JP2006088669A - Flange molding method for flanged container, flanged container and easily-unsealable container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flanged container allowing easy dimensional control in forming a projection when a flange is formed on the flanged container and allowing easy formation of a resin accumulated piece, in excellent shape reproducibility, formed by fusing and pressing down the protrusion when a lid is heat-sealed to the flange, and to provide an easily-unsealable container on which such an accumulated resin piece is formed. <P>SOLUTION: A mold 10 comprises a pair of a lower mold 12 and an upper mold 13, the lower mold 12 and the upper mold 13 hold the portion corresponding to the flange 4 of a thermoplastic resin sheet 16 with flange holding faces 122 and 132 and form in cooperation the flange 4 of the flanged container 1. A groove part 133 is formed in the flange holding face 132 of the upper mold 13, and a vent hole 134 communicating with the groove part 133 and opened to the outside of the mold is provided in the upper mold 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a flange forming method for a flanged container, a flanged container, and an easily openable container that can increase the sealing strength while maintaining easy opening when a lid is heat sealed to the flange.

  A flanged container that seals and accommodates contents by forming a cup shape or a tray shape into a predetermined container shape, forming a flange along the periphery of the container opening, and heat-sealing a lid on the flange. It is widely used as a sealed container for foods and chemicals. In this type of container, when the container is opened and the contents are taken out, it is required to be easily opened so that the lid can be easily peeled off, but by heat sterilization after the contents are hermetically sealed, Pressure is generated inside the sealed container. At this time, the lid member is lifted outward, and a strong peeling force acts on the heat seal portion between the container and the lid member, thereby causing peeling of the heat seal portion.

  In order to solve this problem, various easily openable containers have been proposed that have a strong heat seal strength against the pressure from the inside of the container and can easily peel the lid material from the outside of the container toward the center (for example, patents). Document 1 and Patent Document 2).

  These containers are peeled from the outside to the inside by cohesive failure of the heat seal resin layer of the lid material, or by interface peeling between the thermoplastic resin of the flange and the heat seal resin layer of the lid material. Opening can be done easily. On the other hand, for the peeling force from the inside of the container to the outside, peeling of the heat seal part is prevented by converting the peeling force into shearing stress by the rise of the resin piece of the flange resin. To do.

JP-A-4-253656 Japanese Patent Laid-Open No. 9-99933

  By the way, in Patent Document 1, the resin reservoir (opening rising piece) is formed by crushing a protrusion provided on the upper surface of the flange during molding of the container into a thin plate shape along the flange surface toward the inside of the container (implementation). Example 1, FIG. 2, etc.) and forming the outer peripheral side of the flange thickly and cutting the stepped portion inwardly or crushing it (Comparative Test 4) are described. However, these methods have a problem in the shape reproducibility of the resin reservoir. The same applies to Patent Document 2.

  The present invention has been proposed in order to solve the above-described problems of the prior art, and facilitates dimensional control of the formed protrusion when forming the protrusion on the flange of the flanged container. The flange-molding method of the flanged container that can obtain the flanged container in which the resin pool piece formed by melting and pressing the protrusion when the lid is heat-sealed to the flange can be formed with good shape reproducibility, It is an object of the present invention to provide a flanged container capable of forming the resin pool piece with good shape reproducibility and an easy-open container formed with the resin pool piece.

  A flange forming method for a flanged container according to the present invention has a gripping surface in which a groove is formed continuously or intermittently along a circumferential direction, and an air-permeable structure capable of discharging atmospheric gas in the groove from the groove The upper mold with a grip is used, and the portion corresponding to the flange of the molding material made of thermoplastic resin is gripped by the grip surface of the upper mold and the grip surface of the lower mold that is paired with the upper mold However, the molding material is thermoformed into a predetermined container shape to form a flange at the peripheral edge of the container opening and to form a protrusion corresponding to the groove on the top surface of the flange.

  By adopting such a configuration, the protrusion corresponding to the groove formed on the holding surface of the upper mold can be shaped with good shape reproducibility in the portion corresponding to the flange of the molding material, and the flange In forming the protrusion on the flange of the attached container, the dimension control of the formed protrusion is facilitated. As a result, the flanged container obtained by the flange molding method of the flanged container according to the present invention has a shape reproducibility of the resin pool piece formed by melting and pressing the protrusion when the lid is heat sealed to the flange. It is well formed, and the lid member and the resin pool piece are well bonded.

  Therefore, by forming such a resin pool piece, the sealing strength is large with respect to the force for peeling the lid from the inside of the container to the outside, and from the outside of the container to the inside. When peeling the lid, it is possible to provide a flanged container suitable for stably producing an easy-open container that can be easily peeled off.

  The flange forming method for a flanged container according to the present invention can also be applied to the case of forming a flange of a flanged container in which a flange is formed on the periphery of the container opening. That is, using the upper mold having a gripping surface in which grooves are formed continuously or intermittently along the circumferential direction, and having a ventilation structure capable of discharging the atmospheric gas in the grooves from the grooves. A flange having a thermoplastic resin layer on at least the top surface formed on the peripheral edge of the container opening is formed by the gripping surface of the mold and the gripping surface of the lower mold paired with the upper mold. It can also be set as the method of shape | molding the projection part corresponding to the said groove part in the top | upper surface of the said flange by thermoforming.

  Further, when a flange of a flanged container having a flange formed on the periphery of the container opening is formed, a groove is formed continuously or intermittently along the circumferential direction, and is projected adjacent to the groove. An upper mold having a gripping surface formed with a portion is formed on the periphery of the container opening by the gripping surface of the upper mold and the gripping surface of the lower mold that makes a pair with the upper mold. In addition, it is possible to adopt a method of forming a protrusion corresponding to the groove on the top surface of the flange by gripping and thermoforming at least a flange having a thermoplastic resin layer on the top surface.

  In the flange forming method for a flanged container according to the present invention, as a specific aspect of the ventilation structure capable of discharging the atmospheric gas in the groove portion from the groove portion, at least the portion where the groove portion is formed is porous. The upper mold may be configured so as to be made of a natural material, and the upper mold may include a vent hole that communicates with the groove and opens to the outside of the mold. In the latter case, it is preferable that the vent hole communicates with the deepest portion of the groove portion. Thereby, when shaping | molding a projection part, the atmospheric gas in a groove part can be discharged | emitted efficiently from a vent hole, and a projection part can be shaped with shape reproducibility.

  Further, in the flange molding method for a flanged container according to the present invention, the peripheral resin is pushed toward the groove part and enters the groove part by forming a convex part adjacent to the groove part on the gripping surface of the upper mold. The amount of resin that can be increased can be increased, and the shapeability of the protrusions is further improved. In this case, it is preferable that the convex portion has an inclined surface such that the convex portion becomes thinner toward the groove portion. Thereby, directionality arises in the motion of the resin pushed toward the groove part, and the resin that can enter the groove part can be increased.

  Furthermore, a convex part can also be formed in the position corresponding to the said groove part in the holding surface of the said lower metal mold | die. As a result, the resin on the back surface side of the flange can be pushed closer and the resin that can enter the groove can be increased, and the shapeability of the protrusions can be further improved.

  On the other hand, the flanged container according to the present invention is a flanged container manufactured by the flange forming method described above, and has a width of 0.3 to 2.0 mm and a height of 0.2 to 0.00 on the top surface of the flange. 7 mm projections are formed. By forming the protrusion formed on the top surface of the flange in such a range, the shape reproducibility of the resin pool piece is improved.

  Further, the easy-open container according to the present invention has a lid material having an easy-open heat-sealing layer on the top surface of the flange of the flanged container manufactured by the flange forming method described above, on the top surface of the flange. An easy-open container formed by heat-sealing with the easy-open heat-sealing layer facing each other, wherein the protrusion formed on the top surface of the flange is melt-pressed at the time of heat-sealing to the inside of the container And a resin pool piece having a length of 0.1 mm or more and less than 1.0 mm and a thickness of 0.04 to 0.3 mm. The resin pool piece is formed so as to be able to stand up. It is as the structure joined to the easily openable heat seal layer.

  Further, the easy-open container according to the present invention is provided on the top surface of the flange of the flanged container in which a flange having a thermoplastic resin layer formed with a protrusion on the top surface is formed on the periphery of the container opening. An easily openable container formed by heat-sealing a lid material having an easy-open heat-seal layer on the inner surface, with the easy-open heat-seal layer facing the top surface of the flange, and the top surface of the flange Resin having a length of 0.1 mm or more and less than 1.0 mm and a thickness of 0.04 to 0.3 mm, which is formed to protrude toward the inside of the container by melting and pressing the protrusions formed in the heat seal A pool piece may be provided, and the resin pool piece may be joined to the easy-open heat seal layer of the lid member so that the resin pool piece can rise.

  The easy-open container according to the present invention formed in this way has a large seal strength against the force to peel off the lid from the inside of the container to the outside, and from the outside of the container to the inside. When the cover material is peeled off, the cover material can be easily peeled off.

  According to the present invention, the protrusion corresponding to the groove formed on the holding surface of the upper mold is formed on the flange with good shape reproducibility, and the dimension management of the protrusion becomes easy. As a result, when the lid material is heat sealed to the flange of the obtained flanged container, the resin pool piece formed by melting and pressing the protrusion is formed with good shape reproducibility, and the lid material and the resin pool piece are formed. It will be well bonded.

  Therefore, according to the present invention, when the lid is heat-sealed to the flange, a resin pool piece is formed between the flange and the lid so that the easy-open property is maintained and the easy-opening is performed to increase the seal strength. It is possible to provide a flanged container suitable for stably manufacturing an adhesive container, and an easily openable container having such easy opening performance.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[Flanged containers and easy-open containers]
Fig.1 (a) is a perspective view which shows schematically one Embodiment of the container with a flange which concerns on this invention, FIG.1 (b) is AA sectional drawing of Fig.1 (a). In the example shown in FIG. 1, the container 1 includes a body portion 2, a bottom portion 3 that is continuous with the lower end of the body portion 2, and a heat sealing flange 4 that is continuous with the upper end of the body portion 2. The flange 4 projects in the horizontal direction along the periphery of the container opening 1a. Further, a projection 5 having a cross-sectional shape as shown in FIG. 1B is formed on the top surface 4 a of the flange 4.

  Moreover, as shown in FIG. 2, the easy-open container 9 according to the present invention has a lid 6 having a heat sealable resin layer 7 on the top surface 4a of the flange 4 of the container 1 as described above. It is formed by heat sealing. In heat sealing, a lid 6 is placed so that the heat-sealable resin layer 7 is in contact with the top surface 4a of the flange 4, a heat sealing bar, a high frequency induction heating heat sealing head, a dielectric heating heat sealing head, ultrasonic heat. This is performed by heating and pressurizing the heat seal portion with a seal head or the like.

  2A is a perspective view schematically showing an embodiment of the easy-open container according to the present invention, and FIG. 2B is a cross-sectional view taken along line BB in FIG. 2A. is there. In FIG. 2 (b), the cover 6 and the flange 4 are separated from the resin pool piece 8 (described later) on the inner side of the container (left side in FIG. 2 (b)). The lid 6 is sealed to the flange 4 also inside the container from the resin reservoir piece 8 except for the vicinity of the resin reservoir piece 8.

As a general lid 6, the heat sealable resin layer has a three-layer structure of outer layer / inner layer / inner layer (heat-sealable resin layer 7) or a two-layer structure of outer layer / inner layer (heat-sealable resin layer 7). The sealing strength between the flange 7 and the flange 4 is set to 0.5 to 3.0 N / 15 mm in consideration of the unsealing property. The heat sealing condition is appropriately set so that the lid 6 is securely sealed to the flange 4, but is usually performed at a heat sealing temperature of 160 to 200 ° C. The pressing force of the sealing head is usually about 1~2.5MPa (10~25kg / cm ^2), heat-sealing time is usually about 0.5 to 2.0 seconds.

  When the lid 6 is heat sealed to the flange 4, the protrusion 5 formed on the top surface 4 a of the flange 4 is melted. The melted protruding portion 5 is pressed by the seal head to form a resin pool piece 8 protruding inward of the container as shown in FIG. 3A and joined to the heat-sealable resin layer 7 of the lid member 6.

  Therefore, for example, when a force is applied to peel off the cover material 6 from the inside of the container to the outside due to an increase in the pressure in the container, as shown in FIG. Piece 8 stands up. At this time, a shearing force is generated between the lid member 6 and the resin pool piece 8 in the direction of the arrow in the figure, but a force for peeling the both hardly occurs. As a result, the separation between the flange 4 and the lid member 6 is made by material breakage such as the resin pool piece 8 being torn from the flange 4 or the lid member 6 being torn, so that the sealing strength is increased.

  On the other hand, when a force is applied to peel off the lid member 6 from the outside of the container to the inside, the cohesive failure of the heat-sealable resin layer 7 of the lid material 6 or the flange 4 and the heat-sealable resin layer 7 occurs. Interfacial peeling occurs and the lid 6 can be easily peeled off, so that easy peel properties are ensured.

  At this time, the resin of the heat-sealable resin layer 7 melts and flows by heating during heat sealing and enters between the resin pool piece 8 and the top surface 4a of the flange 4 so that the resin covers the tip of the resin pool piece 8. The resin pool piece 8 and the heat-sealable resin layer 7 are preferably bonded to increase the bonding strength. However, the resin pool piece 8 and the heat-sealable resin layer 7 are bonded to the resin pool piece 8. It is only necessary to be bonded to such an extent that can be raised together with the lid member 6.

  Moreover, it is preferable that the length L of the resin pool piece 8 is 0.1 mm or more and less than 1.0 mm. If the length is not less than the above range, the length of the resin pool piece 8 becomes insufficient, the resin pool piece 8 cannot stand up together with the lid member 6, and the stress applied to the interface between the lid material 6 and the resin pool piece 8 becomes large and sufficient sealing is achieved. Strength will not be obtained. On the contrary, if the resin pool piece 8 becomes longer beyond the above range, the tip portion of the resin pool piece 8 pressed by the seal head is brought into close contact with the top surface 4a of the flange 4 and melted between the two. It becomes difficult for heat-sealable resin to enter.

  The thickness t of the resin pool piece 8 is preferably 0.04 to 0.3 mm. If it is less than the above range, the strength of the resin pool piece 8 will be insufficient, it will be easily torn from the flange 4, and sufficient seal strength will not be obtained. On the other hand, when the above range is exceeded, the resin pool piece 8 becomes difficult to elastically deform, and the rise of the resin pool piece 8 is hindered.

  Incidentally, in the example shown in FIG. 1, the protrusion 5 is formed over the entire circumference of the flange 4, but the protrusion 5 may be formed intermittently along the circumferential direction. When the protrusions 5 are formed intermittently, a plurality of protrusions 5 having a predetermined length may be formed at equal intervals along the circumferential direction. Moreover, although the protrusion part 5 is formed in the width direction substantially center of the flange 4, the formation position of the protrusion part 5 is a container inner side (left side in FIG.1 (b)) or a container outer side (as needed). It may be shifted to the right side in FIG. Thus, how to form the protrusion 5 is not particularly limited as long as the effect obtained by forming the resin pool piece 8 as described above is obtained.

  Moreover, the cross-sectional shape of the protrusion part 5 should just be what can form the resin pool piece 8 in the range mentioned above with sufficient shape reproducibility. For example, the shape can be a semicircular shape, a triangular shape, a rectangular shape, or the like, but in order to form the resin pool piece 8 with good shape reproducibility, the shape is such that an edge is formed on the inner side of the container. It is preferable that the edge is clearly formed without being chipped or rounded.

  Specifically, as shown in FIG. 1B, it is preferable to have a substantially triangular shape having an inclined surface that becomes thicker from the outside of the container toward the inside of the container. Among these, it is particularly preferable that the inner side of the container rises substantially perpendicular to the top surface 4 a of the flange 4. When the cross-sectional shape of the protrusion 5 is substantially triangular, the inclined surface can be an upwardly convex or downwardly convex curved surface. Moreover, you may form an inclined surface combining several inclined surfaces from which inclination differs. Another example of the protrusion 5 is shown in FIG. FIG. 4A is an example in which the cross-sectional shape of the protrusion 5 is rectangular, and FIG. 4B is an example in which the protrusion 5 is formed by connecting a plurality of protrusion components 5a. .

Width _{L 0} and the height _{t 0} of the protrusion 5, the material and forming the protrusions 5, varies depending on conditions such as heat seal, the width _{L 0} is preferably in the range of 0.3~2.0mm Particularly preferably, it is 0.5 to 1.5. The height t ₀ is preferably 0.2 to 0.7 mm, particularly preferably 0.3 to 0.6. When the protrusion 5 is formed to have a substantially triangular cross section, the inclination angle α of the inclined surface is preferably 5 to 65 degrees, although it varies depending on the material forming the protrusion 5 and the heat seal conditions. Especially preferably, it is 20 to 50 degrees.

  By managing the dimensions of the protrusion 5 within such a range, the resin pool piece 8 can be formed with good shape reproducibility, and the above-described effects can be obtained effectively. That is, in order to reliably obtain the effect of forming the resin pool piece 8, it is necessary to strictly manage the dimensions of the resin pool piece 8, and if there are variations in the heat seal conditions and the dimensions of the protrusions 5, The size of the resin pool piece 8 formed at the time of sealing also varies, and the effect of forming the resin pool piece 8 cannot be obtained stably. For this reason, if the dimensions of the protrusion 5 are strictly controlled within the above range, the resin pool piece 8 can be formed with good shape reproducibility even if there is some variation in the heat seal condition. The effect by forming can be stably obtained.

[Flange forming method]
Next, an embodiment of a flange forming method for a flanged container according to the present invention will be described. 5 and 6 are schematic views showing the molding process in the present embodiment. In the present embodiment, a thermoplastic resin sheet 16 is used as a molding material.

  The molding apparatus 10 mainly includes a plug 11, a lower mold 12, an upper mold 13, and a sheet fixture 14. FIG. 5 shows a preparation state before molding. At this time, the plug 11, the lower mold 12, and the upper mold 13 are in the most distant positional relationship. In this state, a thermoplastic resin sheet 16 in a molten state supported by the sheet fixture 14 is supplied between the plug 11 and the lower mold 12. The temperature of the thermoplastic resin sheet 16 at this time depends on the resin used, but is generally 170 to 200 ° C. in the case of a polypropylene resin. When the temperature is lower than about 170 ° C., molding failure occurs or the container is deformed by heat and pressure sterilization. On the other hand, when the temperature is higher than about 200 ° C., the molten sheet sagging increases, and in the case of multi-cavity molding, wrinkles are partially generated and the container wall becomes thin.

  The plug 11 is for guiding the thermoplastic resin sheet 16 while being drawn into the lower mold 12, and has a shape substantially similar to a container to be molded. Further, it is connected to a drive shaft (not shown) and can move relatively in the axial direction. Further, even when the plug 11 is moved downward relative to the upper mold 13, an annular gas passage 111 is formed between them (see FIG. 6). Further, the inside of the upper mold 13 is connected to a pressurized gas mechanism (not shown) so that pressurized gas can be supplied into the mold through the gas passage 111.

  The lower mold 12 has an open cavity inside, and has a bottom wall surface that defines a bottom wall of a container to be molded, and a side wall surface that defines a container side wall. A flange gripping surface 122 for forming the flange 4 in cooperation with the upper mold 13 is provided on the upper end surface of the lower mold 12. In addition, a gas passage 121 is formed in the bottom wall portion of the lower mold 12 to discharge or decompress the air between the container wall being molded and the inner surface of the lower mold 12. The lower mold 12 is provided so as to be movable in the vertical direction in FIG. 5 and is in the lowest lowered position in FIG.

  The upper mold 13 is for forming the flange 4 in cooperation with the lower mold 12 and is a hollow cylindrical body. In addition, the upper mold 13 has an inner surface having substantially the same diameter as the open cavity of the lower mold 12, and a flange gripping surface 132 facing the flange gripping surface 122 of the lower mold 12 is provided on the lower end surface thereof. It is.

  In FIG. 6 showing the vacuum and / or compressed air forming state, the plug 11 is in the state of being most deeply inserted into the lower mold 12. At this time, the upper mold 13 is also lowered, and the upper mold 13 and the lower mold 12 are sealed with the thermoplastic resin sheet 16 sandwiched therebetween. At the same time, pressurized air is blown between the narrowed thermoplastic resin sheet 16 and the plug 11 through the gas passage 111 between the upper mold 13 and the plug 11. The cavity is evacuated (reduced pressure) through the gas passage 121. As a result, the squeezed thermoplastic resin sheet 16 is expanded and cooled by contacting the inner surface of the lower mold 12 to form the flanged container 1.

  At this time, the lower mold 12 and the upper mold 13 grip the portion corresponding to the flange 4 of the thermoplastic resin sheet 16 with the flange gripping surfaces 122 and 132, and cooperate to form the flange 4. A groove 133 is formed in the flange gripping surface 132 of the upper mold 13. The groove 133 is for forming the protrusion 5 on the top surface 4 a of the flange 4, and when the flange 4 is formed between the flange holding surfaces 122 and 132 of the lower mold 12 and the upper mold 13. A part of the resin forming the flange 4 enters the groove 133, and the protrusion 5 is formed (see FIG. 6).

  Here, FIG. 7A is an enlarged cross-sectional view of the flange gripping surface 132 of the upper mold 13. The groove 133 is formed in a shape corresponding to the protrusion 5. That is, when forming the protrusion 5 having a triangular cross section as shown in FIG. 1B, the groove 133 is formed so as to correspond to the protrusion 5 as shown in FIG. Good.

  At this time, if the protrusion 5 is formed over the entire circumference of the flange 4, the groove 133 may be continuously formed along the circumferential direction of the flange gripping surface 132. Further, when the protrusion 5 is intermittently formed along the circumferential direction of the flange 4, the groove 133 may be intermittently formed along the circumferential direction of the flange gripping surface 132, and a plurality of protrusions having a predetermined length are formed. Similarly, when the portions 5 are formed at equal intervals along the circumferential direction, the groove portions 133 may be formed corresponding to the protruding portions 5. Furthermore, the position where the groove 133 is formed is also appropriately selected according to the position where the protrusion 5 is formed.

  As described above, the protrusion 5 is formed by shaping the shape of the groove 133 to the flange 4. However, if the resin forming the flange 4 does not sufficiently enter the groove 133, the protrusion 5 Cannot be formed with good shape reproducibility. As described above, it is preferable that the protruding portion 5 has a clear edge formed on the inner side of the container. However, the atmosphere gas remains in the groove portion 133 and the resin is sufficiently deep into the groove portion 133. If it does not enter, the formation of the edge will be hindered, and the edge will be chipped or rounded.

  In the present embodiment, in order to prevent such a problem from occurring, the upper mold 13 is provided with a vent hole 134 that communicates with the groove 133 and opens to the outside of the mold. Therefore, according to the present embodiment, the atmospheric gas in the groove part 133 is discharged out of the mold from the vent hole 134 without staying in the groove part 133, and the resin forming the flange 4 easily enters to the back of the groove part 133. Can do.

  Here, it is preferable that the vent hole 134 communicates with the portion where the resin is finally filled so that the atmospheric gas in the groove 133 can be efficiently discharged from the vent hole 134. Thus, it is preferable to communicate with the deepest portion of the groove 133. Further, the diameter of the air hole 134 is preferably about 0.1 to 0.5 mm so that the resin does not enter the air hole 134 and hinder the shaping of the protrusion 5.

  By providing such an air hole 134 in the upper mold 13, the shapeability of the protrusion 5 is improved, and the protrusion 5 can be formed with good shape reproducibility. Management becomes easy. As a result, the flanged container 1 obtained according to the present embodiment allows the resin pool piece 8 to have a good shape reproducibility even when there is some variation in the heat sealing conditions when the lid 6 is heat sealed to the flange 4. The effect by forming the resin pool piece 8 as described above can be stably obtained. Thus, this embodiment also has an effect that the range of heat sealing conditions such as temperature and pressure is widened.

  Therefore, according to the present embodiment, by forming such a resin pool piece, the sealing strength is large with respect to the force for peeling the lid member 6 from the inside of the container to the outside, and the container When peeling the lid 6 from the outside to the inside, a container with a flange suitable for stably producing the easy-open container 9 that can be easily peeled off. 1 can be provided.

  In the present embodiment, as the ventilation structure capable of discharging the atmospheric gas in the groove part 133 from the groove part 133, a configuration is adopted in which the upper mold 13 is provided with a ventilation hole 134 that communicates with the groove part 133 and opens to the outside of the mold. However, by forming at least the portion of the upper mold 13 where the groove 133 is formed of a porous material such as stainless steel, brass, titanium, etc., the atmospheric gas in the groove 133 is formed through a hole communicating with the inside of the porous material. It is also effective to discharge the water from the groove 133. If such a ventilation structure is employed, the traces of the ventilation holes can be made inconspicuous. In this case, for example, a mold piece made of a porous material in which the groove 133 is formed may be assembled to the upper die 13, but the entire upper die 13 can also be formed of a porous material.

  Moreover, in this embodiment, as shown in FIG.7 (b), you may form the convex part 135 adjacent to the groove part 133. FIG. Thereby, when the flange 4 is formed, the resin of the peripheral flange 4 is pushed toward the groove part 133 side, and the resin that can enter the groove part 133 can be increased, and the shapeability of the protrusion part 5 is further increased. improves. When forming the convex part 135 adjacent to the groove part 133, it is preferable that the convex part 135 is provided with the inclined surface which becomes thin toward the groove part 133 so that it may show in figure. By making the shape of the convex part 135 in this way, directionality occurs in the movement of the resin pushed toward the groove part 133, and the resin that can enter the groove part 133 can be increased. As shown in FIG. 7C, the same applies to the case where the cross-sectional shape of the protrusion 5 is rectangular.

  Moreover, when forming the convex part 135 adjacent to the groove part 133, since the resin extruded by the convex part 135 moves along a taper, the convex part 135 respond | corresponds to the container outer side with respect to the groove part 133. It is preferable to form it at a position (right side in FIG. 7).

  Further, in order to further improve the shapeability of the protrusion 5, a convex portion 123 is formed at a position corresponding to the groove 133 of the flange gripping surface 122 of the lower mold 12 as shown in FIG. 8. It can also be left. Thereby, when the flange 4 is formed, the resin on the back surface side of the flange 4 is pushed toward the top surface 4a side, and the amount of resin that can enter the groove 133 can be increased. The property becomes even better.

  In the present embodiment, the thermoplastic resin sheet 16 is used as a molding material. However, the thermoplastic resin sheet 16 is a crystal of a polyolefin resin such as polyethylene or polypropylene, or a polyamide resin such as polyamide 6, polyamide 66, or polyamide 46. Either a sheet made of a conductive resin, or a sheet made of a polyester resin such as polyethylene terephthalate (PET) or polybutylene terephthalate, or a sheet made of an amorphous resin such as polycarbonate, polyarylate, or cyclic olefin copolymer may be used. Moreover, as these sheets, not only a single layer sheet but also a sheet having a plurality of layers may be used. In the present embodiment, the shape forming property can be applied even to a material in which the shape forming of the protruding portion 5 is difficult by a normal method such that the melt index (MI) of the resin to be used is about 1.0 or less. The protrusion 5 can be formed well.

  The thermoplastic resin may be blended with known plastic compounding agents such as antioxidants, heat stabilizers, ultraviolet absorbers, antistatic agents, fillers, colorants and the like. For the purpose of making the molded container opaque, fillers such as calcium carbonate, calcium silicate, alumina, silica, various clays, gypsum, talc, magnesia, titanium white, yellow iron oxide, bengara, ultramarine blue, chromium oxide, etc. Inorganic pigments and organic pigments can be blended.

  The thermoplastic resin sheet 16 can have other layers such as a gas barrier layer and an oxygen-absorbing resin layer in order to impart various functions to the resulting container. The other layers can be used as an inner layer or an outer layer in a two-layer configuration, or can be used as an intermediate layer in a three-layer configuration. Thereby, various functions can be provided to the resin container obtained by the present embodiment. Moreover, although the thickness of the thermoplastic resin sheet 16 changes also with the magnitude | sizes, etc. of a container, it is preferable from the point of the intensity | strength of a container, or a moldability that it is 0.5-5 mm, especially 1-3 mm.

  The gas barrier layer may be formed of any known material such as ethylene-vinyl alcohol copolymer (EVOH), nylon resin (Ny), gas barrier polyester resin (BPR), cyclic olefin copolymer, and the like. However, a layer made of a metal foil such as an aluminum foil, a tin foil, a steel foil, or a tin foil may be used.

  As the oxygen-absorbing resin layer, a layer containing a metal-based oxidation catalyst and an oxidizing organic component is used. The oxidizing organic component is a resin that is oxidized by oxygen in the air by the catalytic action of a transition metal catalyst, and includes (i) a carbon side chain (a) and a carboxylic acid group in the main chain or side chain. A resin containing at least one functional group (b) selected from the group consisting of a carboxylic acid anhydride group, a carboxylic acid ester group, a carboxylic acid amide group and a carbonyl group, (ii) a polyamide resin, and (iii) an ethylene-based resin An unsaturated group-containing polymer is used.

  As the metal-based oxidation catalyst, Group VIII metal components of the periodic table such as iron, cobalt and nickel are preferable, but other Group I metals such as copper and silver: Group IV metals such as tin, titanium and zirconium , Va group V, chromium and other group VI, and manganese and other group VII metal components. Among these metal components, the cobalt component is particularly suitable because of its high oxygen absorption rate. The transition metal catalyst is generally used in the form of a low-valent inorganic acid salt, organic acid salt or complex salt of the transition metal. These catalysts are preferably used in an amount of 100 to 1000 ppm per resin.

  Furthermore, the flanged container obtained according to the present embodiment may have any other resin layer in addition to the thermoplastic resin layer and the gas barrier layer. For example, when there is no thermal adhesiveness between the thermoplastic resin layer and the gas barrier layer, an adhesive resin layer can be interposed between the two resin layers. The adhesive resin is not particularly limited, and acid-modified olefin resins such as maleic anhydride grafted polyethylene and maleic anhydride grafted polypropylene can be used.

  Next, the present invention will be described in more detail with reference to specific examples.

[Examples 1 to 4]
(1) Molding material By ordinary coextrusion sheet molding, outer layer: polypropylene (PP, MI = 0.5) + titanium white pigment (630 μm) / adhesive layer: maleic anhydride modified polypropylene (30 μm) / barrier layer: ethylene -A multi-layer sheet (lamicon sheet) having a total thickness of 1.5 mm with 3 types and 5 layers composed of vinyl alcohol copolymer (180 μm) / adhesive layer: same as above (30 μm) / inner layer: PP (630 μm).
(2) Lid material By an ordinary dry laminating method, an outer layer: biaxially stretched polyester film (12 μm) / intermediate layer: biaxially stretched nylon film (15 μm) / inner layer: a polypropylene composite material (50 μm) is produced. did.

  The multilayer sheet is heated to about 180 ° C. by a far-infrared heater, and the outer diameter of the container is 75 mm and the height is 85 mm (the inner capacity is 215 ml) with a clamping force of 20 kN (mold area: 600 mm × 600 mm) by a normal vacuum / pressure forming machine. ) Round container with flange. At that time, it has a grip part in which a groove part is formed continuously or intermittently along the circumferential direction, and is connected to the groove part and has a vent hole outside the mold, and a grip surface of the lower mold, A minute protrusion was formed on the top surface of the flange.

  After filling the obtained flanged container with 200 g of soup, the lid was heat sealed to the flange under heat sealing conditions of 180 ° C., sealing pressure 1.5 MPa, and 1.5 seconds. At this time, the microprojections are melted and flowed in the heat seal portion to form resin pool pieces toward the inside of the flange, and the protruding resin portion melted and flowed from the easy-open heat seal layer of the lid material is formed in close contact with the heat seal portion. A filled container was prepared.

  Here, in Examples 1 and 2, the groove as shown in FIG. 7A was continuously formed over the entire circumference of the gripping surface of the upper mold. In Example 3, 36 grooves having a length of 2.6 mm were intermittently formed at intervals of 6 mm along the circumferential direction as shown in FIG. In Example 4, the groove as shown in FIG. 7C was continuously formed over the entire circumference of the holding surface of the upper mold. Table 1 also shows the dimensions of the minute protrusions formed on the top surface of the flange and the dimensions of the resin pool formed during heat sealing.

The obtained filled container was subjected to an isobaric retort sterilization treatment at 120 ° C. for 30 minutes, and the container performance such as the unsealing property and the sealing strength was tested. The results are shown in Table 1 for each of Examples 1 to 4. The contents of the test are as follows.
Opening strength test: The force required to peel off the lid material from the outside to the inside of the obtained filled container was measured with a tensile test device. The average value of the number of samples (n =) 10 is shown in Table 1.

Seal strength test: The heat-sealed portion of the obtained filled container was cut to a length of 15 mm, and the force required to peel the lid member from the inside toward the outside was measured with a tensile test device. The average value of the number of samples (n =) 10 is shown in Table 1.
Drop strength test: The temperature of 20 arbitrarily selected filling containers was adjusted to 5 ° C. and dropped 10 times in an inverted state from a height of 1.2 m. Table 1 shows how many of the 20 containers have broken seals.

[Comparative Examples 1-4]
A filled container was produced in the same manner as in the example except that the configuration of the upper mold was changed. Here, in Comparative Example 1, an upper mold having no groove on the grip surface was used. In Comparative Examples 2 and 3, grooves similar to those in Examples 1 and 2 were formed, respectively. In Comparative Example 4, the same groove as in Example 4 was formed. In any of the comparative examples, a ventilation structure for discharging the atmospheric gas in the groove portion out of the mold was not provided. Table 1 also shows the dimensions of the minute protrusions formed on the top surface of the flange and the dimensions of the resin pool formed during heat sealing.

  The obtained filled container was subjected to an isobaric retort sterilization treatment at 120 ° C. for 30 minutes, and the container performance such as unsealing property and seal strength was tested in the same manner as in the examples. The results are shown in Table 1 for each of Comparative Examples 1 to 4.

  In Examples 1 to 4, the protrusions were formed with good shape shaping, and the shape reproducibility of the resin pool pieces was also good. on the other hand. In Comparative Examples 1 to 4, the shape forming property of the protrusion was poor, and the resin pool piece could not be formed with good shape reproducibility. In addition, as shown in Table 1, the containers of Examples 1 to 4 in which the predetermined resin pool pieces are formed in the heat seal portion according to the present invention have greatly improved sealing performance and dropping performance while maintaining easy opening. It was confirmed to improve. On the other hand, the containers of Comparative Examples 1 to 4 produced by methods other than the present invention are unstable in the formation of the resin pool pieces of the seal part and do not maintain the predetermined shape, so both the sealing performance and the drop performance are improved. It was not seen.

  Although the present invention has been described with reference to the preferred embodiment, it is needless to say that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. . For example, the present invention is not limited to the above method, and can be performed using various molding methods.

  Specifically, a thermoplastic resin is molded into a container-forming intermediate such as a preform or a menco by a method such as extrusion molding, injection molding, or compression molding, and these container-forming intermediates are used as a molding material. While holding the portion corresponding to the flange of such a molding material with the gripping surface 132 of the upper mold 13 and the gripping surface 122 of the lower mold 12, compressed air molding, plug assist molding, overhang molding, press It can also be formed into a predetermined container shape by molding, drawing, drawing and ironing, blow molding or the like.

  Furthermore, the present invention can also be applied to the case of molding a flange of a flanged container in which a flange is formed on the periphery of the container opening. In this case, the flange of the flanged container is gripped and thermoformed by the gripping surface 132 of the upper mold 13 and the gripping surface 122 of the lower mold 12, and the protrusion corresponding to the groove portion 133 is formed on the top surface 4 a of the flange 4. The part 5 may be molded. The container used at this time is provided with a thermoplastic resin layer on at least the top surface 4a of the flange 4, and the main material is paper as long as the projection 5 can be formed on the top surface 4a of the flange 4. Alternatively, it may be made of metal or the like. In such a case, if the convex portion 135 is formed on the gripping surface 132 of the upper mold 13 so as to be adjacent to the groove 133, the ventilation structure for discharging the atmospheric gas in the groove 133 is provided. 13 may not be provided.

  Moreover, although the cup-shaped thing was mentioned as an example as a container shape, it can apply also to the resin-made containers which have other shapes, such as tray shape or bottle shape.

  As described above, the present invention has a large sealing strength against the force to peel the lid from the inside of the container to the outside, and when peeling the lid from the outside of the container to the inside. The present invention provides a flanged container suitable for stably producing an easy-open container that can easily peel off a lid, and such an easy-open container.

It is a figure which shows the outline of one Embodiment of the container with a flange which concerns on this invention. It is a figure which shows the outline of one Embodiment of the easily openable container which concerns on this invention. It is explanatory drawing which shows notionally the state which the force which tries to peel a cover material from the container inner side acted. It is sectional drawing which shows the other example of a protrusion part roughly. It is the schematic which shows the shaping | molding process in one Embodiment of the flange shaping | molding method of the flanged container which concerns on this invention, and has shown the preparation state before shaping | molding. It is the schematic which shows the shaping | molding process in one Embodiment of the flange shaping | molding method of the flanged container which concerns on this invention, and has shown the vacuum and / or pressure forming state. It is a general | schematic expanded sectional view of the lower end surface of an upper metal mold | die. It is a general | schematic expanded sectional view of the lower end surface of an upper metal mold | die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Container 1a Container opening part 4 Flange 4a Top surface 5 Protrusion part 6 Lid material 7 Easy-opening heat seal layer 8 Resin pool piece 9 Easy-opening container 12 Lower mold 122 Flange holding surface 123 Convex part 13 Upper mold 132 Flange Gripping surface 133 Groove part 134 Vent hole 135 Convex part 16 Thermoplastic resin sheet (molding material)

Claims (12)

Using an upper mold having a gripping surface in which a groove is formed continuously or intermittently along the circumferential direction, and having a ventilation structure capable of discharging the atmospheric gas in the groove from the groove,
While holding the portion corresponding to the flange of the molding material made of thermoplastic resin by the holding surface of the upper die and the holding surface of the lower die that is paired with the upper die, the molding material is By thermoforming into a container shape,
A flange forming method for a flanged container, wherein a flange is formed on a peripheral edge of the container opening, and a protrusion corresponding to the groove is formed on the top surface of the flange. Using an upper mold having a gripping surface in which a groove is formed continuously or intermittently along the circumferential direction, and having a ventilation structure capable of discharging the atmospheric gas in the groove from the groove,
A flange having a thermoplastic resin layer on at least the top surface is formed at the periphery of the container opening by the gripping surface of the upper mold and the gripping surface of the lower mold paired with the upper mold. And by thermoforming
A flange forming method for a flanged container, wherein a protrusion corresponding to the groove is formed on the top surface of the flange. A groove part is formed continuously or intermittently along the circumferential direction, and an upper mold having a grip surface on which a convex part is formed adjacent to the groove part,
A flange having a thermoplastic resin layer on at least the top surface is formed at the periphery of the container opening by the gripping surface of the upper mold and the gripping surface of the lower mold paired with the upper mold. And by thermoforming
A flange forming method for a flanged container, wherein a protrusion corresponding to the groove is formed on the top surface of the flange.   The flange forming method for a flanged container according to claim 1 or 2, wherein at least the portion of the upper mold in which the groove is formed is made of a porous material.   The flange molding method for a flanged container according to claim 1 or 2, wherein the upper mold includes a vent hole communicating with the groove and opening to the outside of the mold.   The flange forming method for a flanged container according to claim 5, wherein the vent hole communicates with the deepest portion of the groove portion.   The flange forming method for a flanged container according to any one of claims 1, 2, 4, 5, and 6, wherein a convex portion adjacent to the groove portion is formed on a gripping surface of the upper mold.   The flange forming method for a flanged container according to claim 3 or 7, wherein the convex part adjacent to the groove part is provided with an inclined surface such that the convex part becomes thinner toward the groove part.   The flange forming method for a flanged container according to any one of claims 1 to 8, wherein a convex portion is formed at a position corresponding to the groove portion on the gripping surface of the lower mold. A flanged container manufactured by the flange forming method of a flanged container according to any one of claims 1 to 9,
A flanged container, wherein a protrusion having a width of 0.3 to 2.0 mm and a height of 0.2 to 0.7 mm is formed on the top surface of the flange. A lid member having an easy-open heat seal layer on the top surface of the flange of the flanged container manufactured by the flange forming method for a flanged container according to any one of claims 1 to 9, An easy-open container formed by heat-sealing the easy-open heat-seal layer facing the surface,
The protrusion formed on the top surface of the flange is melt-pressed at the time of heat sealing, and is formed to protrude toward the inside of the container. The length is 0.1 mm or more and less than 1.0 mm, and the thickness is 0.04 to It has a 0.3mm resin pool piece,
An easily openable container characterized in that the resin pool piece is joined to an easily openable heat seal layer of the lid material so that the resin pool piece can rise. A lid having a flange having a thermoplastic resin layer with protrusions on the top surface and a flange having a flange formed on the periphery of the container opening, and an easily openable heat seal layer on the inner surface. An easy-open container formed by heat-sealing the material with the easy-open heat-seal layer facing the top surface of the flange,
The protrusion formed on the top surface of the flange is melt-pressed at the time of heat sealing, and is formed to protrude toward the inside of the container. The length is 0.1 mm or more and less than 1.0 mm, and the thickness is 0.04 to It has a 0.3mm resin pool piece,
An easily openable container characterized in that the resin pool piece is joined to an easily openable heat seal layer of the lid material so that the resin pool piece can rise.

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