JP2005280329A - Plastic vessel and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method capable of easily inexpensively forming a recessed portion on a body portion of a plastic-made cup-like vessel or the like. <P>SOLUTION: The manufacturing method of the cup-like vessel 1 comprises a blow-molding process of biaxially stretching and blow-molding a preform 6 into a vessel 1A using a removal mold having a truncated conical forming surface on its inner circumference, and a laser forming process of making a recessed portion 3a on the body portion 3 of the vessel 1A by irradiating laser light. It is possible to easily give the recessed portion for various uses such as decoration, reinforcement, stacking, prevention of label omission and the like to the outer circumference of the body portion of the blow-molded vessel 1A using the inexpensive removal mold. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a plastic container suitable for forming reinforcing ribs and stacking ribs on a container produced by blow-molding a preform which is a primary plastic molded product.

  As a plastic container, a bottle-shaped container such as a PET bottle and a cup-shaped container having an inverted truncated cone-shaped cylindrical body having the widest upper end opening are known and widely used in various applications. Has been. A bottle-shaped container is generally manufactured by a blow molding method, and a cup-shaped container is generally manufactured by pressure forming a plastic extruded sheet. In addition, a label such as a shrink film is attached to the body of the manufactured plastic container, and the contents are filled.

  The compressed air molding method is a method in which a thermoplastic plastic extruded sheet is heated and softened, and the sheet in this state is pressed against a female mold using vacuum pressure or compressed air pressure to be molded. This method is not suitable for forming a deep-bottom wide-mouth container. In addition, since the sheet portion after the molded wide-mouth container is removed is wasted, there is a problem that the utilization efficiency of the molding material is poor. Therefore, the present applicant has proposed a method of manufacturing a wide-mouth container by biaxial stretch blow molding in Patent Document 1 below.

On the other hand, as a cup-shaped container, there is known a compressed air molded cup in which vertical ribs for stacking are formed on the barrel so that a gap is formed between the mouth flanges of the upper and lower cup-shaped containers when stacking up and down. For example, it is disclosed in Patent Document 2 below.
International Publication No. 03/008176 Pamphlet JP 2004-10171 A

  Here, in a bottle-shaped container and a cup-shaped container, in order to give predetermined intensity | strength, recessed parts, such as a vertical rib and a horizontal rib, may be formed in the trunk | drum. When manufacturing by the blow molding method, it is necessary to use a blow mold having a corresponding recess, and a blow mold having a complicated recess is generally expensive. Moreover, there is a restriction that a concave portion that causes an undercut cannot be provided.

  On the other hand, the cup-shaped container is molded by a blow molding method and a pressure molding method. In blow molding, a die that is cheaper than the split die can be used. However, in the case where the body portion is provided with a recess, there is a restriction that a recess that causes an undercut cannot be provided. Similarly, there is a restriction that a concave portion that causes an undercut cannot be formed even by the pressure forming method.

  An object of the present invention is to propose a plastic container manufacturing method capable of easily and inexpensively forming a stacking recess and a reinforcing recess in a blow molded or pressure molded plastic container.

In order to solve the above problems, the method for producing a plastic container of the present invention comprises:
A molding process for molding a bottomed cylindrical plastic container;
A laser molding step of irradiating a predetermined portion of the molded container with laser light to partially form a recess in the container.

  Here, the molding step is a blow molding step of molding a container from a preform which is a primary plastic product, or a pressure molding step of molding the container from a plastic film or a plastic extruded sheet by a pressure molding method. can do.

  According to the experiments by the present inventors, laser light irradiation is performed without causing whitening by irradiating the barrel portion of a blow molded or compressed air molded container from outside with a laser light whose output is appropriately adjusted for a predetermined time. It was confirmed that a concave portion having a predetermined depth can be formed in the portion. Therefore, according to the present invention, a container is molded using an inexpensive one having no complicated molding surface such as a concave surface as a blow molding die or a pressure air molding die, and then a concave portion having a desired shape is formed. It can be easily formed in a desired portion of the container.

  The method for manufacturing a plastic container according to the present invention includes a cylindrical body portion with a bottom, a small-diameter mouth portion formed at the upper end of the body portion, and a male screw portion formed on the outer peripheral surface of the mouth portion. It can be used as a method for producing a bottle-shaped container. Also, a cup-shaped body including a cylindrical body portion having the same cross section or a gradually increasing cross section from the bottom surface of the lower end toward the opening portion of the upper end, and a mouth flange formed at the edge of the opening portion of the body portion It can be used as a manufacturing method of a container.

  In the laser molding step of the present invention, the body portion of the container may be irradiated with laser light to form the body portion reinforcement or the bottom portion reinforcement, or the concave portion for the body portion decoration or the bottom portion decoration. . Further, in the laser molding step, the concave portion for stacking can be formed on the bottom side portion of the body portion of the cup-shaped container.

  The method for producing a plastic container of the present invention is suitable for use in forming a recess for preventing a shrink label from being removed from a body of a molded cup-shaped container. Such a recess is formed along the circumferential direction of the body portion, and the upper end edge portion or the lower end edge portion of the shrink label is shrunk and adhered to the recess. As a result, it is possible to reliably prevent the label attached to the cylindrical or inverted frustoconical barrel from coming out from the barrel to the bottom side.

  In particular, a cup-shaped container having a recess extending in the circumferential direction cannot be molded using a punching die, and an expensive split die must be used in the case of blow molding. According to the present invention, after forming a cylindrical or frustoconical container using a punching die, a recess for preventing removal can be easily attached by irradiating a laser beam.

  In the method for producing a plastic container of the present invention, a desired recess is formed by irradiating the molded container with laser light. Therefore, it is not necessary to use an expensive mold having a concave complicated molding surface as a blow molding mold or a pressure molding mold. Moreover, the recessed part which was not able to be formed conventionally can also be formed.

  Furthermore, it is possible to form a container having a common shape using a common mold, and then attach different recesses to each container. Therefore, it is not necessary to prepare various molds, and the manufacturing cost can be reduced from this point.

  Furthermore, in the case of a cup-shaped container, a container can be shape | molded using an inexpensive shaping | molding die, and a recessed part can be attached to arbitrary sites. Therefore, it is possible to inexpensively manufacture a cup-like container having a stacking recess, a reinforcing recess, or the like formed in the body.

  Below, with reference to drawings, the manufacturing method of the plastic container to which this invention is applied is demonstrated.

(Example 1)
FIG. 1 is a front view, a bottom view, and a partial detail view showing a cup-shaped container manufactured by the method of the present invention. The cup-shaped container 1 is formed from a thermoplastic plastic such as PEN, PET, PP, etc., and has a bottom part 2 and a cylindrical body part 3 that spreads upward from the bottom part 2 in an inverted truncated cone shape. And have. At the edge of the opening 4 at the upper end of the body 3, an annular mouth flange 5 is formed spreading outward. Accordingly, the body 3 has the largest outer diameter at the opening 4. Here, a single annular recess 3 a formed along the circumferential direction of the trunk portion is formed at the upper end portion of the trunk portion 3. The concave portion 3a has an arc-shaped cross section, and functions as a reinforcing rib for the upper end portion of the body portion, and also functions as a retainer for the shrink label attached to the body portion 3.

  That is, as indicated by an imaginary line, the shrink label 10 is wound in a state where the upper edge portion 10a overlaps the recess 3a. Therefore, after the heat shrinkage, the upper edge portion 10a shrinks more than the lower portion and adheres closely to the surface of the recess 3a. As a result, the shrink label 10 is reliably prevented from coming out downward from the body portion 3 whose outer diameter gradually decreases downward.

  The cup-shaped container 1 having this shape includes a blow molding process in which a preform which is a plastic primary molded product is biaxially stretch blow molded to form a container without the recess 3a, and a container obtained by the blow molding process. It is manufactured through a laser molding process in which the recesses 3a are formed by irradiating the laser beam. In place of the blow molding process, a pressure molding process in which a plastic film is used to pressure mold a container without the recess 3a can be employed.

  FIG. 2A is a front view showing the preform used for manufacturing the cup-shaped container 1 in an inverted state. The preform 6 of this example is formed along a shallow bowl-shaped stretch-molded portion 7 that becomes the bottom 2 and the body 3 by biaxial stretch blow molding, and along the edge of the opening 8 of the stretch-molded portion 7. The shape is provided with a mouth flange 9 that remains as the mouth flange 5 of the cup-shaped container 1 without being molded.

  As shown in FIG. 2B, the stretch-molded portion 7 of the preform 6 is stretched in the blow mold 11 as indicated by an imaginary line to form the bottom 2 and the body 3 of the cup-shaped container 1. To do. The blow molding die 11 is a punching die arranged on the base 12 so as to be opened and closed up and down, and a frustoconical molding surface 11a is formed therein. Therefore, by carrying out biaxial stretch blow molding of the preform 6, a container 1 </ b> A provided with the body 3 without the recess 3 a is obtained. In addition, as a biaxial stretch blow molding apparatus of the cup-shaped container 1, what is disclosed by WO03 / 008176 which concerns on the applicant's application can be used, for example.

  Next, in the laser molding process, the outer peripheral surface of the barrel portion 3 is irradiated with laser light while rotating the blow-molded container 1A around its central axis to form the recess 3a. As the laser light, it is desirable to use a carbon dioxide laser having a center wavelength of about 10.6 microns. When the container 1A is rotated while irradiating the outer peripheral surface of the body with 60W laser light, and the temperature of the irradiated part is set to 170 ° C. to 180 ° C., an arc-shaped recess 3a as shown in FIG. It was done. In addition, the plastic part irradiated with the laser beam was not deteriorated by whitening.

  Here, in the cup-shaped container 1 of this example, the single recess portion 3a is formed in the body portion 3, but a plurality of the recess portions 3a may be formed. For example, as shown in FIG. 3, two recesses 3a (1) and 3a (2) may be formed. If a plurality of concave portions are formed, the strength of the body portion 3 is increased. In addition, if the shrink label is placed in a state covering these recesses and thermally contracted, the upper edge portion of the shrink label contracts along these recesses, so that the shrink label can be prevented from coming off from the body more reliably. Become.

(Example 2)
Next, FIG. 4 is a front view, a bottom view, and a partial detail view showing a cup-shaped container in which a recess is formed in a lower part of the trunk. In the cup-shaped container 20 of this example, a cylindrical short neck portion 26 having the same outer diameter is formed at the upper end portion of the body portion 23 that gradually spreads upward from the bottom portion 22 in an inverted truncated cone shape. An annular flange 25 is formed outside the edge of the opening 24 at the upper end. A single annular recess 23 a is formed in a lower portion of the outer peripheral surface of the body portion 23. Similarly to the cup-shaped container 1 of the first embodiment, the cup-shaped container 20 having this shape can be manufactured through a blow molding process and a laser molding process.

  The concave portion 23a of this example can also be used as a reinforcing rib and a rib for preventing the shrink label from coming off. Furthermore, it can also be used as a stacking rib when stacking the cup-shaped container 20 up and down. As shown in FIG. 5, it is of course possible to form a plurality of concave portions 23a, for example, three concave portions 23a (1), 23a (2), 23a (3).

(Example 3)
FIG. 6 is a front view, a bottom view, and a cross-sectional view showing a cup-shaped container in which vertical ribs are formed. The cup-shaped container 30 of this example includes a blow molding process in which a preform 6 having the same shape as that of the cup-shaped container 1 of the first embodiment is blow-molded to produce a container 1A (see FIG. 2), and a vertical rib 33a on the container 1A. It is manufactured through a laser molding process for forming the film. In forming the vertical ribs 33a on the container 1A, the container 1A may be moved up and down in the direction of the axis 1a while applying laser light to the outer peripheral surface of the body 33. In this example, six reinforcing ribs 33a are formed on the body 33, but it is also possible to form different numbers of vertical ribs. Since the cup-shaped container 30 in FIG. 6 has the same shape as the cup-shaped container 1 in FIG. 1, parts other than the body portion 33 are denoted by the same reference numerals, and description thereof is omitted.

(Other embodiments)
In addition, although said example is an example which applied this invention to manufacture of a cup-shaped container, it is also possible to apply this invention to manufacture of a bottle-shaped container. In this case, a bottle-shaped container is manufactured by a generally known biaxial stretch blow molding, and then the body of the bottle-shaped container is irradiated with a laser beam to be a target vertical rib for decoration. Or ribs for retaining the shrink label, ribs for stacking, or ribs for reinforcement.

  The above example is an example in which a concave portion is formed in a cup-shaped container obtained by blow molding, but it is needless to say that the concave portion may be formed in a container molded by pressure forming.

  Furthermore, all of the above examples are examples in which concave portions extending in the circumferential direction and the vertical direction are formed in the body portion of the cup-shaped container. The concave portion that can be imparted to the body portion in the laser molding step may be in a direction other than this or a curved shape.

  Furthermore, it is also possible to form a convex part on the body part by irradiating laser light from the inside of the body part to the inner peripheral surface of the body part. Accordingly, it is possible to form concave portions and convex portions for various purposes such as decoration, reinforcement, stacking, and shrink label prevention in the body of the cup-shaped container and bottle-shaped container.

  In addition to this, it is also possible to form a concave portion or a convex portion on the portion other than the trunk portion in the cup-shaped container or the bottle-shaped container, for example, the bottom portion, for the purpose of decoration, reinforcement or the like, if necessary. .

It is the front view, bottom view, and partial detail drawing of the cup-shaped container manufactured by the method of this invention. It is a front view of the preform used in order to manufacture the cup-shaped container of FIG. 1, and explanatory drawing which shows a blow molding process. It is the front view, bottom view, and partial detail drawing of the cup-shaped container manufactured by the method of this invention. It is the front view, bottom view, and partial detail drawing of the cup-shaped container manufactured by the method of this invention. It is the front view, bottom view, and partial detail drawing of the cup-shaped container manufactured by the method of this invention. It is the front view, bottom view, and partial detail drawing of the cup-shaped container manufactured by the method of this invention.

Explanation of symbols

1, 20, 30 Cup-shaped container 1A Container 2, 22 Bottom 3, 23, 33 Body 4, 24 Opening 5, 25 Opening flange 3a, 23a, 33a Recess 6 Preform 7 Stretched molding 8 Opening 9 Flange 10 Shrink label 11 Blow mold

Claims (11)

A molding process for molding a bottomed cylindrical plastic container;
A method of manufacturing a plastic container, comprising: a laser molding step of irradiating a predetermined portion of the molded container with laser light to partially form a recess in the container. In claim 1,
The method of manufacturing a plastic container, wherein the molding step is a blow molding step of molding a container from a preform that is a primary plastic molded product. In claim 1,
The said formation process is a manufacturing method of the plastic container which is a pressure forming process which shape | molds the said container by a pressure forming method from a plastic film or a plastic extrusion sheet | seat. In claim 2 or 3,
The container includes a cylindrical barrel portion having the same cross section or a gradually increasing cross section from the bottom surface of the lower end toward the upper end opening portion, and a mouth flange formed at the edge of the opening portion of the barrel portion. A method for producing a plastic container which is a cup-shaped container. In claim 2,
The container is a bottle-shaped container including a cylindrical body portion with a bottom, a small-diameter mouth portion formed at the upper end of the body portion, and a male screw portion formed on the outer peripheral surface of the mouth portion. A method for manufacturing plastic containers. In any one of claims 1 to 5,
In the laser molding step, a method of manufacturing a plastic container in which the body portion of the container is irradiated with laser light to form the recess for body body reinforcement or bottom part reinforcement, or body part decoration or bottom part decoration. In claim 4,
In the laser molding step, a plastic container manufacturing method in which the concave portion for stacking is formed in a bottom side portion of the body portion of the cup-shaped container. In claim 4,
In the laser molding step, a plastic container manufacturing method in which the concave portion for preventing a shrink label from dropping is formed in the body portion of the cup-shaped container. In claim 8,
The method of manufacturing a plastic container, wherein the recess is one or a plurality of annular recesses extending in a circumferential direction of the body portion. In claim 4,
In the molding step, a plastic container manufacturing method using a die that is opened and closed along the axial direction of the cup-shaped container.   A plastic container manufactured by the manufacturing method according to any one of claims 1 to 10.

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