JP5750002B2 - Plastic bottle preform and plastic bottle - Google Patents

Description

  The present invention relates to a plastic bottle having a required buckling strength while achieving weight reduction and a preform for a plastic bottle capable of molding the same.

  Plastic bottles such as PET bottles are usually manufactured by blow-molding a bottomed cylindrical molded product called a preform into a bottle shape. In recent years, plastic bottles have been reduced in weight from the viewpoint of resource and cost reduction, and the bottles tend to be thinner and have lower strength.

  Therefore, it is performed to form irregularities for the purpose of reinforcement on the wall surface of the plastic bottle. For example, a plurality of ribs are formed on the outer peripheral surface of the intermediate portion in the axial direction of the preform in parallel with the axial direction of the preform, and the preform of the plastic bottle is formed by biaxial stretching blow molding. And the technique of forming a protrusion rib in the outer peripheral surface of a shoulder part is disclosed (for example, refer patent document 1). Also, ribs along the vertical direction are provided on the inner wall and outer wall of the preform and the barrel, and the preform is formed on the bottom and barrel walls of a plastic bottle obtained by biaxial stretching blow molding. A technique for forming vertical ribs is disclosed (see, for example, Patent Document 2). Although not intended to improve strength, as a method of forming irregularities on the wall surface of a plastic bottle, an irregular pattern is formed on at least one of the outer peripheral surface or inner peripheral surface of the preform, and this preform is biaxially stretched. A technique for forming a concavo-convex pattern on the inner peripheral surface of a plastic bottle by blow molding is disclosed (for example, see Patent Document 3).

Japanese Patent Application Laid-Open No. 07-052234 Japanese Utility Model Publication No. 62-144612 JP 2010-126193 A

  By the way, for example, when plastic bottles are used as containers for beverages, they are transported and stored in cardboard boxes in units of several to several tens. At this time, since the cardboard boxes are stacked, a vertical compression load is applied to the plastic bottle. Therefore, the plastic bottle is desired to have a buckling strength against a longitudinal compression load. As in Patent Document 1, in a plastic bottle in which protruding ribs are formed only on the outer peripheral surfaces of the trunk and the shoulder, the strength against internal pressure is improved, but the buckling strength at the bottom is insufficient. In addition, the plastic bottle described in Patent Document 3 is originally intended to decorate the peripheral wall using a change in the optical visual effect due to the uneven pattern, so that the bottom is uneven. It does not reinforce the buckling strength of the bottom. In biaxial stretch blow molding, the preform is reheated from the outer peripheral surface side. At this time, if the rib ribs are formed on the inner wall surface as in Patent Document 2, there is a problem that heat is hardly transmitted to the rib ribs and the moldability is inferior.

  An object of the present invention is to provide a plastic bottle having a required buckling strength and a plastic bottle preform having good releasability and capable of forming a plastic bottle having the required buckling strength while reducing the weight. It is to be.

The preform for a plastic bottle according to the present invention includes a mouth part provided with a neck support ring at a lower end, a cylindrical body part connected to the bottom of the neck support ring, and a bottom part connected to the bottom of the body part. In the preform for a plastic bottle comprising: the body portion and the bottom portion are thinned from the outer peripheral surface side, and a vertical rib extending from the upper end of the body portion to the bottom portion is formed on the outer peripheral surface of the body portion and the bottom portion. a plurality of setting only, the longitudinal ribs, the horizontal width, characterized in that it is a gradually decreased to taper downward a maximum at the upper end of the barrel.

The preform for a plastic bottle according to the present invention includes a mouth part provided with a neck support ring at a lower end, a cylindrical body part connected to the bottom of the neck support ring, and a bottom part connected to the bottom of the body part. In the preform for a plastic bottle comprising: the body portion and the bottom portion are thinned from the outer peripheral surface side, and a vertical rib extending from the upper end of the body portion to the bottom portion is formed on the outer peripheral surface of the body portion and the bottom portion. A plurality of the vertical ribs are formed continuously from the upper end of the body portion to the lower portion of the body portion with the same width and the lower end of the equal width portion, and gradually increase in width toward the lower portion. It has a taper part which makes it small. In the preform for a plastic bottle according to the present invention, it is preferable that the vertical rib further has a narrow equal width portion formed with the same width from the lower end of the tapered portion downward.

The preform for a plastic bottle according to the present invention includes a mouth part provided with a neck support ring at a lower end, a cylindrical body part connected to the bottom of the neck support ring, and a bottom part connected to the bottom of the body part. In the preform for a plastic bottle comprising: the body portion and the bottom portion are thinned from the outer peripheral surface side, and a vertical rib extending from the upper end of the body portion to the bottom portion is formed on the outer peripheral surface of the body portion and the bottom portion. A plurality of the vertical ribs are characterized in that the horizontal width is constant in the vertical direction and has a uniform width and a straight belt shape.

In the preform for a plastic bottle according to the present invention, it is preferable that the vertical ribs intersect at the center of the bottom. The buckling strength at the bottom of the plastic bottle can be further increased.

In the preform for a plastic bottle according to the present invention, it is preferable that the vertical ribs are arranged at 3 or more and 8 or less at equal intervals along the circumferential direction of the preform. The buckling strength of the plastic bottle can be further increased while reducing the weight of the plastic bottle.

  The plastic bottle according to the present invention is produced by blow-molding the plastic bottle preform according to the present invention.

  The present invention provides a plastic bottle having a required buckling strength and a plastic bottle preform having good releasability and capable of molding a plastic bottle having the required buckling strength while reducing the weight. Can do.

It is a front view which shows an example of the preform for plastic bottles which concerns on this embodiment. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is an expanded sectional view of the part shown by C of FIG. It is the figure which looked at the preform of Drawing 1 from the D direction. It is a front view which shows the 1st modification of a longitudinal rib. It is a front view which shows the 2nd modification of a longitudinal rib. It is sectional drawing which shows an example of the metal mold | die 900 for carrying out the injection molding of the preform 100, (a) is the state in which the metal mold | die is open, (b) shows the state at the time of injection molding. It is a front view which shows an example of the plastic bottle obtained by blow-molding the preform for plastic bottles which concerns on this embodiment. It is EE sectional drawing of FIG. It is a graph which shows the relationship between the amount of displacement of the perpendicular direction in buckling strength evaluation, and a perpendicular load (compression load).

  Next, the present invention will be described in detail with reference to embodiments, but the present invention is not construed as being limited to these descriptions. As long as the effect of the present invention is exhibited, the embodiment may be variously modified.

  FIG. 1 is a front view showing an example of a preform for a plastic bottle according to the present embodiment. FIG. 2 is a cross-sectional view taken along the line AA of FIG. 3 is a cross-sectional view taken along line BB in FIG. A preform 100 for a plastic bottle according to the present embodiment includes a mouth portion 10 provided with a neck support ring 14 at a lower end, a cylindrical body portion 20 connected under the neck support ring 14, and a body portion 20. In a preform for a plastic bottle having a bottom 30 connected to the bottom, the body 20 and the bottom 30 are thinned from the outer peripheral surface S2 side, and the upper end of the body 20 is formed on the outer peripheral surface S2 of the body 20 and the bottom 30. A plurality of vertical ribs 50 extending from 20a to the bottom 30 are provided.

  The preform 100 is a plastic molded body that has been previously molded into a shape suitable for molding a plastic bottle. As shown in FIG. 1, the preform 100 includes a mouth portion 10, a trunk portion 20, and a bottom portion 30 in order from above. The mouth portion 10 has a cylindrical peripheral wall 11 with an upper end 10a opened, and functions as a filling port and a spout for contents in a plastic bottle. On the outer peripheral surface of the peripheral wall 11, there are a male screw portion 12 screwed into a cap (not shown), a bead ring 13 provided below the male screw portion 12, and a neck support ring 14 provided at the lower end of the mouth portion 10. However, it protrudes and is formed. As shown in FIG. 2, the body portion 20 has a cylindrical shape with a hollow inside. The cross-sectional shape in the horizontal direction of the inner peripheral surface S1 of the trunk portion 20 is, for example, a circle as shown in FIG. In addition, the cross-sectional shape in the horizontal direction of the inner peripheral surface S1 of the trunk portion 20 is not limited to a circle, and may be a polygon such as a quadrangle, a pentagon, a hexagon, or an octagon. The bottom 30 is, for example, hemispherical as shown in FIGS. Note that the shape of the bottom 30 is not limited to a hemispherical shape, and may be, for example, a conical shape, a pyramid shape, a cylindrical shape, or a prism shape.

  The trunk | drum 20 and the bottom part 30 have the thin part 40 and the vertical rib 50 alternately along the circumferential direction, as shown in FIG. In FIG. 3, an outer peripheral surface (hereinafter referred to as a virtual outer peripheral surface) S0 passing over the vertex 50a of the vertical rib 50 is indicated by a dotted line, but the thin-walled portion 40 has its outer peripheral surface S2 as a virtual outer peripheral surface S0. Compared with the central axis O side, it is a thinned portion. By reducing the thickness from the outer peripheral surface S2 side, the amount of resin used can be further reduced.

  As shown in FIG. 1, the thin-walled portion 40 is preferably not formed on the straight portion 21 spaced a predetermined distance from the upper end 20 a of the trunk portion 20. Since the straight portion 21 is a portion that is gripped by the gripper in the molding line, by not forming the thin portion 40, it is not necessary to change the shape of the gripper and can be applied to a conventional line. The region 21 is, for example, a region from 3.0 to 7.0 mm below the neck support ring 14.

  The vertical ribs 50 are provided in a state of projecting on the outer peripheral surface S2 of the trunk portion 20 and the bottom portion 30 as shown in FIG. 3 by leaving the space between the thin portions 40 without thinning them. Since the vertical ribs 50 are provided from the upper end 20a of the body portion 20, that is, directly below the neck support ring 14, there is no need to forcibly remove the preform 100 at the time of molding, and the releasability is good. Further, in the preform 100 according to the present embodiment, the vertical rib 50 is formed to extend in the vertical direction from the upper end 20a of the trunk portion 20 to the bottom portion 30, so that the resulting plastic bottle has high buckling strength. Therefore, in the preform 100 according to the present embodiment, the required buckling strength can be exhibited even if the thinning ratio of the thin portion 40 is increased, and further weight reduction is possible. Further, by providing the vertical ribs 50 on the outer peripheral surface S2, heat transfer to the vertical ribs 50 becomes good at the time of molding, and the moldability can be made good.

  In the preform 100 for a plastic bottle according to the present embodiment, it is preferable that the vertical ribs 50 are arranged at 3 or more and 8 or less at equal intervals along the circumferential direction of the preform 100. By arranging in this way, it is possible to further increase the buckling strength of the plastic bottle while reducing the weight of the plastic bottle. The preform 100 in FIG. 1 has a configuration in which four vertical ribs 50 are arranged every 90 °, as shown in FIG. As another form example (not shown) arranged at equal intervals along the circumferential direction of the preform 100, three vertical ribs 50 are arranged every 120 °, and five vertical ribs 50 are arranged every 72 °. In this configuration, six vertical ribs 50 are arranged every 60 °, seven vertical ribs 50 are arranged every 51.4 °, and eight vertical ribs 50 are arranged every 45 °. In this embodiment, it is preferable that the plurality of vertical ribs 50 have the same shape in that a plastic bottle having a well-balanced buckling strength can be formed.

  The ratio (w / w0) of the total w (w1 + w2 + w3 + w4 +...) Of the width of the vertical rib 50 to the peripheral length w0 of the virtual outer peripheral surface S0 is preferably 10 to 60%. More preferably, it is 20 to 50%. Here, the width w1, w2, w3, w4,... Of the vertical rib 50 is the shortest distance between one end e1 and the other end e2 of the vertical rib 50 on the virtual outer peripheral surface S0. If w / w0 is less than 10%, the reinforcing effect of the vertical ribs in the plastic bottle may be insufficient. If w / w0 exceeds 60%, weight reduction is insufficient. In the present embodiment, the widths w1, w2, w3, w4... Of the plurality of vertical ribs 50 are preferably all the same.

  FIG. 4 is an enlarged cross-sectional view of a portion indicated by C in FIG. The height h1 of the vertical rib 50 is preferably 0.1 mm or more. More preferably, it is 0.2 mm or more. Here, the height h <b> 1 of the vertical rib 50 is a distance between the virtual outer peripheral surface S <b> 0 and the outer peripheral surface S <b> 2 of the trunk portion 20, and indicates the thickness of the thin portion 40 that has been reduced. If the height h1 of the vertical rib 50 is less than 0.1 mm, the weight reduction of the plastic bottle is insufficient. In addition, the height h1 of the vertical rib 50 is preferably t / 10 mm or less, where the thickness at the apex 50a of the vertical rib 50 is tmm. More preferably, it is t / 12 mm or less. When the height h1 of the vertical rib 50 exceeds t / 10 mm, the strength of the plastic bottle may be reduced. Moreover, the level | step difference of the vertical rib 50 and the thin part 40 is too large, and it is difficult to heat uniformly and a moldability may be inferior.

  FIG. 5 is a view of the preform of FIG. 1 as viewed from the D direction. In the preform 100 for a plastic bottle according to the present embodiment, it is preferable that the vertical ribs 50 intersect each other at the central portion 30 a of the bottom portion 30. The vertical ribs 50 intersect with each other at the central portion 30a of the bottom portion 30, whereby the buckling strength at the bottom portion of the plastic bottle can be further increased.

  An example of reducing the weight of the preform 100 is shown below. In the conventional preform (for 500 ml) having a virtual outer peripheral surface S0 indicated by a dotted line in FIG. 3, the mass is uniform at the body 20 and the bottom 30, whereas the mass is 20.16 g. As shown by the solid line in FIG. 3, the longitudinal rib 50 is thinned from the outer peripheral surface S <b> 2 side of the portion 20 and the bottom portion 30 and has a height h <b> 1 of 0.2 mm and a width w <b> 1 of 5.0 mm. In addition, the preform (for 500 ml) according to the present embodiment, which is formed every 90 °, has a mass of 19.32 g and can be reduced by about 4.2%.

  In FIG. 1, the vertical rib 50 has a horizontal width w1 that is constant in the vertical direction, and has a uniform width and a straight belt shape. However, the present embodiment is not limited to this. Next, a modification of the vertical rib is shown. FIG. 6 is a front view showing a first modification of the vertical rib. In the plastic bottle preform 101 according to the present embodiment, as shown in FIG. 6, the vertical rib 51 has a taper that maximizes the horizontal width w1 at the upper end 20a of the body portion 20 and gradually decreases downward. It is preferable that it is a shape. In this form, the upper part of the shoulder part and the trunk part of the plastic bottle can be strengthened.

  FIG. 7 is a front view showing a second modification of the vertical rib. In the plastic bottle preform 102 according to the present embodiment, the vertical rib 52 is continuous to the lower end of the equal width portion 52a and the lower end of the equal width portion 52a formed with the same width from the upper end 20a of the trunk portion 20 downward. And a tapered portion 52b that gradually decreases in width downward. More preferably, it further has a narrow equal width portion 52c formed with the same width downward from the lower end of the tapered portion 52b. In this form, the upper part of the shoulder part and the trunk part of the plastic bottle can be strengthened.

  The preforms 100, 101, and 102 according to the present embodiment shown in FIGS. 1, 6, and 7 do not have to be forcibly removed during molding, and have good releasability.

  Next, a method for forming the preforms 100, 101, 102 will be described. The preforms 100, 101, and 102 are molded by a molding method such as an injection molding method or a PCM molding method (preform compression molding) using a thermoplastic resin as a main raw material. The thermoplastic resin used as the main raw material of the preforms 100, 101, 102 is, for example, polyethylene terephthalate resin (PET), polybutylene terephthalate resin, polyethylene naphthalate resin, polyethylene resin, polypropylene resin, cycloolefin copolymer resin, ionomer resin, Poly-4-methylpentene-1 resin, polymethyl methacrylate resin, polystyrene resin, ethylene-vinyl alcohol resin, acrylonitrile resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyamide resin, polyamideimide resin, polyacetal resin, polycarbonate resin Polysulfone resin, tetrafluoroethylene resin, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin. Among these, PET is more preferable.

  Here, the case where the molding method is an injection molding method will be described using the preform 100 as an example with reference to FIG. FIG. 8 is a cross-sectional view showing an example of a mold 900 for injection molding the preform 100. FIG. 8A shows a state in which the mold is open, and FIG. 8B shows a state at the time of injection molding. A mold 900 for injection molding the preform 100 includes a core mold 910 for molding the inner surface of the preform 100 and an outer surface of the mouth portion 10 of the preform 100 as shown in FIG. A mouth forming mold 920 to be molded and a cavity mold 930 to mold the outer surface of the body 20 and the bottom 30 of the preform 100 are provided.

  The core mold 910 has a core portion 911 that is cylindrical and has a tip 910a that is semispherical. The mouth forming mold 920 has a recess 921 corresponding to the shape of the outer surface of the mouth 10. The cavity mold 930 includes a recess 931 corresponding to the shape of the outer surface of the body 20 and the bottom 30 and a gate 932 for filling resin. A protrusion (not shown) corresponding to the shape of the thin portion 40 is provided in the cavity mold 930.

  After clamping the core mold 910, the mouth forming mold 920, and the cavity mold 930, as shown in FIG. 2B, the gate 932 enters the cavity 940 having the shape of the preform 100. The preform 100 is molded by injecting a material containing a molten thermoplastic resin. When the preform 100 is cooled to a predetermined temperature, the mold 900 is opened and the preform 100 is taken out.

  FIG. 9 is a front view showing an example of a plastic bottle obtained by blow molding the preform for a plastic bottle according to the present embodiment. The plastic bottle 200 according to the present embodiment is manufactured by blow molding the plastic bottle preform 100 according to the present embodiment. Blow molding is, for example, biaxial stretch blow molding.

  As shown in FIG. 9, the plastic bottle 200 includes a mouth portion 210, a shoulder portion 220, a trunk portion 230, and a bottom portion 260 in order from above. In blow molding, the mouth portions 10 of the preforms 100, 101, 102 remain unstretched and do not deform and become the mouth portions 210 of the plastic bottle 200. That is, the mouth part 210 of the plastic bottle 200 has the same shape and dimensions as the mouth part 10 of the preforms 100, 101, 102 according to this embodiment. Therefore, description of common points is omitted here. The body part 20 of the preforms 100, 101, 102 becomes the shoulder part 220 and the body part 230 of the plastic bottle 200. The shoulder portion 220 has a truncated cone shape and is a portion that connects the mouth portion 210 and the trunk portion 230. In addition, although the shoulder part 220 shown in FIG. 9 is formed with the curved surface, you may form from several surfaces. The trunk portion 230 has, for example, a cylindrical shape with a hollow inside, and is mainly a portion that is gripped by the user. In addition, although the trunk | drum 230 shown in FIG. 9 makes the external shape the cylinder shape, a prismatic shape may be sufficient. The bottom 30 of the preforms 100, 101, 102 becomes the bottom 260 of the plastic bottle 200. The bottom portion 260 is a portion that becomes the bottom surface of the bottle. In the present embodiment, the shape of the plastic bottle 200 is not limited to the shape shown in FIG.

  10 is a cross-sectional view taken along line EE in FIG. When the preform 100 according to the present embodiment shown in FIG. 1 is blow-molded, the body portion 20 and the bottom portion 30 of the preform 100 are stretched while maintaining the correlation between the thickness of the thin portion 40 and the longitudinal rib 50, Pressed against the cavity surface of the blow mold. As a result, as shown in FIG. 9, the vertical rib 1 provided in a state protruding from the outer peripheral surface S2 of the body part 20 and the bottom part 30 of the preform 100 has a shoulder part 220, a body part 230 and a bottom part of the plastic bottle 200. The vertical ribs 250 are provided so as to protrude from the inner peripheral surface S3 of the 260, and the thin portion 240 is formed between the vertical ribs 250. In blow molding, the height H1 of the vertical ribs 250 is preferably stretched to be 0.03 mm or more. More preferably, it is 0.05 mm or more. In addition, for example, in a plastic bottle having a volume of 500 ml, the thickness of the body is generally 0.25 to 0.50 mm, whereas in the plastic bottle 200 according to the present embodiment, the plastic bottle 200 is thin. The thickness T of the part 240 can be set to 0.10 to 0.20 mm, for example. As described above, in the plastic bottle 200 according to the present embodiment, the vertical rib 250 serves as a support column, so that the shoulder portion 220, the trunk portion 230, and the bottom portion 260 have the necessary buckling strength while being thinned.

  Next, although an example of the present invention is given and explained, the present invention is not limited to these examples.

Example 1
A preform (resin amount 19.3 g) made of PET having the shape shown in FIG. 1 was prepared. The region where the vertical ribs 50 are provided is a region of 64.0 mm from directly below the neck support ring 14, and the vertical ribs 50 intersect with each other at the central portion 30 a of the bottom portion 30. The wall thickness t at the apex 50a of the vertical rib was 3.15 mm, the height h1 of the vertical rib 50 was 0.2 mm, and the widths w1, w2, w3, and w4 were all 5.0 mm. The peripheral length w0 of the virtual outer peripheral surface S0 was 70.6 mm, and w / w0 was 28.3%. This preform was blow-molded to obtain a plastic bottle having a shape shown in FIG. 9 and having a height of 205 mm, a barrel outer diameter of 66 mm, and a capacity of 500 ml. The obtained plastic bottle had an average height H1 of the longitudinal ribs of 0.05 mm and an average thickness T of the thin portion of 0.20 mm.

(Comparative Example 1)
A preform (resin amount 19.3 g) having the same shape and material as the preform prepared in Example 1 was prepared except that the vertical ribs 50 were not provided and the thickness of the body and the bottom was made uniform. . The thickness of the trunk and the bottom was 3.15 mm and uniform. This preform was blow-molded to obtain a plastic bottle having a height of 205 mm, an outer diameter of the body portion of 66 mm, and a capacity of 500 ml having the outer shape shown in FIG. The resulting plastic bottle had an overall average wall thickness of 0.21 mm.

(Comparative Example 2)
A preform (resin amount 19.3 g) having the same shape and material as the preform prepared in Example 1 was prepared except that the vertical rib 50 was formed only on the body portion 20. The region where the vertical ribs 50 are provided is a region of 53.5 mm from directly below the neck support ring 14. This preform was blow-molded to obtain a plastic bottle having a height of 205 mm, an outer diameter of the body portion of 66 mm, and a capacity of 500 ml having the outer shape shown in FIG. In the obtained plastic bottle, the vertical rib had a length of 80 mm with the lower end at a position 40 mm from the bottom and the upper end at a position 120 mm from the bottom. Further, the average height H1 of the longitudinal ribs was 0.05 mm, and the average thickness T of the thin portion was 0.20 mm.

(Buckling strength)
The buckling strength was measured about the plastic bottle of the Example and the comparative example. The buckling strength was measured by filling a plastic bottle with 500 ml of water (23 ° C.), sealing it with a cap. A vertical load was applied from the top side of the cap at a speed of 50 mm / min. And the load when a plastic bottle buckled was made into buckling strength. FIG. 11 shows the relationship between the amount of displacement in the vertical direction and the vertical load (compressive load). In FIG. 11, the maximum value of the compressive load is the buckling strength.

  The plastic bottles of Example 1, Comparative Example 1 and Comparative Example 2 all have substantially the same amount of resin, but as shown in FIG. 11, the buckling strength is 170.9 N in Example 1 (displacement amount 1.. In Comparative Example 1, it was 124.7 N (displacement amount 1.08 mm), and in Comparative Example 2, it was 112.3 N (displacement amount 1.24 mm). In Example 1, the buckling strength was confirmed to be 1.4 times higher than that of Comparative Example 1 and 1.5 times higher than that of Comparative Example 2. Although the comparative example 2 has formed the vertical rib, since it formed only in the trunk | drum, the buckling strength is a little inferior to the comparative example 1 which does not form the vertical rib, and the reinforcement effect by the vertical rib is exhibited. Confirmed that there is no. From this, it was confirmed that by extending the vertical rib not only to the trunk but also to the bottom, a reinforcing effect by the vertical rib can be obtained and the buckling strength can be improved. From the above, since the plastic bottle obtained by blow molding the preform according to the present invention has high buckling strength, the ratio of thinning the thin portion is increased while maintaining the buckling strength necessary for the plastic bottle. can do.

DESCRIPTION OF SYMBOLS 10 Mouth part 10a Upper end 11 Mouth wall 12 Male thread part 13 Bead ring 14 Neck support ring 20 Trunk part 20a Upper end 21 of trunk part Straight part 30 Bottom part 30a Bottom center part 40 Thin part 50, 51, 52 Vertical rib 52a etc. Width portion 52b Tapered portion 52c Narrow equal width portion 50a Vertical rib apex 100, 101, 102 Preform 200 Plastic bottle 210 Mouth portion 220 Shoulder portion 230 Body portion 240 Thin portion 250 Vertical rib 260 Bottom portion 900 Mold 910 Core mold 910a Tip portion 911 Core portion 920 Mouth forming die 921 Recess 930 Cavity die 931 Recess 932 Gate O Central axis S0 Virtual outer peripheral surface S1 Inner peripheral surface S2 Outer peripheral surface

Claims (7)

In a preform for a plastic bottle comprising a mouth provided with a neck support ring at the lower end, a cylindrical body part connected to the bottom of the neck support ring, and a bottom part connected to the bottom of the body part,
And thinned from the outer peripheral surface of the barrel portion and the bottom portion, the outer circumferential surface of the body portion and said bottom portion, a plurality of set of longitudinal ribs extending in the bottom part from the upper end of the barrel,
The preform for a plastic bottle , wherein the vertical rib has a taper shape in which a horizontal width is maximized at an upper end of the body portion and gradually decreases downward . In a preform for a plastic bottle comprising a mouth provided with a neck support ring at the lower end, a cylindrical body part connected to the bottom of the neck support ring, and a bottom part connected to the bottom of the body part,
And thinned from the outer peripheral surface of the barrel portion and the bottom portion, the outer circumferential surface of the body portion and said bottom portion, a plurality of set of longitudinal ribs extending in the bottom part from the upper end of the barrel,
The vertical rib is formed with a constant width portion having the same width from the upper end of the body portion to the lower side and a tapered portion formed continuously from the lower end of the constant width portion and gradually decreases in width downward. And a preform for a plastic bottle. The preform for a plastic bottle according to claim 2, wherein the vertical rib further has a narrow equal width portion formed with the same width from the lower end of the tapered portion downward. In a preform for a plastic bottle comprising a mouth provided with a neck support ring at the lower end, a cylindrical body part connected to the bottom of the neck support ring, and a bottom part connected to the bottom of the body part,
And thinned from the outer peripheral surface of the barrel portion and the bottom portion, the outer circumferential surface of the body portion and said bottom portion, a plurality of set of longitudinal ribs extending in the bottom part from the upper end of the barrel,
A preform for a plastic bottle, characterized in that the vertical rib has a uniform width in the vertical direction and a strip shape of a uniform width and a straight line . The preform for a plastic bottle according to any one of claims 1 to 4, wherein the vertical ribs intersect at the center of the bottom. The plastic bottle plug according to any one of claims 1 to 5, wherein the vertical ribs are arranged in an interval of 3 or more and 8 or less along the circumferential direction of the preform. Renovation. A plastic bottle produced by blow molding the preform for a plastic bottle according to any one of claims 1 to 6 .