JP2018150077A - Plastic bottle and manufacturing method of plastic bottle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plastic bottle in which a design property is enhanced and the content can be poured easily, and a manufacturing method of the plastic bottle.SOLUTION: A PET bottle 1 includes a mouth part 10, a trunk part 20, and a bottom part 30 in series in the axial direction. The mouth part 10 and a support ring lower part 21 of the trunk part 20 are connected to each other, and the trunk part 20 has a narrow part 22 with a trunk diameter (a minimum trunk diameter Dc) smaller than that (a trunk diameter Ds) of the support ring lower part 21. The PET bottle 1 includes: a process in which a heated preform is fitted to a metal mold; a longitudinal stretching process in which the preform is stretched in the axial direction using a stretching rod; and a transverse stretching process in which the preform is expanded in the radius direction by injecting air. The PET bottle may be manufactured by a method in which the transverse stretching process is applied after the preform is stretched until its trunk diameter is reduced in the longitudinal stretching process.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a plastic bottle and a method for manufacturing a plastic bottle, and more particularly, to a plastic bottle having a feature in shape and a method for manufacturing a plastic bottle.

  As containers filled with beverages, plastic bottles, especially PET (PolyEthylene Terephthalate) bottles are often used. The application range of PET bottles is expanding.

  In Patent Document 1, in a multilayer resin container composed of a plurality of resin layers, as an innermost layer, (A) 20 μm or more composed of a polyester or copolymer polyester resin having an intrinsic viscosity of 0.6 to 1.2 dl / mol is used. It has a polyester resin layer and, as an outermost layer, (B) a notched Izod impact strength (according to JIS K7110) having a polyester resin layer of 20 μm or more made of polyester or copolymer polyester resin having a viscosity of 40 to 120 J / m. A multilayer polyester resin container is disclosed.

JP 2009-249006 A

  According to Patent Document 1, it is said that the multilayer polyester resin container is excellent in aroma retention and cold shock resistance and can be suitably used particularly as a container for sake. Patent Document 1 describes that various types of containers such as a cup container, a bottle container, a tray container, and a tube container can be used. However, in patent document 1, only the cup container for sake is disclosed, and the detailed shape of various containers is not touched at all. Furthermore, in patent document 1, it is not interested in the container of the form which pours and uses for liquor, such as a cup. And it is hard to say that the cup container for sake of Patent Document 1 has both high designability and functionality that allows the contents to be poured easily.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a plastic bottle with improved design and easy filling, and a method for producing the plastic bottle.

  In order to solve the above problems, the present invention provides a plastic bottle in which a mouth portion, a trunk portion, and a bottom portion are sequentially provided in an axial direction, and the mouth portion and an end portion of the trunk portion are connected. The body diameter has a small-diameter portion having a diameter smaller than that of the end portion.

  Furthermore, the curvature radius of the small diameter portion that curves toward the inside of the plastic bottle is 10 mm or more and 80 mm or less.

  Further, the ratio of the barrel diameter of the small diameter portion to the barrel diameter of the end portion is 0.70 or more and 0.98 or less.

  Further, the body portion has a rib extending in a circumferential direction of the plastic bottle.

  Furthermore, the present invention includes a step of mounting a heated preform on a mold, a longitudinal stretching step of stretching the preform in the axial direction with a stretching rod, and inflating the preform in the radial direction by injecting air. In the method for producing a plastic bottle having a transverse stretching step, the preform is stretched in the longitudinal stretching step until the body diameter of the preform is reduced, and then the transverse stretching step is performed.

  Further, the preform has a neck portion, a diameter reduction portion, and a trunk middle portion sequentially in the axial direction, and a trunk diameter of the trunk middle portion is configured to be equal to or less than a trunk diameter of the neck portion, and the trunk diameter of the neck portion, The difference from the body diameter of the middle part of the body is 5 mm or less.

  Furthermore, in the longitudinal stretching step, the preform is stretched until the body diameter of the middle portion of the body is reduced to 65% to 95%, and then the transverse stretching step is performed.

  Furthermore, the plastic bottle has a small-diameter portion, and in the longitudinal stretching step, the preform is stretched until the trunk diameter of the trunk middle portion is reduced to 55% to 95% with respect to the small-diameter portion. It progresses to a horizontal extending process, It is characterized by the above-mentioned.

  According to the present invention, in the plastic bottle having the mouth portion, the trunk portion, and the bottom portion sequentially in the axial direction, and the mouth portion and the end portion of the trunk portion are connected, the trunk portion has a trunk diameter larger than that of the end portion. Since it has a small-diameter portion with a small diameter, it is possible to improve the design of the plastic bottle and to easily pour the contents.

  Furthermore, according to the configuration in which the radius of curvature of the small diameter portion curved toward the inside of the plastic bottle is 10 mm or more and 80 mm or less, better blow moldability can be obtained.

  Furthermore, according to the configuration in which the value of the ratio of the barrel diameter of the small diameter portion to the barrel diameter of the end portion is 0.70 or more and 0.98 or less, better blow moldability can be obtained.

  Furthermore, according to the configuration in which the body portion has a rib extending in the circumferential direction of the plastic bottle, it is possible to absorb a change in the internal pressure of the plastic bottle and prevent an undue deformation of the plastic bottle.

  Furthermore, according to the present invention, a process of mounting a heated preform on a mold, a longitudinal stretching process of stretching the preform in the axial direction with a stretching rod, and inflating the preform in the radial direction by injecting air. In the method of manufacturing a plastic bottle having a transverse stretching step, since the preform is stretched until the preform diameter is reduced in the longitudinal stretching step, the process proceeds to the transverse stretching step, regardless of the shape of the preform. It is possible to form a small-diameter portion whose diameter is smaller than that of the end portion.

  Further, the preform has a neck portion, a diameter reduction portion, and a trunk middle portion in the axial direction, and the trunk diameter of the trunk middle portion is configured to be equal to or smaller than the trunk diameter of the neck portion. When the difference is 5 mm or less, better blow moldability can be obtained.

  Further, in the longitudinal stretching step, when the preform is stretched until the body diameter of the middle portion of the body is reduced to 65% to 95%, the process proceeds to the lateral stretching step, whereby better blow moldability can be obtained.

  Further, the plastic bottle has a small-diameter portion, and in the longitudinal stretching step, when the preform is stretched until the trunk diameter of the middle portion of the trunk is reduced to 55% to 95% with respect to the small-diameter portion, the process proceeds to the transverse stretching step. Better blow moldability can be obtained.

It is the front view by which the PET bottle as an example of the plastic bottle which concerns on this embodiment was shown. It is a bottom view of a PET bottle. It is the fragmentary sectional view in which an example of the preform for shape | molding the plastic bottle which concerns on this embodiment was shown. It is sectional drawing by which an example of the heating apparatus of preform was shown. FIG. 2 is a cross-sectional view schematically showing a preform and a PET bottle after blow molding. It is the front view by which the PET bottle as an example of the plastic bottle which concerns on another embodiment was shown. It is a front view of the PET bottle of a comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the configuration of the plastic bottle according to the present embodiment will be described in detail. The plastic bottle according to the present embodiment is a blow-molded container that is processed by blow molding from a preform (preliminary molded body) that is a prototype. FIG. 1 is a front view showing a PET bottle 1 as an example of a plastic bottle according to the present embodiment. In the following, for convenience of explanation, the mouth portion 10 in which the contents are taken in and out in the state of FIG. The PET bottle 1 has a mouth part 10, a body part 20, and a bottom part 30 in order in the axial direction. The length in the axial direction of the PET bottle 1 is, for example, 120 mm.

  The upper end of the substantially cylindrical mouth portion 10 has an annular shape in plan view, and the inner peripheral side thereof is an opening 11. The opening 11 serves as a filling port and a spout for the contents. If the diameter of the opening 11 is too small, the contents will not flow easily. A diameter of the opening 11 of 20 mm is sufficient for the contents to flow. The diameter of the opening 11 may be a wide mouth such as 38 mm. The opening 11 formed in the wide mouth can make the contents easier to pour.

  On the other hand, the mouth part 10 has an annular support ring 12 projecting toward the outside in the radial direction of the PET bottle 1 at the lower end thereof. The support ring 12 is used for support when the PET bottle 1 is blow-molded or conveyed. The length of the mouth portion 10 in the axial direction is, for example, 18.3 mm.

  The mouth portion 10 has a male screw 13 on the outer periphery thereof for attaching a lid (not shown). The PET bottle 1 is sealed by attaching a lid to the mouth portion 10. The PET bottle 1 may be configured to be hermetically sealed. For example, when a stoppered lid is used, a protrusion or a groove may be formed on the outer periphery of the mouth portion 10 instead of the male screw 13.

  Between the support ring 12 and the external thread 13, an annular cover 14 that protrudes radially outward from the outer periphery of the mouth portion 10 may be formed. When the PET bottle 1 is transported, a gripper included in the transport facility can grip the PET bottle 1 with the recess between the turnip 14 and the support ring 12 interposed therebetween. The support ring 12 protrudes to the outer side in the radial direction than the turnip 14.

  The mouth portion 10 may be crystallized until it is colored white by heating in a so-called crystallization apparatus so as to have heat resistance necessary for filling the contents at high temperature. It is preferable that the mouth portion 10 can cope with filling up to, for example, 75 ° C. when the material is amorphous, and 95 ° C. when crystallized.

  The trunk portion 20 is continuous with the mouth portion 10 at the upper end in the axial direction, and is continuous with the bottom portion 30 at the lower end in the axial direction. The body part 20 has a support ring lower part 21 that is an end part of the body part 20, a constricted part 22 as an example of a small diameter part, and an inflating part 23 in this order toward the lower side in the axial direction. The trunk portion 20 illustrated in FIG. 1 has a portion that is the thinnest in the radial direction above the center in the axial direction, and the lower side in the axial direction is configured in a bottle-like shape that bulges outward in the radial direction. .

  The support ring lower part 21 is connected to the support ring 12 of the mouth part 10. The support ring lower part 21 illustrated in FIG. 1 has a substantially true cylindrical shape whose trunk diameter and wall thickness hardly change vertically in the axial direction. The axial length of the support ring lower part 21 is 4 mm, for example. Here, the trunk diameter is the diameter at the center of the wall thickness, which is larger than the inner diameter and smaller than the outer diameter. The outer diameter of the support ring lower part 21 is 34.9 mm, for example. The outer diameter of the support ring lower portion 21 is smaller than that of the support ring 12. Accordingly, the lower surface of the support ring 12 extends outward in the radial direction with the outer peripheral surface of the support ring lower portion 21 as a root. When the PET bottle 1 is transported, the gripper of the transport facility can grip the PET bottle 1 using the lower surface of the support ring 12 or the outer peripheral surface of the support ring lower portion 21.

  The trunk portion 20 has a constricted portion 22 whose trunk diameter is smaller than that of the support ring lower portion 21. This relationship is the same in the outer diameter and the inner diameter. The outer diameter of the constricted portion 22 is 33.0 mm, for example. By making the outer diameter smaller at the constricted portion 22 than at the lower part of the support ring 21, it is possible to give the PET bottle 1 high design properties and make it easier to hold the PET bottle 1. Furthermore, since the inner diameter is made smaller at the constricted portion 22 than at the lower portion of the support ring 21, the amount of content dispensed can be suppressed. Therefore, the design diameter of the PET bottle 1 can be enhanced and the contents can be poured easily by making the trunk diameter smaller at the small diameter portion such as the constricted portion 22 than at the support ring lower portion 21.

  Here, the support ring lower part 21 is not necessarily a true cylindrical shape. In such a case, it is sufficient that the diameter of the small diameter portion such as the constricted portion 22 is smaller than the minimum diameter of the support ring lower portion 21.

  The constricted portion 22 is configured to bend toward the radially inner side of the PET bottle 1 in a front view. As a result, the outside of the PET bottle 1 has a larger contact area with the finger when the constricted part 22 is gripped, and the upper side in the axial direction is widened so that the finger is caught and the PET bottle 1 is more stable. Can have. Furthermore, since there is no bending point in the constricted portion 22, the touch when holding the PET bottle 1 can be made comfortable. On the other hand, the constricted part 22 inside the PET bottle 1 can prevent the contents from being poured out at a stroke by appropriately clogging the flow of the contents. Further, the flow rate of the contents flowing through the constricted portion 22 is reduced, so that the flow rate is increased, and when a beverage containing particles such as citrus sand is poured out, the particles are poured out smoothly. It can also be prevented from remaining in the PET bottle 1.

  The small diameter portion is not limited to the constricted portion 22. The small-diameter portion may be configured such that the diameter decreases linearly from the support ring lower portion 21 and the inflating portion 23, and is configured by connecting two curves that curve outward in the radial direction. Alternatively, the upper and lower sides in the axial direction may have the same thin diameter.

  Here, the body diameter at the most curved portion radially inward of the constricted portion 22 is defined as the minimum body diameter Dc of the constricted portion 22. If the minimum body diameter Dc of the constricted portion 22 is too small with respect to the body diameter Ds of the support ring lower part 21, it will be difficult to perform blow molding. On the other hand, if the minimum body diameter Dc of the constricted part 22 is too large with respect to the body diameter Ds of the support ring lower part 21, the constricted part 22 is lost. Therefore, the value of the ratio of the minimum body diameter Dc of the constricted portion 22 to the body diameter Ds of the support ring lower part 21 is preferably 0.70 or more and 0.98 or less. As a result, better blow moldability can be obtained, and the action as a small diameter portion such as the constricted portion 22 is fully exhibited.

  If the radius of curvature r of the constricted constricted portion 22 is too small, blow molding becomes difficult and the function of the constricted portion 22 described above cannot be exhibited. On the other hand, even if the curvature radius r of the constricted constricted portion 22 is too large, the function of the constricted portion 22 described above cannot be exhibited. Therefore, it is preferable that the curvature radius r of the constricted portion 22 that curves toward the inside of the PET bottle 1 is 10 mm or more and 80 mm or less. As a result, better blow moldability can be obtained, and the function as the constricted portion 22 is fully exhibited. The radius of curvature r of the constricted portion 22 described above may be a value at a position having the minimum body diameter Dc if it is not constant vertically in the axial direction.

  The respective wall thicknesses are extremely small with respect to the body diameter Ds of the support ring lower portion 21 and the minimum body diameter Dc of the constricted portion 22. There is no significant difference between the thickness of the lower support ring 21 and the thickness of the constricted portion 22. Therefore, there is no problem even if the outer diameter or inner diameter is used instead of the value of the ratio of the minimum body diameter Dc in the small diameter portion such as the constricted portion 22 to the body diameter Ds of the support ring lower portion 21.

  The axial length Hc of the small diameter portion such as the constricted portion 22 may be designed from the viewpoint of ease of pouring the contents in a range where the blow moldability of the PET bottle 1 is good. The axial length Hc of the constricted portion 22 is preferably at least longer than the width of the first finger, and more preferably longer than the width of the second finger and the third finger. On the other hand, it is better to be shorter than the width from the second finger to the fifth finger. In the configuration of the constricted portion 22 that curves inward in the radial direction of the PET bottle 1, for example, the first finger, the second finger, and the third finger that are used for gripping are closely aligned with the constricted portion 22, and the PET bottle 1 is Easy to hold. The length Hc in the axial direction of the constricted portion 22 does not necessarily fit in the second finger and the third finger, and is, for example, 21.0 mm.

  The inflating part 23 is formed in a hollow, substantially spherical shape that is cut in the horizontal direction both on the upper and lower sides in the axial direction. That is, the expansion part 23 is configured to bend toward the radially outer side of the PET bottle 1 in a front view. The inflating part 23 is a main part that accommodates the contents. Since the PET bottle 1 has the inflating portion 23, the volume thereof is secured, and the PET bottle 1 is stable when placed with the center of gravity lowered.

  By the way, the PET bottle 1 is filled at a high temperature, for example, 70 ° C., and then cooled to room temperature, for example, 30 ° C., or filled at room temperature is warmed to a high temperature, for example, 55 ° C. or more. Sometimes. With such a temperature change, a change in pressure (internal pressure) occurs inside the PET bottle 1.

  The inflatable portion 23 tends to be thinner than the support ring lower portion 21 and the constricted portion 22. For this reason, there exists a possibility that the expansion | swelling part 23 of PET bottle 1 by which thickness was made thin and weight reduction will deform | transform by the excessive change of the internal pressure of PET bottle 1. FIG. Therefore, the body part 20 may have a rib 24 extending in the circumferential direction of the PET bottle 1 in the inflating part 23. The rib 24 has a function of increasing the rigidity of the expanding portion 23. The rib 24 illustrated in FIG. 1 is bent in a convex shape toward the radially outer side. The rib 24 may have a groove shape that bends inward in the radial direction.

  As illustrated in FIG. 1, it is more preferable that the ribs 24 included in the inflatable portion 23 are plural. A panel 25 is formed in the area between the adjacent ribs 24. The panel 25 illustrated in FIG. 1 is curved inward in the radial direction. The panel 25 may be curved toward the radially outer side. When the internal pressure of the PET bottle 1 changes, the panel 25 has a function of absorbing the change in the internal pressure by deforming inward and outward in the radial direction and changing the internal volume. On the other hand, even when the internal pressure of the PET bottle 1 changes, the structure itself of the inflating part 23 is maintained with the rib 24 as a skeleton. Therefore, the configuration in which the inflating portion 23 has the ribs 24 can absorb the change in the internal pressure of the PET bottle 1 and prevent the PET bottle 1 from being distorted.

  The rib 24 may be used as a scale for the remaining amount of contents. In this case, the ribs 24 are not equally spaced vertically in the axial direction, and the spacing at the larger inner diameter is narrower. By doing so, the PET bottle 1 can be given an appearance with an irregular structure having a high design and not having a regular and simple structure but weakened artificial elements. Thus, the rib 24 also has a function of improving design properties.

  FIG. 2 is a bottom view of the PET bottle 1. The bottom portion 30 continues to the lower side of the inflating portion 23 of the trunk portion 20. The bottom part 30 has a corner part 31, a bottom wall 32, and a dome 33. The corner portion 31 is curved toward the lower side in the axial direction of the PET bottle 1 and the outer side in the radial direction. The substantially flat plate-shaped bottom wall 32 extends in a direction perpendicular to the axial direction in which the body portion 20 extends, and serves as a ground contact surface of the PET bottle 1.

  The dome 33 is formed in a hollow hemispherical shape that curves toward the inside (the upper side in the axial direction) of the PET bottle 1. The dome 33 has a function of preventing deformation caused by changes in the temperature of the contents of the PET bottle 1 and the internal pressure. The dome 33 only needs to be designed with an inclination angle with respect to the ground contact surface within a range in which the internal pressure or the like is effectively dispersed to prevent the deformation of the PET bottle 1 and the shapeability is good. As illustrated in FIG. 1 and the like, the dome 33 may be configured to protrude in a plurality of stages toward the upper side in the axial direction on the inner side in the radial direction.

  The dome 33 illustrated in FIG. 2 has eight radial ribs 34. Each of the radial ribs 34 extends radially in bottom view. The radial ribs 34 are formed so as to protrude toward the upper side in the axial direction from the dome 33. The radial ribs 34 have a function of reinforcing the dome 33. The radial ribs 34 may be formed so as to protrude within a range where whitening due to overstretching and deterioration of the shapeability of the PET bottle 1 do not occur.

  A receiving portion 35 that curves downward in the axial direction may be formed at the radial center of the bottom portion 30, that is, at the top of the dome 33. The receiving portion 35 is configured such that the tip of the stretching rod enters when the PET bottle 1 is blow-molded from the preform. The receiving portion 35 has a function of preventing the bottom portion 30 from being eccentric in the radial direction by the rod.

  The bottom portion 30 is not limited to the example shown in FIG. 2 and the like, and may be configured so as not to be deformed downward even when positive pressure is applied in a state where it is easily deformed by heat as in filling. As a result, the full capacity of the PET bottle 1 is increased from the design value, and it is possible to prevent the change in the internal pressure from becoming larger due to the increase in the proportion of air in the container. The dome 33 is designed to be maintained at least higher than the ground plane of the PET bottle 1 even if it is deformed by heat. Accordingly, the bottom portion 30 is prevented from protruding outward (lower side) from the bottom wall 32, and rattling or overturning of the PET bottle 1 can be prevented.

  The PET bottle 1 according to this embodiment is not limited by size, and can be applied to various sizes. However, a smaller bottle is preferable because the effect of the configuration of the PET bottle 1 according to the present embodiment is more exhibited. For example, the internal volume of the PET bottle 1 is preferably 80 ml or more and 700 ml or less, and more preferably 150 ml to 450 ml. The total length in the axial direction of the PET bottle 1 may be 90 mm or more and 220 mm or less, and the maximum outer diameter of the inflating part 23 may be 40 mm or more and 80 mm or less. Furthermore, the outer diameter of the support ring lower part 21 is preferably 20 mm or more and 45 mm or less, and the minimum outer diameter of the small diameter part such as the constricted part 22 is preferably 15 mm or more and 40 mm or less.

  Examples of the material of the plastic bottle exemplified by the PET bottle 1 include high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, polypropylene, and other polyolefins, ethylene-vinyl alcohol copolymers, plants, and the like. Various plastics that can be blow molded, such as polylactic acid, can be used. However, the plastic bottle is preferably composed mainly of polyester such as polyethylene naphthalate, particularly polyethylene terephthalate. In addition, various additives such as a colorant, an ultraviolet absorber, a release agent, a lubricant, a nucleating agent, an antioxidant, and an antistatic agent are blended with the above-described resin within a range that does not impair the quality of the molded product. be able to.

  As the ethylene terephthalate thermoplastic resin constituting the PET bottle 1, the ethylene terephthalate unit occupies most of the ester repeating portion, generally 70 mol% or more, and has a glass transition point (Tg) of 50 ° C. or higher and 90 ° C. The melting point (Tm) in the range of 200 ° C. or higher and 275 ° C. or lower is preferable. As an ethylene terephthalate thermoplastic polyester, polyethylene terephthalate is particularly excellent in terms of pressure resistance, but in addition to ethylene terephthalate units, it consists of dibasic acids such as isophthalic acid and naphthalenedicarboxylic acid, and diols such as propylene glycol. Copolyesters containing a small amount of ester units can also be used.

  Polyethylene terephthalate has the highest production volume among thermoplastic synthetic resins. The polyethylene terephthalate resin has various characteristics such as excellent heat resistance, cold resistance, chemical resistance, and wear resistance. Furthermore, polyethylene terephthalate resin has a lower proportion of petroleum in its raw materials than other plastics, and can be recycled. Thus, according to the structure which has a polyethylene terephthalate as a main component, a material with much production amount can be used and the outstanding various characteristic can be utilized.

  Polyethylene terephthalate is obtained by condensation polymerization of ethylene glycol (ethane-1,2-diol) and purified terephthalic acid. As a polymerization catalyst for polyethylene terephthalate, at least one of a germanium compound, a titanium compound, and an aluminum compound is preferably used. By using these catalysts, it is possible to form a container having higher transparency and excellent heat resistance than using an antimony compound.

  A plastic bottle can be produced by stretching a preform in which the above-described material is injection-molded. FIG. 3 is a partial cross-sectional view showing an example of a preform 5 for molding a plastic bottle according to the present embodiment. The preform 5 has a bottomed cylindrical shape that is open at one end in the axial direction, and includes a mouth portion 10 on the open side and a body portion 50 on the bottom side. In FIG. 3, the front surface of the mouth portion 10 and the cross section of the body portion 50 are shown. The length of the preform 5 in the axial direction is, for example, 72.3 mm.

  The shape of the mouth portion 10 does not change even after being blow-molded from the preform 5 into a plastic bottle. Accordingly, the mouth portion 10 has the same configuration as that of the PET bottle 1 described above. That is, the mouth portion 10 has an opening 11 on the inner peripheral side at the upper end in the axial direction, and includes a support ring 12, a male screw 13, and a turnip 14.

  The body part 50 is a cylindrical part, and is a part that swells to have a bottle shape during blow molding. The trunk portion 50 has a neck portion 51, a diameter reduction portion 52, a trunk middle portion 53, and a bottom portion 54 in order in the axial direction.

  The neck portion 51 is connected to the lower surface of the support ring 12 of the mouth portion 10. The neck portion 51 has a substantially true cylindrical shape whose trunk diameter and wall thickness hardly change in the vertical direction. However, the neck 51 may be provided with a draft that is an inclination for facilitating removal from the mold used when the preform 5 is produced by injection molding, that is, mold release. Further, the body diameter and the wall thickness of the neck portion 51 may slightly change in the axial direction. The length of the neck 51 in the axial direction is, for example, 3.3 mm, the outer diameter is, for example, 34.1 mm, and the inner diameter is, for example, 30.4 mm.

  The diameter reduction part 52 is configured in an inverted truncated cone shape whose diameter is reduced from the neck part 51 side toward the body middle part 53 side, for example. That is, the body diameter of the diameter reducing portion 52 is smaller at the lower end than at the upper end in the axial direction. As a result, the cross-sectional area below the neck 51 in the axial direction is reduced, and the preform 5 and the plastic bottle to be blow-molded can be reduced in weight. Furthermore, the diameter reduction part 52 may be comprised so that thickness may increase toward the trunk | drum center part 53 side from the neck part 51 side from a viewpoint of making blow moldability favorable. That is, the thickness of the diameter reducing portion 52 may be larger at the lower end than at the upper end in the axial direction. The length in the axial direction of the diameter reducing portion 52 is, for example, 11.2 mm.

  In addition, the diameter reduction part 52 may be comprised so that the outer diameter may hardly change to the upper and lower sides of an axial direction. That is, the outer diameters of the neck portion 51, the diameter reduction portion 52, and the trunk middle portion 53 can be substantially the same in the vertical direction.

  The trunk middle part 53 has a substantially true cylindrical shape whose trunk diameter and wall thickness hardly change vertically in the axial direction. The trunk diameter of the trunk middle part 53 is configured to be equal to or smaller than the trunk diameter of the neck part 51. Similarly to the neck portion 51, a draft angle may be provided in the trunk middle portion 53, and the trunk diameter and thickness may slightly change in the upper and lower directions in the axial direction. The outer diameter of the trunk middle portion 53 is, for example, 31.24 mm to 31.45 mm, and the inner diameter is, for example, 25.24 mm to 25.45 mm.

  As the difference between the trunk diameter of the neck 51 and the trunk diameter of the trunk middle section 53 increases, the inner diameter of the trunk middle section 53 decreases. If the difference between the body diameter of the neck portion 51 and the body diameter of the body middle portion 53 becomes too large, excessive pressure is applied to the mold during injection molding of the preform 5, resulting in uneven thickness of the preform 5. Then, there is a risk that the stretching of the PET bottle 1 may be unsuccessful due to uneven stretching during blow molding. Therefore, the difference between the body diameter Dn of the neck portion 51 and the body diameter D1 of the body middle portion 53 may be 5 mm or less. Thereby, the preform 5 having a small uneven thickness can be used, and as a result, better blow moldability can be obtained.

  On the other hand, when the preform 5 having a small outer diameter of the body middle portion 53 is used, blow molding of a small diameter portion such as the constricted portion 22 becomes easier.

  The bottom portion 54 is configured in a substantially hemispherical shape that curves toward the outside (the lower side in the axial direction) of the preform 5. The bottom portion 54 may have a conical shape, a cylindrical shape with rounded corners, or other shapes. The bottom 54 is attached with a solidified portion formed incidentally at the molten resin inlet (gate) when the preform 5 is produced by injection molding. FIG. 3 shows a form after the portion is cut out.

  In addition, it is preferable that length H1 of the trunk | drum 50 which is the distance from the lower surface of the support ring 12 to the lower end of the bottom part 54 is 10 mm or more and 120 mm or less. Furthermore, it is preferable that the trunk diameter D1 of the trunk middle part 53 is 10 mm or more and 40 mm or less.

  Next, an example of a method for blow-molding the plastic bottle according to the present embodiment from the preform 5 will be described in detail. When a plastic bottle is blow-molded from the preform 5, the preform 5 is first heated. FIG. 4 is a cross-sectional view showing an example of the heating device 60 for the preform 5. FIG. 4 shows a cross section perpendicular to the conveying direction of the preform 5.

  The heating device 60 includes a transport device 61 and a heater 62. The transport device 61 is configured to transport the preform 5 while rotating around the axis of the preform 5 in order to uniformly heat the body portion 50 of the preform 5 in the circumferential direction. The heater 62 includes a plurality of halogen lamps, for example, and is configured to heat the body portion 50 to a temperature suitable for blow molding, for example, 80 ° C. to 140 ° C. Further, the heating device 60 includes a reflecting plate 63 for reflecting the heat from the heater 62 to the body portion 50, a shielding member 64 for preventing the heat from the heater 62 from escaping to the outside of the heating device 60, and the like. May be provided. In addition, in the heating apparatus 60 of FIG. 4, the preform 5 is heated while being conveyed with the mouth portion 10 facing downward.

  Here, the diameter reduction part 52 illustrated in FIG. 4 and the like has a diameter that decreases from the neck part 51 side toward the trunk middle part 53 side. Such a portion having a reduced diameter is more distant from the heater 62 than the portion having a reduced diameter because the positional relationship with the heater 62 is further away. On the other hand, the diameter-reduced portion 52 increases in thickness from the mouth portion 10 side toward the trunk middle portion 53 side. Since the heat capacity of the preform 5 is increased, the thick portion is less likely to be warmed by the heater 62, but once warmed, it is difficult to cool. Therefore, in the diameter reduction part 52, the side of the trunk middle part 53 is easily stretched by blow molding. Thus, the preform 5 illustrated in FIG. 4 and the like is designed such that the resin is more efficiently stretched in the diameter-reduced portion 52 where the degree of stretching greatly varies depending on the position.

  The heated preform 5 is then formed into a plastic bottle, for example a PET bottle 1, by a blow molding machine. FIG. 5 is a cross-sectional view schematically showing the preform 5 and the PET bottle 1 after blow molding. A biaxial stretching blow molding apparatus 70 as an example of a blow molding machine includes a mold 71, a stretching rod 72, a high-pressure air supply device (not shown), and a control device (not shown) that controls them. Although a downward blow molding method is illustrated in FIG. 5, an upward blow molding method in which the material is hardly affected by gravity may be used.

  Here, approximately before and after blow molding, the diameter-reduced portion 52 of the preform 5 corresponds to the constricted portion 22 of the PET bottle 1, and the trunk middle portion 53 of the preform 5 corresponds to the inflated portion 23 of the PET bottle 1. The bottom 54 of the reform 5 corresponds to the bottom 30 of the PET bottle 1.

  The mold 71 has a shape corresponding to the PET bottle 1 to be formed, and includes, for example, a body mold 71 a configured in half corresponding to the body section 20, and a bottom mold 71 b corresponding to the bottom section 30. Have The surface temperature of the mold 71 is configured to be controlled at, for example, 30 ° C. to 130 ° C. according to the use of the PET bottle 1, particularly the heat resistance.

  The mold 71 may be roughened. As a result, it is possible to improve the peeling characteristics of the blow-molded PET bottle 1 from the mold 71, and to process the PET bottle 1 into a tactile sensation different from a smooth surface. Furthermore, the transmitted light can be diffused on the roughened surface of the PET bottle 1, and design properties different from those of a highly transparent container can be imparted.

  The extending rod 72 is configured to be extendable and contractable within the mold 71. And the extending | stretching rod 72 is comprised so that the trunk | drum 50 of the preform 5 in which the opening | mouth part 10 was attached to the metal mold | die 71 may be extended | stretched in a vertical (axial) direction. When the trunk portion 50 is stretched in the longitudinal direction, the inner diameter of the preform middle portion 53 of the preform 5 can be reduced to the extent that the outer peripheral surface of the stretching rod 72 does not hit.

  The high-pressure air supply device is configured to blow out the temperature-controlled high-pressure air h. The high-pressure air h may be supplied to the inside of the preform 5 attached to the mold 71, may be blown from the stretching rod 72, or may be blown from a member different from the stretching rod 72. The high-pressure air h is configured to extend the body portion 50 of the preform 5 in the transverse (diameter) direction and lower the surface temperature of the body portion 50 after the stretching.

  The method for producing a plastic bottle according to the present embodiment includes a step of attaching the heated preform 5 to the mold 71, a longitudinal stretching step of stretching the body 50 of the preform 5 in the axial direction with the stretching rod 72, and A transverse stretching step of inflating the body portion 50 of the preform 5 in the radial direction by injecting air.

  When the preform 5 is mounted on the mold 71, the mouth portion 10 is prevented from moving with the support ring 12 as a support. Thereafter, the body portion 50 of the preform 5 is stretched in the longitudinal direction by the stretching rod 72. In this case, the longitudinal stretching ratio from the preform 5 to the PET bottle 1 is preferably 1.8 times or more and 4.0 times or less.

  Here, the longitudinal draw ratio is a ratio (H2 / H1) of the length H2 from the lower surface of the support ring 12 of the PET bottle 1 to the lower end of the bottom portion 30 with respect to the length H1 of the body portion 50 of the preform 5. The molecules of the preform 5 having an amorphous structure that is an aggregate of the amorphous part and the crystal part undergo orientational crystallization by stretching, and as a result, the strength, rigidity, heat resistance, and the like of the PET bottle 1 are increased. When the longitudinal draw ratio is less than 1.8, the molecular orientation of the PET bottle 1 (preform 5) does not increase. On the other hand, when the longitudinal draw ratio is greater than 4.0, the PET bottle 1 is molded. It becomes difficult to do.

  Further, the body portion 50 of the preform 5 stretched in the longitudinal direction is stretched by the high-pressure air h in the lateral direction until it hits the mold 71. In this case, the transverse stretch ratio from the preform 5 to the PET bottle 1 is preferably 1.5 times or more and 6.0 times or less.

  Here, the transverse stretch ratio is a ratio (D2 / D1) of the maximum body diameter D2 in the inflated portion 23 of the PET bottle 1 to the body diameter D1 in the body middle portion 53 of the preform 5. Here, the diameter at the position where the opposing wall surfaces of the inflating part 23 are farthest is the body diameter D2 of the inflating part 23. The molecules of the preform 5 are similarly oriented and crystallized by stretching in the transverse direction. As a result, the strength, rigidity, heat resistance, etc. of the PET bottle 1 are increased. When the transverse draw ratio is less than 1.5, the molecular orientation of the PET bottle 1 (preform 5) does not increase. On the other hand, when the transverse draw ratio is greater than 6.0, the PET bottle 1 is molded. It becomes difficult to do.

  Thus, in the molding by the biaxial stretch blow molding apparatus 70, the stretching ratio in the longitudinal direction is 1.8 times or more and 4.0 times or less, and the stretching ratio in the transverse direction is 1.5 times or more and 6.0 times or less. According to the configuration of the biaxial stretch blow molding, the PET bottle 1 can be molded from the preform 5 with better blow moldability.

  In the method for manufacturing a plastic bottle according to the present embodiment, in the longitudinal stretching process, it is preferable to advance the preform 5 in the axial direction until the body diameter of the preform 5, particularly the diameter reducing portion 52 is reduced, and then proceed to the lateral stretching process. . By such a longitudinal stretching process, in particular, the gap from the diameter reducing portion 52 to the mold 71 can be further increased. Thereby, the diameter reduction part 52 grade | etc., Becomes difficult to contact the metal mold | die 71 in a longitudinal stretch process. And, regardless of the shape of the preform 5, it is possible to satisfactorily form a small diameter portion such as the constricted portion 22 having a smaller diameter (minimum body diameter Dc) than the body diameter Ds of the support ring lower portion 21 of the body portion 20.

  Here, the minimum body diameter of the diameter reducing portion 52 illustrated in FIGS. 3 and 5 is substantially equal to the body diameter D1 of the body middle portion 53. In such a configuration, in the longitudinal stretching step, the preform 5 is stretched until the body diameter D1 of the body middle portion 53 corresponding to the minimum body diameter of the diameter reducing portion 52 is reduced to 65% to 95%, and then the transverse stretching step. As the process proceeds, better blow moldability can be obtained.

  Furthermore, in another aspect, in the longitudinal stretching step, the barrel diameter D1 of the barrel middle portion 53 corresponding to the minimum barrel diameter of the diameter-reduced portion 52 is the smallest outside of the small-diameter portion such as the constricted portion 22 of the PET bottle 1 that is a blow molded product. When the preform 5 is stretched until it is reduced to 55% to 95% with respect to the diameter and then the transverse stretching process is performed, better blow moldability can be obtained.

  In the present embodiment, the use of the PET bottle 1 is not limited. Therefore, the PET bottle 1 may be molded so as to have pressure resistance, heat resistance, and the like.

  A filling body is constituted by the PET bottle 1 and the liquid to be filled. The filling body is manufactured by filling a liquid such as a beverage or a seasoning from the mouth portion 10 of the PET bottle 1 and sealing with a lid (not shown) attached to the mouth portion 10.

  The lid may also be configured to serve as a container for receiving the contents. Furthermore, the filling body may be provided with a separate container covering from above the lid. These bowls may be, for example, a cup for drinking sake or shochu, a cup for drinking soft drinks, and a hand-salt plate for the contents of desktop seasonings such as soy sauce bottles. It may be a measuring cup for measuring the volume of the concentrate.

  The PET bottle 1 may be packaged with a label such as a shrink label on which information on the contents, a pattern for improving design properties, and the like are printed. The shrink label may cover a part of the PET bottle 1 such as the body part 20, the mouth part 10, the constricted part 22, or the like, or may be a full shrink label that covers the entire PET bottle 1. A biaxially stretched polystyrene film or the like having good heat shrinkability may be used for the shrink label attached by heat shrinkage.

  As described above, the PET bottle 1 has the mouth portion 10, the body portion 20, and the bottom portion 30 sequentially in the axial direction, the mouth portion 10 and the support ring lower portion 21 of the body portion 20 are connected, and the body portion 20. Has a small diameter portion such as a constricted portion 22 whose body diameter is smaller than the support ring lower part 21 (body diameter Ds) (minimum body diameter Dc). According to such a configuration, it is possible to provide the PET bottle 1 with improved design and easy filling.

  Further, the PET bottle 1 includes a process of mounting the heated preform 5 on the mold 71, a longitudinal stretching process of stretching the preform 5 in the axial direction by the stretching rod 72, and injecting the preform 5 by injecting air. And a horizontal stretching step that expands in the radial direction, and in the longitudinal stretching step, the preform 5 may be stretched until the body diameter of the preform 5 is reduced, and then the method may proceed to the lateral stretching step. According to such a manufacturing method, a small diameter portion such as a constricted portion 22 having a smaller diameter (minimum body diameter Dc) than the body diameter Ds of the support ring lower portion 21 of the body portion 20 is formed regardless of the shape of the preform 5. can do.

  In addition, the plastic bottle according to the present embodiment has other configurations as long as the barrel diameter has a smaller diameter portion (minimum barrel diameter Dc) than the support ring lower portion 21 (body diameter Ds), for example, a constricted portion 22. May be different. FIG. 6 is a front view showing a PET bottle 2 as an example of a plastic bottle according to another embodiment. The PET bottle 2 has a so-called wine bottle shape.

  The PET bottle 2 has a mouth part 10, a body part 120, and a bottom part 30 in the axial direction sequentially, the mouth part 10 and the support ring lower part 21 of the body part 120 are connected, and the body part 120 has a body diameter. The neck portion 22 has a smaller diameter (minimum body diameter Dc) than the support ring lower part 21 (body diameter Ds). A large-diameter portion 123 is continued below the constricted portion 22. The large-diameter portion 123 corresponding to the inflating portion 23 of the PET bottle 1 has a substantially true cylindrical shape in which the body diameter hardly changes vertically in the axial direction.

  Even in the case of the PET bottle 2 configured as described above, it is possible to enhance the design and make it easy to pour the contents.

  Hereinafter, the present disclosure will be described in more detail and specifically with reference to examples. However, the present disclosure is not limited to the following examples.

<Material and manufacturing method>
[Example 1]
The PET bottle 1 shown in FIG. 1 and the like having a full injection capacity of 200 ml made of 24 g of polyethylene terephthalate was used. The outer diameter of the support ring lower part 21 was 34.9 mm, and the outer diameter of the constricted part 22 at the most curved portion in the radial direction was 33.0 mm. The PET bottle 1 was filled with 180 ml of water and then closed with a lid (not shown) to produce a filled body. The PET bottle 1 according to Example 1 has features such as having a constricted portion 22 as a small diameter portion whose diameter is smaller than the support ring lower portion 21 (body diameter Ds) (minimum body diameter Dc). Had.

[Comparative Example 1]
FIG. 7 is a front view of the PET bottle 200 of Comparative Example 1. FIG. Comparative Example 1 was the same as Example 1 except that a PET bottle 200 that did not have a configuration corresponding to the constricted portion 22 of Example 1 was used.

  The PET bottle 200 has a mouth part 10, a body part 220, and a bottom part 30 in the axial direction sequentially, and the body part 220 is configured to have a support ring lower part 221 and an inflating part 23 in order in the axial direction. The support ring lower portion 221 has a substantially true cylindrical shape whose trunk diameter and wall thickness hardly change in the vertical direction. The outer diameter of the support ring lower part 221 was 34.9 mm which is the same as the support ring lower part 21 in the PET bottle 1 of Example 1. Therefore, the filler according to Comparative Example 1 did not have the characteristics according to the present embodiment.

<Evaluation method (monitoring survey)>
(Creativity)
Each filling body of Example 1 and Comparative Example 1 was prepared, and 100 people in their 20s to 70s chose which filling body felt superior in design. The selected ones were counted as one point. Table 1 shows the total score.

(Ease of holding)
Each packing body of Example 1 and Comparative Example 1 was prepared, and 100 monitors in their 20s to 70s had each packing body, and selected which packing body was easy to hold. The selected ones were counted as one point. Table 1 shows the total score.

(Ease of pouring)
Each filling body of Example 1 and Comparative Example 1 is prepared, and the contents are poured out to 100 monitors in their 20s to 70s with each filling body, which filling body is easy to pour. I had you choose. The selected ones were counted as one point. Table 1 shows the total score.

(Comprehensive evaluation)
Based on the above-described monitoring survey of designability, ease of holding, and ease of pouring, comprehensive evaluation of the PET bottle 1 of Example 1 and the PET bottle 200 of Comparative Example 1 was performed. Table 1 shows the results of comprehensive evaluation. Comprehensive evaluation is described by (circle): favorable and x: no aptitude.

  The following points were derived from the examples described above. In the PET bottle 1 according to Example 1, the design property was highly evaluated from many monitors, and the ease of holding was supported. Furthermore, in the PET bottle 1 according to Example 1, the ease of pouring was supported by many monitors because the flow rate of the contents poured out was stable, coupled with the ease of holding.

  On the other hand, there were not so many monitors that evaluated the PET bottle 200 of Comparative Example 1 as being excellent in design and ease of holding. Furthermore, in Comparative Example 1, there was also a scene in which the contents flowed out and spilled at a stroke, and the ease of pouring was not supported from the monitor.

  From the results of the above examples, it is shown that the PET bottle 1 according to the present embodiment can have high designability, ease of holding, and ease of pouring even with a slight difference in configuration. It was done. Therefore, in this embodiment, it was shown that the design property is improved and the PET bottle 1 in which the contents can be easily poured can be provided.

  The present disclosure can be suitably used for various plastic bottles filled with liquid as contents. However, the present disclosure is not limited to the above-described embodiments and examples. Plastic bottles of the present disclosure include, for example, water, green tea, oolong tea, various non-carbonated beverages and carbonated beverages such as tea, coffee, fruit juice, and soft drinks, or seasonings such as soy sauce, sauce, mirin, edible oil, sake and shochu It is useful for the storage of foods including alcoholic beverages, detergents, cosmetics, pharmaceuticals, and all other contents. In particular, since the plastic bottle of the present disclosure is excellent in the ease of pouring the contents, it is suitable for usage in which it is transferred to another container. Furthermore, since the plastic bottle of the present disclosure is excellent in the operability of the container when the contents are poured out, the plastic bottle is also suitable for contents such as concentrated seasonings that require weighing during use.

1 PET bottle (plastic bottle)
5 Preform 10 Mouth 20 PET Bottle Body 21 Lower Support Ring (End)
22 Constricted part (small diameter part)
24 Rib 30 Bottom portion of PET bottle 51 Neck portion 52 Diameter reducing portion 53 Body middle portion 71 Mold 72 Stretching rod D1 Body diameter at the middle portion Dc Minimum body diameter at the neck portion Dn Body diameter at the neck portion Ds Body diameter at the bottom of the support ring r Constriction portion Radius of curvature

Claims (8)

In a plastic bottle having a mouth part, a body part, and a bottom part sequentially in the axial direction, and connecting the mouth part and an end part of the body part,
The trunk is
A plastic bottle characterized by having a small-diameter portion whose diameter is thinner than that of the end portion. The plastic bottle according to claim 1, wherein a radius of curvature of the small-diameter portion that curves toward the inside of the plastic bottle is 10 mm or more and 80 mm or less. 3. The plastic bottle according to claim 1, wherein a value of a ratio of a body diameter of the small diameter part to a body diameter of the end part is 0.70 or more and 0.98 or less. The trunk is
The plastic bottle according to claim 1, further comprising a rib extending in a circumferential direction of the plastic bottle. Attaching the heated preform to the mold; and
A longitudinal stretching step of stretching the preform in the axial direction with a stretching rod;
In a method for producing a plastic bottle, comprising a transverse stretching step of inflating the preform in a radial direction by injecting air,
The method for producing a plastic bottle, wherein in the longitudinal stretching step, the preform is stretched until the body diameter of the preform is reduced and then the lateral stretching step is performed. The preform has a neck portion, a diameter-reduced portion, and a trunk middle portion sequentially in the axial direction,
The trunk diameter of the trunk middle part is configured to be equal to or smaller than the trunk diameter of the neck part,
The method for producing a plastic bottle according to claim 5, wherein a difference between a body diameter of the neck part and a body diameter of the body middle part is 5 mm or less. The plastic bottle manufacturing method according to claim 6, wherein in the longitudinal stretching step, the preform is stretched until the body diameter of the middle portion of the body is reduced to 65% to 95%, and then the transverse stretching step is performed. Method. The plastic bottle has a small diameter portion,
The longitudinal stretching step includes extending the preform until the body diameter of the middle portion of the body is reduced to 55% to 95% with respect to the small diameter portion, and then proceeding to the transverse stretching step. The manufacturing method of the plastic bottle of any one of thru | or 7.

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