JP4392702B2 - Blow molding container - Google Patents

Description

  The present invention relates to a blow molded container that is molded into a relatively thin wall and used as a refill container.

As a plastic container for refilling liquid contents, a pouch container in which a synthetic resin film is folded and welded and assembled has been used in the past. For example, a pouch-like blow molded container formed into a thin wall by blow molding as disclosed in Patent Document 1 has been used.
JP 2004-18086 A

  In the pouch-shaped blow-molded container for refilling as described above, in addition to the method of screwing the cap onto the cylindrical mouth tube portion and sealing it, the mouth end portion of the mouth tube portion is integrally provided so that it can be peeled off with a fingertip. A method of sealing with a piece of tearing has been proposed, but it has been difficult to form a weakened portion at a predetermined portion by blow molding so that it can be easily peeled off.

  An object of the present invention is to form a mouth tube portion that can be easily scraped off in a refilling container that is blow molded into a relatively thin wall as described above at the same time as blow molding, so that it can be conveniently used at low cost. The purpose is to provide a container.

  Among the means for solving the above technical problem, the means of the invention according to claim 1 is a blow molded container having a mouth tube portion standing upright above the body portion, and in the extrusion molding of the parison, the mouth tube of the parison By generating a melt fracture at a portion corresponding to a predetermined height position of the portion, a weakened portion is formed at the predetermined height position of the mouth tube portion, and the mouth tube portion is formed so as to be tearable. is there.

  Melt fracture (melt fracture) is a phenomenon that generally occurs when the extrusion speed is increased to increase the production speed when extruding a molten resin, for example. In the initial stage, the melt fracture is extruded and melted. It is limited to the very surface of the body, and irregularities, so-called rough skin, occur on the surface of the molded product. Further, when the extrusion speed is further increased, the breakage progresses to the inside of the extruded melt, and unevenness occurs over the entire thickness range of the molded product. In an extreme case, a hole is generated in a thin molded product in the form of a film.

  From a phenomenological point of view, melt fracture that extends to the inside of the melt occurs when a stress above the critical level is applied to the melt. In addition to increasing the extrusion speed, the resin temperature is relatively low. Or when the gap between the resin flow paths is narrowed.

  The structure according to claim 1 actively utilizes this phenomenon of melt fracture generation, and generates melt fracture at a portion corresponding to a predetermined height position of the mouthpiece portion of the parison in the extrusion molding of the parison. As a result, it is possible to form irregularities over the entire thickness of the cylindrical wall at a predetermined height position of the mouth tube portion of the blow molded container.

  These irregularities are in a state in which a number of concave and convex grooves extend in a direction substantially perpendicular to the flow direction of the resin and are not limited to simply forming irregular shapes, but are also melt fracture (melting of the melt). As shown in the phrase, since the continuity in the molten state is partially lost, the molded product that has been cooled and solidified can be in a state without toughness, and this melt fracture occurrence site is weakened. It becomes possible to easily tear off the mouth tube part from a predetermined height position by using it as a part.

  According to a second aspect of the present invention, in the first aspect of the invention, a relatively low temperature molten resin is supplied at a predetermined timing, and the parison has a portion corresponding to a predetermined height position of the mouth tube portion. To generate melt fracture.

In the extrusion molding of a parison, a resin is extruded in a molten state by an extruder, and this molten resin is introduced into a die having an annular flow path to form a tubular parison. Here, as means for generating a melt fracture at a predetermined position and a predetermined range of the parison, a relatively low temperature molten resin is supplied at a predetermined timing, an extrusion speed is increased, and a flow passage gap of the annular flow path is set. Although there are means such as narrowing, the method of supplying a relatively low temperature molten resin can relatively easily generate a melt fracture within a specified range, and aspects such as overall production process control To preferred.

  For example, a part of the molten resin from the extruder is stored in an accumulator adjusted to a relatively high temperature, and the molten resin is directly supplied from the extruder to the die, and at a predetermined timing, the molten resin having a low temperature is supplied from the accumulator. It is possible to generate a melt fracture at a predetermined position of the parison by the method of supplying to the die.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the mouth tube portion is formed so that the tip portion can be sealed by a crush-like welding seal.

  According to the above-described configuration of the third aspect of the present invention, it is possible to form the mouth tube portion relatively thinly so that the tip portion of the mouth tube portion can be sealed with a crushed weld seal, and in particular, a screw cap. Since it is not necessary to be sealed, the cost is low, the separation after use is unnecessary, and the container is suitable for a refill container.

  According to a fourth aspect of the present invention, in the first, second, or third aspect of the invention, the part formed on the mouthpiece of the parison is formed in the biting portion as a cut-off portion by a split mold. A part of the burr is to be used as a picking piece in the cutting operation.

  According to the above-described configuration of the fourth aspect, since the tab for stripping can be formed at the same time as blow molding, the container can be manufactured at low cost in terms of material and productivity.

  According to a fifth aspect of the present invention, in the invention according to the first, second, third, or fourth aspect, the wall has at least a three-layer structure in which an inner layer, an intermediate layer, and an outer layer are laminated.

  A synthetic resin material, which is a molding material for each layer, can be selected according to functions, characteristics, physical properties, and the like required for the container. For example, a blow molded container having a high gas barrier property can be obtained by molding the intermediate layer with a synthetic resin material having a high gas barrier property.

The present invention has the above-described configuration, and has the following effects.
In the invention described in claim 1, since the melt fracture is in a state in which the continuity in the molten state is considerably impaired, the molded product that has been cooled and solidified can be in a state without toughness. The mouth tube portion can be easily peeled off from a predetermined height position by using the melt fracture occurrence site as the weakening portion.

  In the invention of claim 2, relatively low temperature molten resin is supplied to a portion corresponding to a predetermined height position of the mouthpiece portion of the parison, and the melt fracture is limited within a specified range relatively easily. Can be generated automatically.

  In the invention according to claim 3, since the tip portion of the mouth tube portion can be sealed with a crushed weld seal, it is not particularly necessary to seal with a screw cap, so that the cost is low. Also, separation after use is unnecessary, and it is more suitable for a refill container.

  In the invention described in claim 4, since the picking piece for tearing can be formed simultaneously with the blow molding, the container can be manufactured at low cost from the viewpoint of material and productivity.

  In the invention described in claim 5, a synthetic resin material that is a molding material for each layer can be selected according to the function, characteristics, physical properties, and the like required for the container. For example, a blow molded container having a high gas barrier property can be obtained by molding the intermediate layer with a synthetic resin material having a high gas barrier property.

Embodiments of the present invention will be described below with reference to the drawings.
1 and 2 show a first embodiment of a blow molded container of the present invention, which has a mouth tube part 2, a shoulder part 3, a body part 4 and a bottom part 5, and has an inner layer / intermediate layer / outer layer, This is a blow molded container having a high gas barrier property composed of two types and three layers composed of polypropylene (PP) / ethylene polyvinyl alcohol copolymer (EVOH) / polypropylene (PP). In addition, FIG. 5 is explanatory drawing which showed the outline of the blow molding method.

  The container 1 is formed into a thin wall as a whole including the mouth tube portion 2, and the flat cross-sectional shape of the body portion 4 is substantially oval, and crease lines 7 are formed on the left and right sides and the bottom portion 5 of the body portion 4. And after use, it can be easily crushed flatly including the mouth tube part 2. In the present embodiment, the shape of the mouth tube portion 2 is made flat so that the lower half is cylindrical and the upper half is easy to be pressed and sealed (see FIG. 2).

  The lower half of the mouth tube part 2 and the part formed in a cylindrical shape correspond to the melt fracture generating part MF when the parison P is extruded (see FIG. 5). In this portion, a weakened portion W is formed in which a large number of concave-convex grooves extend in the circumferential direction. Further, the knob 8 located on the side wall of the mouthpiece part 2 has a part formed in the mouthpiece part 2 of the parison P as a cutout part by the split mold M, and from a part of the burr generated in this biting part. Formed.

  The container 1 of the present embodiment is used as a refill container, and in a state in which the content liquid is accommodated therein, the distal end portion of the mouth tube portion 2 is welded in a pressing shape to form a seal portion 6 and hermetically sealed. Stored and sold in state. In use, the knob 8 is picked up and pulled up (in the direction of the white arrow in FIG. 1), the weakened portion W is broken, the mouth tube portion 3 is peeled off, and the content liquid is transferred to another container. .

  Here, the weakened portion W is formed by locally generating melt fracture at the time of extrusion molding of the parison P by a method described later, and is in a state in which a large number of concave and convex portions extend substantially in the circumferential direction. At the same time, as indicated by the phrase melt fracture (melting fracture), the continuity in the melted state is considerably impaired, so the molded product that has been cooled and solidified should not have toughness. It can be picked with a finger and easily peeled off, and no itch is required to open the seal portion, so that it can be used very conveniently.

  Next, a method for forming the weakened portion will be described. FIG. 5 is an explanatory diagram showing an outline of the blow molding method. In the extrusion molding of the parison P, an annular flow path in which the resin is extruded in an molten state by the extruder E and the molten resin is disposed in the die D. To form a tubular parison P. The parison P is sandwiched between the split molds M and air blown to form the container 1. The two-layer / three-layer parison P as in this embodiment has three annular flow paths arranged concentrically from the inside for the inner layer, the intermediate layer, and the outer layer in the die D and extruded into each. PP, EVOH, and PP resin are supplied from the machine, and molding can be performed by joining three layers of resin at the tip of the die D. In the case of this example, the outer layer and the inner layer are the same PP resin, and the PP resin extruded from one extruder can be distributed to the inner layer and the outer layer, so that it can be molded by a total of two extruders.

  Here, in this embodiment, melt fracture is generated at a predetermined position and a predetermined range of the parison P by a method of locally supplying a relatively low temperature molten resin. Specifically, an accumulator is provided in a bypass shape in a supply line that supplies a relatively high-temperature molten resin from the extruder to each of the annular flow paths for the inner layer, the intermediate layer, and the outer layer. A part of the parison P is fed by a method of feeding a relatively low temperature molten resin from the accumulator to a supply line at a predetermined timing while usually supplying the molten resin directly to the die from the extruder. It becomes possible to generate a melt fracture at a predetermined position.

  The temperature of the molten resin supplied directly from the extruder is 230 ° C., and the temperature of the molten resin supplied from the accumulator is in the range of 180 to 200 ° C. The container 1 of this example could be molded by selecting appropriately while observing the ease of tearing of the weakened portion W when blow molded into the container. Even in the case of two types and three layers as in this embodiment, the melt fracture can be formed with good reproducibility over a predetermined position and a predetermined range of the parison P by selecting an appropriate temperature.

  3 and 4 show a second embodiment of the blow molded container of the present invention, which has a mouth tube part 2, a shoulder part 3, a body part 4 and a bottom part 5, and is made of polypropylene (PP). It is a container and is formed into a thin wall as a whole including the mouth tube portion 2, and the cross-sectional shape of the body portion 4, the bottom portion 5, and the shoulder portion 3 is substantially oval.

  The shape of the mouth tube portion 2 is made flat over the entire height range so as to facilitate pressing and sealing (see FIG. 4), and the base end portion of the mouth tube portion 2 has a first embodiment. A similar weakened portion W is formed. A pair of knobs 8 are formed on the side wall of the mouthpiece 2.

  The container 1 of the present embodiment is a PP single layer. In this case as well, the temperature of the molten resin directly supplied from the extruder is 230 ° C., and the temperature of the molten resin supplied from the accumulator is suitably in the range of 180 to 200 ° C. By selecting an appropriate temperature, it was possible to form a melt fracture with good reproducibility over a predetermined position and a predetermined range of the parison P, and to form a weakened portion W having an appropriate tear-off property.

  In the above two embodiments, the PP / EVOH / PP type 2 and 3 layer system and the PP single layer system have been described. However, melt fracture is a phenomenon that generally occurs in synthetic resins. The effect is not limited to the resin or resin combination of this embodiment.

  Further, the method for generating the melt fracture at a predetermined position of the parison is not limited. For example, as a means for generating the melt fracture locally, the extrusion speed in the annular flow path is increased at a predetermined timing, for example. It is also possible to use a means for narrowing the flow path gap at the tip of the die.

  As described above, the container of the present invention is formed by making use of the melt fracture phenomenon in the extrusion molding of a parison so that the mouth tube portion can be easily peeled off, and can be manufactured at a low cost. A wider use is expected.

It is a front view which shows 1st Example of the container of this invention. The perspective view which shows the mouth tube part vicinity of the container of FIG. It is a front view which shows 2nd Example of the container of this invention. The perspective view which shows the mouth tube part vicinity of the container of FIG. Explanatory drawing which shows the outline of a blow molding method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Container 2; Mouth part 3; Shoulder part 4; Trunk part 5; Bottom part 6; Seal part 7; Folding line 8; Site W: weakened part

Claims (5)

A blow molded container in which a mouth tube portion (2) is erected above a body portion (4), and a predetermined height of the mouth tube portion (2) of the parison (P) in extrusion molding of the parison (P). A melt fracture is generated at a portion corresponding to the position, a weakened portion (W) is formed at the predetermined height position of the mouth tube portion (2), and the mouth tube portion (2) is formed so that it can be peeled off. Blow molded container. A relatively low temperature molten resin is supplied at a predetermined timing, and a melt fracture is generated at a portion corresponding to a predetermined height position of the mouthpiece (2) of the parison (P). The blow molded container according to 1. The blow-molded container according to claim 1 or 2, characterized in that the end tube (2) is formed so that the tip can be sealed with a crushed weld seal. The part formed in the mouthpiece part (2) of the parison (P) is used as a cutting part by the split mold (M), and a part of the burr formed in the cutting part (9) The blow molded container according to claim 1, 2 or 3. The blow molded container according to claim 1, 2, 3, or 4, wherein the wall has at least a three-layer structure in which an inner layer (11), an intermediate layer (12), and an outer layer (13) are laminated.