JP6580304B2 - Plastic bottles and preforms - Google Patents

Description

  The present invention relates to a plastic bottle and a preform used when producing such a plastic bottle.

  Conventionally, there has been known a plastic bottle including an external screw, a cap located below the external screw, a cap portion having a support ring located below the cap screw, and a bottle body provided below the cap portion. It has been.

  Such a plastic bottle is nipped by a horizontally disposed gripper and conveyed. In this case, the gripper holds the concave annular surface and the support ring in the plug portion.

  Now, there is a demand for weight reduction of plastic bottles, and for example, it is considered to reduce the thickness of an annular recess formed between a turnip and a support ring in a stopper part of a plastic bottle (for example, a patent) Reference 1).

  On the other hand, the gripper that holds the plastic bottle is installed in advance in the molding line and the filling line of the plastic bottle, and it is difficult to change the shape of the gripper in accordance with the change in the shape of the plastic bottle. Conventionally, the cap to be attached to the cap portion of the plastic bottle is determined in a predetermined shape, and it is difficult to change the shape of the cap according to the shape of the cap portion of the plastic bottle. For this reason, when reducing the weight of the stopper portion of the plastic bottle, various restrictions are imposed.

JP 2010-95269 A

  The present invention has been made in consideration of the above points, and is a plastic that can reduce the overall weight by thinning a part of the plug portion without changing the shape of the existing cap. The object is to provide bottles and preforms.

The present invention provides a plastic bottle comprising: an outer screw having an upper end and a lower end; a turnip located below the outer screw; a support ring located below the turnip; the turnip and the support ring. includes a mouth part having a concave annular surface formed on the outer surface between, and a bottle body provided in the spout section below, the crest diameter is the outer diameter of the outer screw and d _1, the The plastic bottle is characterized in that the relationship of 1.125 ≦ d ₁ / d ₂ ≦ 1.165 is established, where d ₂ is the thread root diameter, which is the inner diameter of the outer screw.

The present invention is the plastic bottle characterized in that the turnip diameter d _A which is the diameter of the turnip is 25 mm to 32 mm, and the diameter d _B of the concave annular surface is 24 mm to 27 mm.

  The present invention is characterized in that the plug portion has a top surface and an inner peripheral surface extending from the top surface, and a chamfered portion is formed at a ridge line of a joint portion between the top surface and the inner peripheral surface. It is a plastic bottle.

  The present invention is the plastic bottle characterized in that an annular groove recessed radially inward is formed on the concave annular surface.

In the preform, the present invention includes an external screw having an upper end and a lower end, a turnable located below the external screw, a support ring located below the turnover, the turnip and the support ring. A mouthpiece portion having a concave annular surface formed on the outer surface therebetween, and a preform body provided below the mouthpiece portion, and a thread diameter that is an outer diameter of the outer screw is d ₁ , The preform is characterized in that the relationship of 1.125 ≦ d ₁ / d ₂ ≦ 1.165 is established, where d ₂ is the thread root diameter, which is the inner diameter of the outer screw.

The present invention, turnip diameter _{d A} is the diameter of the turnip is 25Mm～32mm, the diameter _{d B} of the concave annular surface is a preform which is a 24Mm～27mm.

  The present invention is characterized in that the plug portion has a top surface and an inner peripheral surface extending from the top surface, and a chamfered portion is formed at a ridge line of a joint portion between the top surface and the inner peripheral surface. Is a preform.

  The present invention is the preform characterized in that an annular groove recessed radially inward is formed on the concave annular surface.

According to the present invention, when the thread diameter that is the outer diameter of the outer screw is d ₁ and the thread root diameter that is the inner diameter of the outer screw is d ₂ , 1.125 ≦ d ₁ / d ₂ ≦ 1.165 The relationship is established. Thus, the volume of the fact that reducing the size of the screw root diameter d ₂ to the size of the crest diameter d _1, without changing the shape of the existing cap, part of the mouth part (external thread) , And the weight of the entire plastic bottle and preform can be reduced.

FIG. 1 is a side view showing a plastic bottle according to an embodiment of the present invention. FIG. 2 is a plan view showing the plastic bottle according to the embodiment of the present invention (viewed in the direction of arrow II in FIG. 1). FIG. 3 is an enlarged side view showing a plug portion of a plastic bottle according to an embodiment of the present invention. FIG. 4 is an enlarged side view showing a support ring of a plastic bottle according to an embodiment of the present invention. FIG. 5 is an enlarged cross-sectional view showing an upper end portion of a stopper portion of a plastic bottle according to an embodiment of the present invention. FIG. 6 is a partial cross-sectional view showing a state in which a screw-in type cap is screwed into a stopper part of a plastic bottle according to an embodiment of the present invention. FIG. 7 is a side view showing a preform according to an embodiment of the present invention. FIG. 8 is a side view showing a modified example of the plastic bottle. FIG. 9 is a side view showing a modification of the preform.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  First, a plastic bottle 10 according to the present embodiment will be described with reference to FIGS. In the present specification, “upper” and “lower” refer to the upper side and the lower side in a state where the plastic bottle 10 is erected (FIG. 1), respectively.

  As shown in FIGS. 1 and 2, the plastic bottle 10 includes a cap portion 15 and a bottle main body 11 provided below the cap portion 15. Among these, the plug portion 15 includes an external screw 13, a turnip 16 located below the external screw 13, and a support ring 17 located below the turnover 16. A concave annular surface 18 that is recessed radially inward is formed on the outer surface between the turnip 16 and the support ring 17.

  A cap 60 with a tamper-proof function (see FIG. 6) is attached to the plug portion 15, and the cap 60 has a peeling ring 70 that is peeled off when opened. When the cap 60 is removed and opened, the peeling ring 70 of the cap 60 comes into contact with the turnip 16 of the cap portion 15 so that the peeling ring 70 peels from the cap body 61 and the peeling ring 70 peeled from the cap body 61 has a concave shape. It falls to the annular surface 18 and is held on the support ring 17. The configuration of the cap 60 will be described later.

  Moreover, the stopper part 15 is substantially cylindrical as a whole, has an opening 19 at one end, and is connected to the bottle body 11 at the other end. The plug portion 15 includes a top surface 15a which is an end surface on the opening 19 side, an outer peripheral surface 15b extending from the top surface 15a in the radial direction of the plug portion 15 to the bottle body 11 side, and the top surface 15a. And an inner peripheral surface 15c that extends radially inward of the cap portion 15 and extends toward the bottle body 11 side. The top surface 15a is a flat surface.

  An outer screw 13 is provided on the outer peripheral surface 15 b of the plug portion 15. The external thread 13 is preferably a single thread, but may be a double thread or a triple thread, and has an upper end 13a and a lower end 13b. A vent slot 14 is formed in the external screw 13 in parallel to the axis A of the plastic bottle 10. The vent slot 14 uses a carbonated beverage as the content liquid to be filled in the plastic bottle 10, or if the content liquid rots and the internal pressure rises, the vent slot 14 releases the internal pressure at the time of opening and prevents the cap from jumping. Fulfill. Therefore, when the content liquid does not contain carbonic acid, such as water, the vent slot 14 is not necessarily provided.

  The external screw 13 has a predetermined winding angle θ (see FIG. 2) from the upper end 13a to the lower end 13b. The winding angle θ is preferably 550 ° to 800 °, and more preferably 650 ° to 750 °. The winding angle θ refers to an angle at which the external screw 13 is disposed from the upper end 13a to the lower end 13b when viewed from the plane direction (see FIG. 2). For example, when the winding angle θ is 720 °, the external screw 13 13 makes two rounds around the plug portion 15. By setting the winding angle θ to 550 ° or more, it is possible to prevent the cap from flying due to the pressure of the content liquid. On the other hand, by setting the winding angle θ to 800 ° or less, an increase in the weight of the plastic bottle 10 can be prevented.

As shown in FIG. 3, the outer diameter (thread diameter d ₁ ) of the external screw 13 is preferably 26 mm to 28 mm, for example, and particularly 27.43 mm ± 0.13 mm, it is generally distributed The cap can be used for sealing the plug portion 15. The inner diameter of the outer screw 13 (the screw root diameter _d 2), i.e. the diameter of the outer circumferential surface 15b is preferably, for example, with 23Mm～25mm. Furthermore, it is preferable that the diameter (mouth inner diameter d ₃ ) of the inner peripheral surface 15 c of the plug portion 15 is, for example, 21 mm to 23 mm.

In this case, it is preferable that a relationship of 1.125 ≦ d ₁ / d ₂ ≦ 1.165 is established between the thread diameter d ₁ and the thread root diameter d ₂ . By setting the above value d ₁ / d ₂ to 1.125 or more, the existing cap 60 is attached without changing the shape of the existing cap 60, that is, the size of the thread diameter d _1. while maintaining the possible size, it is possible to reduce the size of the screw root diameter d _2, it is possible to reduce the weight of the mouth part 15. On the other hand, by setting the value d ₁ / d ₂ to 1.165 or less, it is possible to improve the injection moldability when the preform 30 (described later) is injection molded. Further, since the value d ₁ / d _{2 is set} to 1.165 or less, it is possible to prevent the strength of the plug portion 15 from being lowered. When the portion 15 is heated, it is possible to prevent a problem that the plug portion 15 is deformed by heat. Further, by setting the above value d ₁ / d ₂ to 1.165 or less, there is no gap between the cap 60 and the external screw 13 of the plug portion 15, and the sealing property of the cap 60 is maintained. Can do.

The screw width w _A of the external screw 13 is preferably 0.5 mm to 1.0 mm. By setting the screw width w _A to 0.5 mm or more, it is possible to prevent the occurrence of a problem called a short (filling failure) when the preform 30 (described later) is injection-molded. On the other hand, when the screw width w _A is 1.0 mm or less, it is possible to prevent the weight of the plastic bottle 10 from increasing.

  By the way, as described above, the plug portion 15 has the upper portion of the bracket 16 and the lower portion of the support ring 17.

The turnip 16 has an inclined surface 16a over which the peeling ring 70 rides when the cap 60 is attached. The turnip diameter d _A which is the diameter of the turnip 16 is preferably 25 mm to 32 mm. By the fogged diameter d _A and above 25 mm, when transporting the plastic bottle 10 in the molding line and filling line of the plastic bottle 10, it is possible to prevent a problem that the plastic bottle 10 falls from the gripper (not shown) . On the other hand, the weight of the plastic bottle 10 can be prevented from increasing by setting the turnover diameter d _A to 32 mm or less.

The width w _B of the turnip 16 is preferably 1.2 mm to 2.0 mm. By preventing the width w _{B of the} turnip 16 from being equal to or greater than 1.2 mm, the peeling ring 70 partially remains on the turnover 16 when the cap 60 is attached and prevents the cap 60 from being attached obliquely (oblique cover). Can do. On the other hand, by setting the width w _{B of the} turnip 16 to 2.0 mm or less, it is possible to prevent the weight of the plastic bottle 10 from increasing.

On the other hand, the concave annular surface 18 is formed over the entire circumference of the mouth part 15, the diameter d _B of the concave annular surface 18 has a uniform vertically along the axis A of the plastic bottle 10.

The diameter _{d B} of the concave annular surface 18 is preferably set to 24Mm～27mm. By the diameter d _B of the concave annular surface 18 and above 24 mm, when transporting the plastic bottle 10 in the molding line and filling line of the plastic bottle 10, prevents the problem that the plastic bottle 10 falls from the gripper (not shown) can do. On the other hand, a diameter d _B of the concave annular surface 18 by less 27 mm, it is possible to prevent the weight of the plastic bottle 10 is increased. It should be noted that the relationship d _B / d _A <1 is established between the diameter d _B of the concave annular surface 18 and the turnover diameter d _A.

  Further, as shown in FIGS. 1 and 3, the upper surface 17 a (that is, the surface on the concave annular surface 18 side) of the support ring 17 has a step 21 and is formed in multiple stages. In this case, the support ring 17 has one step 21 and is formed in two steps. However, the support ring 17 is not limited to this, and may have two or more steps 21. On the other hand, the lower surface 17b (surface on the bottle body 11 side) of the support ring 17 is a horizontal flat surface.

  Further, the support ring 17 includes an outer region 22 located outward in the radial direction of the step 21 (left and right direction in FIG. 3) and an inner region 23 located radially inward of the step 21. Since the support ring 17 has the step 21 as described above, the volume of the support ring 17 can be reduced by the amount of the step 21. For this reason, compared with the case where the level | step difference 21 is not provided, the support ring 17 can be reduced in weight.

  As shown in FIG. 4, the surface 22a of the outer region 22 of the support ring 17 is an inclined surface. In this case, when the angle formed by the surface 22a of the outer region 22 and the lower surface 17b of the support ring 17 is α, it is preferable that 10 ° <α <16 °. When the angle α exceeds 10 °, the resin can be sufficiently distributed to the tip of the support ring 17 when the preform 30 is injection molded, and the injection moldability can be improved. Moreover, the thickness of the base can be secured by providing the angle, and the strength of the support ring is improved. On the other hand, when the angle α is less than 16 °, it is possible to prevent the height of the concave annular surface 18 from being shortened, and it is possible to prevent a conveyance failure from occurring when the plastic bottle 10 is conveyed.

  Further, the surface 23a of the inner region 23 of the support ring 17 is an inclined surface. In this case, when the angle formed by the surface 23a of the inner region 23 and the lower surface 17b of the support ring 17 is β, it is preferable that β> α. The angle β is preferably 20 ° <β <60 °. When the angle β exceeds 20 °, the injection moldability can be improved. Moreover, the thickness of the base can be secured by providing the angle, and the strength of the support ring is improved. On the other hand, when the angle β is less than 60 °, it is possible to prevent the height of the concave annular surface 18 from being shortened and to prevent the occurrence of a conveyance failure when the plastic bottle 10 is conveyed.

Furthermore, as shown in FIG. 4, when the radial length of the outer region 22 is L ₁ and the radial length of the inner region 23 is L ₂ , 1.5 <L ₁ / L ₂ <4.0. It is preferable that this relationship holds. When the value of L ₁ / L ₂ exceeds 1.5, an increase in the weight of the plastic bottle 10 can be prevented. On the other hand, when the value of L ₁ / L ₂ is less than 4.0, when the preform 30 is injection-molded, the resin can be sufficiently distributed to the tip of the support ring 17 and the injection moldability is good. Can be.

Furthermore, the thickness t _A at the outer end of the support ring 17 (ie, the outer end of the outer region 22) is preferably 1.0 mm to 1.5 mm. By setting the thickness t _A to 1.0 mm or more, the resin can be sufficiently distributed to the tip of the support ring 17 when the preform 30 is injection molded, and the injection moldability can be improved. Further, by setting the thickness t _A to 1.5 mm or less, it is possible to prevent the height of the concave annular surface 18 from being shortened, and to prevent poor conveyance when the plastic bottle 10 is conveyed.

In FIG. 3, the distance h ₁ between the top surface 15 a of the plug portion 15 and the lower surface 17 b of the support ring 17 is, for example, 20 mm to 22 mm, and the step 21 between the top surface 15 a of the plug portion 15 and the support ring 17. distance _{h 2} between the upper end, for example, 18Mm～20mm, distance _{h 3} between the lower surface of the top face 15a and turnips 16 of mouth part 15 is, for example, 13Mm～15mm.

  FIG. 5 is an enlarged cross-sectional view showing the vicinity of the upper end portion of the plug portion 15. As shown in FIG. 5, a chamfered portion 15d is formed on the ridgeline of the joint portion between the top surface 15a and the inner peripheral surface 15c. Thus, by forming the chamfered portion 15d at the ridge line of the joint portion between the top surface 15a and the inner peripheral surface 15c, the plug portion 15 can be reduced in weight and the top surface 15a of the plug portion 15 can be reduced. It is possible to reduce scratches such as dents in the vicinity of the joint between the inner peripheral surface 15c and the inner peripheral surface 15c (near the portion where the chamfered portion 15d is provided).

  Further, an end 15e on the top surface 15a side of the chamfered portion 15d (ridge line of the joint portion between the chamfered portion 15d and the top surface 15a) and an end portion 15f on the inner peripheral surface 15c side of the chamfered portion 15d (on the inside of the chamfered portion 15d and the inner surface) R edges are respectively formed on the ridgeline of the joint with the peripheral surface 15c. In addition, as for the magnitude | size of this R removal part, radius 0.2mm-0.4mm are preferable. When this R chamfered portion is not formed, the ridgeline of the joint portion between the chamfered portion 15d and the top surface 15a and the ridgeline of the joint portion between the chamfered portion 15d and the inner peripheral surface 15c are edges. When a cap 60 (to be described later) is screwed into the plug portion 15, the inner ring 65 and the contact ring 66 of the cap 60 come into contact with this edge. Due to the contact with the edge, the inner ring 65 and the contact ring 66 of the cap 60 may be damaged. Therefore, as described above, it is desirable to form R-removal portions at the end portions 15e and 15f, respectively.

  Here, the angle γ of the chamfered portion 15d with respect to the top surface 15a is preferably 20 ° to 60 °. When the angle γ of the chamfered portion 15d is less than 20 ° or exceeds 60 °, the beating in the vicinity of the joint portion between the top surface 15a of the plug portion 15 and the inner peripheral surface 15c (near the location where the chamfered portion 15d is provided) will be described later. It may be difficult to reduce scratches such as marks.

The width _{w 2} in the height direction of the width _{w 1} and the chamfered portion 15d in the radial direction of the chamfer 15d, it preferably each is 0,15Mm～0.45Mm. When the width w ₁ or the width w ₂ of the chamfered portion 15d is less than 0.15 mm, the chamfered portion 15d is small, so that the vicinity of the joint portion between the top surface 15a of the plug portion 15 and the inner peripheral surface 15c (the chamfered portion is described later). Scratches such as dents in the vicinity of the portion where 15d is provided cannot be reduced. Further, when the width w ₁ or the width w ₂ of the chamfered portion 15d exceeds 0.45 mm, the chamfered portion 15d is large, and thus the cap portion 15 may not be properly sealed or capped by the cap 60 described later.

  An annular projecting portion 27 projecting sideways is formed at the upper end of the outer peripheral surface 15b.

  FIG. 6 shows a state in which a screw-in type cap 60 is screwed into the plug portion 15. As shown in FIG. 6, the plug portion 15 is sealed by the cap 60 being screwed together. The cap 60 includes a cap body 61 and a peeling ring 70. The cap body 61 includes a disk-shaped upper part 62 and a cylindrical body part 63 that hangs down from the periphery of the upper part 62. On the inner peripheral surface of the body portion 63, an internal screw 64 that is screwed with the external screw 13 of the plug portion 15 is formed. An inner ring 65, a contact ring 66, and an outer ring 67 are formed on the upper part 62.

  The inner ring 65, the contact ring 66, and the outer ring 67 are annular protrusions that hang down from the inner surface of the upper portion 62. On the outer peripheral surface of the inner ring 65, a protruding portion that protrudes outward of the cap 60 is formed. The protruding portion of the inner ring 65 is in contact with the inner peripheral surface 15 c of the plug portion 15. The lower end portion of the contact ring 66 is in contact with the top surface 15a of the plug portion 15. A protruding portion that protrudes inward of the cap 60 is formed on the inner peripheral surface of the outer ring 67. The protruding portion of the outer ring 67 is in contact with the annular protruding portion 27 of the plug portion 15.

  The peeling ring 70 has a ring shape. A plurality of flaps 71 projecting inward and upward are formed on the inner peripheral surface of the peeling ring 70. The cap body 61 and the peeling ring 70 are connected via a connecting member 72 that can be broken when the cap 60 is initially opened.

  At the time of initial sealing, the flap 71 is disposed between the turnip 16 and the support ring 17. When the cap 60 is rotated in the opening direction, the upper end of the flap 71 comes into contact with the turnip 16 and the movement of the peeling ring 70 is prevented. When the cap 60 is further rotated, the connecting member 72 is broken, and the cap body 61 and the peeling ring 70 are separated. The peeling ring 70 is held between the turnip 16 and the support ring 17, and the cap body 61 can be removed from the plug portion 15.

  By the way, the shape of the bottle main body 11 is not particularly limited, and may have various conventionally known shapes. For example, in FIG. 1, the bottle main body 11 has a neck portion 11a, a shoulder portion 11b, a trunk portion 11c, and a bottom portion 11d. In addition, when using a carbonated drink as the content liquid with which the plastic bottle 10 is filled, the bottom 11d may have a petaloid shape.

  Further, the size (capacity) of the plastic bottle 10 is not limited, and may be any size bottle, but may be 500 ml to 600 ml, for example.

  The main material of the plastic bottle 10 is preferably a thermoplastic resin, particularly PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), PEN (polyethylene naphthalate), and is a plant-derived biomass plastic. For example, PLA (polylactic acid) can also be used. The plastic bottle 10 is preferably sterilized by adding hydrogen peroxide and peracetic acid.

  Next, the preform 30 according to the present embodiment will be described with reference to FIG. FIG. 7 is a view showing a preform 30 used when the plastic bottle 10 shown in FIGS. 1 to 6 is manufactured.

  As shown in FIG. 7, the preform 30 includes a plug portion 15 and a preform main body 31 provided below the plug portion 15. The plug portion 15 is formed on the outer surface of the external screw 13, the turnable 16 located below the external screw 13, the support ring 17 located below the turnover 16, and the turnover 16 and the support ring 17. And a concave annular surface 18 formed. The preform body 31 corresponds to the bottle body 11 described above, and has a substantially cylindrical body portion 31a and a substantially hemispherical bottom portion 31b. The preform body 31 is not limited to this, and may have various conventionally known shapes.

  As described above, in the plug portion 15, the chamfered portion 15d is formed on the ridge line of the joint portion between the top surface 15a and the inner peripheral surface 15c. And when the bottom part 31b of the other preform 30 is inserted in the opening part 19 of the plug part 15, the outer peripheral surface of this bottom part 31b and the chamfering part 15d collide. When the plug portion 15 of another preform 30 is inserted into the opening portion 19 of the plug portion 15, the outer peripheral surface 15b of the plug portion 15 and the chamfered portion 15d collide with each other. At this time, since the collision site is the chamfered portion 15d, the occurrence of scratches on the top surface 15a and the inner peripheral surface 15c of the plug portion 15 can be reduced. And generation | occurrence | production of the damage | wound of the cap part 15 can reduce, and generation | occurrence | production of the damage | wound to the inner ring 65 or the contact ring 66 at the time of screwing of the cap 60 can be reduced. And the sealing performance of the cap part 15 by the cap 60 can be improved.

  In FIG. 7, the configuration of the plug portion 15 is the same as the configuration of the plug portion 15 of the plastic bottle 10 shown in FIGS. In FIG. 7, the same parts as those of the embodiment shown in FIGS. 1 to 6 are denoted by the same reference numerals, and detailed description thereof is omitted.

  Next, the operation of the present embodiment having such a configuration will be described.

  First, pellets made of thermoplastic resin such as PET (polyethylene terephthalate) are put into an injection molding machine (not shown), and the pellets are heated and melted and pressed by the injection molding machine. Thereafter, the pellets become molten plastic and are injected into an injection mold having an internal shape corresponding to the preform 30 (see FIG. 7).

  After a predetermined time has elapsed, the molten plastic is cured in the injection mold, and the preform 30 is formed. Thereafter, the injection mold is separated, and the preform 30 shown in FIG. 7 is taken out from the injection mold.

  The preform 30 is then heated in a heating device (not shown) in the blow molding machine. At this time, the preform 30 is transported in the heating device and is uniformly heated in the circumferential direction by the heater while rotating around the central axis. During this time, the preform 30 is heated to a temperature of 80 ° C. to 140 ° C., for example. Thereafter, the heated preform 30 is sent to a blow molding section (not shown).

  The preform 30 sent to the blow molding part is inserted into the blow molding die of the blow molding part. Thereafter, high-pressure air is supplied from the stretching rod inserted into the preform 30 into the preform 30, and the preform 30 is stretched by stretching the stretching rod to perform biaxial stretching blow molding (blow molding). Process). By such blow molding, the plastic bottle 10 shown in FIGS. 1 and 2 is obtained.

  The plastic bottle 10 molded in the blow molding line is transported from the blow molding unit into a filling machine (not shown) by air transport means or neck transport means. Thereafter, the content liquid is filled into the plastic bottle 10 in the filling machine, and then the cap 60 is attached to the plastic bottle 10 using the capper. At this time, the plastic bottle 10 is supported on the lower surface 17 b of the support ring 17, and the cap is mounted so as to cover the plug portion 15. At this time, the peeling ring 70 of the cap 60 gets over the turnip 16 and comes into contact with the upper surface 17a of the support ring 17 and stops.

  As described above, according to the present embodiment, the winding angle from the upper end to the lower end of the external screw 13 is set to 550 ° to 800 °. Thereby, without changing the shape of the existing cap 60, the volume of a part of the plug portion 15 (the external screw 13) can be reduced, and the overall weight of the plastic bottle 10 and the preform 30 can be reduced. Can do.

Further, according to the present embodiment, a relationship of 1.125 ≦ d ₁ / d ₂ ≦ 1.165 is established between the screw thread diameter d ₁ and the thread root diameter d ₂ . Thereby, without changing the shape of the existing cap 60, the volume of a part of the plug portion 15 (the external screw 13) can be reduced, and the overall weight of the plastic bottle 10 and the preform 30 can be reduced. Can do.

Next, a modification of the present embodiment will be described.

  In the embodiment described above, the concave annular surface 18 has a uniform diameter along the vertical direction (the direction of the axis A), but is not limited thereto.

  As shown in FIGS. 8 and 9, an annular groove 26 that is recessed radially inward may be formed in the concave annular surface 18. The concave annular surface 18 includes a sandwiching portion 25 that is a portion that is sandwiched by the gripper during conveyance, and an annular groove 26 that has a smaller diameter than the sandwiching portion 25. That is, the clamping part 25 and the annular groove 26 have circular cross sections with different diameters. The annular groove 26 is formed over the entire circumferential direction of the concave annular surface 18.

  Thus, by providing the annular groove 26 in the concave annular surface 18, the volume of the plug portion 15 can be further reduced, and the weight of the plastic bottle 10 and the preform 30 as a whole can be reduced.

  8 and 9 is substantially the same as the above-described embodiment except for the shape of the concave annular surface 18. 8 and 9, the same parts as those in the embodiment shown in FIGS. 1 to 7 are denoted by the same reference numerals, and detailed description thereof is omitted.

(Example)
Next, specific examples of the present embodiment will be described.

  First, the following three types of plastic bottles (Example 1 and Comparative Examples 1 and 2) were produced.

Example 1
A preform 30 according to the present embodiment shown in FIG. 7 was produced by injection molding, and this preform 30 was blow-molded to obtain a plastic bottle 10 (Example 1) shown in FIGS. In this plastic bottle 10 (Example 1), the winding angle θ from the upper end 13a to the lower end 13b of the external screw 13 was set to 700 °. The ratio (d ₁ / d ₂ ) of the thread diameter d ₁ to the thread valley diameter d ₂ was 1.135. The weight of the stopper portion of the plastic bottle 10 (Example 1) was 4.2 g.

(Comparative Example 1)
By changing the size of the screw root diameter _{d 2,} the ratio screw root diameter _{d 2} of the crest diameter _{d 1 (d} 1 / _{d 2)} that it has a 1.115 and in the same manner as in Example 1 except Thus, a plastic bottle (Comparative Example 1) was produced. The size of the crest diameter d ₁ were the same as those of Example 1. The weight of the plug portion was 5.0 g.

(Comparative Example 2)
By changing the size of the screw root diameter _{d 2,} the ratio screw root diameter _{d 2} of the crest diameter _{d 1 (d} 1 / _{d 2)} that it has a 1.175 and in the same manner as in Example 1 except Thus, a plastic bottle (Comparative Example 2) was produced. The size of the crest diameter d ₁ were the same as those of Example 1. The weight of the plug part was 3.5 g.

  Here, 10,000 pieces of each of the above three types of plastic bottles (Example 1 and Comparative Examples 1 and 2) were produced. Next, each plastic bottle was filled with a carbonated beverage, and then each plastic bottle was closed using a capper.

  For each of Example 1 and Comparative Examples 1 and 2, whether or not a weight reduction effect was obtained and the injection moldability of the preform were evaluated.

  In addition, a cap sealability confirmation test (leakage test) and a cap jump test were performed, and the ratio of bottles lacking cap sealability and the ratio of bottles where cap jump occurred were calculated. Among these, in the cap sealability confirmation test (leakage test), it was confirmed whether or not bubbles were generated in the water when a sealed plastic bottle was immersed in water and 0.7 MPa of air was injected from the top of the cap. . In the cap jump test, it was confirmed whether or not a cap jump occurred when the bottle was opened quickly.

  As a result, for the plastic bottle 10 of Example 1, both the weight reduction effect and the injection moldability of the preform are good, and there is no leak in the cap sealability confirmation test. None of the jumps occurred.

  On the other hand, with regard to the plastic bottle of Comparative Example 1, the preform has good injection moldability, there is no leak in the cap sealability confirmation test, and there is also a cap jump in the cap skip test. There was no lightening effect.

  In addition, the plastic bottle of Comparative Example 2 was excellent in weight reduction effect, but the injection moldability of the preform was not good.

  The above results are summarized in Table 1. In Table 1, the evaluation criterion “◎” indicates “excellent”, the evaluation criterion “◯” indicates “good”, and the evaluation criterion “×” indicates “poor”.

DESCRIPTION OF SYMBOLS 10 Plastic bottle 11 Bottle main body 13 External screw 13a Upper end 13b Lower end 14 Vent slot 15 Plug part 15a Top surface 15b Outer peripheral surface 15c Inner peripheral surface 15d Chamfered portion 16 Cabler 17 Support ring 18 Annular surface 19 Opening portion 26 Annular groove 27 Annular protrusion 30 Preform 31 Preform body 60 Cap

Claims (6)

In plastic bottles,
An outer screw having an upper end and a lower end, a turnable located below the outer screw, a support ring located below the turnip, and a concave shape formed on an outer surface between the turnip and the support ring A plug portion having an annular surface;
A bottle body provided below the cap portion,
The relationship of 1.125 ≦ d ₁ / d ₂ ≦ 1.165 is established, where d ₁ is the thread diameter that is the outer diameter of the outer screw and d ₂ is the thread root diameter that is the inner diameter of the outer screw. And
The plug portion has a top surface and an inner peripheral surface extending from the top surface, and forms a linear chamfered portion in a sectional view on a ridge line of a joint portion between the top surface and the inner peripheral surface,
An R chamfer having a radius of 0.2 mm to 0.4 mm is formed at the end on the top surface side of the linear chamfer and the end on the inner peripheral surface side of the linear chamfer. ,
The angle of the chamfered portion with respect to the top surface is 20 ° to 60 °,
The plastic bottle according to claim 1, wherein a width in the radial direction of the chamfered portion and a width in the height direction of the chamfered portion are 0.15 mm to 0.45 mm, respectively . The turnips turnip diameter _{d A} is the diameter of a 25Mm～32mm, the diameter _{d B} of the concave annular surface, the plastic bottle according to claim 1, wherein it is 24Mm～27mm.   3. The plastic bottle according to claim 1, wherein an annular groove that is recessed inward in the radial direction is formed in the concave annular surface. In the preform,
An outer screw having an upper end and a lower end, a turnable located below the outer screw, a support ring located below the turnip, and a concave shape formed on an outer surface between the turnip and the support ring A plug portion having an annular surface;
A preform body provided below the plug portion,
The relationship of 1.125 ≦ d ₁ / d ₂ ≦ 1.165 is established, where d ₁ is the thread diameter that is the outer diameter of the outer screw and d ₂ is the thread root diameter that is the inner diameter of the outer screw. And
The plug portion has a top surface and an inner peripheral surface extending from the top surface, and forms a linear chamfered portion in a sectional view on a ridge line of a joint portion between the top surface and the inner peripheral surface,
An R chamfer having a radius of 0.2 mm to 0.4 mm is formed at the end on the top surface side of the linear chamfer and the end on the inner peripheral surface side of the linear chamfer. ,
The angle of the chamfered portion with respect to the top surface is 20 ° to 60 °,
The preform having a width in the radial direction of the chamfered portion and a width in the height direction of the chamfered portion is 0.15 mm to 0.45 mm, respectively . The preform according to claim 4, wherein a turnip diameter d _A which is a diameter of the turnip is 25 mm to 32 mm, and a diameter d _B of the concave annular surface is 24 mm to 27 mm.   The preform according to claim 4 or 5, wherein an annular groove recessed radially inward is formed in the concave annular surface.

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