JPS62220443A - Duplex rolled plastic can - 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 (Field of Industrial Application) The present invention relates to a plastic can with a metal lid, and more specifically to a plastic can with a metal lid.
Regarding planutic cans.

(Prior Art) A composite container formed by wrapping a plastic container body and a metal lid 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 is also used as a plastic container body to improve attractability, flavor retention,
Polyethylene terephthalate (PE) with excellent mechanical properties
Composite containers using polyester such as
This is already known from Japanese Patent No. 5-3915. In addition, this latter publication states that by maintaining the seamed part with the metal lid at a temperature near the glass transition point of the polyester resin,
It is described that defects such as flange cracking can be prevented.

Recently, Japanese Unexamined Patent Publication No. 60-45146 describes that in this type of composite container, the thermoplastic polyester in the seam portion is whitened by thermal crystallization.

(Problems to be Solved by the Invention) However, in order to double-seal the end of the plastic container body and the metal lid, the plastic end must be approximately 180
It is necessary to be able to bend υ many times and mechanically engage firmly with the metal lid ψ component, but plastic has poor bendability compared to metal, and is also less rigid than metal. It has the characteristic of being poor in

For this reason, in double-sealed parts using plastic container bodies, it is difficult to ensure a sufficiently large overlap width between the body hook and cover hook, which is said to be most important for sealing. The sealing performance is still fully satisfactory. In addition, it is often difficult to mechanically securely fix the seaming end of the plastic container body within the double seaming part, and the seaming end of the container body may come off. The drawback is that sufficient pressure-resistant sealing power cannot be obtained.

Therefore, the present invention provides a plastic can with a metal lid that is double-sealed between the metal lid and the open end of the body of the plastic container, in which the overlap width between the body hook and the cover hook is made sufficiently large. It is an object of the present invention to provide a means for firmly mechanically fixing the double seaming part of the seaming part 4 of the container body.

(Means for Solving the Problems) The present invention provides a plastic can body made of plastic and having a seaming end at its open end, and a metal can body made of metal and having a seaming end around its periphery. In a plastic can consisting of a lid and a seaming part formed between the plastic can body and the metal lid, the plastic can body has a part between the tip and the base of the flanz part and a seam of 7 runs. App1 is characterized in that it has a groove that is thicker or smaller on the side in the seaming direction, and that the front end of the flange serves as a body hook that engages with the lid hook. The above problems can be effectively solved.

(Function) In FIG. 1 showing the main parts of the plastic can body used in the present invention, this can body 1 has a circumferential 0111 wall portion 4 having an inner circumferential surface 2 and an outer circumferential surface 3, and the tip thereof has a diameter of about 90 mm. It is bent outward to form a 7 lanso 6. This Franz 6
A groove portion 8 with a reduced wall thickness is formed between the root portion 5 and the forefoot portion 7.

This groove portion 8 is provided on the lower side of the flange portion 6, that is, on the side in the tightening direction of the flange. That is, the circumferential side wall portion 4 is Tw
On the other hand, the groove portion 8 has a thickness To that decreases in accordance with the depth of the groove, and the width of the groove portion in the radial direction is W. It becomes. Although not necessarily restricted, the thickness of the flange portion tip 7 may be the same as the thickness Tw of the circumferential side wall portion.

In FIG. 2 showing the structure of the double seam portion 9, the plastic container body 1 has a downwardly directed media hook (body hook) 10, and this body hook 10 is similar to the flange portion 6 in FIG.
is formed by being forcibly bent downward together with the seaming edge of the metal lid 11. On the other hand, the metal lid 11 is
Cover hook (lid hook) 1 facing upward in the tightened state
2, and an outer peripheral portion 13 on the outer peripheral side of the cover hook 12.
Also, there is an inner circumferential portion 14 on the inner circumferential side of the cover hook 12. Thus, the defutter 10 of the plastic container body is clamped between the cover hook 12 and the outer periphery 13 of the metal lid, and the straight top 15 of the plastic container body is engaged with the inner periphery 14 of the metal lid, or even the inner periphery. Part 14
and a cover 7crew 12. Furthermore, there is a lower gap 16 at the tip of the body hook 10, and an upper gap 17 at the tip of the cover hook 12.

The present invention provides a structure in which the flange portion 6 of the plastic container body 1 is provided with a groove portion 8 whose wall thickness is reduced.
It is possible to make the width of the overlap part OL where the pick 10 overlaps with the cover 7 and the lever 12 sufficiently large,
This is based on the knowledge that seaming workability and sealing reliability are significantly improved.

In FIG. 3 for a detailed explanation of the present invention, when double seaming is performed, the thickness of the flange portion 6 of the body 7 is t (WlK), the neutral radius of bending is the axis r, and the elasticity of the plastic constituting the body flange is If the ratio is E (k19/m♂) and the diameter of the flange bending part is D (mi), then the bending moment M
Ckg/home is calculated using the following formula (%).As mentioned above, the bent 7 langes are held in place by the frictional force between the inner surface of the can lid and the 7 langes, and this bending moment (M) is the friction. If the force becomes larger than the above force, the 7-lunge portion may become pack-ring or come off. The frictional force is constant and at the minimum possible bending radius (rm) of the 7 flange,
Assuming that this balance is maintained, from the above equation (1), the equation r=kIIt3. 0. ,,． 18. (2)
In the formula, k is a coefficient, which is calculated by δ. That is, it becomes clear that the possible minimum bending radius rm of the seven flange portions is proportional to the cube of the thickness t of the flange portion. This means that the thickness of the 7-lunge part (1)
It acts on the order of the third power in reducing the minimum bending radius (rm) that can be made smaller, and for example, if the thickness of the 7 flange part is increased, it means that the minimum bending radius can be reduced to 1/8. ing.

In the double seaming part, the curve of the 7 lunge part can be obtained by making the radius smaller, which means that the length of the dehook can be increased, and the overlap width between the body hook and the cover hook can be increased. This makes it possible to significantly improve seaming workability and sealing reliability.

In fact, a polyester can 41 with a 7-lunge thickness (t = 0.35 mm and a 7-lunge inner bending radius rl = 0.2 m)
and polyester canned 2 with flange thickness (t*) = 0.6 mm and 7-lunge bending inner radius rz = 0.2 mtn.
And about gas? Filled with 4.0 times the amount of carbonated beverage, sealed with a metal lid, and stored at 37℃ for 24 hours.
When inspecting for leaks, there were zero leaks out of 200 cans for 7f&1, but 1 out of 200 cans for A2.
Leakage occurred at a rate of 5 cans. This means that the flange bending radius of the &2 can is (tx/lx
)" should be about 5.04 times, but this seems to be because the flange was forced to bend and the overlap width became extremely small.

In the case of an actual plastic can body, the thickness of the circumferential side wall 4 (
The thickness of Tw) cannot be lower than a certain standard value from the viewpoint of shape retention and pressure deformability of the container. On the other hand, in the seaming portion with the metal lid, due to the rigidity of the metal lid, sufficient shape retention and pressure deformability can be obtained even if the thickness of the seaming end portion is small. In the present invention, from this point of view, the groove portion 8 is provided in the portion where the flange portion 6 is bent, and the wall thickness (To) of this portion is reduced, thereby making the thickness of the circumferential side wall portion 4 sufficiently large. However, it is possible to make the possible minimum bending radius (rrn) sufficiently small, thereby making it possible to make the length of the pyy dihook part 10 sufficiently long, and making it possible to make the overlap width OL sufficiently large. That is.

In this case, it is also important that the groove portion 8 is provided below the seven flange portions 6, that is, on the side in the seaming direction. That is, in FIG.
Compressive stress occurs in the bending part below the neutral plane NJI) of bending, and tensile stress occurs above the neutral plane NJI), which exerts a dominant influence on the minimum possible bending radius Dm). It is believed that a lotus is a compressive stress applied to the lower side of a bend, but in the present invention, the part where this compressive stress should occur is cut out, so it is understood that the structure is even easier to bend. Good morning.

(Operations and Effects of the Invention) According to the present invention described above, it is possible to form a double-sealed portion with excellent sealing reliability and pressure-resistant sealing force between the plastic container body and the metal lid. It has become possible to reliably prevent leakage problems even for contents that have their own pressure, such as drinks and beer, or for contents that have reduced pressure or vacuum inside (Description of preferred embodiments of the invention ] The plastic container body used in the present invention can be made of any nolastic material, such as polyolefins such as polyethylene, polyglopylene, ethylene-propylene copolymers, and ionomers; polyesters such as polyethylene terephthalate;
Nylon 6, Nylon 6.6, Nylon 6/Nylon 6
．． It can be made of any resin such as polyamide such as 6-copolymer polyamide; various polycargonates; polyvinyl chloride resin; vinylidene chloride resin: polystyrene, nutyrene-butadiene copolymer, and the like. These resins may be used alone for the container body, or may be used in the form of a blend of two or more types, and may be used as a laminate of multiple resins or as a coating material.
It may also be used to form a container body in the form of a k Ha structure.

A suitable example of a laminate is an inner and outer layer of polyolefin or polyester and a gas barrier resin, such as ethylene.
It consists of an intermediate layer of vinyl alcohol copolymer He IJ amide, vinylidene chloride resin, etc. Suitable examples of the coating structure include an inner layer and/or outer layer of polyolefin, polyester, polycargonate, styrene resin, etc. A coating layer of vinylidene chloride resin is provided on the side.

The plastic container body of the present invention may have a cylindrical shape with both ends open, as shown in FIG. It may be something. Further, in any of these cases, a neck-in portion 21 narrowed to a small diameter may exist directly below the flange portion 7.

The plastic container body 1 can be obtained by any molding method, such as an injection molding method, an extrusion molding method, a blow molding method, a stretch blow molding method, a drawing method, or a drawing method.

The circumferential side wall portion 4 of the plastic container body 1 may be substantially unoriented, but from the viewpoint of mechanical strength, rigidity, impact resistance, Ganupara property, transparency, etc., it may be oriented in at least one axis, preferably in two directions. Preferably, the molecules are oriented. For example, a container body with biaxially oriented molecules can be obtained by pulling and stretching a preformed matrix tube or a 7-ohm glue in the axial direction, and expanding and stretching it in the circumferential direction. A container with molecular orientation can be obtained by stretching a sheet, pipe, or other preform by means of stretch stretching, drawing, drawing, ironing, or the like.

The present invention is applicable to the various plastics mentioned above, but is particularly advantageously applicable to containers made of thermoplastic polyesters, particularly polyesters containing ethylene terephthalate repeating units as a main component. Here, thermoplastic polyester having ethylene terephthalate as a main repeating unit usually has an acid component of 80 or more moles, preferably 90 moles or more of terephthalic acid, and a glycol component of 80 moles or more, preferably 90 moles or more of ethylene glycol. The remaining acid components are inophthalic acid, diphenyl ether 4,4'-nocargenic acid, naphthalene 1,4- or 2,6-nocardic acid, adipic acid, sepa7anoic acid, decane 1.10 -dicardic acid, hexahydalothylephthalic acid, and other glycol components such as propylene glycol, 1,4-butanol, neopentyl glycol, diethylene glycol, 1,6-hexylene glycol, cyclohexane dimetatool, 2
．． 2-bis(4-hydroxyphenyl)chronomer, 2
, 2-pine(4-hydroxyethoxyphenyl)furopane, or a polyester containing P-oxybenzoic acid, P-hydroethoxybenzoic acid, etc. as an oxyacid. Further, a trifunctional or higher functional component may be copolymerized within a range that does not impair moldability. Also? diethylene tele7
By mixing the tallate with other thermoplastic polyesters, the amount of ethylene terephthalate should be 80 moles or more.
It may be a mixture of more than one species.

The thermoplastic polyester used must have an intrinsic viscosity of 0.55 or more, preferably 0.6 or more, and more preferably 0.7 to 1.4. Intrinsic viscosity is phenol/tetrachloroethane mixed solvent (6
/4 weight ratio] solution of polyester 'fr, 3
Intrinsic viscosity measured at 0°C. The present invention also provides a laminate or coating of polyester and other resins having excellent gas barrier properties such as metaxylylene group-containing polyamide, polyvinylidene chloride, acrylonitrile styrene co-N polymer, and ethylene vinyl alcohol copolymer. It also includes a filled container made of a polyester cylinder. This 71J ester container is heated at 20°C.
The density is 1.335 or more than 700, especially 1.36
0 f! It is desirable that the material is oriented and crystallized so that /ac, and that it is heat-set for use in hot-filling the contents.

In the plastic container body used in the present invention, the thickness (Tw) of the circumferential side wall portion 4 varies depending on the type of plastic, but is generally 0.2 to 1.0 mm, %KO, 2 to 0.8 m+t. It is preferable to have a thickness of 7
The thickness (TG) of the flange groove 8 is preferably in the range of 0.1 to 0.7 mm, particularly 0.1 to 0.5 mm, and
/TF is preferably in the range of 0.1 to 3.5, particularly 0.125 to 2.5. Further, the width CWa) of the groove portion 8 in the radial direction of the flange is 0.3 to 2.5 rrx, particularly 0.5 to 2.5 rrx. It is preferable that it be in the range of Omtn.

If TG is smaller than the above range, the mechanical strength of the flange part is insufficient, and if the TG is larger than the above range, the minimum possible bending radius (rm) becomes too large, making it difficult to use a normal can. It becomes difficult to provide sufficient overlap width with the lid.

The cross-sectional shape of the groove portion 8 can be any desired cross-sectional shape as long as the above-mentioned dimensional relationship is satisfied. For example, the rectangular cross-sectional groove shape shown in Fig. 6-A, the trapezoidal cross-sectional groove shape shown in Fig. 6-B, the semicircular cross-sectional groove shape shown in Fig. 6-C, and the cross-sectional groove shape shown in Fig. 6-D. The cross-sectional groove shape can be semi-elliptic as shown in FIG. 6-E, or the V-shaped cross-sectional groove shape is shown in FIG. 6-E. From the viewpoint of eliminating stress concentration in the groove portion 8 and making bending easier, those shown in FIGS. 6-B and 6-D are preferable.

Any means can be used to form the seaming flange having the shape and structure described above on the plastic container body. For example, when manufacturing a container body by injection molding, the shape and dimensions of the corresponding capacity mold and core mold should correspond to the shape and dimensions of the seven seaming flange described above. I hope you understand.

In addition, when using a plastic container body made by other molding methods, as shown in FIG. Using this combination, the open end of the container body 1 is bent outward by approximately 90 degrees, and the groove portion 8 is formed by compression molding using the die 25 and the grate 24. These processes are performed at temperatures above the glass transition point of the plastic used.

The end cap is made of surface-treated steel sheets such as tin-plated steel sheets, tin-free steel (electrolytic chromic acid treated steel sheets), and light metals such as aluminum, and the surface is coated with epoxy-phenol paint or epoxy-urea paint. A material provided with a protective coating such as a paint, an epoxy-acrylic paint, an epoxy-vinyl paint, or a vinyl-7 enol paint is used.

A circumferential groove is provided around the end cap for engagement with the seaming end of the container body, and the groove is lined with a sealing rubber composition. The center funnel portion of the end cap may be provided with a known easy-to-open mechanism.

The thickness of the can lid varies depending on the thickness of the metal material, but
Generally 0.15 to 0.50 dragon, especially 0.20 to 0.
It is best to have 45 dishes.

FIG. 8 shows a preferred example of the end cover, in which a circumferential seaming groove 32 is provided around the center panel portion 30 via an annular rim portion 31, and a sealing groove is provided in this groove. A lining layer 33 of rubber composition is provided. The center panel portion 30 has a score 35 that demarcates the portion 34 to be opened.
is provided, and an opening piece 36 is attached to this portion 34 to be opened via a fixing portion 37 such as a rivet.

For the double seaming of the plastic container body and end cap, a seamer conventionally used for seaming metal sources can be used.

According to the present invention, it is easy to set the overlap width between the body hook and the cover hook to O15 or more, particularly 0.7 mm or more.

(Example) Example 1 Polyethylene terephthalate was extruded using a conventional method to form a sheet with an outer diameter of 53-851 mm, an inner diameter of 52.65 mm, and a plate thickness of 0°6.
A dragon-shaped cylindrical plastic tube was produced, and then both ends were cut to form a tube body with a height of 135 nm.

This was then subjected to seven-lunge forming using a combination of a flanging goug and a support plate having protrusions as shown in FIG. At this time, a trapezoidal protrusion was used, and all flange processing was done by thermoforming. The characteristic values of the flange portion of the plastic can body thus obtained were as follows.

Flange length 3.0 Flange thickness -1) - (Tr) 0.59~0.
60 mm 7 lange groove thickness (To) o, 3o
Tomiatsu TO/TP O, 508~0
．． 500 Groove Width (WG) 1.5 plates After a metal lid (plate thickness 0.39 mm, 5052 aluminum material) is air-wound on one side of the plastic can body with this grooved flantz added, 2.5 gas is applied in the filling machine. A high-speed seamer that is filled with carbonated water and has a seaming speed of 500 cans per minute.
We double-sealed about 2,000 easy-open aluminum aluminum lids, and no trouble occurred during the seaming process. In addition, the width of the 7" (OL) was measured by cutting the seaming part after filling (n=30
can], all of them showed good seaming performance with a time of 0.8 ms or more.

Furthermore, this filled plastic can (SOO can) was heated to 37℃.
When stored for 24 hours, no aluminum lids were found to have come off due to internal pressure.

We also performed a drop test from a height of 1 m using the same filled plastic cans packed in cartons, but no aluminum lids were found to come off or any leaks were found, and no pressure drop was confirmed when measuring the internal pressure. There wasn't.

Comparative Example 1 Plastic cans were made in the same manner as in Example 1, except that they were molded without providing a groove in the flange, and a storage test was conducted. 3S0 out of 3.500 cans were made of aluminum. The lid came off and leakage occurred.

At this time, the seaming condition after filling was observed, and the width of the overlap was as small as 0 to 0.6 m, and the variation in overlap was also very large.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the main parts of a plastic can according to the present invention;
FIG. 2 is an enlarged cross-sectional view showing the structure of the double seam part, FIG. 3 is a detailed view of the present invention, and FIGS. 4 and 5 are examples of can bodies showing preferred embodiments of the present invention. A cross-sectional view showing 6-A
Figures 6-8, 6-0, 6-D, and 6-E are cross-sectional views of various shapes of the groove portion according to the present invention, and Figure 7 shows the formation of the can body flange portion of the present invention. FIG. 8 is a drawing showing a preferred example of a metal lid. DESCRIPTION OF SYMBOLS 1... Can body, 4... Circumferential side wall part, 6... Flange part, 8... Groove part, 9... Double seam part, 10... Body hook, 11... Metal lid, 12... Cover hook, 15... Straight top, 16... Lower gap, 17... Upper gap, 20... Bottom, 21...
N, Queen part, 23...Protrusion part, 24...Support plate, 25...7 lunge part, 30...Fnelt part on center no., 31...Annular rim part, 32... Circumferential groove for winding, 33... Lining layer, 35... Score part, 36... Opening piece, 37... Fixing part. Figure 1 Figure 2 Figure 3 '$4 Figure

Claims (1)

[Claims] (1) Between the plastic can body made of plastic and having a seaming flange at the opening end, the metal lid made of metal and having a seaming end around the periphery, and the plastic can body and the metal lid. In the plastic can, the plastic can body has a groove portion between the tip and the base of the flange portion and having a smaller wall thickness on the side in the seaming direction of the flange. A double-sealed plastic can, characterized in that the tip of the flange portion is a body hook that engages with a lid hook.