JP5011321B2 - Method for forming multilayer container - Google Patents

Description

The present invention relates to a method of molding a multilayer container.

A multilayer container molded by punching from a multilayer body has an intermediate resin layer exposed on the cut end surface of the container, resulting in poor appearance. In particular, an intermediate resin layer provided with an oxygen absorbing layer is mainly composed of an iron-based metal, and thus causes problems such as scattering of iron particles and generation of rust. Thus, conventionally, a method has been proposed in which the surface resin layer of the multilayer body is stretched around the cut end face during punching to cover the end face of an intermediate resin layer such as an oxygen absorbing layer (for example, Patent Document 1, (See Patent Document 2).
These molding methods use a punching die of male and female blades as punching means. When punching a multilayer body, the surface resin layer is hooked and pulled to cover the cut end surface of the intermediate resin layer. It was.

JP 7-227259 A Japanese Patent Laid-Open No. 11-48385

However, in the case of the conventional molding method, it is configured to cut by the shearing action of the male blade and female blade, so it is assumed that the coating amount will change greatly due to the meshing gap between the blade edge of the male blade and female blade, and the mold has high accuracy. Is required.
Even if the gap is appropriate, there is a problem that it is extremely difficult to keep the coating amount constant due to environmental conditions such as environmental temperature, wear of the mold over time, etc., and stable quality cannot be expected.

Conventionally, the punching die is heated to the vicinity of the Vicat softening point of the surface resin layer, and it is necessary to control the temperature of the die.
Further, since punching is performed by shearing, burrs are generated at the lower end of the cut end face, and it is necessary to deburr. If the burr is large, a part of the intermediate resin layer is exposed outside the covered region of the end face.
Furthermore, since the end surface covering portion by the surface resin layer is configured to be stretched in the shearing direction of the cut end surface serving as the shear surface, the adhesion with the cut end surface is poor. Further, since the cut end face is cut by shearing, the end of the end face covering portion is easily caught and turned up.

The present invention has been made to solve the problems of the prior art described above, provides the time of cutting the multi-layer body, the molding how multi layer containers that may cover the intermediate layer stably There is.

To achieve the above object, the present invention, when at least one layer of resin in which a plurality of resin layers constituting the multilayer body that is laminated to mold the container body by the multilayer body or et molding a molten state at the same time, multi-layer In the method for forming a multi-layer container in which the flange portion is formed by cutting the peripheral edge of the container body with a predetermined width,
Preparing a pair of molds sandwiching the multilayer body, providing a press cutting blade on one mold side and providing a blade receiving part on the other mold side;
By biting a predetermined amount of cutting blades on the multi-layer body support molten state to the blade receiving portion, it is compressed and deformed into thin while stretching the layers as upper layers bites into the lower layers,
After the press cutting blade bites into the multilayer body by a predetermined amount, one mold is brought into contact with the upper surface of the multilayer body, and the inner side from the biting portion of the press cutting blade is clamped ,
When clamping is completed, the container body is molded by bringing the multilayer body into close contact with the inner periphery of the cavity provided in the other mold by air pressure,
By pushing the cutting blade until it finally hits the blade receiving part, the thinly compressed part is pressed, and each layer of the intermediate layer and the surface resin layer is converged to the abutting part of the pressing blade and the blade receiving part. And

It also may be configured intermediate layer comprises a gas barrier layer for blocking at least the gas may be an oxygen-absorbing layer containing at least ferrous oxygen absorber, the second oxygen-absorbing layer and the gas barrier layer A layer structure may be used.

According to the first aspect of the present invention, the container body is molded by molding from a multilayer body in which at least one layer is in a molten state, and the flange body is formed by cutting the peripheral edge of the container body of the multilayer body with a predetermined width. In the container molding method, as described above, the flange portion is cut by biting the pressing blade while at least one layer of the multilayer body is in a molten state, so that the flange portion can be cut simultaneously with the molding process of the container body portion. it can.
Moreover, since the press cutting blade is provided on one mold side and the blade receiving portion is provided on the other mold side, the press cutting can be performed in conjunction with the opening and closing of the mold, and the number of processes can be reduced. Can do.
Moreover, since the final pressing of the flange portion is performed after the container main body portion is formed, the dimension of the flange portion can be accurately cut.

In the case of a gas blocking layer that blocks a gas such as oxygen as in the invention according to claim 2 , it is possible to prevent elution of chemical components from the gas blocking layer.
When the intermediate layer is an oxygen absorbing layer containing an iron-based oxygen scavenger as in the invention according to claim 3 , it is possible to prevent the oxygen scavenger from spilling and rusting.
As in the invention according to claim 4 , even when the intermediate layer has a two-layer structure of the oxygen absorbing layer and the gas blocking layer, two layers can be covered together.

1A to 1D are diagrams schematically showing a method for cutting a multilayer body that is a premise of the present invention. FIG. 2 schematically shows a multilayer container formed by the method for forming a multilayer container of the present invention, wherein FIG. 2 (A) is a half sectional front view, FIG. 2 (B) is an enlarged sectional view of a flange end, FIG. 3C is an enlarged cross-sectional view of the flange end portion having a clamp mark. 3A is a cross-sectional view showing a mold for the multilayer container of FIG. 2, FIG. 3B is a perspective view of the press blade of FIG. 3A, and FIG. 3C is a press cut of FIG. It is a perspective view of the state which rounded the blade. 4 (A) to 4 (D) are diagrams showing a molding process of a multilayer container. FIGS. 5A to 5E are views showing a molding process of a multilayer container. FIGS. 6A to 6H are views showing examples of cross-sectional photographs of the flange portion molded by the multilayer container molding method of the present invention.

The present invention will be described below based on the illustrated embodiments.
FIG. 1 schematically shows a method for cutting a multilayer body which is a premise of the present invention. The multilayer body 10 to be cut is constituted by a sheet having a three-layer structure including an intermediate resin layer 11 as an intermediate layer and a pair of surface resin layers 12 and 13 sandwiching the intermediate resin layer 11. Between each layer, an adhesive layer (not shown) for bonding the layers is appropriately provided.
The upper layer bites into the lower layer by biting a predetermined amount of the press cutting blade 15 from the other side surface of the multilayer body 10 in which at least one layer of the multilayer body 10 is in a molten state and one side surface is supported by the blade receiving portion 14. In this way, the layers 11, 12, and 13 are compressed and deformed into thin walls while being stretched (see FIGS. 1A and 1B). Although not shown here, the lower resin layer is pushed left and right by the side surfaces 15 a and 15 b of the press cutting blade 15 and slightly rises on both sides of the press cutting blade 15. The size of the raised curved portion 121a varies depending on the molding conditions, the thickness of the resin layer, the angle of the pressing blade, and the like.

Next, the thinly compressed portion S is pushed in by pushing the tip of the press cutting blade 15 until it abuts against the blade receiving portion 14, and the intermediate resin layer 11 and the surface resin layers 12, 13 are pressed into the press cutting blade 15 and the blade receiving portion 14. And converge to the butting portion A (see FIG. 1C).
Since at least one layer bites the press cutting blade 15 in a molten state, the molten resin layer is not cut but only deformed into an inclined surface following the shape of the side surface of the press cutting blade 15. The end surface 10a is maintained in a state where the intermediate resin layer 11 is covered with the one surface resin layer 12 without being exposed.

Furthermore, since the thin portion S is finally pushed, each layer is crushed to a small thickness and cut, and the cutting points A1 and A2 converge to almost one point. In particular, with respect to the intermediate resin layer 11, the cut portion has a slight thickness and is hidden by the cut portions of the pair of front and back surface resin layers 12 and 13.
As the biting dimension of the pressing blade 15 in the molten state, an appropriate dimension is selected depending on the thickness of the multilayer body 10, the layer configuration, the resin material, and the like.
The thin-walled portion S may be cut after the resin constituting each layer of the multilayer body 10 is cooled to a melting point or lower and cured, or may be performed while the resin is in a molten state.

It is preferable that the temperature of the pressing blade 15 is a normal temperature. The blade receiver 14 that supports the multilayer body 10 is also preferably set to room temperature.
The press cutting blade 15 is constituted by a flexible belt-like blade. It can be cut in a straight line by a belt-like blade, can be cut in a curved shape, or can be cut into an endless shape such as a circle.

The press cutting blade 15 has a double-edged shape in which both side surfaces 15a and 15b are formed as inclined surfaces. If the opening angle is too small, the surface resin layer 12 will be cut, so it is preferable to set it to 30 ° or more.
The shape of the pressing blade 15 may be an asymmetrical angle between the side surfaces 15a and 15b of the pressing blade 15, or may be a one-blade shape that is inclined only on one side surface.
That is, as shown in FIG. 5 (E), when the side surface on the 15a side of the press cutting blade 15 hits the flange end surface 121 on the flange portion 120 side of the container 100 has a flat shape and the opposite 15b side has an inclined surface. Is more preferable in that the raised curved portion 121a can be minimized.

In FIG. 2, the multilayer container shape | molded from the sheet-like multilayer body 10 is shown.
The multilayer container 100 includes a cup-shaped container main body 110 formed by drawing from the sheet-shaped multilayer body 10 as described above, and a flange 120 that projects outward from the periphery of the opening of the container main body 110. And a portion corresponding to the outer end of the flange portion 120 of the multilayer body 10 is cut between the pressing blade 15 and the blade receiving portion 14 and cut into a predetermined shape using the multilayer body cutting method described above. .
In this example, the thickness of each resin layer of the multilayer body 10 is such that the lowermost surface resin layer 13 (which becomes the outer layer of the container) is about half as thick as the whole, and the uppermost surface resin layer 12 (the inner layer of the container). Is the thinnest, and the intermediate resin layer 11 has an intermediate thickness.

2B, the flange portion 120 has a flange lower surface 123 and a flange upper surface 124 that are parallel to each other. The flange lower surface 123 is larger in diameter than the flange upper surface 124, and the flange end surface 121 is on the flange upper surface 124 side. The inclined surface expands downward from the outer diameter end toward the outer diameter end on the flange lower surface 123 side.
An acute-angled lower end edge portion of the flange end surface 121 serves as a cutting point 122 by the press cutting blade 15, and each layer constituting the flange portion 120 converges to the cutting point 122 at the end portion.

Each resin layer 11, 12, 13 of the flange portion 120 has a parallel structure parallel to the flange lower surface 123 and the flange upper surface 124, and has a converging structure that converges to the cutting point 122 at the flange portion end. Moreover, between the parallel structure and the converging structure, there is a bent portion that is pushed left and right by the side surface of the pressing blade 15 and rises toward the flange upper surface 124 side.
That is, the cross-sectional convergence shape of the lowermost surface resin layer end portion 13a is an angular shape having the cutting point 122 as an apex, and the angle between the flange lower surface 123 and the boundary surface m1 with the upper intermediate resin layer 11 is the flange end surface. The angle is smaller than 121.

The cross-sectional shape of the intermediate resin layer end portion 11a is a ridge shape extending so that the cutting point 122 becomes the apex, and overlaps the lower triangular surface resin layer end portion 13a.
The uppermost surface resin layer end 12a is thin, extends to the cutting point 122, and overlaps the lower bowl-shaped intermediate resin layer end 11a.
The bent portion 13b of the lowermost surface resin layer 13 has a configuration in which a boundary surface m1 between the surface resin layer 13 and the intermediate resin layer 11 is raised to the intermediate resin layer 11 side, and an intermediate layer is formed on the bent portion 13b. 11 bend portions 11b and the bend portion 12b of the surface resin layer 12 located on the uppermost layer overlap each other.

  Since the uppermost surface resin layer end portion 12a is thin and stretched as a whole, the change in thickness that tapers toward the tip as in the lower layer is small. On the other hand, the lowermost surface resin layer end portion 13a does not extend downward, and is compressed and deformed so as to be pushed right and left by the biting of the pressing blade 15, and the bent portion 13b becomes larger. The intermediate resin layer 11 is an intermediate deformation. The deformation state changes depending on the thickness of each layer, the positional relationship, and the like.

FIG. 2C is an example having a clamp mark 125 when the flange portion 120 is pressed by a mold during molding. Since the flange portion 120 is compressed by the clamp pressure, the bent portions 13b, 11b, and 12b between the clamp portion and the converging structure of the flange end portion tend to be exaggerated more.
As the surface resin layers 12 and 13 of the multilayer body 10 constituting the multilayer container 100, for example, a thermoplastic resin such as a polypropylene resin is used, and the intermediate resin layer 11 is a single unit of an oxygen absorption layer or a gas barrier layer. It is composed of a layer structure or a two-layer structure of both.

For the oxygen absorbing layer, a thermoplastic resin containing an iron-based oxygen scavenger, other oxygen absorbing polymers (olefin-based, polyester-based, urethane-based, etc.) are used.
Examples of oxygen-absorbing polymers include saponified ethylene-vinyl acetate copolymers, other gas barrier properties of polyamides such as nylon 6, nylon 6/6, nylon 6/6/6 copolymer, and metaxylylene adipamide. Some resins are blended with an oxidizing resin and a transition metal catalyst.

The oxidizing resin is selected from the group consisting of (1) a carbon side chain and having a carboxylic acid group, a carboxylic acid anhydride group, a carboxylic acid ester group, a carboxylic acid amide group, and a carbonyl group in the main chain or side chain. And a resin containing at least one functional group, (2) a polyamide resin such as metaxylylene adipamide, and (3) an ethylenically unsaturated group-containing polymer.
The transition metal catalyst serves as a catalyst for the oxidation reaction of the oxidizing resin, and is an organic acid salt or organic complex salt of a transition metal. Examples of transition metal catalysts include iron, cobalt, nickel, copper, silver, tin, titanium, zirconium, vanadium, chromium, manganese and the like.

Gas barrier layer is saponified ethylene-vinyl acetate copolymer, other nylons, nylon 6,6, nylon 6 / 6,6 copolymers, polyamides such as metaxylylene adipamide, resin coating agent, An inorganic vapor deposition layer or the like is used.
For the surface resin layers 12 and 13, a thermoplastic resin such as polypropylene resin, polystyrene resin, or polyethylene terephthalate resin is used. The pair of front and back surface resin layers 12 and 13 may use different resin materials.

  The intermediate resin layer 11 may be an oxygen absorption layer alone, a gas barrier layer alone, or another resin. Further, the intermediate layer is not limited to the resin layer, and may be a metal layer such as an aluminum foil in some cases. The multilayer body provided with a metal layer such as an aluminum foil in the intermediate layer is suitable for a pouch film, for example.

Next, based on FIG. 3 thru | or FIG. 5, the shaping | molding method of the said multilayer container is demonstrated in detail.
The multilayer container 100 is formed by forming the three-dimensional shape of the container body 110 from the sheet-like multilayer body 10 by pressure forming, vacuum forming, vacuum pressure forming or the like. Thus, the flange portion 120 is punched out and cut.

First, the mold will be described with reference to FIG.
The mold 200 includes first and second molds 210 and 220 as a pair of molds sandwiching the multilayer body 10, and the press cutting blade 15 is provided in one second mold 220 and constitutes a blade receiving portion. A supporting base 212 is provided on the other first mold 210 side.
The first mold 210 includes a cavity 211 for molding the container main body 110 and a flat annular support base 212 provided at the periphery of the cavity opening. The second mold 220 includes a clamp portion 221 that engages with a region on the inner diameter side of the upper surface of the support base 212 of the first mold 210.

On the second mold 220 side, a plug 230 for pushing the multilayer body 10 in which at least one layer is molten into the cavity 211 is provided. In the illustrated example, the second mold 220 and the plug 230 are described so as to move together, but the second mold 220 and the plug 230 may be configured as separate bodies and moved independently.
In addition, an ejector mold 240 is provided at the bottom of the cavity 211 of the first mold 210 so as to release the multilayer container 100 that is formed so as to protrude into the cavity 211 after molding.

Furthermore, a pressing blade 15 for pressing the flange portion 120 is provided on the second mold 220 side. The pressing blade 15 is disposed outside the outer end of the clamp portion 221 of the second mold 220 and at a position facing the upper surface of the support base 212 of the first mold 210. The scheduled cutting position by the tip portion of the press cutting blade 15 is at a position away from the outer end of the clamp region by the clamp portion 221 of the second mold 220 by a predetermined distance.
The surface layer of the support base 212 is preferably made of a hard and heat-insulating material, and a soft material 213 such as brass is embedded in the lower layer to absorb the impact when the pressing blade 15 abuts. .

  The press cutting blade 15 is a flexible belt-like blade that is used by connecting both ends thereof in an endless manner (see FIGS. 3B and 3C). The shape is retained. In the illustrated example, the shape is a circle, but by changing the shape of the holder 250 in accordance with the shape of the container, it can be formed into an arbitrary shape such as a square shape or an oval shape.

Next, the forming process will be described with reference to FIGS.
The molding process includes a sheet feed process, a preceding plug insertion process, a mold closing process, a pressure forming process, a flange part cutting process, and a knockout process.
In the sheet feeding process, as shown in FIG. 4A, at least one layer of the resin constituting the multilayer body 10 is fed into the molten upper surface of the first mold 210 of the molding die. The multilayer body 10 hangs down in the cavity 211 due to its own weight.

  In the preceding plug insertion step, as shown in FIG. 4B, the plug 230 is pushed down prior to the formation of the container body 110, and the multilayer body 10 is pushed into the cavity 211 of the first mold 210 by a predetermined amount.

In the mold closing step, as shown in FIG. 4 (C), a predetermined amount of the cutting blade 15 is bitten into the multilayer body 10 while at least one layer of the multilayer body 10 before molding of the container body 110 is in a molten state. When the second mold 220 comes into contact with the multilayer body 10, the temperature of the multilayer body 10 rapidly decreases and hardens, so that the second mold 220 is not in contact with the multilayer body 10, that is, the multilayer body 10. While maintaining the temperature above the melting point, the cutting blade 15 is bitten from the other side of the multilayer body 10, and each layer is deformed into a shape that follows the cross-sectional shape of the pressing blade 15 in the cut portion of the multilayer body 10. Compress to thin wall. At this point in time, it is not pushed completely, and the tip of the push cutting blade 15 and the upper surface of the support base 212 are separated by the thin portion S.
Since it is in a molten state, each layer of the intermediate resin layer 11 and the pair of surface resin layers 12 and 13 is not cut, and each layer is stretched to be thin with a three-layer configuration.
From the preceding plug insertion process to the mold closing process (FIGS. 4A to 4C) proceeds in a very short time, and at least one layer of the multilayer body 10 is maintained in a molten state.

Immediately after the pressing blade 15 bites into the multilayer body 10 by a predetermined amount, the lower surface of the second mold 220 comes into contact with the upper surface of the multilayer body 10 and clamps the inside from the biting portion of the pressing blade 15.
As shown in FIG. 4D, the multilayer body 10 is compressed by the lower surface of the second mold 220 by the clamping pressure, and is not compressed between the lower surface of the second mold 220 and the biting portion 16 by the pressing blade 15. There is an uncompressed portion 17. Therefore, the fluidized resin material moves to the non-compressed portion 17 side from the portion 18 compressed by the second mold 220 and the biting portion 16 of the pressing blade 15, and each layer rises as a whole in the non-compressed portion 17. Fold like so.
The temperature of the pressing blade 15 is preferably normal temperature.

  As shown in FIG. 5A, in the compressed air forming process, when clamping is completed, compressed air is blown into the space between the second mold 220 and the multilayer body 10, and the multilayer body 10 is formed into the cavity of the first mold 210. 211 is brought into close contact with the inner periphery, and the multilayer body 10 is cooled and cured. The container body 110 may be formed by evacuation of the space between the first mold 210 and the multilayer body 10 instead of blowing the compressed air. Moreover, you may shape | mold by both compressed air and a vacuum.

  As shown in FIG. 5 (B), the flange part press-cutting step raises the first mold 210 with the press-cutting blade 14 stopped after the container body 110 is formed, and finally the tip of the press-cutting blade 15 Is pressed against the support base 212, and the thin portion S is pressed and the flange portion 120 is formed. The cutting may be performed by fixing the first mold 210 and pushing the pressing blade 15 downward.

  As a result, as shown in FIG. 5D, each of the intermediate resin layer 11 and the surface resin layers 12 and 13 converges on the abutting portion A between the pressing blade 15 and the support base 12. After pressing out, the molded product is knocked out.

  In the knockout process, as shown in FIG. 5C, while the first mold 210 is stopped, the second mold 220 and the pressing blade 15 are raised and the knockout mold 240 located at the bottom is pushed up. Then, the bottom of the container body 110 is pushed up to release the container body 110 from the cavity 211 of the first mold 210.

In the above embodiment, as a multi-layer molded article is that described as an example a multilayer container formed by cutting the periphery of the container, such as a three-dimensional cup and tray.

6 (A) to 6 (H) show cross-sectional photographs of the flange portion of the actually molded multilayer container.
In any case, at the flange end, each resin layer 11, 12, 13 converged to the cutting point, and the flange end face was completely covered with one resin layer without exposing the intermediate layer to the flange end face.
Moreover, about the clamp trace, as shown to FIG.6 (C), (E), the case where it did not come out depending on conditions was recognized, for example. Also, the bent portion hardly occurs in FIG. 6 (E).

10 multilayer body,
11 Intermediate resin layer 12 Surface resin layer (pressing blade side)
13 Surface resin layer (blade receiving part side)
14 Blade receiving part 15 Press cutting blade, 15a, 15b Side surface S Thin part A Abutting part A1, A2 Cutting point 100 Container,
110 Container body part 120 Flange part 121 Flange end face, 122 Cutting point, 123 Flange bottom face,
124 Flange upper surface, 125 Clamp mark 121a Curved part 200 Molding die 210 First die 220 Second die 211 Cavity 212 Support base 213 Soft material 221 Clamping part 230 Plug 240 Ejector die 250 Holder

Claims (4)

At the same time a plurality of resin layers at least one layer of the resin constituting the multi-layer body which is laminated to mold the container body by the multilayer body or et molding a molten state, by cutting the container body rim of the multi-layer body with a predetermined width In the molding method of the multilayer container for molding the flange portion,
Preparing a pair of molds sandwiching the multilayer body, providing a press cutting blade on one mold side and providing a blade receiving part on the other mold side;
By biting a predetermined amount of cutting blades on the multi-layer body support molten state to the blade receiving portion, it is compressed and deformed into thin while stretching the layers as upper layers bites into the lower layers,
After the press cutting blade bites into the multilayer body by a predetermined amount, one mold is brought into contact with the upper surface of the multilayer body, and the inner side from the biting portion of the press cutting blade is clamped ,
When clamping is completed, the container body is molded by bringing the multilayer body into close contact with the inner periphery of the cavity provided in the other mold by air pressure,
By pushing the cutting blade until it finally hits the blade receiving part, the thinly compressed part is pressed, and each layer of the intermediate layer and the surface resin layer is converged to the abutting part of the pressing blade and the blade receiving part. A method for forming a multilayer container. The intermediate layer forming method of the multilayer container according to the claim 1, characterized in that it comprises a gas barrier layer that blocks at least gas. The method for forming a multilayer container according to claim 1 or 2 , wherein the intermediate layer is an oxygen absorbing layer containing at least an iron-based oxygen scavenger. The method for forming a multi-layer container according to claim 1 or 2, wherein the intermediate layer has a two-layer structure of an oxygen absorption layer and a gas barrier layer.

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