JPH04352644A - Saturated polyester vessel - Google Patents

Abstract

PURPOSE:To improve the adhesive property with a saturated polyester and a gas barrier property by use of a film which does not prevent regeneration of vessels, to use them again by silicon oxide, derivatives thereof, titanium oxide or its derivatives as a film substrate. CONSTITUTION:A film is silicon oxide, derivatives thereof, titanium oxide, or delivatives thereof is formed at least at one of the outer face and inner face of a saturated polyester vessel. The film of silicon oxide, delivatives thereof, titanium oxide, or delivatives thereof is transparent and excellent in adhesion with saturated polyester vessels and further, has a high gas barrier property even if it is thin. The material forming this film is easily and evenly dispersed in the dissolved saturated polyester. And the molding characteristics is not spoiled unless these are added excessively.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to saturated polyester containers widely used, for example, as containers for soft drinks, and more particularly to improving the gas barrier properties of such containers.

0002

[Prior Art] Saturated polyester containers, especially biaxially stretched and blow-molded saturated polyester containers, have excellent heat resistance, moisture permeability, transparency, impact resistance, and light weight, so they can be used for soft drinks. It is used as a variety of containers including .

[0003] Since the body of this saturated polyester container is highly stretched during biaxial stretch blow molding, it has relatively good gas barrier properties, but this is not necessarily sufficient when compared to glass bottles and aluminum cans. . Also, the bottom, shoulders, neck, and mouth of the container are not subject to significant stretching.
The barrier properties are also inferior to that of the body.

[0004] If gas barrier properties are not sufficient, gases such as oxygen will enter the container and deteriorate the contents, shortening the shell life of the contents and causing moisture in the contents to easily evaporate during storage. It has been proposed to form containers from bottomed parisons coated with barrier resins such as ethylene-vinyl acetate copolymer, 6-nylon, polyvinylidene chloride, and the like.

[0005]

However, since the above-mentioned barrier resin has poor adhesion to saturated polyester, there is a problem in that the film tends to peel off. Particularly, when hot-packing a fruit juice-containing beverage, peeling of the coating becomes more likely to occur due to the difference in thermal shrinkage rate between the laminated materials.

[0006] Although it is conceivable to provide a coating of the above-mentioned barrier resin through an adhesive, in injection molding used for molding a bottomed parison, it is possible to simultaneously inject three types of saturated polyester, an adhesive, and a barrier resin. Can not. It is also conceivable to co-extrude these three types by extrusion molding to form a bottomed parison, but this poses problems in that it is difficult to control the dimensional accuracy of the bottomed parison and the process becomes expensive.

Furthermore, when a saturated polyester container provided with a barrier resin coating is collected and recycled after use, different resins with poor compatibility are mixed together, which impedes moldability. There are also problems that make recycling difficult.

The present invention was made in view of these problems, and aims to improve the gas barrier properties of saturated polyester containers with a coating that has excellent adhesive properties and does not hinder the recycling of the containers. shall be.

[0009]

[Means for Solving the Problems] To this end, the present invention provides
A method is taken in which a coating of silicon oxide, a silicon oxide derivative, titanium oxide, or a titanium oxide derivative is formed on at least one of the outer surface and inner surface of the saturated polyester container.

[0010] The coating formed to improve the barrier properties in the present invention is a coating of silicon oxide [SiOx (2≧x≦1)], a silicon oxide derivative, titanium oxide, or a titanium oxide derivative. Formation of these coatings on the saturated polyester container can be carried out after the saturated polyester container is formed by, for example, vapor deposition,
This can be performed by a sputtering method, a plasma CVD method, a liquid phase growth method, or the like.

For example, a silicon dioxide film can be formed by a CVD method using silane gas, a sputtering method using a quartz plate as a target, a dipping method using an organic solvent of an organosilicon compound, or a saturated polyester container is coated with silicon dioxide. This can be carried out by a precipitation method in which silicon dioxide is precipitated by immersion in a supersaturated hydrofluorosilicic acid solution. Among these, the precipitation method using silicon dioxide is preferred because it is easy to work with and can easily provide a uniform coating.

[0012] The thickness of the coating varies somewhat depending on the material, but it is generally preferably 500 to 3000 Å. If it is too thin, it will be difficult to obtain sufficient gas barrier properties, and if it is too thick, the manufacturing cost will be high and the film will be prone to cracking.

[0013] The surface on which the film is formed is generally the outer surface of the saturated polyester container, but it may be the inner surface, the outer surface, or both of the surfaces of the saturated polyester container, and the surface may be selected depending on the method of forming the film. .

The saturated polyester container itself may be the same as the conventional one, and may be obtained in the same manner as the conventional one, but a biaxially stretched blow-molded bottle is most suitable. After molding, this biaxially stretched blow-molded bottle is produced at a temperature above the temperature at which residual internal stress can be relaxed but below the melting temperature, specifically 100 to 220°C.
It is preferable to heat the material to a temperature to relax and remove residual internal stress, since this makes it difficult to shrink due to heat.

[0015]

[Function] The film of silicon oxide, a derivative of silicon oxide, titanium oxide or a derivative of titanium oxide is transparent and exhibits high gas barrier properties even when thin, and has excellent adhesion to saturated polyester containers. Further, the above-mentioned material constituting this coating is easily and uniformly dispersed in the molten saturated polyester, and its moldability is not impaired unless an excessive amount is added.

Example 1 Polyethylene terephthalate (“R” manufactured by Nippon Unipet Co., Ltd.)
A bottomed parison was molded using an injection molding machine.

Next, the entire bottomed parison except for the mouth part is heated to a temperature above the secondary transition temperature and below the crystallization temperature, and is set in a mold maintained at 15° C., and the stretching rod is inserted into the bottomed parison. While projecting out and stretching in the axial direction, pressurized fluid was simultaneously blown into the bottomed parison to expand it in the radial direction to perform blow molding, thereby molding an intermediate product with a volume of 1550 cc. This intermediate product is set in a heat-stabilized mold heated to 150°C, which has an internal shape that is almost the same as the external shape of the intermediate product, and the wall surface of the mold is stabilized by blowing pressurized fluid for 4 seconds. After the intermediate product was brought into close contact with the container to release residual internal stress, the intermediate product was cooled with circulating air to obtain a container as shown in FIG.

[0018] Plasma CVD is applied to the entire outer surface of the container.
A SiOx film with a thickness of 3000 Å was formed by the method, and the oxygen permeability and water permeability were measured as shown below.

The results are shown in Table 1.

[0020] Also, 150 °C of hot water at 85°C was placed in this container.
After filling with 0 cc and leaving it for one day without plugging, the volume shrinkage rate was 1%, and no peeling of the coating occurred.

(Oxygen permeability) Measured using "Model OX-TRAN" manufactured by MOCON.

(Moisture permeability) 85°C hot water was poured into a container for 15 minutes.
After filling the container with 00 cc and hand-tightening the screw cap, the remaining water amount was measured after being left in a constant temperature and humidity room at a temperature of 23° C. and a humidity of 50% for one year, and the water permeability was calculated from the following formula.

Moisture permeability = (filling water amount - remaining water amount after 1 year) ÷ filling water amount x 100 Comparative Example 1 Oxygen permeability and water permeability were determined in the same manner as in Example 1 except that no SiOx film was formed. Measurements were taken.

The results are shown in Table 1.

[0025]

[Table 1]

[0026]

[Effects of the Invention] The present invention is as described above, and has the following effects.

(1) Excellent gas barrier properties, so
It has high protection performance for the contents and can extend the storage period.

(2) Since the coating that provides gas barrier properties has good adhesion to the saturated polyester container,
The coating is less likely to peel off, and stable high gas barrier properties can be obtained over a long period of time.

(3) Even if the saturated polyester container having this coating is melted again, there is almost no effect on the moldability, so it can be recovered and recycled after use.

(4) Since the coating is transparent, the transparency of the saturated polyester container is not impaired.

[Brief explanation of drawings]

FIG. 1 is a front view of a container molded in an example of the present invention.

Claims (1)

[Claims] 1. A saturated polyester container characterized in that a coating of silicon oxide, a silicon oxide derivative, titanium oxide, or a titanium oxide derivative is formed on at least one of the outer surface and the inner surface.