen permeability of the example and the containers before coating were measured.

(Surface area 620cIL2. Average wall thickness 330μ, : '-Ting amount near S'r/m') Also, carbon dioxide absorption coefficient is 4. OK, fill with dissolved water, 3
The area stored in the power month room 11 is as shown below (the measurement is
It was measured at 20C using a gas internal pressure gauge. ) Furthermore, there were no problems such as peeling of the coating layer during storage.

As mentioned above, the product of the present invention not only has excellent transparency and storage stability, but also has excellent adhesive strength, so its barrier properties do not deteriorate easily. Co., Ltd. Representative Kazuo Suzuki

Claims (1)

[Claims] The main component of the stretch-blow-molded container is polyethylene terephthalate and has a density of at least 1.35.The main component is at least one surface resin layer of vinylidene chloride-acrylonitrile copolymer on the body. Multi-layer blow molded container.