JPH0427928B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laminated bottomed parison and a method for manufacturing the same, more specifically, the inner and outer layers are made of saturated polyester, the center layer is made of ethylene-vinyl alcohol copolymer, and the cap engagement of threaded portions etc. The present invention relates to a laminate bottomed parison formed with a laminate and a method for manufacturing the same.

A saturated polyester bottle, such as a polyethylene terephthalate bottle, formed by biaxial stretching blow molding is molded from a bottomed parison, and most of the bottle, especially the body, except for the mouth and neck, which serves as the gripping part, undergoes molecular orientation due to biaxial stretching. As a result, container properties such as transparency, gas barrier properties, and impact resistance have been improved, and recently containers have been used to store liquid foods containing carbon dioxide such as beer and carbonated drinks. It is expanding.

However, if the bottle is made of saturated polyester alone, such as polyethylene terephthalate alone, the gas barrier properties will not be sufficiently improved; for example, when a carbonated drink is stored, carbon dioxide gas will permeate through the bolt wall and escape over time. ,
In the case of bottles with an internal volume of about 1 to 2 liters, there is a problem in that the preferable storage period is about 3 months, which is relatively short. Furthermore, since the mouth and neck are not stretched and are usually amorphous, their hardness is relatively low, and therefore the cap engagement parts such as threaded parts are easily damaged, which can cause gas leakage when filled with carbonated drinks etc. However, there was a problem that the sealing performance was easily impaired.

The present invention solves the conventional problems mentioned above.
Suitable for producing biaxially stretched blow molded bolts,
The purpose of the present invention is to provide a bottomed parison and a method for manufacturing the same.

In order to achieve the above object, the present invention consists of a laminate in which the inner and outer layers are made of saturated polyester and the center layer is made of ethylene-vinyl alcohol copolymer, and the saturated polyester in the cap engaging part is crystallized. The present invention provides a laminated body bottomed parison having the following characteristics.

Furthermore, the present invention is characterized in that the inner and outer layers are made of saturated polyester.
A laminate pipe piece whose center layer is made of ethylene-vinyl alcohol copolymer and whose ends are open.
A method for manufacturing a laminate bottomed parison having a cap engaging portion by welding and closing a first end to form a bottom portion and forming a cap engaging portion at a second end, the method comprising: The method includes placing the second end heated to the crystallization temperature of the saturated polyester in a mold having a shape corresponding to the cap engaging portion, and while crystallization is proceeding, the second end is heated to the crystallization temperature of the saturated polyester. The present invention provides a method for manufacturing a laminated body bottomed parison, characterized in that the cap engaging portion is formed by expanding the cap engaging portion by blowing and bringing the cap engaging portion into close contact with the mold.

The present invention will be described below with reference to the drawings which are examples.

1 and 2 show a laminated bottomed parison (hereinafter referred to as a parison) which is an embodiment of the present invention, and the parison 1 is made of saturated polyester, such as polyethylene terephthalate. a relatively thick inner layer 2 and an outer layer 3, a relatively thin center layer 4 made of ethylene-vinyl alcohol copolymer, and a very thin modified polyester,
Alternatively, it has a five-layer laminate structure composed of an inner adhesive layer 5a and an outer adhesive layer 5b made of acid-modified polyolefin.

The thickness of the inner layer 2 and outer layer 3 of the body 7 is, for example, 1
~4 mm, and the thickness of the central layer 4 is, for example, 0.3 ~ 1 mm.
mm. The center layer 4 is relatively thin, but is made of ethylene-
Vinyl alcohol copolymer has much higher (for example, about 50 times) carbon dioxide and oxygen barrier properties (compared to the same thickness) than polyethylene terephthalate, which has been molecularly oriented by stretching. Bottles formed by blow molding have much higher carbon dioxide and oxygen barrier properties than stretch blow molded bottles made of polyethylene phthalate alone and having the same wall thickness.

Further, the inner and outer layers 2 and 3 of the mouth and neck part 8, which has a threaded part 8a and a retaining ring 8b and has an end face 8c, are crystallized. Although not shown, the threaded portion 8
Only the saturated polyester of a and end face 8c, in this case polyethylene terephthalate, may be crystallized. Therefore, the threaded portion 8a and the end surface 8c
Since it has been hardened, there is less risk of damage to the threaded portion 8a and end face 8c during the process of stretch blow molding the bottle and before filling and sealing the bottle, making it easier to seal the bottle. Secured.

Next, a method for manufacturing parison 1 will be described.

FIG. 3 shows an example of a laminate pipe piece 10 (hereinafter referred to as a pipe piece) that is the material of the parison 1. The pipe piece 10 is formed by melt extrusion from a multilayer coextrusion die and then rapid cooling. It is obtained by cutting the long pipe having the five-layer laminate structure into a predetermined length, and the resin constituting each layer has a transparent amorphous structure.

The first end 10a of the pipe piece 10 is heated to the melting temperature of polyethylene terephthalate, then welded and pressure-sealed using a mold (not shown), closed, and then rapidly cooled to form an amorphous structure and a dome-shaped exterior. The pipe piece 10' is formed into a bottomed pipe piece 10' having a bottom part 6 projecting in the opposite direction (FIG. 4).

The bottomed pipe piece 10' then has an open end portion 8' corresponding to the neck 8 of the parison 1 to be formed (corresponding to the second end 10b of the pipe piece).
While rotating with a heater 18 (for example, an infrared heater), the crystallization temperature of the polyethylene terephthalate forming the inner and outer layers 2 and 3 is 140 to 210°C, more preferably, the end face 8c of the neck at the end of the blow described later.
In order to prevent the molten ethylene-vinyl alcohol copolymer from flowing out, the melting point of the ethylene-vinyl alcohol copolymer forming the center layer 4 (usually 160~
185°C) lower than the above crystallization temperature, e.g. 140~
It is heated to a predetermined temperature within the range of 170°C.

After that, while the crystallization is not completed, that is, while the crystallization is progressing, as shown in FIG. Blow mold 13 having
and insert the open end portion 8' into the blowing mold 1.
The air 14 blown from the outer mold 12 blows, that is, expands, and brings the threaded portion 8a, end surface 8c, and retaining ring 8b into close contact with the inner surface of the outer mold 12.
A mouth and neck part 8 is formed. Note that 19 is the bottom 6
It is a holder.

The outer mold 12 has a heating part 12 corresponding to the mouth and neck part 8.
a, and a cooling part 12b cooled by a cooling pipe 17, which corresponds to the trunk wall part 9 expanded below the retaining ring 8b. (consisting of fluororesin film). Heating section 1
2a and the blow mold 13 are heated to a predetermined temperature by built-in heaters 15 and 16, respectively.
Sufficient crystallization of the mouth and neck region 8 is now achieved.

When the body wall portion 9 (which becomes the shoulder of the stretch-blown bottle) is heated by the heater 18, it is heated to the crystallization temperature or lower by heat conduction, etc., and reaches the glass transition point (in the case of polyethylene terephthalate). The cooling portion 12b of the outer mold is provided in the portion where the temperature has increased to about 70° C. or more, to restrict expansion of the portion 9, prevent crystallization, and enable stretching.

After the crystallization of the mouth and neck portion 8 is completed, the outer mold 12 is opened and the blowing mold 13 is taken out. The time required to complete crystallization of the saturated polyester will vary depending on temperature and thickness, but for example, if the pipe piece 10 is
mm of polyethylene terephthalate,
It takes about 2 minutes at 140℃ and about 1 minute at 170℃.

The method of the present invention is not limited to the above examples; for example, the heating temperature may be controlled so as to crystallize only the threaded portion 8a and the end face 8c without crystallizing the retaining ring 11b. good.
The present invention is also applicable to a bottomed parison in which an annular protrusion for connecting the cap by winding is provided at the open end instead of the threaded portion 8a. In this case, the annular protrusion is crystallized in the same manner as above.

According to the present invention, there is provided a bottomed parison that has excellent barrier properties against gases such as carbon dioxide gas, is resistant to crystallization and scratches in the cap engaging portion, and is suitable for molding a saturated polyester bottle with excellent sealing performance. It has the effect of being provided.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a parison that is an embodiment of the present invention, and FIG. 2 is a section A in FIG. 1 and a section B in FIG. 3.
3 is a vertical cross-sectional view of an example of the pipe piece that is the material of the parison shown in Fig. 1, and Fig. 4 is an opening of a bottomed pipe piece formed by forming a bottom part on the pipe piece shown in Fig. 3. FIG. 5 is a vertical cross-sectional view showing a state in which the end portion is heated; and FIG. DESCRIPTION OF SYMBOLS 1... Laminated body bottomed parison, 2... Inner layer, 3... Outer layer, 4... Center layer, 6... Bottom, 8a... Threaded part (cap engaging part), 8c... End face (cap engaging part), 1
0...Pipe piece, 10a...First end, 10b...Second end, 12...Outer mold, 13...Blowing mold.

Claims (1)

[Claims] 1. The product is characterized in that the inner and outer layers are made of a laminate made of saturated polyester, the center layer is made of ethylene-vinyl alcohol copolymer, and the saturated polyester in the cap engaging part is crystallized. Laminated bottomed parison. 2. The first end of a laminate pipe piece, which is open at both ends and whose inner and outer layers are made of saturated polyester and whose center layer is made of ethylene-vinyl alcohol copolymer, is welded closed to form a bottom part, and the second end is welded closed. A method for manufacturing a laminated bottomed parison having a cap engaging portion by forming a cap engaging portion at an end thereof, the method comprising: forming a second end heated to the crystallization temperature of the saturated polyester; The second end is placed in a mold having a shape corresponding to the cap engaging part, and while crystallization is progressing, the second end is expanded by blowing and brought into close contact with the mold. A method for producing a laminated bottomed parison, the method comprising forming an engaging portion.