Synthetic resin bottle

Abstract

A technical problem is to fully make up for a restricted upper limit to the preform body wall thickness. An object is to provide a bottle which is narrow-mouthed and yet has a substantially expanded body. In principle, the bottle may include a mouth opening portion with a bore diameter of 10 mm or less and a maximum diameter of the body is 2.5 times or more than the bore diameter of the mouth opening portion, and wherein a maximum diameter portion of the body has a minimum wall thickness of 0.45 mm or more.

Claims

1. A synthetic resin bottle which is a biaxially drawn, blow molded bottle, comprising: a body portion with a flat cross section having a circular shape; a mouth opening portion disposed on a body, the mouth opening portion having a bore diameter of 10 mm or less; and a cylindrical shaped neck portion disposed between the mouth opening portion and the body, wherein a maximum diameter of the body is at least 2.5 times more than the bore diameter of the mouth opening portion, wherein a screw thread is notched on an outer peripheral surface of the mouth opening portion and a height of the mouth opening portion is formed to be less than a height of the neck portion, wherein a maximum diameter portion of the body has a minimum wall thickness of 0.45 mm or more, wherein the neck portion has a minimum outer diameter in a range from an outer diameter of the mouth opening portion to 2.0 times as much as the bore diameter of the mouth opening portion, and wherein a flat ring portion is disposed under the neck portion and between the neck portion and the body.

2. The synthetic resin bottle according to claim 1, wherein the maximum diameter of the body is 3.0 times or more as much as the bore diameter of the mouth opening portion.

3. The synthetic resin bottle according to claim 1, wherein a cap in a roofed cylindrical shape is screwed on the mouth opening portion so that the cap covers the neck portion.

4. The synthetic resin bottle according to claim 1, wherein the bottle is utilized as a container for accommodating a make-up liquid.

5. The synthetic resin bottle according to claim 1, wherein a polypropylene series resin is used as a synthetic resin material for the bottle.

6. The synthetic resin bottle according to claim 1, wherein a polyethylene naphthalate series resin or a polyacrylonitrile series resin is used as a synthetic resin material for the bottle.

7. The synthetic resin bottle according to claim 1, wherein an overhang is formed on an inner peripheral surface of the bottle on a border between the mouth opening portion and the neck portion, a locking mechanism being formed using the overhang.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an explanatory diagram showing an embodiment of the molding process of this invention.

(2) FIG. 2 is a front view of the bottle of this invention molded by the molding process shown in FIG. 1, with a right half portion shown in a vertical section.

(3) FIG. 3 is a plan view of the bottle shown in FIG. 2.

(4) FIG. 4 is a front view, with the right half in a vertical section, of an example of the make-up container for mascara, in which the bottle of FIG. 1 is utilized as the container.

DESCRIPTION OF REFERENCE SIGNS

(5) 1. Preform

(6) 2. Mouth opening portion of preform

(7) 3. Body

(8) 4. Bottom

(9) 4S. Bottom (obtained after thermal shrinkage)

(10) 11. Bottle

(11) 12. Mouth opening portion of bottle

(12) 13. Body

(13) 13f. Maximum diameter portion

(14) 14. Bottom

(15) 15. Neck portion

(16) 16. Flat ring portion

(17) 17. Overhang

(18) 21. Cap

(19) 22. Application unit

(20) 22a. Shaft

(21) 22b. Brush

(22) 23. Built-in cylinder

(23) 23a. Squeezer

(24) H1, H2, H3. Height

(25) D1a. Bore diameter (of the mouth opening portion of the preform or the bottle)

(26) D1b. Outer diameter (of the mouth opening portion of the preform or the bottle)

(27) D2b. Outer diameter (of the bottle neck portion)

(28) D3bx. Maximum outer diameter (of the bottle body)

PREFERRED EMBODIMENTS

(29) This invention is further described with respect to preferred embodiments, now referring to the drawings. FIG. 1 is an explanatory diagram showing an embodiment of the molding process of this invention combined with the biaxial drawing and blow molding step. For the convenience of showing dimensional relationships, the injection molded preform 1 (partly shown in the vertical section) is superimposed with the bottle 11 (a front view drawn by a chain double-dashed line), while respective mouth opening portions 2 and 12 are positionally aligned. FIG. 2 is a front view, with the right half in the vertical section, and FIG. 3, a plan view, respectively showing the embodiment of a synthetic resin bottle molded by the molding process shown in FIG. 1. FIG. 4 is a front view, with the right half in the vertical section, showing an example of a makeup container for mascara, in which this bottle is utilized.

(30) The preform 1 made of a polypropylene resin has the following dimensions:

(31) Total height: 69.8 mm

(32) Height H1 excluding the mouth opening portion 2: 62.1 mm

(33) Bore diameter D1a of the mouth opening portion 2: 8.3 mm

(34) Outer diameter D1b of the mouth opening portion 2: 9.9 mm

(35) Average outer diameter of the body 3: 11.6 mm

(36) Wall thickness of the body 3: 3.05 mm

(37) Weight: 4.4 g

(38) The bottle 11 shown in FIG. 2 is obtained by biaxially drawing and blow molding the above preform 1. The bottle 11 has a cylindrical neck portion 15, which has been blow molded to have a somewhat larger diameter than that of the mouth opening portion 12. Under the neck portion, and by way of a flatly disposed ring portion 16, the bottle has a body 13 blow molded in a substantially expanded shape. The bottle 11 has the following dimensions:

(39) Bore diameter D1a of the mouth opening portion 12: 8.3 mm

(40) Outer diameter D1b of the mouth opening portion 12: 9.9 mm

(41) Total bottle height: 65.0 mm

(42) Height H3 excluding that of the mouth opening portion 12: 57.3 mm

(43) Outer diameter D2b of the neck portion 15: 14.0 mm

(44) (The neck portion in this embodiment has the shape of a right circular cylinder, and the outer diameter D2b is equal to the minimum outer diameter.)

(45) Maximum outer diameter D3bx of the body 13: 27.0 mm

(46) Minimum wall thickness (n=6) for the maximum diameter portion 13f of the body 13: 0.55-0.61 mm The above dimensions indicate that the maximum outer diameter D3bx of the body 13 is 3.3 times as much as the bore diameter D1a of the mouth opening portion 12 and that the (minimum) outer diameter Db2 of the neck portion 15 is larger than the outer diameter D1b of the mouth opening portion 12 and is 1.7 times as much as the bore diameter D1a of the mouth opening portion 12.

(47) Because cooling water is passed through the injection core mold, there is a limitation in decreasing the diameter of the core mold. The bore diameter of the body 3 of the preform 1 is thus determined by the diameter of this core mold. In the case of the above bottle 11 having a slim, cylindrical neck portion 15, attention has to be paid to the dragging that occurs in the vicinity of the split blow mold cavity where this neck portion 15 is formed (because dragging tends to occur more frequently if the bottle 11 has a flat ring portion 16 as in this embodiment), and also to the lateral draw ratio in the biaxial drawing and blow molding to form the neck portion 15. If these points are taken into consideration, the outer diameter of the body 3 of the preform 1 is larger by only about 2 mm than the outer diameter D1b of the mouth opening portion 2 at the longest. In the case of the preform in this embodiment, the mouth opening portion 2 has a bore diameter D1a of 10 mm or less, and the thickness of the body 3 of the preform 1 inevitably has an upper limit of about 3 mm.

(48) The process for molding the preform 1 into the bottle 11 comprises the following steps of (1), (2), and (3):

(49) (1) heating the body 3 and the bottom 4 of the preform 1 except for the mouth opening portion 2 to a temperature of 120 to 130 C. to make the portions other than the mouth opening portion 2 shrink from a height H1; (This heating step doubles as preliminary heating for the biaxial drawing and blow molding. Standard preliminary heating is usually conducted at a temperature of about 110 C., but in this case, a higher temperature of 120 to 130 C. is used so as to proceed with the thermal shrinkage to a large extent. Due to this thermal shrinkage, the bottom 4 goes up to the height position 4S as shown in FIG. 1 by a chain double-dashed line. The body 3 except for the mouth opening portion 12 would shrink to a height H2 of about 46 mm. The rate of shrinkage, calculated by a formula of ((H1-H2)/H1)100, accounts for about 26 percent.)

(50) (2) taking out from the heating furnace the preform 1 that has been thermally shrunk in the step of (1), and setting the shrunk preform in the split blow mold; and

(51) (3) molding the bottle 11 in the biaxially drawing and blow molding step.

(52) As described above, the preform 1 has a height H2 of 46 mm after the thermal shrinkage step (1). This height is considerably smaller than the height H3 of the bottle 11, and thus, the preform 1 can be set smoothly in the split blow mold. The vertical draw ratio in the biaxial drawing and blow molding, as calculated by H3/H2, is about 1.25 times. The lateral draw ratio for the maximum diameter portion 13f of the body 13 of the bottle 11 is about 2.3 times. At this ratio, the minimum thickness of the peripheral wall in this portion is in a range of 0.55 to 0.61 mm. In this range, the wall would be sufficiently rigid with no dent in the wall of the body 3 in ordinary handling of bottles.

(53) If the preform was injection molded to give the height H1 of 46 mm, assuming a vertical draw ratio of 1.25 times but without thermal shrinkage as has been so in prior art, then the weight limit is about 3.4 g, and the minimum thickness of the peripheral wall in the maximum diameter portion would be in a range of 0.4 to 0.45 mm. Thus, it has been confirmed that according to the above embodiment associated with the molding process of this invention, the minimum wall thickness in the maximum diameter portion 13f of the body 13 of the bottle 11 can be increased by about 1.4 times.

(54) An example of how the bottle 11 of this embodiment is used will be described below. FIG. 4 is a front view, with the right half in the vertical section, of an example of the make-up container for mascara, in which the bottle 11 of FIG. 2 is utilized as the container. The container comprises the bottle 11 and the roofed cylindrical cap 21 which is screwed on the mouth opening portion 12 of the bottle 11. The cap 21 is fitted around the neck portion 15, and softly covers the neck portion 15 to the lower end. From the roof ceiling hangs the application unit 22 comprising a shaft 22a and a brush 22b fitted at the front end of the shaft 22a.

(55) A built-in cylinder 23 made of an elastomer resin is fitted firmly inside the mouth opening portion 12 in an area ranging from the upper end of the mouth opening portion 12 to the upper end of the neck portion 15. This built-in cylinder 23 is provided with a funnel-shaped squeezer 23a which performs a function of squeezing an extra amount of the make-up liquid from the brush 22b.

(56) When the bottle 11 is molded, an overhang 17 is formed on the inner peripheral surface of the bottle 11 on the border between the mouth opening portion 12 and the neck portion 15. A locking mechanism is formed by using this overhang 17 to prevent the built-in cylinder 23 from slipping out of the mouth opening portion 12.

(57) This invention has been described with respect to a preferred embodiment, but this invention should not be construed as limitative to the above embodiment. In addition to the PP resin, there are other synthetic resins, such as PEN and PAN resins, which have been used conventionally in the biaxial drawing and blow molding. All these resins have high rates of thermal shrinkage enough to adjust the height of the injection molded preform adequately in this invention. The above embodiment associated with the molding process comprises that the thermal shrinkage of the preform 1 doubles as the preliminary heating, but this step of thermal shrinkage may be separated from the preliminary heating step. The bottle of this invention does not necessarily have a limited use as a make-up container for mascaras and eyeliners described above in the embodiment.

INDUSTRIAL APPLICABILITY

(58) As described above in details, the molding process of this invention can fully make up for the restricted upper limit to the preform body wall thickness. The bottle of this invention has a narrow mouth and yet has a substantially expanded body, and can be provided additionally with a slim neck portion. Because of its unique shape, the bottle is expected to have wide use in the field of narrow-mouthed bottles to be used as the containers for mascaras and eyeliners.