JP7070721B1 - Synthetic resin container, preform and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily separate a container main body and a coating layer in a synthetic resin container provided with a peelably laminated coating layer on the outer peripheral surface side of the container body, in particular, a fragment on the terminal side of the coating layer is provided. Make sure that it does not peel off and remain on the container body. SOLUTION: A container main body 1a formed in a predetermined container shape including a mouth portion 2, a body portion 3 and a bottom portion 4 is releasably laminated on an outer peripheral surface side of the container main body 1a, and the end side is a lower end portion of the mouth portion 2. In the container 1 provided with the coating layer 5 covering the side, an easily torn portion 6 having a thickness of the coating layer 5 thinner than the surroundings is formed on the terminal side of the coating layer 5. [Selection diagram] Fig. 5

Description

The present invention relates to a synthetic resin container provided with a peelably laminated coating layer on the outer peripheral surface side of the container body, and a preform and a method for producing the same.

Conventionally, a container made of synthetic resin, in which a bottomed tubular preform is formed using a thermoplastic resin such as polyethylene terephthalate, and then this preform is molded into a bottle shape by biaxial stretch blow molding or the like, is used. It is used in a wide range of fields as a container containing various beverages and various seasonings.

In recent years, this type of synthetic resin container has become more and more familiar, and various proposals have been made accordingly. For example, Patent Document 1 proposes a composite container in which a plastic member is provided in close contact with the container body so that it can be peeled off and removed while the container body can be recycled as in the conventional case.

Japanese Unexamined Patent Publication No. 2016-055523

However, in Patent Document 1, in order to peel off and remove the plastic member from the container body, the plastic member is cut off using a blade or the like, or the plastic member is peeled off along a cutting line provided on the plastic member. Although it is stated that it can be done, it is not really easy to peel off the plastic member that is in close contact with the container body, and it is not easy for the pieces of the plastic member to remain on the container body without being peeled off. Not preferred.

Therefore, the present inventors have made it possible to easily separate the container body and the coating layer in a synthetic resin container provided with a peelably laminated coating layer on the outer peripheral surface side of the container body, in particular, the container mouth portion. As a result of diligent studies to prevent the fragment on the terminal side of the coating layer covering the lower end side of the container from remaining on the container body without being peeled off, the present invention has been completed.

The synthetic resin container according to the present invention is detachably laminated on the outer peripheral surface side of the container body with a container body formed in a predetermined container shape including a mouth portion, a body portion and a bottom portion, and the end side is the mouth portion. A coating layer that covers the lower end side of the coating layer is provided, and an easily torn portion is formed on the end side of the coating layer so that the thickness of the coating layer is thinner than that of the surroundings . It is composed of a thin-walled portion that is thinned in a groove shape .

Further, the preform according to the present invention is a preform for blow molding the synthetic resin container, and is formed on the mouth portion forming region to be the mouth portion and the body portion and the bottom portion stretched. A preform main body formed into a bottomed tubular shape including a stretched region, and a covering material layer that is releasably laminated on the outer peripheral surface side of the preform main body and whose end side covers the lower end side of the mouth portion forming region. On the terminal side of the covering material layer, an easily torn portion is formed in which the thickness of the covering material layer is made thinner than the surroundings, and the easily torn portion is made thin in a groove shape. It is composed of a thin part .

Further, the method for producing a preform according to the present invention is a method for producing a preform for blow-molding the synthetic resin container, which is a method for producing a preform which is stretched to form a mouth portion to be a mouth portion and the body portion. A primary injection step of injection-molding a preform body formed into a bottomed tubular shape including a stretched region formed on the bottom portion, and a detachably laminated layer on the outer peripheral surface side of the preform body, the end side being the terminal side. A secondary injection step of injection molding a covering material layer covering the lower end side of the mouth portion forming region is included, and the lower end side of the mouth portion forming region is molded among the cavity surfaces of the injection molding mold used in the primary injection step. By engraving one or more grooves extending with a predetermined length in the range, one or more ridges formed by the grooves are formed on the lower end side of the mouth forming region. This is a method of forming a groove-shaped thin-walled portion at a portion overlapping the ridge portion on the terminal side of the coating material layer that is injection-molded in the secondary injection step.

According to the present invention, in a synthetic resin container provided with a peelable laminated coating layer on the outer peripheral surface side of the container body, a coating layer covering the lower end side of the container mouth portion when the coating layer is peeled from the container. By ensuring that the end side of the container is torn, the container body and the coating layer can be easily separated.

It is a perspective view which shows the outline of the synthetic resin container which concerns on embodiment of this invention. It is a front view which shows the outline of the synthetic resin container which concerns on embodiment of this invention. It is a back view which shows the outline of the synthetic resin container which concerns on embodiment of this invention. FIG. 2 is an end view taken along the line AA of FIG. It is an enlarged sectional view of the main part of the synthetic resin container which concerns on embodiment of this invention. It is explanatory drawing which shows an example of the blow molding mold which targets the synthetic resin container which concerns on embodiment of this invention. It is a vertical sectional view which shows the outline of the preform which concerns on embodiment of this invention. It is a BB end view of FIG. It is explanatory drawing of the primary injection process. It is explanatory drawing of the secondary injection process.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Synthetic resin container]
First, a synthetic resin container according to an embodiment of the present invention will be described.
1 is a perspective view showing an outline of a synthetic resin container according to the present embodiment, FIG. 2 is a front view of the same, FIG. 3 is a rear view of the same, and FIG. 4 is an end view of AA of FIG. , FIG. 5 shows an enlarged cross section of a main part of the portion surrounded by the chain line in FIG.

The container 1 shown in these figures has a container body 1a formed into a predetermined container shape including a mouth portion 2, a body portion 3 and a bottom portion 4, and a coating layer releasably laminated on the outer peripheral surface side of the container body 1a. It is equipped with 5. In the illustrated example, the container 1 (container body 1a) is formed into a substantially cylindrical shape, and is formed into a so-called petaloid shape and a body portion 3 in which the upper portion in the height direction is reduced in diameter toward the mouth portion 2. The shape of the container includes the bottom 4, but the shape of the container 1 is not limited to this.

Here, FIG. 2 shows a cross section of the body portion 3 by cutting out a part on the upper end side, but the thickness of the container body 1a and the coating layer 5 appearing in the cross section is exaggeratedly depicted. There is. In other drawings as well, the wall thicknesses of the container body 1a, the coating layer 5, and the like appearing in the cross section are appropriately exaggerated and depicted.
Further, the height direction means a direction orthogonal to the horizontal plane when the container 1 is upright on the horizontal plane with the mouth portion 2 side facing up, and the vertical and horizontal directions and the vertical and horizontal directions of the container 1 are the mouth. It shall be specified in the state shown in FIG. 2 with the part 2 side facing up.

The mouth portion 2 is a cylindrical portion that serves as an injection outlet for the contents. A screw thread 2a for attaching a lid (not shown) is provided on the side surface of the mouth portion 2 on the opening end side.
Further, the mouth portion 2 is provided with an annular neck ring 2b that projects outward along the circumferential direction. The mouth portion 2 includes the lower neck portion 2c that hangs in a cylindrical shape from directly below the neck ring 2b, and the lower end of the mouth portion 2 is a body portion whose diameter is reduced toward the mouth portion 2. It is connected to the upper end of 3.

In the present embodiment, the covering layer 5 is laminated so that the terminal side thereof covers the lower end side of the mouth portion 2. In the illustrated example, the entire peripheral surface of the body portion 3 from the bottom surface of the bottom portion 4 is covered with the covering layer 5, and the terminal side of the covering layer 5 covers the entire circumference of the lower neck portion 2c on the lower end side of the mouth portion 2. It is laminated so as to cover it and reach directly under the neck ring 2b (see FIG. 5). An easy-to-tear portion 6 having a thickness smaller than that of the surroundings is formed on the terminal side of the coating layer 5, and the details of the easy-to-tear portion 6 will be described later.

Further, the coating layer 5 is releasably laminated on the container body 1a so that it can be peeled off from the used container 1 and separately disposed of after the contents have been consumed. A tear guide portion 7 may be provided to facilitate tearing of the coating layer 5 when peeling from 1. In the illustrated example, the tear guide portion 7 formed in a linear or chain linear shape (perforation shape) is provided so as to extend in a predetermined direction along the peripheral surface of the body portion 3.

The specific form of the tear guide portion 7 is not particularly limited as long as the coating layer 5 can be easily torn. In the illustrated example, starting from the central portion in the height direction of the body portion 3, the chain linear first guide groove portion 7a toward the mouth portion 2 side along the circumferential direction and the bottom portion 4 side along the circumferential direction, respectively. A chain-shaped second guide groove portion 7b is included, and a tear starting portion 7c imitating a pull ring used for an easy open-end can lid is formed on the starting end side thereof in order to easily attract the user's attention. ..

By providing such a tear guide portion 7, when the coating layer 5 is peeled off from the used container 1 and separately disposed of, the fingertips of the fingers are hooked on the contour portion imitating the pull ring of the tear start portion 7c. The covering layer 5 can be torn along the tear guide portion 7 by breaking the portion and pulling the separated portion while picking it up with a finger.

When tearing the covering layer 5 in this way, the covering layer 5 is torn while being guided by the first guide groove portion 7a and the second guide groove portion 7b extending along the peripheral surface of the body portion 3. At that time, on the terminal side of the covering layer 5 covering the lower end side of the mouth portion 2, an easily torn portion 6 having a thickness smaller than that of the surroundings is formed, so that the mouth portion 2 side. On the side of the first guide groove portion 7a toward the mouth portion 2, the end side of the covering layer 5 covering the lower end side of the mouth portion 2 is surely torn without the tearing being interrupted before reaching the mouth portion 2. Can be done. As a result, the container body 1a and the coating layer 5 can be easily separated by peeling off the remaining portion while rolling the terminal side of the coating layer 5 peeled off from the container body 1a. can.

[Manufacturing method of synthetic resin container]
Next, a method for manufacturing a synthetic resin container according to the embodiment of the present invention will be described.

FIG. 6 shows an example of the blow molding die 100 in which the container 1 is the molding target, and the blow molding die 100 includes a body die 103 for molding the body 3 and a bottom die 104 for forming the bottom 4. It is equipped with. The body mold 103 is composed of a pair of split molds configured to be openable and closable, and FIG. 6 shows a simplified cross section of the blow molding mold 100 cut out on the surface including the parting surface of the body mold 103.

Further, FIG. 7 shows an example of the preform 10 suitable for blow molding the container 1 described above, and the preform 10 can be peeled off from the preform main body 10a and the outer peripheral surface side of the preform main body 10a. It is provided with a covering material layer 50 laminated on the above.

When the preform main body 10a is blow-molded as described later, the preform main body 10a has a mouth portion forming region 20 that becomes the mouth portion 2 of the container main body 1a while maintaining its appearance substantially, and the body portion 3 of the container main body 1a that is stretched. It is formed into a bottomed cylinder including a stretched region 30 formed on the bottom portion 4 and the bottom portion 4. The mouth forming region 20 of the preform main body 10a is provided with a screw thread 2a and a neck ring 2b having the same reference numerals as those attached to the container 1, and the neck ring 2b of the mouth forming region 20 is provided. The lower part is the lower part of the neck 2c of the container body 1a.

Here, FIG. 7 is a vertical cross-sectional view of the preform 10, and the wall thickness of the preform main body 10a and the covering material layer 50 appearing in the cross section is exaggeratedly depicted. In other drawings as well, the wall thicknesses of the preform main body 10a, the covering material layer 50, and the like appearing in the cross section are appropriately exaggerated and depicted.
Further, the vertical / horizontal and vertical / horizontal directions of the preform 10 are defined in the state shown in FIG. 7 with the mouth forming region 20 side facing up.

The covering material layer 50 laminated on the preform main body 10a is laminated so that its end side covers the lower end side of the mouth portion forming region 20, and in the illustrated example, the entire surface of the stretched region 30 is covered. It is covered with the material layer 50, and the end side of the covering material layer 50 covers the entire circumference of the lower part of the neck ring 2b of the mouth forming region 20 (the part that becomes the lower neck portion 2c of the container body 1a). It is laminated so as to reach directly below the neck ring 2b.

The preform 10 is softened by heating so that it can be blow-molded, and then is set in the blow-molding mold 100 as shown in FIG. 6, and if necessary, it is axially (longitudinal) by a drawing rod. While being stretched, it is stretched in the axial direction and the circumferential direction (lateral direction) by the blow air blown into the preform 10. Then, the cavity shape of the blow molding die 100 is transferred to the stretched portion, so that the container 1 has a predetermined container shape.
In addition, in FIG. 6, the preform 10 set in the blow molding die 100 is shown by the alternate long and short dash line.

When heating the preform 10, for example, the preform 10 is heated from the coating material layer 50 side by an infrared heater or the like, and a rod-shaped high frequency induction heating element heated by the high frequency induction heating is inserted into the preform 10. It is preferable to appropriately adjust the heating temperature from the inside and outside by heating from the inner surface side of the preform main body 10a as well.

In this way, when the preform 10 is blow-molded, the mouth portion forming region 20 of the preform main body 10a is not stretched except for the connection portion with the stretched region 30 on the lower end side thereof, and its appearance is generally maintained. It becomes the mouth 2 of the container body 1a. Then, the stretched region 30 is stretched and the cavity shape of the blow molding die 100 is transferred to form the body 3 and the bottom 4 of the container body 1a, and the covering material laminated on the preform body 10a. The layer 50 is integrally molded with the preform main body 10a to become a coating layer 5 laminated on the container main body 1a.

At this time, by providing a protrusion 107 that protrudes so as to bite into the surface of the covering material layer 50 on the cavity surface of the blow molding die 100 in correspondence with the tear guide portion 7 as described above, the tear guide portion is provided. 7 can be shaped into the covering layer 5, but the range in which the tear guide portion 7 can be shaped is limited. That is, in the preform 10 set in the blow molding mold 100, the lower portion of the neck ring 2b (the portion that becomes the lower neck portion 2c on the lower end side of the mouth forming region 20) is usually on the upper end side of the body mold 103. Since it is held so as to be sandwiched between the two (see FIG. 6), the range in which the tear guide portion 7 can be formed is limited to the range up to the vicinity of the upper end of the body portion 3.

Therefore, even if the covering layer 5 is provided with the tearing guide portion 7 so that the covering layer 5 can be torn along the tearing guide portion 7, the tearing is interrupted before reaching the mouth portion 2, and the mouth portion 2 is used. Fragments on the terminal side of the coating layer 5 covering the lower end side of the container may not be peeled off and may remain on the container body 1a, which may hinder the separation of the container body 1a and the coating layer 5. .. Therefore, in the present embodiment, by forming an easily torn portion 6 having a thickness of the coating layer 5 thinner than the surroundings on the terminal side of the coating layer 5, the front portion reaches the mouth portion 2. The end side of the coating layer 5 is surely torn without the tearing being interrupted.

The easily torn portion 6 formed on the terminal side of the coating layer 5 can be formed, for example, by a thin portion in which the thickness of the coating layer 5 is made thinner in a groove shape with respect to the periphery. In such an embodiment, the easily torn portion 6 composed of the thin-walled portion formed into a groove shape can be formed at the stage of manufacturing the preform 10, and the preform 10 in the present embodiment has two colors. It can be manufactured as follows by an injection molding method called molding or double molding.

First, the core mold 200 that forms the inner peripheral surface and the upper end surface of the preform main body 10a, the upper mold 201 that forms the upper outer peripheral surface of the preform main body 10a including the upper surface and the peripheral end surface of the neck ring 2b, and the neck ring. The first lower mold 202a that forms the lower outer peripheral surface of the preform main body 10a from the lower surface to the bottom of 2b is molded, and the resin material that forms the preform main body 10a is injected (see FIG. 9). ). As a result, the preform main body 10a formed into a bottomed tubular shape including the mouth forming region 20 and the stretched region 30 is injection-molded (primary injection molding).

It should be noted that the mouth forming region 20 of the preform main body 10a thus injection-molded includes the lower portion of the neck ring 2b (the portion serving as the lower neck portion 2c of the container main body 1a) as described above. It's a street.

Next, instead of the first lower mold 202a, a second lower mold 202b configured to form a gap for forming the covering material layer 50 between the molded preform main body 10a and the molded preform main body 10a is used. After remolding, the resin material forming the covering material layer 50 is injected (see FIG. 10). As a result, the covering material layer 50 is injection-molded on the outer peripheral surface side of the preform main body 10a so as to be peelably laminated and the end side covers the lower portion of the neck ring 2b (the lower end side of the mouth forming region 20) (2). Next injection process).

The first and second lower molds 202a and 202b are usually provided with a gate serving as an injection port for the resin material at a position corresponding to the bottom side of the preform 10, but FIGS. 9 and 10 show. In the example shown in, the illustration of the gate is omitted.

As the resin material forming the preform body 10a (that is, the resin material forming the container body 1a), an ethylene terephthalate-based thermoplastic polyester such as polyethylene terephthalate is preferably used in consideration of the recyclability required for the container 1. can.

As the resin material forming the covering material layer 50 (that is, the resin material forming the covering layer 5), the covering material layer 50 (coating layer 5) is releasably laminated on the preform main body 10a (container main body 1a). From the viewpoint of making the preform body 10a, it is preferable to use a thermoplastic resin that is incompatible with the resin material that forms the preform body 10a. For example, when an ethylene terephthalate-based thermoplastic polyester is used as the resin material for forming the preform main body 10a, a polyolefin-based resin such as polypropylene or polyethylene can be used as the resin material for forming the covering material layer 50. When the container 1 is required to have a gas barrier property, the resin material forming the coating material layer 50 is a thermoplastic resin having a gas barrier property such as an ethylene-vinyl alcohol copolymer or polymethoxylylen adipamide (MXD6). Can also be used. It is also possible to add a pigment, a colorant, or the like to the resin material forming the dressing layer 50 to color it to a desired hue to impart light-shielding properties. In order to enhance the decorative effect, a plurality of pigments and colorants can be mixed and added to form a marble pattern. Various additives can be added to the resin material forming the dressing layer 50, if necessary, without being limited by the recyclability required for the container 1.

In this way, when the preform 10 is injection-molded, in the primary injection step, the cavity surface of the first lower mold 202a that forms the outer peripheral surface from the lower surface to the bottom of the neck ring 2b of the preform main body 10a. Among them, one or more extending in a predetermined length along the axial direction in the range for forming the lower portion (lower end side of the mouth forming region 20) of the neck ring 2b of the mouth forming region 20. The groove 208 is engraved (see FIG. 9). As a result, one or more ridges 8 shaped by the groove 208 are formed in the lower portion of the neck ring 2b of the mouth forming region 20.

Next, in the secondary injection step, a second lower mold 202b configured to form a gap for forming the covering material layer 50 is used between the preform main body 10a formed in the primary injection step and the preform main body 10a. The mold is re-tightened, but at this time, in the portion where the ridge portion 8 of the preform main body 10a is formed, the portion where the ridge portion 8 is formed is with the cavity surface of the second lower mold 202b. The interval between them becomes narrower. As a result, in the coating material layer 50 injection-molded in the secondary injection step, a thin-walled groove-shaped portion is formed at a portion overlapping the ridge portion 8 formed on the preform main body 10a on the terminal side thereof. It is formed.

Here, in the illustrated example, by forming a plurality of ridges 8 along the circumferential direction on the lower end side of the mouth forming region 20, the peripheral direction is on the terminal side of the dressing layer 50. A plurality of thin-walled portions are arranged in a row along the above (see FIG. 8).
Note that FIG. 8 is an end view taken along the line BB of FIG. 7.

By going through the primary injection step and the secondary injection step as described above, a protrusion extending along the outer peripheral surface of the mouth portion forming region 20 covered by the terminal side of the dressing layer 50 on the lower end side. To manufacture a preform 10 in which a strip 8 is formed and an easily torn portion 6 composed of a groove-shaped thin portion is formed at a portion overlapping the protrusion 8 on the terminal side of the covering material layer 50. Can be done. Then, in the preform 10 produced in this way, the lower end side of the mouth portion forming region 20 held so as to be sandwiched between the upper end side of the body mold 103 by blow molding as described above is the mouth. It is formed into a container 1 having a predetermined container shape so as to be a lower neck portion 2c on the lower end side of the portion 2.

Here, in the illustrated example, an easily torn portion consisting of a ridge portion 8 formed on the lower end side of the mouth portion forming region 20 and a groove-shaped thin-walled portion formed overlapping the ridge portion 8 is easily torn. The portion 6 is formed so that these extending directions coincide with the axial direction of the preform 10.

When the preform 10 is blow-molded, it is easily composed of a ridge portion 8 formed on the lower end side of the mouth portion forming region 20 and a groove-shaped thin-walled portion formed overlapping the ridge portion 8. The torn portion 6 does not disappear or is significantly deformed by blow molding, and is generally maintained in the same state as it is. Therefore, by blow molding the preform 10 manufactured as described above, a ridge portion extending along the outer peripheral surface on the lower end side of the mouth portion 2 covered by the end side of the coating layer 5 It is possible to obtain a container 1 in which an easily torn portion 6 made of a thin-walled groove-shaped thin portion is formed at a portion where the 8 is formed and overlaps with the ridge portion 8 on the terminal side of the coating layer 5.

Since the easy tearing portion 6 and the ridge portion 8 can be regarded as substantially the same before and after blow molding (see FIGS. 4 and 8), the preform 10 and the container 1 are indicated by the same reference numerals. ing. The reason why the screw thread 2a and the neck ring 2b are indicated by the same reference numerals is the same reason.

Although the present invention has been described above with reference to preferred embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. Nor.

For example, in the above-described embodiment, the ridges formed on the lower end side (lower end side of the mouth portion forming region 20) of the mouth portion 2 covered by the end side of the coating layer 5 (coating material layer 50). The easy-to-tear portion 6 composed of the portion 8 and the groove-shaped thin-walled portion formed on the ridge portion 8 has their extension direction in the axial direction of the container 1 (preform 10). It is formed to match, but is not limited to this. When the tear guide portion 7 is provided in the coating layer 5, the direction in which the coating layer 5 is torn along the tear guide portion 7 so that the tear by the tear guide portion 7 can easily propagate to the tear guide portion 6. Therefore, the ridge portion 8 and the easily torn portion 6 may be formed so as to be inclined at a predetermined angle with respect to the axial direction.

Further, in the above-described embodiment, the ridges formed on the lower end side (lower end side of the mouth portion forming region 20) of the mouth portion 2 covered by the end side of the coating layer 5 (coating material layer 50). A plurality of easy-to-tear portions 6 composed of a groove-shaped thin-walled portion formed on the ridge portion 8 and a groove-shaped thin-walled portion are provided in a plurality of rows along the circumferential direction, but the limitation is limited to this. Not done. When the preform 10 is set in the blow molding die 100, if it can be aligned with the tear guide portion 7 formed on the coating layer 5, for example, when the tear guide portion 7 is provided in the above-described embodiment. May provide only one easy-to-tear portion 6 composed of a thin-walled groove-shaped thin portion on the extension line of the first guide groove portion 7a.

Further, in the above-described embodiment, by forming the ridge portion 8 on the lower end side of the mouth portion 2 (the lower end side of the mouth portion forming region 20), the end side of the covering layer 5 (covering material layer 50) is formed. In addition, the easily torn portion 6 made of a thin-walled portion formed into a groove shape is formed, but the specific shape of the ridge portion 8 is not particularly limited. The shape, dimensions, etc. of the ridge portion 8 can be appropriately designed in consideration of the easiness of tearing of the easily tear portion 6 formed of the thin-walled groove-shaped portion formed on the ridge portion 8. ..

Further, in the above-described embodiment, the terminal side of the coating layer 5 (coating material layer 50) is the lower part of the neck on the lower end side of the mouth portion 2 (the portion below the neck ring 2b of the mouth portion forming region 20). The coating layer 5 (coating material layer 50) is laminated on the outer peripheral surface side of the container body 1a (preform body 10a) so as to cover the entire circumference and reach directly below the neck ring 2b, but the present invention is not limited to this. The coating layer 5 (coating material layer 50) extends the terminal side thereof, covers the lower surface of the neck ring 2b, and reaches the peripheral edge of the neck ring 2b so as to reach the peripheral edge of the neck ring 2b. It may be laminated on the outer peripheral surface side. In such an embodiment, in order to ensure that the terminal side of the coating layer 5 is torn, the easily torn portion 6 composed of the thin-walled portion formed into a groove shape is the terminal side of the coating layer 5. Since it is preferable that the protrusion reaches the edge, the protrusion 8 is necked so that the protrusion 8 formed on the lower end side of the mouth forming region 20 further reaches the peripheral edge of the neck ring 2b. By extending to the lower surface of the ring 2b, it is preferable to form the easily torn portion 6 formed of the thinned portion formed into a groove shape so as to reach the end edge on the terminal side of the covering layer 5. Further, the neck ring 2b can be omitted if necessary.

Further, in the above-described embodiment, in manufacturing the preform 10, a ridge portion 8 is formed on the lower end side of the mouth portion forming region 20, and the ridge portion 8 is overlapped with the ridge portion 8 to be thinned in a groove shape. The easy tearing portion 6 is formed, but the present invention is not limited to this. The protrusion 8 formed on the lower end side of the mouth portion forming region 20 is omitted, and the protrusion corresponding to the cavity surface of the second lower mold 202b is formed when the covering material layer 50 is injection-molded in the secondary injection step. By providing the strip portion, an easily torn portion 6 made of a thin-walled portion formed into a groove may be formed on the terminal side of the covering material layer 50. Further, the easy tearing portion 6 may be formed by using, for example, a CO ₂ laser or the like. In this case, the irradiation direction of the CO ₂ laser is controlled regardless of before and after blow molding so that the terminal side of the coating layer 5 (coating material layer 50) has, for example, a knurled appearance. The easily torn portion 6 composed of the thinned portion may be formed.

Further, in the above-described embodiment, the coating layer 5 is provided with the tear guide portion 7 to facilitate the tearing of the coating layer 5, but the tear guide portion 7 may be omitted. In this case, for example, a cut may be made near the upper end of the body portion 3 of the coating layer 5 by using a blade or the like, and the coating layer 5 may be torn from that as a starting point. Even if the coating layer 5 is peeled off in this way, the end side of the coating layer 5 can be reliably torn, and the end side of the coating layer 5 peeled off from the container body 1a is peeled off while being rolled up. By peeling off the remaining portion, the container body 1a and the coating layer 5 can be easily separated.

1 Container 1a Container body 2 Mouth 2b Neck ring 2c Neck lower part 3 Body 4 Bottom 5 Covering layer 6 Easy tearing part 8 Protruding part 10 Preform 10a Preform body 20 Mouth forming area 30 Stretching area 50 Covering material layer 202a First lower mold (injection molding mold)
208 Groove

Claims (10)

A container body formed in a predetermined container shape including the mouth, body and bottom, and
It is laminated on the outer peripheral surface side of the container body so as to be peelable, and has a coating layer whose end side covers the lower end side of the mouth portion.
On the terminal side of the coating layer, an easily torn portion is formed in which the thickness of the coating layer is made thinner than the surrounding area .
A container made of synthetic resin , wherein the easily torn portion is composed of a thin-walled portion that is thinned in a groove shape . The mouth portion is provided with an annular neck ring that projects outward along the circumferential direction, and the end side of the coating layer covers the entire circumference of the lower neck portion on the lower end side of the mouth portion. The synthetic resin container according to claim 1, which reaches directly under the ring. The synthetic resin container according to claim 1 or 2 , wherein the thin-walled portions are arranged in a plurality of rows along the circumferential direction. A ridge extending along the outer peripheral surface is formed on the lower end side of the mouth portion covered with the end side of the coating layer.
The synthetic resin container according to any one of claims 1 to 3 , wherein the thin-walled portion is formed at a portion of the end side of the coating layer that overlaps the ridge portion. A preform for blow molding a synthetic resin container according to any one of claims 1 to 4 .
A preform body formed into a bottomed cylinder including a mouth forming region to be a mouth and a stretched region to be stretched and formed into the body and the bottom.
It is laminated on the outer peripheral surface side of the preform body so as to be peelable, and has a covering material layer whose end side covers the lower end side of the mouth portion forming region.
On the terminal side of the dressing layer, an easily torn portion is formed in which the thickness of the dressing layer is made thinner than the surrounding area .
A preform characterized in that the easily torn portion is composed of a thin-walled portion that is thinned in a groove shape . The mouth forming region is provided with an annular neck ring that projects outward along the circumferential direction, and the end side of the dressing layer is a portion below the neck ring of the mouth forming region. The preform according to claim 5 , which covers the entire circumference of the neck ring and reaches immediately below the neck ring. The preform according to claim 5 or 6 , wherein the thin-walled portions are arranged in a plurality of rows along the circumferential direction. A ridge extending along the outer peripheral surface is formed on the lower end side of the mouth portion forming region covered by the end side of the dressing layer.
The preform according to any one of claims 5 to 7 , wherein the thin-walled portion is formed at a portion of the end side of the dressing layer that overlaps the ridge portion. A method for producing a preform for blow molding a synthetic resin container according to any one of claims 1 to 4 .
A primary injection step of injection-molding a preform body formed into a bottomed cylinder including a mouth-forming region to be a mouth portion and a stretched region to be stretched and formed into the body portion and the bottom portion.
The present invention includes a secondary injection step of injecting and molding a dressing layer which is peelably laminated on the outer peripheral surface side of the preform main body and whose end side covers the lower end side of the mouth portion forming region.
Of the cavity surface of the injection molding mold used in the primary injection step, one or a plurality of grooves extending with a predetermined length are carved in a range for molding the lower end side of the mouth portion forming region. One or more ridges formed by the grooves are formed on the lower end side of the mouth forming region.
A method for producing a preform, which comprises forming a groove-shaped thin-walled portion at a portion overlapping the ridge portion on the terminal side of the coating material layer which is injection-molded in the secondary injection step. In the primary injection step, an annular neck ring protruding outward along the circumferential direction is formed in the mouth forming region.
In the secondary injection step, the dressing layer is provided so that the end side of the dressing layer covers the entire circumference of the lower portion of the neck ring in the mouth forming region and reaches directly below the neck ring. The method for manufacturing a preform according to claim 9 , wherein the preform is injection-molded.

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