JP6987702B2 - Preform and manufacturing method of preform - Google Patents

Description

The present invention relates to a preform used for blow molding of a synthetic resin container including an inner layer body and an outer layer body laminated on the outer surface of the inner layer body, and a method for producing the preform.

Conventionally, a preform used for blow molding of a synthetic resin container having an inner layer body and an outer layer body laminated on the outer surface of the inner layer body has been known. For example, in Patent Document 1, a holed portion is provided at the bottom of the outer preform, and a resin for the inner preform is filled in a mold through the holed portion to manufacture a preform having a laminated structure. Is disclosed.

Japanese Unexamined Patent Publication No. 2000-43126

However, in the method for manufacturing a preform described in Patent Document 1, when the inner preform is formed, the gate side end of the core body is not supported, so that the core body is radially displaced with respect to the outer preform. As a result, the wall thickness of the inner preform may be biased. In particular, when the wall thickness is thin, there is room for improvement because if the core body is displaced, the molding stability and the appearance of the product after molding are adversely affected.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a preform in which a bias in the wall thickness is unlikely to occur, and a method for producing the preform.

The preform of the present invention is
A synthetic resin preform having an inner body and an outer body laminated on the outer surface of the inner body and used for stretch blow molding.
With a tubular mouth and
The torso connected to the mouth and
It is provided with a bottom that closes the lower end of the body.
The inner surface of the bottom of the inner body is provided with a convex portion protruding inward or a concave portion recessed outward .
On the bottom side when the inner body is divided into two in the longitudinal direction, the inner body has a protrusion protruding outward from the outer surface.
The outer surface of the protrusion is characterized in that it is smoothly connected to the outer surface of the outer body.

Further, in the above configuration, it is preferable that at least a part of the protruding portion of the preform of the present invention is formed on an R surface provided at the bottom of the inner body.

Further, the method for producing the preform of the present invention is:
A synthetic resin having an inner body and an outer body laminated on the outer surface of the inner body, and having a tubular mouth portion, a body portion connected to the mouth portion, and a bottom portion closing the lower end of the body portion. It is a method of manufacturing preforms.
A step of forming an inner body having a convex portion protruding inward or a concave portion recessed outward on the inner surface of the bottom portion.
The step of arranging the inner body in the cavity of the mold,
A step of fitting a core concave portion corresponding to the convex portion or a core member having a core convex portion corresponding to the concave portion on the inner surface of the inner body.
Look including the step of forming the outer body in the space between the outer surface of the inner member and the cavity,
The inner body has a protrusion protruding outward from the outer surface on the bottom side when the inner body is divided into two in the longitudinal direction.
The inner body is characterized in that the protrusion is arranged in the cavity so as to abut on the cavity .

According to the present invention, it is possible to provide a preform in which the thickness is less likely to be biased and a method for producing the preform.

It is a front sectional view of the preform which is one Embodiment of this invention. It is a figure which shows the variation of the convex part provided in the bottom part of an inner body. It is a figure which shows the variation of the protrusion provided in the inner body. It is a flowchart which shows each process of the manufacturing method of the preform which is one Embodiment of this invention. It is a front sectional view of the inner body which comprises the preform which is one Embodiment of this invention. FIG. 3 is a front sectional view showing a state in which a core member is fitted to an inner surface of an inner body constituting a preform according to an embodiment of the present invention. FIG. 6 is an enlarged cross-sectional view of the bottom portion in FIG. FIG. 6 is a front sectional view showing a state in which an outer body is formed and a preform is completed.

Hereinafter, the present invention will be described in more detail with reference to the drawings. In the present specification, claims, and drawings, the vertical direction means an upward direction or a downward direction with the mouth portion 14 of the preform 11 facing upward as shown in FIG. Further, the radial outer side is a direction toward the outside along a straight line perpendicular to the central axis O through the central axis O of the preform 11 in FIG. 1, and the radial inner side is a central axis line along the straight line. It shall mean the direction toward O. A gate 41 (see FIG. 7) for injection molding the preform 11 is arranged below FIG. Therefore, the lower side of FIG. 1 is the gate 41 side.

The preform 11 according to the embodiment of the present invention shown in FIG. 1 is an intermediate product for manufacturing a synthetic resin container by stretch blow molding. The preform 11 has a double structure including an inner body 13 made of synthetic resin forming an inner layer of a container made of synthetic resin and an outer body 12 made of synthetic resin forming an outer layer, and has an outer shape thereof. The shape is a bottomed tubular shape (substantially test tubular) having a cylindrical mouth portion 14, a cylindrical body portion 15 connected below the mouth portion 14, and a bottom portion 16 that closes the lower end of the body portion 15. It has become.

The mouth portion 14 is formed in a shape corresponding to the mouth portion of the synthetic resin container, and a male screw 14a is provided on the outer peripheral surface. With the male screw 14a, a pouring member such as a pouring cap or a pouring pump can be screwed and attached to the mouth portion 14. The mouth portion 14 may be provided with an annular protrusion in place of the male screw 14a, and may be mounted by engaging a pouring member such as a pouring cap in an undercut shape by tapping. .. A neck ring 19 is provided at the lower part of the mouth portion 14 for fixing to a mold for blow molding when, for example, a synthetic resin container is molded by stretch blow molding.

As shown in FIG. 1, the bottom portion 16 of the preform 11 is formed in a curved shape (hemispherical shape) having an R surface. Further, in the example shown in FIG. 1, the thickness of the outer body 12 is thinner than the thickness of the inner body 13. This is because, in the illustrated example, the inner body 13 forms the inner layer forming the skeleton portion of the synthetic resin container, whereas the outer body 12 shields the contents from the external light in the synthetic resin container. This is because it forms an outer layer body as a light-shielding layer, and it is assumed that the outer layer body is peeled off from the inner layer body and separately discarded after using the contents in the synthetic resin container. However, the present invention is not limited to this aspect, and the thickness of the inner body 13 is formed to be thinner than the thickness of the outer body 12, and the outer body 12 forms an outer layer body forming the skeleton portion of the synthetic resin container, and the inner body 13 is formed. However, it may form an inner layer body as a protective layer that protects the contents from coming into direct contact with the outer layer body.

In the present embodiment, the inner body 13 is formed of a synthetic resin material such as polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), etc., which can be stretched and blown. Further, the outer body 12 is formed of a synthetic resin material such as polyethylene terephthalate (PET), polypropylene (PP), polyethylene (PE), nylon or ethylene-vinyl alcohol copolymer resin (EVOH). The outer body 12 is formed to be thinner than the inner body 13, and is laminated so as to cover the entire body portion 15 and bottom portion 16 on the outer surface of the inner body 13. When beer or other carbonated drink is assumed as the content, it is preferable to use a material having excellent gas barrier properties for the outer body 12. Further, assuming a beverage such as beer or wine that requires light-shielding property as the content, the outer body 12 is made of a material having a low light transmittance for light of a predetermined wavelength such as ultraviolet rays, or is specified. It is preferable to use a material colored so as to have a low light transmittance for light having a wavelength of. When the outer body 12 is made of a material different from that of the inner body 13, the outer layer can be separated from the inner layer and disposed of separately after using the contents in the synthetic resin container.

As shown in FIG. 1, a convex portion 16a projecting inward is provided on the inner surface of the bottom portion 16 of the inner body 13. The convex portion 16a has a pyramidal trapezoidal shape in the example shown in FIGS. 1 and 2A. As will be described later, when the preform 11 is insert-molded using the inner body 13 as an insert material, or when the outer body 12 is molded by two-color molding or the like after the inner body 13 is molded, it is fitted to the inner surface of the inner body 13. By fitting the convex portion 16a into the core concave portion 36a provided at the end on the gate 41 side of the core member 30 (see FIGS. 6 to 8) of the mold, the convex portion 16a is fitted in the radial direction of the inner body 13 with respect to the core member 30. The position can be aligned.

The shape of the convex portion 16a may be a truncated cone shape shown in FIG. 2 (a), a truncated cone shape shown in FIG. 2 (b), or a spherical band shape shown in FIG. 2 (c). .. When the pyramidal trapezoidal shape is adopted as the shape of the convex portion 16a, not only the radial alignment of the inner body 13 and the core member 30 but also the circumferential alignment can be performed. On the other hand, when a truncated cone shape or a spherical band shape is adopted as the shape of the convex portion 16a, the convex portion 16a can be fitted to the core concave portion 36a regardless of the position in the circumferential direction. In particular, when a spherical band shape is adopted as the shape of the convex portion 16a, the convex portion 16a is relatively easily fitted to the core concave portion 36a even when the axes of the inner body 13 and the core member 30 are slightly tilted. be able to.

On the bottom side (lower side of FIG. 1) when the inner body 13 is divided into two in the longitudinal direction (vertical direction in FIG. 1), the inner body 13 has a protruding portion 16b protruding outward from the outer surface. In the example of FIG. 1, the protrusion 16b is formed on the R surface at the bottom 16 of the inner body 13. As will be described later, the protruding portion 16b is used when the preform 11 is insert-molded using the inner body 13 as an insert material, or when the outer body 12 is molded by two-color molding after the inner body 13 is molded. When the protruding portion 16b provided on the outer surface of the mold abuts on the inner surface of the cavity 40 (see FIG. 7), the radial position of the inner body 13 with respect to the cavity 40 can be aligned.

The shape of the protruding portion 16b includes a shape that shrinks in both width and thickness at the upper and lower ends shown in FIG. 3A, a track shape shown in FIG. 3B, and a rectangular shape shown in FIG. 3C. May be. When a shape that shrinks in both width and thickness at the upper and lower ends shown in FIG. 3A is adopted as the shape of the protruding portion 16b, the corner portion of the protruding portion 16b is chamfered and the inner body 13 is formed into the cavity 40. When arranged inside, the protrusion 16b can be smoothly brought into contact with the inner surface of the cavity 40. On the other hand, when the track shape shown in FIG. 3B or the rectangular shape shown in FIG. 3C is adopted as the shape of the protruding portion 16b, the area of the outer surface of the protruding portion 16b that abuts on the cavity 40 is large. Therefore, the radial position of the inner body 13 with respect to the cavity 40 can be more accurately aligned.

Next, a method for producing the preform 11 according to the embodiment of the present invention will be described.

FIG. 4 is a flowchart showing a procedure for implementing the manufacturing method of the preform 11 according to the present embodiment. When manufacturing the preform 11, first, the inner body 13 shown in FIG. 5 is molded by injection molding or the like (step S101). As shown in FIG. 5, the inner body 13 is provided with a convex portion 16a protruding inward on the inner surface of the bottom portion 16, and a protruding portion 16b protruding outward from the outer surface on the R surface provided on the bottom portion 16. It is provided. The protruding portion 16b may be provided on the bottom 16 side (lower side in FIG. 1) when the inner body 13 is divided into two in the longitudinal direction (vertical direction in FIG. 5), and is not necessarily on the bottom 16 or the R surface. It does not have to be provided in.

Next, the inner body 13 formed in step S101 is placed in the cavity 40 (see FIG. 7) of the mold (step S102). The mold referred to here is a mold for molding the outer body 12, and when the preform 11 is insert-molded using the inner body 13 as an insert material and when the outer body 12 is molded in two colors after the inner body 13 is molded. May be molded by Then, regardless of which molding method is used, as shown in FIG. 6, the core member 30 having the core recess 36a corresponding to the convex portion 16a is fitted to the inner surface of the inner body 13 (step S103). The core member 30 has an outer surface shape corresponding to the inner surface shape of the inner body 13, but the diameter thereof is slightly smaller than the diameter of the inner surface of the inner body 13. As a result, since the core member 30 and the inner body 13 form a clearance fit, the core member 30 can be easily fitted inside the inner body 13. Moreover, when the core member 30 is fitted to the inside of the inner body 13, as shown in FIG. 6, the convex portion 16a provided on the inner surface of the bottom portion 16 of the inner body 13 is the end on the gate 41 side of the core member 30. It fits into the core recess 36a provided at the lower end in FIG. As a result, even if the core member 30 and the inner body 13 form a clearance fit, the radial position of the inner body 13 with respect to the core member 30 is positioned by fitting the convex portion 16a and the core concave portion 36a. Therefore, the inner body 13 is eccentric with respect to the core member 30 due to the clearance between the core member 30 and the inner body 13, and the wall thickness of the outer body 12 overmolded to the outer side of the inner body 13 is not biased. .. The shape of the core recess 36a can be appropriately selected from a pyramid cone shape, a truncated cone shape, a spherical band shape, and other shapes according to the shape of the convex portion 16a.

When the core member 30 is moved in the direction of the arrow shown in FIG. 7 and the core member 30 is fitted to the inner body 13, the protruding portion 16b protruding outward from the outer surface of the R-shaped bottom portion 16 of the inner body 13 is formed. , Abuts on the inner surface of the mold cavity 40 (step S104). In the present embodiment, the projecting portion 16b is continuously formed in a band shape in the circumferential direction, and the outer surface of the projecting portion 16b abuts on the inner surface of the cavity 40 so that the inner body 13 is radially with respect to the cavity 40. Positioned to. Then, in the present embodiment, by bringing the protruding portion 16b into contact with the inner surface of the cavity 40 of the mold, the outer surface position of the design outer body 12 and the inner surface position of the cavity 40 can be brought close to each other. Therefore, the space between the outer surface of the inner body 13 and the inner surface of the cavity 40 can be accurately positioned so as to be the space in which the outer body 12 should be formed. Due to the above technical features, the outer surface of the protrusion 16b can be configured to be smoothly connected to the outer surface of the outer body 12. Therefore, it is possible to prevent stress concentration and the like from occurring in the preform 11.

Further, in the present embodiment, since the projecting portion 16b is provided on the hemispherical R surface, the projecting portion 16b is brought into contact with the inner surface of the cavity 40 of the mold, as shown in FIG. Not only the radial position of the body 13 but also the vertical position can be aligned with respect to the cavity 40.

Next, the synthetic resin for the outer body 12 is injected into the space between the cavity 40 and the inner body 13 formed by steps S103 and S104 to form the outer body 12 (step S105). After step S105, the production of the preform 11 is completed by releasing the preform 11 from the mold.

In order to manufacture a synthetic resin container from the preform 11, the neck ring 19 of the preform 11 formed in step S105 is abutted against the reference surface of the blow molding die and fixed, and the preform 11 is stretched and blown. Mold.

As described above, the preform 11 according to the present embodiment has an inner body 13 and an outer body 12 laminated on the outer surface of the inner body 13, and has a tubular mouth portion 14 and a mouth portion 14. A continuous body portion 15 and a bottom portion 16 that closes the lower end of the body portion 15 are provided, and a convex portion 16a projecting inward is provided on the inner surface of the bottom portion 16 of the inner body 13. By adopting such a configuration, the inner body 13 can be positioned in the radial direction with respect to the core member 30 of the mold when the preform 11 is manufactured, so that the core member 30 can be fitted to the inner body 13. It is possible to prevent the thickness of the outer body 12 from being biased while facilitating the above.

Further, in the present embodiment, the inner body 13 is configured to have a protruding portion 16b protruding outward from the outer surface on the bottom 16 side when the inner body 13 is divided into two in the longitudinal direction. By adopting such a configuration, the inner body 13 can be positioned in the radial direction with respect to the cavity 40 of the mold when the outer body 12 is molded, so that the wall thickness of the outer body 12 is further biased. It can be made difficult.

Further, in the present embodiment, the outer surface of the protruding portion 16b is configured to be smoothly connected to the outer surface of the outer body 12. By adopting such a configuration, it is possible to prevent stress concentration and the like from occurring in the preform 11.

Further, in the present embodiment, at least a part of the protruding portion 16b is configured to be formed on the R surface provided on the bottom portion 16 of the inner body 13. By adopting such a configuration, the protruding portion 16b is brought into contact with the inner surface of the cavity 40 of the mold, so that not only the radial position of the inner body 13 but also the vertical position is positioned with respect to the cavity 40. Can be matched.

Further, the method for manufacturing the preform 11 according to the present embodiment has an inner body 13 and an outer body 12 laminated on the outer surface of the inner body 13, and is connected to the tubular mouth portion 14 and the mouth portion 14. A method for manufacturing a synthetic resin preform 11 including a body portion 15 and a bottom portion 16 that closes the lower end of the body portion 15, and is an inner body provided with an inwardly projecting convex portion 16a on the inner surface of the bottom portion 16. A step of forming the 13, a step of arranging the inner body 13 in the cavity 40 of the mold, and a step of fitting a core member 30 having a core concave portion 36a corresponding to the convex portion 16a on the inner surface of the inner body 13. , A step of forming the outer body 12 in the space between the cavity 40 and the outer surface of the inner body 13 is included. By adopting such a configuration, the inner body 13 can be positioned in the radial direction with respect to the core member 30 of the mold when the preform 11 is manufactured, so that the core member 30 can be fitted to the inner body 13. It is possible to prevent the thickness of the outer body 12 from being biased while facilitating the above.

Further, in the present embodiment, the inner body 13 has a protruding portion 16b protruding outward from the outer surface on the bottom portion 16 side when the inner body 13 is divided into two in the longitudinal direction, and the inner body 13 has a protruding portion 16b. It is configured to be arranged in the cavity 40 so as to be in contact with the cavity 40. By adopting such a configuration, the inner body 13 can be positioned in the radial direction with respect to the cavity 40 of the mold when the outer body 12 is molded, so that the wall thickness of the outer body 12 is further biased. It can be made less likely to occur.

Although the present invention has been described with reference to the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and modifications based on the present disclosure. Therefore, it should be noted that these modifications and modifications are included in the scope of the present invention. For example, the functions included in each component can be rearranged so as not to be logically inconsistent, and a plurality of components can be combined or divided into one. It should be understood that these are also included in the scope of the present invention.

For example, in the present embodiment, an example in which the outer body 12 and the inner body 13 are molded by injection molding has been described, but the present invention is not limited to this, and other molding methods such as compression molding may be adopted.

Further, in the present embodiment, the mouth portion 14 and the body portion 15 are formed in a substantially cylindrical shape, but the present invention is not limited to this, and for example, a square cylinder or an elliptical cylinder may be formed.

Further, in the present embodiment, the convex portion 16a protruding inward is provided on the inner surface of the bottom portion 16 of the inner body 13, and the core concave portion 36a is provided on the core member 30 side, but the present invention is not limited to this embodiment. .. A concave portion protruding outward may be provided on the inner surface of the bottom portion 16 of the inner body 13, and a core convex portion may be provided on the core member 30 side.

Further, in the present embodiment, the projecting portion 16b projecting outward from the outer surface is provided on the R surface of the bottom portion 16 of the inner body 13, but the present embodiment is not limited to this embodiment. At least a part of the protrusion 16b may be provided on the R surface. Further, the protruding portion 16b may be provided on the bottom portion 16 other than on the R surface. Further, the protruding portion 16b does not need to be provided on the bottom portion 16 or the R surface, and the bottom portion 16 side (lower side in FIG. 1) when the inner body 13 is divided into two in the longitudinal direction (vertical direction in FIG. 1). It suffices if it is provided in. However, considering the pulling out of the preform 11 after molding the outer body 12, it is preferable that the protruding portion 16b is formed on the R surface.

Further, in the present embodiment, the protruding portion 16b is formed in a band shape continuously in the circumferential direction, but the present invention is not limited to this embodiment. The protruding portions 16b may be provided intermittently at a plurality of locations in the circumferential direction.

11 Preform 12 Outer body 13 Inner body 14 Mouth 14a Male screw 15 Body 16 Bottom 16a Convex 16b Protrusion 19 Neck ring 30 Core member 36a Core concave 40 Cavity 41 Gate O Central axis

Claims (3)

A synthetic resin preform having an inner body and an outer body laminated on the outer surface of the inner body and used for stretch blow molding.
With a tubular mouth and
The torso connected to the mouth and
It is provided with a bottom that closes the lower end of the body.
The inner surface of the bottom of the inner body is provided with a convex portion protruding inward or a concave portion recessed outward .
On the bottom side when the inner body is divided into two in the longitudinal direction, the inner body has a protrusion protruding outward from the outer surface.
A preform characterized in that the outer surface of the protruding portion is smoothly connected to the outer surface of the outer body. At least a portion is formed on the R surface provided on a bottom portion of the inner body, the preform according to claim 1 of the projecting portion. A synthetic resin having an inner body and an outer body laminated on the outer surface of the inner body, and having a tubular mouth portion, a body portion connected to the mouth portion, and a bottom portion closing the lower end of the body portion. It is a method of manufacturing preforms.
A step of forming an inner body having a convex portion protruding inward or a concave portion recessed outward on the inner surface of the bottom portion.
The step of arranging the inner body in the cavity of the mold,
A step of fitting a core concave portion corresponding to the convex portion or a core member having a core convex portion corresponding to the concave portion on the inner surface of the inner body.
Look including the step of forming the outer body in the space between the outer surface of the inner member and the cavity,
The inner body has a protrusion protruding outward from the outer surface on the bottom side when the inner body is divided into two in the longitudinal direction.
A method for manufacturing a synthetic resin preform, wherein the inner body is arranged in the cavity so that the protruding portion abuts on the cavity.

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