JPS6045146A - Polyester vessel with metallic cover - 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] This invention relates to polyester containers with monometallic lids.

Do aluminum cans have superior performance such as airtightness and can strength? ]
Because they are 1-containing, they are widely used as containers for various beverages, but the raw materials are expensive and the containers are opaque, making it difficult to see the contents from the outside. In order to solve this problem, it has been proposed that the opening of a cylindrical polyester container is completely fitted with a ductile metal lid made of aluminum or the like. To fully attach the metal lid to the opening of the polyester container.

The conventional double-sealing method can be applied to aluminum cans, Nutile cans, etc., but thermoplastic polyester has a lower elastic modulus than metal materials, and internal pressure is constantly applied to it, such as when filling carbonated drinks. In some cases, the strain in the thickness direction of the container body at the seamed portion due to internal pressure stress is greater than the strain in the thickness direction of the metal can body. Therefore, in the conventional double seaming method, there are many accidents in which the container body slips through the seam and the metal lid comes off.

In order to solve these problems, it has been proposed to use a contact agent in the seaming part, but it is not perfect in terms of adhesion speed, and is particularly suitable for applications in beverage cans that are filled under high pressure. is inappropriate.

As a result of intensive research aimed at solving the above problems, the inventors of the present invention have invented a polyester container with a metal lid that prevents the container body from slipping through and does not reduce sealing performance.

That is, the present invention consists of a thermoplastic polyester mainly containing ethylene terephthalate repeating units,
Opening 1 of a cylindrical container body extending in at least one axis direction
A polyester container having a ductile metal lid fully double-sealed at the opening, characterized in that at least a portion of the thermoplastic polyester in the seaming portion O is whitened by thermal crystallization (=I It is a polyester container.

This invention will be explained with reference to the drawings. Part 1 shows a partial sectional view of a double-sealed part by the conventional method. 1 is a metal lid, 2 is a cylindrical polyester container body, and A cover hook part 1a on the peripheral edge and a body hook part 2a on the upper edge of the container body 2 are double-sealed to form a seam-fastened part 3. FIG. 2 is a partial cross-sectional view of an embodiment of the present invention, and 13a shows a state in which a part of the polyester in the seamed portion has been whitened by heating and crystallization. FIG. 3 is a cross-sectional view showing four high-frequency induction heating coils for heating and crystallizing the wound portion.

To crystallize the seam by heating the seam, there are two methods: contact heating of the entire seam of the heated mold, and non-contact heating using heated air or infrared heaters. However, high-frequency induction heating is the heating method. This method is most suitable because it allows rapid and localized heating. As shown in Figure 3, by placing a high frequency induction coil close to the outside of the seaming part and passing a high frequency current of 1.00 kHz or higher, a part of the polyester can be whitened by thermal crystallization. .

By crystallizing the seamed portion, the specific gravity of the polyester is improved to 1.365 or more, preferably 1.370 or more, so that even if stress from the internal pressure of the container is applied to the seamed portion, the specific gravity of the polyester is improved in the thickness direction. distortion is reduced and soot leakage is prevented.

In this thermoplastic polyester having ethylene terephthalate as a main repeating unit, 80 mol% or more of the acid component - preferably 90 mol% or more of the acid component is usually terephthalic acid, and 80 mol% of the glycol component, preferably 90 mol% or more. It means a polyester in which ethylene glycol accounts for mol% or more, and the remaining acid components include isofucuric acid, diphenyl ether 4I47-dicarboxylic acid, naphthalene], 4- or 2,6-dicarboxylic acid, adipic acid, sepacic acid, decane 1 , 10-dicarboxylic acid, hexahydroterefugu! phosphoric acid, and other glycol components such as propylene gellicol, 1,4-butanediol, neopentyl glycol, diethylene glycol, 1,6-hequinalene gelicol, and cyclohexane dimetatool% 2
．． 2-bis(4-hydroxyphenyl)propane = 2.
Polyester containers containing 2-bis(4-hydroxyethoxyphenyl)propane, or oxyacids such as P-oxybenzoic acid and P-hydroethoxybenzoic acid. Further, all polyfunctional components having trifunctionality or more may be copolymerized within a range that does not impair moldability. Alternatively, it may be a mixed polyester of two or more types in which ethylene terephthalate becomes 80-[:Jv% or more by mixing polyethylene terephthalate and another thermoplastic polyester.

In addition, the polyester in this invention may contain a colorant, an ultraviolet absorber, an antistatic agent, a thermal oxidative deterioration inhibitor,
Additives such as antibacterial agents, lubricants, and inorganic fillers may all be contained in appropriate proportions.

The thermoplastic polyester of the present invention must have an intrinsic viscosity of 0.55 or more, preferably 0.6 or more,
More preferably, it has an intrinsic viscosity 7 of 0.7 to 1.4. Intrinsic viscosity is phenol/tetrachloroethane mixed solvent (
, 6/4 weight ratio)
It is the intrinsic viscosity measured at 'C. This invention also applies to polyesters and other resins such as metaxylylene group-containing polyamides, polyhynylidene chloride, acrylonitrile styrene-L! It also includes a can-shaped container made of a laminated cylinder with a resin having better anti-corrosion properties such as a polymer or a coated polyester cylinder. To manufacture a cylindrical polyester container body, it is melt-extruded and molded through a die 7 of a predetermined shape of a thermoplastic polyester extrusion molding machine. If the main body of the container is particularly intended to have strength, the melt-extruded pipe is cooled to below room temperature, quenched with a sizer to reduce the pipe shape, and then formed into an amorphous pipe. 1. If the mechanical strength of the container body is to be increased, the extruded pipe should be uniaxially or biaxially stretched by heating to an appropriate temperature for stretching at Q or more + 150"C or less. If the pipe is to withstand high temperatures such as filling or high-temperature sterilization, the stretched pipe is heat-set under tension.

As described above, the container body of the present invention can have any desired performance by completely changing the processing conditions after melt extrusion. Moreover, it can also be applied to the tightening of bottomed containers obtained by deep drawing L by vacuum forming, pressure forming, etc., of unstretched or low-stretched sheets.

The material of the metal lid is a ductile material, such as aluminum, tinplate, plastic laminated or coated metal.

This invention will be explained in detail below.

Example Intrinsic viscosity 0.75 (phenol/tetrachloroethane-
Polyethylene terephthalate (measured at 30°C using a 6/4 weight ratio mixed solvent) was melted at a total temperature of 275°C.

Extruded from pipe die, inner diameter 15.8 myn, outer diameter] 7
Extruded into a tubular shape of 7π7n, blow-stretched with pressurized air of 93° (2kQ10at), and stretched 3 times in the circumferential direction to obtain an inner diameter of 5.
A stretched tube with a length of 2.4 myn and an outer diameter of 53 mm was formed. The specific gravity of this stretched tube was 1.862. 2 lengths of this stretched tube]
It was cut to a length of 40 πm, and then a flange was aged at 100°C using a hand press machine at both end openings. Next, a semi-troseamer (
(manufactured by Handa-Osama Co., Ltd.). Next, a ring-shaped high frequency induction coil placed at a distance of 1.5 mrn from the upper end of the winding part to the lower end 1 of the coil was heated with 25QkH2,1,5
A current of KW was applied for 28 seconds to heat and crystallize the Keboli Nutel in the seamed portion without melting, and then cooled. A portion of the seamed portion was whitened due to crystallization, and the specific gravity of the crystallized portion was 1.378.

As a comparative example, all of the above examples were prepared in which the seaming portion was not entirely heat-treated.

Ten of the polyester containers of the above examples and comparative examples were subjected to an internal pressure of -5.0 kQ/cyA and left in an atmosphere of 70°C. Although none were found, all 10 metal lids came off in the comparative example.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing the structure of a conventional seaming section. FIG. 2 is a sectional view showing the entire structure of a seaming portion showing an example of the present invention, and FIG. 3 is a sectional view of a seaming portion having a high-frequency induction heating coil (vk). ]: Gold m lid, 2: Polyester container body, 3: Sealing part-3a: Crystallized seaming part, 4: High frequency induction heating coil. Patent applicant: Toyobo Co., Ltd. Mitsubishi Heavy Industries, Ltd. Agent: Patent attorney Takeo Sakano Ryoji Yoshida

Claims (1)

[Scope of Claims] [1] Ethylene terephthalate) A cylindrical container body made of thermofusible polyester and having at least a portion stretched in one axis direction. , a metal-attached polyester characterized in that, when a polyester container is double-sealed with a ductile metal lid, at least a portion of the thermoplastic polyester in the first-sealed portion is whitened by thermal crystallization. container.