JPS62233224A - Manufacture of three-piece and two-metal end can made of polyester - Google Patents

Abstract

PURPOSE:To improve pressure resistance and sealing properties of a seaming part, by a method wherein pulling orientation in an axial direction and blow orientation in a circumferential direction are applied to a polyester pipe within a split mold, an obtained blow molded material is cut off at an end of an increasing part of the diameter of the same and molded into a biaxially oriented can shell having flanges on both open ends. CONSTITUTION:A blow molded material 1 as a piemolded material to be used for manufacturing a seamless can shell made of polyester is formed through blow molding within a mold. Then blow molded material 1 possesses closed end parts 4a, 4b at the top and bottom and possesses the upper part 6a and lower part 6b on the central part through a connecting part 5 whose diameter is small. Then the upper part and lower part are provided with a plurality of circumferential parts 7a, 7b having dimensions of a diameter and height corresponding to the final can shell and externally-swollen-out parts 8 are provided respectively among a plurality of the circumferential parts 7a, 7b and on the upper part of the topmost circumferential part 7a and the lower part of the lowermost circumferential part 7b. Then when the blow molded material 1 is cut off at the externally-swollen-out parts 8, a polyester can shell 13 whose circumferential shell part 11 and both ends are provided with seaming flanges 12 can be obtained easily.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for making a 3-piece 2-metal end can made of polyester, and more particularly, it relates to a method for making a 3-piece 2-metal end can made of polyester. The present invention relates to a method for efficiently manufacturing a composite can having multiple metal ends wound together with high precision and high productivity.

(Prior Art) A composite container consisting of a glass container body and a metal lid that are secured together at their securing ends is disclosed in Japanese Utility Model Publication No. 37-25894.
As can be seen in the publication, it has been known for a long time, and as a plastic container body, it has excellent transparency, flexibility, retention properties,
Polyethylene terephthalate with excellent mechanical properties) (P
Composite valley device using polyester such as ET)
5-3915 has already been published. In addition, this latter publication states that by maintaining the seamed part with the metal lid at a temperature near the I-T transition point of the preester resin,
It is described that defects such as 7-run cracking can be prevented.

Recently, as a method for manufacturing polyester can bodies for seaming, Japanese Patent Application Laid-Open No. 59-207216 discloses that a biaxially stretched nozzle tube is held on a mantle and heat set, and then a pipe is heated. It is described that the can body is cut into a predetermined size and then flanged to form a can body for seaming.

(Problems to be Solved by the Invention) However, in the case of polyester container bodies, unlike in the case of full-length can bodies, it is often difficult to process flanges with good dimensional bulk, and therefore it is difficult to maintain the body hook and cover hook. Inadequate contact often results in leakage.

In addition, when seaming with a metal lid, it is necessary to form seaming flanges at both open ends of the polyester body, but a special process is required to form these flanges. There are many problems, and productivity is low.

Therefore, the technical problem of the present invention is that in a composite can consisting of a polyester container body with openings at both ends and a metal lid secured at both ends, a seamed portion with high dimensional bulk is formed, and the seamed portion The retention and fixation of the polyester portion is also performed reliably, and as a result, the pressure-resistant sealing performance of the seamed portion is significantly improved.

Another technical object of the present invention is to provide a method for reliably manufacturing the above-mentioned composite cans with a small number of steps and with high productivity.

(Means for Solving the Problems) According to the present invention, a method for manufacturing a 3-piece 2-metal end can, which comprises tightening both open ends of a seamless polyester can body and a metal lid. In this step, a single-layer or multi-layer pipe made of polyester, which has been formed in advance by an extrusion method, is held at the stretching temperature of polyester, and both ends of the pipe are gripped to correspond to the body of the final can body. The container is stretched in the axial direction within a split mold having a plurality of circumferential portions and grooves of increasing diameter located between the circumferential portions and/or at the ends of the circumferential portions and corresponding to the can body flange portions. At the same time, the three-pin polyester can body is blow-stretched in the circumferential direction, the resulting blow-molded body is cut off at the end of the increased diameter part, and formed into a biaxially stretched polyester can body having flanges at both open ends. A method for manufacturing a one-piece two-metal end can is provided.

(Function) The present invention is constructed by stretching the armhole 10 made of thermosetting polyester in the axial direction (stretching in the direction of the arrow) and then blow-stretching it in the circumferential direction, as shown in FIG. The first feature of the present invention is to manufacture a hollow molded body having a flange that is integrated with the circumferential wall of the can body and has a shape that can be immediately used for seaming with the can lid.

Fig. 2 shows a precursor molded body, that is, a hollow molded body 1, used for manufacturing a seamless polyester can body. It is formed by blow molding. That is, the axially stretched mother ribs are on both sides 2a.

While being pinched off, a fluid is blown through the blowing needle hole 3 to form a predetermined shape as described below.

This hollow molded body 1 has a vertically closed end f1s 4 a
-4b, and has an upper part 6& and a lower part 6b via a small-diameter connecting part 5 in the center. The upper part 6a and the lower part 6b have a plurality of circumferential parts 7h and 7b having diameter and height dimensions corresponding to the final can body, and a plurality of circumferential parts 7.
Between m + 7 b, there is an outwardly bulging portion 8 with an increased diameter.
There is also an outward bulge 8 above the uppermost circumferential portion 7a, and an outward bulge 8 below the lowermost circumferential portion 7b. It is provided. When this hollow molded body 1 and the outwardly bulging portion 8 are cut at the position A-A, a through hole shown in FIG.
12 can be easily obtained.

According to the invention, in this way, the seaming flange 12.1
2 can be formed without the need for special flanging operations.
This has the advantage that the body can be formed in one step with biaxial stretching blow molding to provide excellent mechanical strength, creep resistance, and even transparency, and this flange portion is formed in the blow molding process described above. Since it is formed, it also has very good dimensional bulk.

Moreover, extruding polyester to make pipes and making can bodies from this pipe provides several additional advantages. One of these is that there is no melt viscosity restriction as in injection molding, which allows the use of high molecular weight polyesters, resulting in significant improvements in the mechanical strength and molecular orientation of the final can body. Furthermore, since extrusion molding into a tube or tube is continuous molding, efficiency is improved. Furthermore,
Simultaneous coextrusion of an ethylene-vinyl alcohol copolymer layer and an adhesive layer is possible, and multilayering can be easily and precisely achieved.

Furthermore, since the seaming flange is also given biaxial molecular orientation, it has a structure that is strong against seaming with the metal lid.

In Figure 4 showing a 3 piece 2 metal end can according to the present invention, this can is shown in the polyester can body 13 shown in Figure 3.
This is obtained by placing the metal lid 14 on the flange portion 12.12 of the flange portion 12, and tightening these together.

Since both ends of the polyester can body 13 are fixed with rigid metal lids, the container has excellent pressure resistance and heat resistance.

(Operations and Effects of the Invention) According to the present invention described above, polyester can bodies equipped with flanges that have good dimensional bulk and excellent mechanical frequency can be produced efficiently and at a high production rate. It has become possible to industrially manufacture a 3-piece, 2-metal end can with excellent properties.

(Description of Preferred Embodiments of the Invention) The thermoplastic/IJ ester whose main repeating unit is ethylene terephthalate used in the present invention is usually 80 or more moles of acid component, preferably 90 or more mole of terephthalic acid, and glycol component. It means a polyester in which 80 molar acids or more, preferably 90 molar or more, is ethylene glycol, with the remaining other acid components being in7talic acid, diphenyl ether 4,4'-dicarboxylic acid, naphthalene 1,4- or 2,6- Dicarboxylic acid, adipic acid, sebacic acid, deca/1110-dicarboxylic acid, hexahydroterephthalic acid, and other glycol components such as propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, 1,6-h*sylene Klicol, cyclohexane dimetatool, 2,2
-bis(4-hydroxyphenyl)fronon, 2
．． 2-bis(4-hydroxyethoxyphenyl)globin, or as an oxyacid p-oxybenzoic acid, p-
It means a preester containing ethoxybenzoic acid, etc. Further, a polyfunctional component having trifunctionality or more may be copolymerized within a range that does not impair moldability. Also, for mixing polyethylene terephthalate with other thermoplastic 4-esteryl,
A mixed preester of two or more types in which the ethylene terephthalate content is 80 moles or more may also be used.

In addition, the 4-lyester in the present invention may contain additives such as colorants, ultraviolet absorbers, antistatic agents, thermal oxidative deterioration inhibitors, antibacterial agents, lubricants, and inorganic fillers in appropriate proportions as necessary. can.

The thermoplastic polyester used in the present invention needs to have an intrinsic viscosity of 0.7 or more, preferably 0.8 or more, and more preferably 0.9 to 2.5.

Intrinsic viscosity is a solution of polyester dissolved in a mixed solvent of phenol/tetrachloroethane (6/4 weight ratio).
Intrinsic viscosity measured at °C. Further, the present invention provides a laminated cylinder with a resin having excellent gas barrier properties such as 2 polyester and other resins such as metaxylylene group-containing polyamide, polyvinylidene chloride, acrylonitrile styrene copolymer, and ethylene vinyl alcohol copolymer. It also includes a can-shaped container made of a body or a coated polyester cylinder.

To produce yd +7 ester pipes, thermoplastic I
It is melt-extruded and molded through a die of a predetermined shape on a Lyester extrusion molding machine. When it is desired to impart particular transparency to the container body, the melt-extruded i4 igu is cooled to below room temperature and rapidly cooled with sipes for controlling the shape of the tube to form an amorphous pipe.

For the stretch-blown acid form of the hollow precursor molded body of No. 4 Ib, pipes are cut into appropriate lengths, for example, 85 to 11 mm.
After heating to a polyester stretching temperature of 0° C., it is held with a clamp 7 and stretched in the axial direction, and is also blow stretched in the circumferential direction in a split mold. The axial study magnification is 1.2 to 5.
The stretching ratio in the circumferential direction is preferably 1.1 to 4.5 times, particularly 1.3 to 3.5 times.

The shape of the hollow precursor molded body 1 is not limited to that shown in FIG. 2, and, for example, the shape shown in FIG. 5 or any other shape may be used. Further, the shape of the circumferential side wall is not limited to a cylindrical one, but can be any shape such as a barrel shape, an ellipse shape, a square shape, or a neck-in structure directly below the flange part. good.

The outward bulge of the formed hollow precursor compact? Cut it,
Several 6L can body members are constructed from one precursor molded body.

! The lid is made of various surface-treated steel sheets such as tin-plated steel sheets, tin-free steel (electrolytic chromic acid treated copper sheets), and light metals such as aluminum, and the surface is coated with epoxy-7 enol paint, epoxy urea paint, etc. Those provided with a protective coating such as epoxy-acrylic obstetric paint, epoxy-vinyl paint, vinyl-phenol paint, etc. are used.

A circumferential groove is provided around the can lid for engagement with the seaming end of the barrel, and the inside of the can lid is lined with a sealing rubber composition. The center panel portion of the can lid can be provided with a known easy-to-open mechanism.

Sealing the polyester body and the metal can can be easily done using a seamer which is known per se and is conventionally used for seaming metal cans.

(Examples) Example 1 Polyethylene terephthalate having an intrinsic viscosity of 1.0 was melt-extruded to form a /4' product with an inner diameter of 25 mm and a wall thickness of 4 mm.

This f'ff is cut into a predetermined size of 200 mm, heated to a stretching temperature of approximately 100°C, and then held at both ends of the pipe and a clamping piece and stretched by approximately 2.5 times in the axial direction. At the same time, blow stretching was carried out approximately 3.0 times in the circumferential direction in a mold having a cavity shaped as shown in FIG. 2 to obtain a precursor molded body. The end of the increasing part of the diameter of this precursor molding metal (the tip of the bulging part)
Then, a can body with 7 grooves formed on both ends was formed. The wall thickness of this can body was 0.5 mm. A metal lid was double-sealed to one end of the can body, and after filling with Coke 2500C, a metal lid was double-sealed to the other end.

In a storage test of this sealed can at room temperature for one month, the can was found to be in good condition with no leakage from the seam and no bulging of the body.

Example 2 Nylon 6/nylon 66 copolymer with polyethylene terephthalate having an intrinsic viscosity of 1.0 as inner and outer layers, an ethylene-vinyl alcohol copolymer as an intermediate layer, and interposed between the inner and outer layers and the intermediate layer? Multi-layer with adhesive layer made of Liamide
Mother Eve was coextruded.

This pipe has an inner diameter of 25. So, the wall thickness of the inner layer is 12WI/
Adhesive layer 1.5, / Intermediate layer 3 layers / Adhesive layer 1.5, /
It was in the outer layer 7 area.

This 4-beam was cut into a predetermined size of 150 m, and approximately 100 m long.
After heating to a drawing temperature of 120°C, both ends of the pipe are held with clamping pieces and stretched approximately 2.5 times in the axial direction. A pre-formed product was obtained by blow-stretching the sample by approximately 3.0 times in the circumferential direction in a mold having a spacing. This precursor molded body is cut at the end of the increasing diameter part (flange part), and flanges are formed at both ends of the can body. Molded. A metal lid is double-sealed on one end of this can body, and gas at 85°C is released into a carbon dioxide gas with a volume of 2.0.
After filling 250 cc of juice, a metal lid was double-sealed on the other end.

In a storage test of this sealed can at 37°C for one month, there was no leakage from the seam and no deformation of the body.

Furthermore, there was almost no carbon dioxide loss, and no discoloration or change in taste of the contents was observed.

[Brief explanation of drawings]

Fig. 1 is a front view of a pipe with a partially cutaway cross section, Fig. 2 is a sectional view of the precursor molded body, Fig. 3 is a @ side view of the can body, and Fig. 4 is a partially cutaway 1! A front view of a 3-piece 2-metal end can with a cross section, and FIG. 5 is a cross-sectional view of another precursor molded body. 1... Precursor molded body, 7&, 7b... Circumferential part, 8...
・Multiple part, 10... Pipe, 11... Circumferential body part, 1
2... Sealing flange, 13... Can body, 14...
metal lid.

Claims (1)

[Claims] (1) A method for manufacturing a 3-piece 2-metal end can, which consists of tightening both open ends of a seamless polyester can body and a metal lid. A single-layer or multi-layer pipe is held at the polyester stretching temperature, and both ends of the pipe are gripped to form a plurality of circumferential sections corresponding to the body of the final can body, between the circumferential sections, and between the circumferential sections. The resulting blow-molded product is stretched in the axial direction in a split die equipped with a diameter increasing groove located at the end and corresponding to the can body flange portion, and blow stretched in the circumferential direction. 1. A method for manufacturing a three-piece two-metal end can, which comprises cutting at the end of each section and forming a biaxially oriented polyester can body having flanges at both open ends.