JPS61259946A - Heat-resistant 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 (Industrial Application Field) The present invention relates to a transparent heat-resistant container suitable as a container for contents such as fruit juice drinks that require heat sterilization during filling.

(Prior art and problems) Conventionally, biaxially stretched blow containers made of polyethylene terephthalate resin have begun to be used as containers for fruit juice drinks, but since the contents are sterilized at high temperatures before being filled,
Its production requires various heat-resistant processes, and its cost is high.

For example, a method has been proposed in which the mouth of a container is crystallized and whitened to make it heat resistant (Japanese Patent Publication No. 59-33
1013, its whitening requires long-term holding at the crystallization temperature, and it is difficult to maintain a mouth size of m degrees.
It was necessary to use various techniques to seal the mouth with a cap. In addition, if such heat resistance is not applied, the heat resistance of the U part at the mouth will deteriorate if the container is tipped on its side to sterilize the mouth after filling the container with high temperature contents (e.g. 85C) and sterilizing the container. As a result, the fit between the cap and the neck of the container becomes loose, often resulting in leakage.

(Means for Solving the Interruption Point) The present invention has been devised to solve the above-mentioned interruption point in the prior art, and consists of coating both the inner and outer surfaces of the neck of the container with polyethylene terephthalate resin, and forming an intermediate layer of polyethylene terephthalate resin. It is characterized in that it is formed of a resin layer mainly composed of a heat-resistant resin, and the body and bottom of the container are formed of a resin mainly composed of polyethylene terephthalate a fat. Here, in FIG. 1, the polyethylene terephthalate applied to the outer layer 11) and the inner layer (31) may be any resin suitable for normal biaxial stretch blow molding, and have an IV value (intrinsic viscosity) of 0.5 or more. Also, since this polyethylene terephthalate resin is mainly used for the container body, the blow mold is heated to about 1,000 ℃ during stretch blow molding, and the heat setting after stretch molding is performed for 10 to 50 seconds. In some cases, a step is taken to remove residual stress and increase the heat resistance of the container.

On the other hand, the intermediate layer (2) at the neck of the container is made of a resin with sufficient heat resistance, so that when the container is filled with heated contents, capped, and then turned on its side to sterilize the inside, the inner layer (2) is made of a resin with sufficient heat resistance. Prevent accidents such as weakening of the fit and leakage of contents. The first condition for a resin that can be used as the intermediate layer (2) is that it has good adhesion to the polyethylene terephthalate used as the outer layer (1) and inner layer (3). , the heat resistance of the material itself is Q (even if the interface with polyethylene terephthalate becomes weak and the heat resistance as a container cannot be ensured. As resins, polycarbonate) +tt resin, aromatic polyester carbonate,
Examples include wholly aromatic polyester, and these alone,
Alternatively, a mixture of two or more types or a mixture with polyethylene terephthalate resin can be used as the intermediate layer (2). In addition, other heat-resistant materials such as polyetherketone resin and polyethersulfone resin may also be used by mixing them with polyester resin.

In manufacturing the container of the present invention, a small amount of polyethylene terephthalate resin is first injected into the cavity for molding the bottomed parison (4) using a multi-stage two-color injection molding machine, and then a heat-resistant resin is used to form the intermediate layer. The polyethylene terephthalate resin corresponding to the body of the container is injected from the second cylinder, and then molded so that the cross section of the bottomed parison becomes as shown in the first +Q. Biaxially stretched and blown to form a container. At this time, since the container body is thin and residual stress tends to remain after being stretched and blown, it is necessary to remove this residual stress and prevent the container from deforming as much as possible when hot filling is performed. Therefore, the blow molded container has a mold temperature of about 10
00 for 10 to 50 seconds to remove residual stress. After removing, cool and remove from the mold. Here, it is preferable that the shape of the container body be designed to accommodate deformation under reduced pressure after hot filling. In addition, if the intermediate layer of the neck part has a small proportion of the thickness of the total thickness of the neck part, it will not contribute to improving heat resistance, so it needs to be thicker than the total thickness of the second layer, and
If the thickness is less than 90% of the total thickness, the intermediate layer may be exposed, so it is preferable that the intermediate layer has a thickness of 30 to 90%.

<Example 1> A multi-stage two-color injection molding machine was used to mold the outermost and innermost layers of the bottomed Parynon neck, polyethylene terephthalate resin (IV = 0.65) for the bottom of the bottomed Parynon neck, and Napoli carpo resin (IV = 0.65) for the bottom of the bottomed Parynon neck. nate resin layer (transparent dye 2%
The thickness of the middle layer of the neck part is 1.7mm, the thickness of the inner and outer layers of the J part is 0.4mm, and the body part is made of thick polyester resin. The bottomed parison was heated to about 11 Qc and stretch-blow molded in the vertical and horizontal directions to obtain a self-supporting container. The average wall thickness of the body of this container was about 370 microns. The blow molding mold for this container has a mold surface temperature of approximately 1000°C.
Heat and pressurize for about 40 seconds while applying blow pressure, and remove residual stress during stretching. removed. Furthermore, when taking out the container from the mold, the mold was cooled and the temperature of the container was sufficiently lowered.

Fill the container obtained as above with 85C hot water, fit it to the neck of the mouth with an aluminum camper, turn it sideways, stand it upside down, etc.? After allowing the container to stand naturally, the fit between the container neck and the aluminum cap was examined, and the neck was found to be in good condition with no deformation or leakage of liquid.

<Example 2> By the same process as in Example 1, 0.5
The aromatic polyester has a polyethylene terephthalate layer of G and a heat resistance of 130 C (ASTM-D-648) in the neck middle layer. It is applied to a thickness of approximately 1.0 mm, and the body and bottom of the container are approximately 1/2 of the total thickness. A? A 1B self-supporting container was obtained by stretch blow molding in a conventional manner. The weight of this container was 459-.

This container (4)...fill a bottomed parison with 90C hot water, cap it with an aluminum cap, then leave it to stand naturally without turning it upside down or sideways, and then cool it down to see the appearance of the container, tL leakage, etc.? As a result of the investigation, it was found that the container had good heat resistance, with no deformation in appearance or leakage.

(Effect of the invention) Since the outer and inner layers are made of polyethylene terephthalate resin, and at least the middle layer at the neck part has a heat-resistant resin layer, the heat deformation temperature, which is the weak point of conventional stretch-blown containers, can be dramatically reduced. In addition, there is no need for special processes such as whitening (crystallization) used in conventional technology, which increases production speed, reduces costs, and improves quality. do.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a bottomed parison of a container according to the present invention. ]1)...Outer layer (2) -...Middle layer (3)...Inner layer

Claims (1)

[Scope of Claims] 1) In a container mainly made of polyethylene terephthalate resin, the intermediate layer at the neck of the container is made of a heat-resistant synthetic resin such as polycarbonate resin, aromatic polyester resin, or aromatic polyester carbonate alone or in a mixture. A heat-resistant container, characterized in that an inner layer and an outer layer made of polyethylene terephthalate resin are laminated on the inner and outer surfaces of the intermediate layer. 2) The heat-resistant container according to claim 1, wherein the intermediate layer of the neck has a thickness of 30 to 90% of the total thickness of the neck. 3) The middle layer of the neck has a heat distortion temperature of 120℃ (ASTM-D
-648) The heat-resistant container according to claim 1, characterized in that it is made of the above resin.