JP3823641B2 - Bottle - Google Patents

Description

【００９６】
［比較例１］
射出成形にて目付量２０ｇのプリフォームを成形した。得られたプリフォームを二軸延伸ブロー成形してボトルを得た。得られたボトルの保存試験を行ったところ、４本のボトルの底部中心部分に２ｍｍ程度のクレーズが発生し、別の３本にφ１０ｍｍ程度の白化が発生した。
【００９７】
［比較例２］
圧縮成形にて目付量２０ｇのプリフォームを成形した。このプリフォームの胴部周方向肉厚分布は不均一（最大肉厚−最小肉厚＝０．０８〜０．１５ｍｍ）であった。これを二軸延伸ブロー成形してボトルを得た。得られたボトルは胴部周方向の肉厚の差（最大肉厚−最小肉厚）が０．１５〜０．０６ｍｍであった。
このボトルの保存試験を行ったところ、１０本ともクレーズや白化の発生はなく、保存試験前と同様の外観であった。しかし、軸荷重測定において降伏点強度は３０．２ｋｇｆであり、飲料ボトルとしての性能を満たしていなかった。保存試験及び軸荷重測定の結果を下記表２に示す。
【００９８】
【表２】

【００９９】
【発明の効果】
本発明によれば、ボトル底部中心における流動配向歪みを検出することに成功し、この流動配向歪みが実質上生じないように、熱可塑性樹脂の圧縮成形、特に一段圧縮成形でプリフォームを成形し、このプリフォームを二軸延伸ブロー成形することにより、底部が均一且つ一様に延伸されていると共に、底部に流動配向歪みが少なく、その結果底部の耐衝撃性や座屈強度が向上しており、また底部中心の耐環境亀裂性に優れていて、保存時におけるクレーズや白化の発生がなく、更に外観特性にも優れているボトルを製造することが可能となった。
【図面の簡単な説明】
【図１】本発明のボトルの一例を示す側面図である。
【図２】Ｘ線回折に用いるサンプルを示す説明図である。
【図３】Ｘ線回折の方法を示す説明図である。
【図４】Ｘ線散漫散乱におけるピーク位置と半価幅の求め方を示す説明図である。
【図５】種々のボトル底部における上記ピーク位置と半価幅との関係を示すグラフである。
【図６】種々のボトル底部におけるピーク位置の差（Ｂ−Ａ）と半価幅の差（Ｃ−Ｄ）との関係を示すグラフである。
【図７】一段圧縮成形法に用いる装置の全体の配置を示す平面図である。
【図８】図７の装置の側面図である。
【図９】溶融塊の切断及び供給装置の平面図である。
【図１０】図９の装置の各段階を示す側面図である。
【図１１】圧縮成形工程の各段階を説明するための側断面図である。
【図１２】圧縮成形後のプリフォームの取り出し工程の各段階を説明するための側断面図である。
【図１３】本発明に用いるブロー成形用プリフォームの一例の断面図である。
【図１４】本発明に用いる別のブロー成形用プリフォームの断面図である。
【図１５】本発明に用いる別のブロー成形用プリフォームの断面図である。[0001]
[Industrial application fields]
The present invention relates to a bottle formed by biaxial stretch blow molding of a thermoplastic resin. More specifically, the bottle has a specific orientation at the bottom, and has environmental resistance (ESC) resistance, impact resistance at the bottom, The present invention relates to a bottle excellent in strength and appearance characteristics.
[0002]
[Prior art]
Stretch blow-molded plastic containers made of polyester, polypropylene, etc., especially polyester containers, are now popular, and liquids such as liquid detergents, shampoos, cosmetics, soy sauce, sauces, etc. due to their excellent transparency and moderate gas barrier properties. In addition to products, it is widely used in carbonated beverages such as beer, cola, and cider, other beverage containers such as fruit juice and mineral water, dessert cups, miso containers, and cup products.
[0003]
The production methods of polyester bottles are roughly classified into a hot parison method and a cold parison method. In the former hot parison method, a preform formed by injection molding of polyester is stretch blow molded in a hot state without being completely cooled. On the other hand, in the latter cold parison method, a supercooled bottomed preform, which is considerably smaller than the final container and the polyester is amorphous, is formed in advance by injection molding of polyester, and this preform is preliminarily maintained at its stretching temperature. A method of heating and drawing in the axial direction in the blow mold and blow drawing in the circumferential direction is adopted.
[0004]
As the shape of the bottomed preform, there is a mouth-neck portion corresponding to the mouth-neck portion of the container and a bottomed cylindrical portion to be stretch blow molded, and the shape as a whole for a vertically long container is a test tube. The ones are common. In the mouth and neck, for example, an engagement means with an opening end for sealing or a lid is formed. In addition, a gate portion that protrudes outward from the center of the bottom portion is necessarily formed on the bottom portion because of the necessity of injection molding.
[0005]
[Problems to be solved by the invention]
In polyester bottles using the conventional stretch blow molding method, the most disturbed part of orientation and crystallinity is the bottom of the bottle, especially its central part. Yes.
[0006]
For example, even if the body of a PET bottle is completely transparent, only the gate portion of the preform and its periphery may be whitened, which is generally called gate whitening. This phenomenon is said to occur because PET resin that has undergone flow orientation distortion has the property of being easily crystallized.
[0007]
In order to prevent this gate whitening, it is necessary to perform molding under conditions such that residual strain due to flow does not increase. For example, it is known that gate whitening is less likely to occur as the gate diameter is larger and the injection pressure is lower. It has been.
However, if the gate diameter is large, the diameter of the remaining gate at the bottom of the bottle also becomes large, resulting in poor appearance characteristics, and if the injection pressure is low, the molding of the preform becomes worse and the injection residence time becomes longer. This causes a problem that productivity decreases.
[0008]
The inventors of the present invention have found that the flow orientation distortion generated during the injection molding of the preform is at a low level so as not to cause the above-mentioned gate whitening, and the uniform and uniform stretching of the bottom of the bottle still formed Have been found to adversely affect the performance, resistance to environmental stress cracking and bottle strength.
[0009]
That is, the object of the present invention is that the bottom is substantially free of flow orientation distortion, and the bottom is stretched uniformly and uniformly, resulting in improved impact resistance and buckling strength at the bottom, and at the center of the bottom. An object of the present invention is to provide a bottle that has excellent environmental crack resistance, does not cause crazing or whitening during storage, and has excellent appearance characteristics.
[0010]
[Means for Solving the Problems]
According to the present invention, in a bottle formed by biaxial stretch blow molding of a preform formed by compression molding of a thermoplastic resin, the bottle having a mouth portion, a shoulder portion, a trunk portion, and a bottom portion, the preform Is below There is provided a bottle characterized in that it is formed by compression molding a molten mass in which the temperature drop of the part is suppressed, and the center of the bottom part is substantially outside the influence of residual strain due to flow orientation.
This bottle is a biaxial preform formed by compression molding a cylinder or a shape close to a cylinder, which is supplied to a mold by gripping a portion above the center of gravity of the melt with a gripping member. The preform is preferably formed by stretch blow molding, and the preform is preferably a preform having a difference between the maximum thickness and the minimum thickness (tmax-tmin) in the circumferential direction of the body portion of 0.07 mm or less. In the case of a thermoplastic polyester, the center of the bottom of the bottle is diffusely scattered at 2θ = 19.45 to 20.50 ° when X-ray (Cu-α) is incident on the wall thickness direction and measured. In addition to having a peak, the peak position (A) of the outer surface side portion of the bottom center portion is lower than the peak position (B) of the inner surface side portion of the bottom center portion, and the difference (B−A) is 0. The half-value width (C) of the X-ray diffuse scattering peak at the outer surface side portion of the bottom center portion is 15 degrees or more and larger than the half-value width (D) of the X-ray diffuse scattering peak at the inner surface side portion of the bottom center portion. And the difference (C−D) is preferably 0.10 ° or more.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
In FIG. 1 showing an example of the bottle of the present invention, this bottle is composed of a mouth neck 1 formed by biaxial stretch blow molding of a thermoplastic resin, a shoulder 2 connected to the mouth neck, a body 3 and a bottom 4. It is made up. In this specific example, the bottom part 4 has a self-standing structure, and is composed of an annular grounding part 5 around the bottom part and a central dome part 6 bulging upward. It is a remarkable feature that the bottom center 7 of this bottle is substantially outside the influence of residual strain due to flow orientation (substantially no residual strain due to flow orientation).
[0012]
In other words, as already pointed out, polyester bottles from preforms formed by conventional injection molding always have residual strain due to flow orientation at the bottom center derived from the remainder of the gate. It has a negative effect on resistance and appearance characteristics.
[0013]
The flow orientation distortion can be confirmed by the phenomenon of gate whitening when it is remarkable, but means for effectively detecting this is not known in other cases.
The present inventors succeeded in detecting the flow orientation strain at the center of the bottom of the bottle, and compression molding of thermoplastic resins such as polyester and polypropylene, particularly one-stage compression molding, so that this fluid orientation strain does not substantially occur. By molding a preform and biaxially stretching blow-molding the preform, the bottom is stretched uniformly and uniformly, and there is little flow orientation distortion at the bottom, resulting in impact resistance and buckling at the bottom. It has become possible to produce a bottle having improved strength, excellent resistance to environmental cracking at the center of the bottom, no crazing or whitening during storage, and excellent appearance characteristics.
[0014]
According to the study by the present inventors, the flow orientation strain existing at the center of the bottom of the bottle can be detected as the presence of an oriented mesophase in the thickness direction of the center of the bottom.
[0015]
It is known that a thermoplastic polyester represented by polyethylene terephthalate (PET) has an oriented mesophase in addition to an amorphous phase and a crystalline phase (Journal of the Fiber Society, Vol. 40, No. 6). (1984) p49-56).
In other words, in the crystal phase of PET, regularity is also observed in the arrangement of benzene rings in the molecule, but in this oriented intermediate layer, there is no regularity in the arrangement of benzene rings, but unlike the amorphous phase. In the orientation in the fiber axis direction, a structure having a certain periodicity is recognized. In the case of oriented fibers, this periodic structure is detected as an X-ray diffuse scattering peak having a peak at 2θ = 21 ° in X-ray diffraction.
[0016]
In the bottle of the present invention, when it is made of polyester resin, the center of the bottom of the bottle is measured with X-ray (Cu-α) incident in the direction of the thickness of the vessel wall, and 2θ = 19.45 to 20.50 °. And the peak position (A) of the outer surface side portion of the bottom center portion is at a lower angle than the peak position (B) of the inner surface side portion of the bottom center portion, and the difference (B−A). Is not less than 0.15 degrees, and the half-value width (C) of the X-ray diffuse scattering peak at the outer surface side portion of the bottom center portion is half-width (D) of the X-ray diffuse scattering peak at the inner surface portion of the bottom center portion (D ) And the difference (C−D) is 0.10 degree or more.
[0017]
In FIG. 2 showing a sample for X-ray diffraction image measurement, the bottom of the bottle including the bottom center 7 is cut into a width of 1 mm in the thickness direction, and the surface is polished to prepare a sample 70. An inner surface portion 72 is set at a position of 100 μm from the inner surface 71 of the sample, an outer surface portion 74 is set at a distance of 100 μm from the outer surface 73, and the inner surface portion 72 and the outer surface portion 74 are centered. A central portion 75 is set.
[0018]
In FIG. 3 showing how to measure an X-ray diffraction image, an X-ray 76 is incident on the inner surface side portion 72 (or outer surface side portion 74) of the sample 70 at a Bragg angle θ in the thickness direction, and the Bragg angle θ The counter 78 detects the X-rays 77 scattered by. The dot diameter of the incident X-ray is 100 μm, and the details of the measurement conditions are as described in the examples described later.
[0019]
FIG. 4 is an explanatory diagram showing how to obtain the peak position A ° (or B °) and the half-value width C ° (or D °) from the diffraction intensity distribution image of X-ray diffuse scattering. That is, the half-value width C ° is an interval between two points where the parallel line and the peak intersect when a parallel line is drawn on the horizontal axis through a point of half the intensity at the peak position A °. is there.
[0020]
FIG. 5 shows the relationship between the peak position of X-ray diffuse scattering and the half-value width of this peak at the bottom center of various polyester bottles.
FIG. 6 shows the relationship between the peak position difference (B-A) and the half-value width difference (C-D) measured as described above for the polyester bottle.
[0021]
From these results, the following is clear. In the following description, since the portion in question is limited to the bottom center portion of the bottle, the position is simply specified as the outer surface portion and the inner surface portion.
I. That is, in the bottle formed from the preform by injection molding, the peak position A of the outer surface side portion exceeds 20.50 °, but in the bottle according to the present invention, the peak position B of the inner surface side portion is of course, The peak position A on the outer surface side is also included in the range of 19.45 to 20.50 °.
II. In the bottle according to the present invention, the peak position (A) of the outer surface side portion is at a lower angle than the peak position (B) of the inner surface side portion of the bottom center portion, and the difference (B−A) is 0.15 degrees or more. In contrast, many bottles from known injection molded preforms and bottles from compression molded preforms with uneven thickness do not meet this requirement.
III. Furthermore, in the bottle according to the present invention, in addition to the above-mentioned requirements, the half width (C) of the X-ray diffuse scattering peak is larger than the half width (D) of the X-ray diffuse scattering peak on the inner surface side, and Whereas the difference (C−D) is 0.10 ° or more, no bottle outside the scope of the present invention satisfies the above requirements II and III simultaneously.
[0022]
In general, the flow orientation strain is large at the outer surface portion where the flow direction is not obstructed and is small at the inner surface portion where the flow direction is obstructed, but at the center of the bottom of the bottle having such flow orientation strain, X-ray diffuse scattering is performed. It is believed that the peak appears on the side closer to 2θ = 21 ° in the outer surface portion and on the lower angle side in the inner surface portion. Moreover, it is believed that the half width of the X-ray diffuse scattering peak is narrower in the outer surface portion than in the inner surface portion.
[0023]
On the other hand, in the bottle according to the present invention, the peak position (A) of the outer surface side portion is lower than the peak position (B) of the inner surface side portion, and the difference (B−A) is 0.15 degrees. In addition, the half width (C) of the peak at the outer surface portion is larger than the half width (D) of the peak at the inner surface portion, and the difference (C−D) is 0.10 degrees or more. The fact that there is substantially no flow orientation strain at the bottom center.
[0024]
As described above, the bottle according to the present invention has less fluid orientation distortion at the bottom, and the bottom is stretched uniformly and uniformly. As a result, the impact resistance and buckling strength of the bottom are improved. It is excellent in environmental cracking resistance, does not cause crazing or whitening during storage, and has the advantage of excellent appearance characteristics.
[0025]
[resin]
In the present invention, any plastic material can be used as long as it can be stretch blow molded and thermally crystallized, but thermoplastic polyester, particularly ethylene terephthalate thermoplastic polyester is advantageously used. . Of course, other polyesters such as polybutylene terephthalate and polyethylene naphthalate, or blends with polycarbonate, arylate resin, etc .; acrylic-butadiene-styrene copolymer (ABS resin); polyacetal resin; nylon 6, nylon 66, those Nylon such as copolymer nylon; acrylic resin such as polymethyl methacrylate; polypropylene; polystyrene, etc., low-, medium-, or high-density polyethylene, ethylene-propylene copolymer, ethylene-butene-1 copolymer Styrene-butadiene thermoplastic elastomers, cyclic olefin copolymers, and the like can also be used.
These plastics can be blended with various additives such as a colorant, an ultraviolet absorber, a release agent, a lubricant, a nucleating agent and the like within a range that does not impair the quality of the product.
[0026]
The ethylene terephthalate-based thermoplastic polyester used in the present invention occupies most of the ester repeating units, generally 70 mol% or more, particularly 80 mol% or more of ethylene terephthalate units, and has a glass transition point (Tg) of 50 to 90. Thermoplastic polyesters having a melting point (Tm) of 200 to 275 ° C., particularly 220 to 270 ° C., at 55 ° C., in particular 55 to 80 ° C., are preferred.
[0027]
Homopolyethylene terephthalate is preferred in terms of heat and pressure resistance, but a copolyester containing a small amount of ester units other than ethylene terephthalate units can also be used.
[0028]
Dibasic acids other than terephthalic acid include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; succinic acid, adipic acid, sebacic acid, dodecanedioic acid, etc. 1 type or combination of 2 or more types of diol components other than ethylene glycol include propylene glycol, 1,4-butanediol, diethylene glycol, 1,6-hexylene glycol, cyclohexane di 1 type, or 2 or more types, such as methanol and the ethylene oxide adduct of bisphenol A, are mentioned.
[0029]
Also, it is possible to use a composite material in which ethylene terephthalate-based thermoplastic polyester is blended with about 5% to 25% of polyethylene naphthalate, polycarbonate, polyarylate, etc. having a relatively high glass transition point, so that it can be used at a relatively high temperature. The material strength can be increased.
Further, polyethylene terephthalate and the above-mentioned material having a relatively high glass transition point can be laminated and used.
[0030]
The ethylene terephthalate-based thermoplastic polyester to be used should have at least a molecular weight sufficient to form a film, and an injection grade or extrusion grade is used depending on the application. The intrinsic viscosity (IV) is generally in the range of 0.6 to 1.4 dL / g, particularly 0.63 to 1.3 dL / g.
[0031]
[Preform and its manufacture]
In the present invention, it is preferable to use a preform formed by compression molding of a thermoplastic resin, particularly by one-stage compression molding.
In other words, it has already been described in detail that a bottle having excellent characteristics can be obtained at the bottom of a preform manufactured by the compression molding method with substantially no flow orientation distortion. Many advantages are also obtained.
[0032]
In compression molding, unlike injection molding, processing at a relatively low temperature is possible. In particular, since a preform for blow molding can be obtained by one heat melting and compression molding, the degree of thermal deterioration of the resin is small. A blow bottle with excellent physical properties can be produced.
[0033]
That is, a cheaper resin can be used to produce a blow molded product having the same physical properties (strength / impact resistance), and a blow bottle with more excellent physical properties can be produced when using the same raw material resin. In addition, resin viscosity is high, and even resin raw materials that are unsuitable for injection molding can be easily molded into bottles through preforms, and it is also possible to obtain large blow bottles that require particularly high impact resistance. .
[0034]
Further, in the one-stage compression molding method, the amount of heat that the molten mass of the resin has at the time of melt extrusion of the resin is effectively used, and local cooling of this mass is prevented as much as possible, in particular, the preform bottom of the molten mass. In order to produce a preform having a uniform internal structure and excellent stretch blow moldability, it is preferable not to cool the portion that forms the resin and to prevent the movement of the resin on the mold surface during compression molding.
That is, in order for the orientation characteristics in the X-ray at the center of the bottom of the final bottle to satisfy the above-described requirements, the above conditions must be taken into consideration, and the maximum thickness in the circumferential direction of the body portion of the preform to be formed in particular. And the minimum thickness difference (tmax−tmin) is preferably 0.07 mm or less.
[0035]
For this purpose, an approximately fixed amount of molten mass formed by cutting the extrudate is fed into the female mold (cavity mold) without substantial temperature drop and the fed molten mass is immediately cast ( Core mold) is used for compression molding.
Also, during compression molding, the residual air in the mold is quickly discharged, and compression molding is performed on a preform having a bottomed body portion and a mouth portion.
[0036]
In the one-stage compression molding method, the temperature decrease of the resin after cutting into a molten lump and before it is put into a mold, the uniformity of the structure of the bottomed body to be stretch blow molded of the preform and the stretch orientation, Furthermore, it has a significant influence on the physical properties of the final blow-molded product, particularly impact resistance. The influence of this temperature decrease is particularly noticeable at the lower part of the molten mass forming the bottom of the preform (the bottom of the final blow molded product). That is, when the lower part of the molten resin mass is locally cooled, the degree of distortion at the bottom of the preform increases, which causes poor appearance and reduced impact resistance when the final blow molded product is obtained. In the one-step compression molding method, the molten resin mass is cut from the molten mass until it is put into the mold. Temperature The above trouble can be effectively solved by suppressing the decrease in temperature, in particular, by suppressing the temperature decrease within the above time at the lower part of the molten resin lump.
[0037]
As described above, in order to suppress the temperature drop of the molten lump, the contact between the molten lump and other members is avoided, for example, except for the gripping part, after being cut into the molten lump and before being put into the mold. In particular, contact between the lower part of the molten mass and other members should be avoided as much as possible.
[0038]
In the preferred manufacturing method, for this purpose, the polyester melt is extruded parallel to the axial direction of the male mold (core) and female mold (cavity), and the cut molten mass is substantially maintained in its parallel state. Supply it in the mold as it is.
[0039]
Further, it is preferable to supply the molten mass of the resin in a cylindrical shape or a shape close to a cylindrical shape so that the molten mass can be supplied in a substantially quantitative state and the lower portion is cooled as much as possible.
[0040]
Furthermore, in order to avoid the temperature drop at the lower part of the molten mass as much as possible and to stably supply the molten mass, that is, to prevent the molten mass from collapsing, the molten mass is placed above the center of gravity. It is preferable to grip, move from the cutting position to the mold position, and supply it into the mold.
[0041]
In order to avoid cooling of the molten mass, it is better to start from the cutting to the mold and to start the molding after being put into the mold as quickly as possible. Generally, the cutting to the mold is within 1 second. It is recommended that the process be performed within 0.5 seconds from the start of molding to the start of molding.
[0042]
In the one-stage compression molding method, it is very important to perform compression molding while removing residual air at the bottom of the mold or in the vicinity thereof. That is, under the condition where air remains in the mold, wrinkles tend to occur in a portion attached to the mold or in the vicinity thereof. On the other hand, if the air is quickly removed after the molding is started, the generation of wrinkles can be effectively prevented. The cause of wrinkles is thought to be the fact that the close contact part and non-adhesion part on the mold surface are formed at a fine interval, which is believed to be a phenomenon peculiar to compression molding. Then, it seems that the mold surface and the resin are brought into close contact with each other to form a vessel wall without wrinkles.
[0043]
In order to eliminate the residual air on the surface of the female mold, it is only necessary to form an escape path from the molding site to the outside with respect to the residual air, and the means thereof is not particularly limited. A mold having a gap or a porous portion is preferable. It is particularly effective to forcibly remove residual air with an external vacuum pump or the like at the start of molding.
[0044]
In the one-stage compression molding method, the shape and structure of the female mold and the male mold are not particularly limited as long as the bottomed body part and the mouth part can be molded, but in general, as a male mold, Using a core mold and a driven mold provided around the core mold so as to be openable and closable coaxially with the core mold, a bottomed taper portion between the core mold and the female mold (cavity mold) It is desirable that the mouth part is formed by the core mold and the driven mold. In this case, the driven mold is driven back and forth together with the core mold, but the driven mold is always biased toward the female mold by a biasing means such as a spring, but the bottom dead center of the core mold. The core mold and the driven mold are always kept in a constant contact state.
For this reason, even when there is a slight variation in the amount of molten resin, the preform always has a constant height (height from the bottom inner surface to the top of the mouth) and the mouth shape that is important for sealing is always constant. Will be formed. Moreover, the fluctuation | variation of the quantity of a molten resin lump can be absorbed now by the meshing of a core metal mold | die and a female mold (cavity metal mold | die), ie, the thickness of the bottomed trunk | drum part of the preform formed.
Generally, a support ring for supporting the bottle at the time of filling the contents is generally provided on the outer periphery of the mouth of the bottle, and this mouth structure is formed at the stage of the preform. Then, at the time of this preform molding, an annular groove is formed on the inner peripheral edge of the lower surface of the support ring. By this annular groove, the fluctuation of the molten resin mass is absorbed as the fluctuation of the height of the annular groove, the fluctuation of the thickness of the preform is prevented, and the structure of the preform wall becomes uniform. The annular groove remains in the bottle formed from this preform, and naturally it was also useful for suppressing fluctuations in the thickness of the bottle.
[0045]
The molten resin mass can be supplied almost quantitatively by melting and extruding the resin through an extruder or a gear pump, and cutting it at a certain timing, but the resin supply amount is still within a certain range. Variations are inevitable. The above-described molding method can easily absorb this variation.
[0046]
The one-stage compression molding method has an advantage that the molding force itself is generally considerably small even if a certain amount of pressure is required to prevent sink marks during molding. For this reason, compared with an injection molding apparatus, there exists an advantage that apparatus itself can be reduced in size considerably and apparatus cost can be reduced.
[0047]
The preform for blow molding used in the present invention is formed by compression molding of a melted material such as polyester or polypropylene, and has a mouth portion having a shape and size corresponding to the mouth portion of the final molded body, and a bottomed body to be blow-molded. However, the closed bottom has substantially no distortion of the flow orientation and no gate.
[0048]
The gate part existing in a bottomed preform for injection molding has many problems in terms of productivity, manufacturing cost, and final blow molded product characteristics. In the preform used in the present invention, Since there is no gate part, the cutting process is unnecessary, there is no generation of scrap resin, and the center of the bottom is smooth and homogeneous, and there are no advantages that cause crystallization or whitening. is there.
[0049]
Further, the blow molding preform used in the present invention has a feature that there is no wrinkle at the bottom or in the vicinity thereof in relation to the molding performed under the above-mentioned strict temperature control and residual air exclusion conditions. ing.
[0050]
When the above preform for blow molding is used, there is no flow orientation distortion or gate at the bottom, and there is no wrinkle, and the smoothness and the uniformity of the structure are outstanding. Blow molded products have the advantage that they are remarkably excellent in appearance characteristics and impact resistance at the bottom.
[0051]
In addition, this preform has the advantage that the degree of thermal deterioration of the resin is small as described above, and a blow molded product excellent in various physical properties such as tensile strength, pressure strength, impact resistance, and heat resistance can be produced. ing.
[0052]
[Compression molding equipment]
In FIG. 7 (plan view) and FIG. 8 (side view) showing the overall arrangement of the apparatus used for the one-stage compression molding method, this apparatus is roughly composed of a resin extrusion apparatus 10, a molten lump cutting and feeding apparatus. 20 and a preform compression molding apparatus 30.
[0053]
The extrusion apparatus 10 includes an extruder main body 11 for melting and kneading a resin, and the powder or pellets of the resin to be molded are held in a dry state on the inlet side of the main body and supplied to the extruder main body. A vacuum hopper 12 is provided, and on the outlet side of the main body, a suction vent 13 for sucking and removing decomposition gas in the resin and a die head 14 for receiving the molten resin to be pushed out are provided.
The die head 14 is connected to the extruder nozzle 16 via a pipe 15, and a gear pump 17 for supplying a fixed amount of molten resin may be provided between the die head 14 and the extruder nozzle 16. In FIG. 8, the gear pump 17 is omitted to avoid complication.
[0054]
As shown in FIGS. 9 and 10, the molten lump cutting and feeding device 20 is a combination of a cutter 22 provided on the rotating turret 21 and an outer gripping member 23 and an inner gripping member 24 for gripping the molten lump. It is made up of. The cutter 22 is provided so as to be inclined with respect to the radial direction of the turret 21 and, as the turret 21 rotates, the resin melt 18 extruded from the extruder nozzle 16 can be cut in a direction perpendicular to the extrusion direction. ing.
The outer gripping member 23 includes a portion extending in the radial direction of the turret and an outer portion extending in the circumferential direction, and is fixed to the turret 21. On the other hand, the inner gripping member 24 is provided so as to be movable with respect to the outer gripping member 23 in the radial direction of the turret.
[0055]
The rotary turret 21 of the cutting and feeding device 20 is provided so as to pass below the extruder nozzle 16 of the extrusion device 10 and above the female mold 32 of the compression molding device 30. The molten material 18 is gripped by 23 and 24 and cut by the cutter 22, and the molten mass 19 is moved upward in the gripping state by the gripping members 23 and 24 and melted by releasing the gripping members 23 and 24. The lump 18 is put into the female mold 32.
[0056]
7 to 10, in this one-stage compression molding apparatus, the thermoplastic resin melt 18 is extruded in parallel with the axial direction of the male mold 33 and the female mold 32, and the cut molten mass 19 is substantially in a parallel state. Being supplied into the female mold 32 while being maintained above, the molten lump 18 being supplied in a substantially quantitative state by the gear pump 17, and the molten lump 19 of the resin being supplied in a shape close to a cylinder, or It is apparent that the molten mass 19 is gripped by the gripping members 23 and 24 at a position above the center of gravity, moved from the cutting position C to the mold position M, and supplied into the mold 32.
[0057]
The compression molding apparatus 30 is roughly composed of a combination of a rotating turret 31 and a large number of female molds (cavities) 32 and male molds (cores) 33 arranged around the rotating turret.
The rotating turret 31 is provided with the previously described melt lump cutting and feeding mechanism 20 and a blow blow preform take-out mechanism 34.
[0058]
The rotating turret 31 is supported by a vertical shaft 36 in a horizontal direction and rotatably with respect to the machine base 35, and is driven and rotated by a motor 37 and a drive transmission mechanism 38.
A large number of combinations (sets) of the female mold 32 and the male mold 33 are provided on the outer peripheral upper surface of the rotating turret 31. That is, the female mold 32 is fixed on the gantry 39, while the male mold 33 is coaxial with the female mold 32 by a vertical drive member 42 and a horizontal support member 41 by a lift drive mechanism 42 such as a hydraulic mechanism. And can be moved up and down.
[0059]
In FIG. 11 and FIG. 12 showing the detailed structure of the female mold 32 and the male mold 33 and the molding process step by step, the female mold 32 has a cavity 43 and the bottom of the female mold 32 excludes residual air. The vent portion 45 is also provided at the vent portion 44 and the connecting portion between the bottom portion and the tapered portion.
An upward small protrusion 46 is formed around the upper portion of the cavity 43. The operation will be described later.
Further, a ring-shaped driven member 47 slidable coaxially with the female die is provided around the female die 32. The driven member 47 has a shaft 48 extending downward, and a stopper is provided at the lower end thereof. 49 is formed, and the stopper 49 is accommodated in the lower recess 50 of the female mold 32. Thus, it will be appreciated that the stopper 49 can be raised and lowered between the upper and lower surfaces of the lower recess 50. The stopper 49 is biased upward by means such as a spring (not shown). Further, an engagement taper portion 51 whose diameter increases upward is formed on the upper inner peripheral surface of the driven member 47.
[0060]
On the other hand, the male mold 33 includes a core mold 53 fixed to a support member 52 that can move up and down. The core mold 53 includes a portion 54 for forming the mouth top surface of the preform, a portion 55 for forming the inner peripheral surface of the mouth, and a portion for forming the inner surface of the bottomed tapered body. 56.
[0061]
Around the core mold 33, a driven mold 57 provided coaxially with the core mold 33 so as to be openable and closable is positioned. The driven mold 57 is fixed to a driven support member 58. Although not shown, a push spring is provided between the support member 52 and the driven support member 58 so that the driven mold is moved downward. Energized.
The lower inner peripheral surface of the driven mold 57 is provided with a portion 59 for forming the mouth inner peripheral surface of the preform, while the lower outer peripheral surface is formed with an engaging taper portion 60 whose diameter decreases downward. Yes.
[0062]
In the compression molding apparatus shown in FIGS. 11 and 12, the pressing force (absolute value) of each member is set as follows in order to smoothly perform each operation.
The pressing force of the male mold 33> the pressing force of the driven member 47> the pressing force of the driven mold 57
[0063]
The molding operation by the above apparatus is performed as follows.
(A) Melt extrusion process:
The thermoplastic resin is supplied to the vacuum hopper 12 of the extruder 10 and is melted and kneaded by the screw when it is blown in the extruder body 11 in a state where moisture absorption from the outside air is blocked in a vacuum. Then, a fixed amount is supplied to the nozzle 16 by the gear pump 17 and is extruded from the nozzle 16 into a cylindrical shape.
[0064]
(B) Cutting and feeding process:
The resin stream 18 melt-extruded from the nozzle 16 is cut into a molten lump 19 having a cylindrical shape or a shape close to a cylinder by a cutter 22, and the molten lump 19 is held by holding members 23 and 24, and is cut from a cutting position C. It moves along with the rotation of the turret without causing a substantial temperature drop to the supply position M to the female mold 32 and is put into the female mold 32.
[0065]
(C) Compression molding process:
In the approach step shown in I of FIG. 11, the cavity mold 43 and the core mold 53 are still open, and the molten mass 19 is stored in the cavity 43 in an upright state. The core mold 53 is starting to descend.
[0066]
In the cavity clamping process shown in II of FIG. 11, the core mold 53 is lowered into the cavity, and the molten resin 19 ′ is almost filled in the space defined by the cavity 43 and the core 53. Simultaneously with the start of compression molding, the residual air in the cavity is quickly released to the outside through the vent portions 44 and 45.
At the same time, the driven mold 57 is also lowered and contacts the driven member 47, but there is still a gap between the upper surface of the driven support member 58 and the lower surface of the male support member 52.
[0067]
In the core mold clamping step shown in III of FIG. 11, the core mold 53 is further lowered, and the upper surface of the driven support member 58 and the lower surface of the male mold support member 52 are in contact with each other. Accordingly, the molten resin 19 ′ in the cavity flows into a space defined by the core mold 53 and the driven mold 57.
[0068]
In the solidification process at a high temperature shown in IV of FIG. 11, the core mold 53 is further lowered slightly, and the driven member 47 is also lowered accordingly, and is defined by the cavity 43, the core mold 53 and the driven mold 57. The space to be filled is filled with resin.
[0069]
In the solidification process at a low temperature shown in FIG. 11V, the resin volume shrinkage, that is, sink occurs due to a decrease in the resin temperature, and the distortion caused by this volume shrinkage is caused by the compressive force applied to the male mold (core 53). Can be absorbed.
In this case, it is of course necessary to move the core mold 53 and the cavity 43 so as to engage with each other. However, by engaging the small protrusion 46 on the cavity 43 with the driven mold 57, the volume shrinkage is absorbed. Thus, a blow-molding preform without distortion can be obtained. The portion where the upward small protrusion 46 is engaged with the driven mold 57 is the aforementioned annular groove of the preform.
[0070]
The process of taking out the compression-molded preform is shown in steps I to V of FIG. Step I shows the stage where molding is completed. In Steps II and II, the core mold 53 starts to rise and mold opening is started. In Step III, the core mold 53 is raised before the driven mold 57, and the core is removed from the molded preform 60. In Step IV, the core mold 53 is further raised, and the preform 60 is taken out of the cavity 43. In Step V, the driven mold 57 moves to a radially outward position (position indicated by a dotted line) at the re-raising position of the core mold, and the held blow molding preform 60 is released.
[0071]
[Molding condition]
The melt extrusion temperature of the thermoplastic resin (die head temperature) varies depending on the type of resin, but in the case of a thermoplastic polyester resin, it is generally Tm + 100 ° C. to Tm + 10 ° C. based on the melting point (Tm) of the thermoplastic polyester resin. In particular, it is preferably in the range of Tm + 40 ° C. to Tm + 20 ° C.
If the temperature is lower than the above range, the shear rate may become too high to form a uniform melt extrudate, whereas if the temperature is higher than the above range, the degree of thermal degradation of the resin will increase. Or the drawdown tends to be too large.
[0072]
The weight of the molten mass to be cut, that is, the basis weight, is naturally determined by the final blow bottle, but it is generally preferable to select an appropriate value depending on the required strength from the range of 100 to 2 g, particularly 40 to 10 g. .
[0073]
In addition, it is advantageous in terms of handling that the molten mass is cylindrical or a shape close to it, but the ratio (H / D) of the diameter (D) to the height (H) of the molten mass is generally 0.8. The range of 4 to 4 is advantageous in that the temperature reduction of the molten mass is prevented as much as possible and the molten mass can be easily put into the female mold.
That is, when the H / D is outside the above range, the surface area of the molten mass tends to increase, and the temperature tends to decrease.
[0074]
An arbitrary cutter is used for cutting the molten resin lump, but one that can prevent the resin from sticking is suitable. For example, surface treatment such as shot blasting of the tool surface is particularly effective.
[0075]
As the gripping member for moving the molten resin lump, a member made of a material having a good thermal insulation property and having a contact area with the resin as small as possible is preferably used.
The process from cutting the molten resin mass to putting it into the mold should be performed promptly and within the time already pointed out.
[0076]
As the compression mold, one having a fine gap or porous part formed at the bottom or in the vicinity thereof is used, and the fine gap divides the bottom of the female mold or the vicinity into several pieces, and these pieces are used. It can be formed by forming a fine gap for excluding air between them or by forming a hole for excluding air in the mold. The porous portion can be used by, for example, processing a sintered metal or the like.
[0077]
The surface temperature of the compression mold may be a temperature at which the molten resin is solidified. For example, in the case of polyester, a temperature range of 65 to 30 ° C. is appropriate. In order to maintain the surface temperature of the mold within the above range, a medium such as cooling water or conditioned water may be passed through the mold.
[0078]
One of the features is that the molding force required for compression molding may be quite small. Although the specific molding force varies considerably depending on the type of resin and the size of the preform for blow molding, generally, a molding force of 800 to 50 kgf, particularly 600 to 150 kgf is appropriate.
[0079]
The one-stage compression molding described above provides a blow molding preform that does not have flow orientation distortion at the bottom and does not require any gate or other trimming operations. It can be used and has many advantages in terms of process simplification and productivity.
[0080]
[Preforms for blow molding]
In FIG. 13 showing the blow molding preform of the present invention, the preform 60 is roughly divided into a mouth portion 61 and a tapered bottomed body portion 62. The mouth portion 61 is a mouth portion of a bottle that is a final molded product, and a lid locking portion 63 and a support ring 64 necessary for sealing with the lid are formed on the outer periphery of the mouth portion 61. The bottomed body portion 62 is a portion to be stretch blow molded, and includes a tapered side wall portion 65 and a downward convex bottom portion 66 smoothly connected thereto. As already pointed out, the bottom 66 is substantially free from flow orientation distortion and has no gate residue or wrinkles. The mouth part 61 and the bottomed body part 62 are smoothly connected via a connection part 67.
It will be apparent that an annular groove 68 is formed in the inner peripheral edge of the lower surface of the support ring 64.
[0081]
The tapered side wall portion 65 and the bottom portion 66 have a certain preferable range with respect to their dimensions and shape in terms of compression moldability and formability at the time of final stretch blow. In general, the outer surface of the side wall portion 65 is a truncated cone surface, and the outer surface of the bottom portion 66 is preferably a partial spherical surface that is smoothly connected to the truncated cone surface in terms of moldability. The shape is acceptable.
On the other hand, the inner surface of the side wall portion 65 is also a truncated cone surface connected via an inclined portion 66 whose thickness increases from the inner periphery of the connection portion.
The taper angle (θ) of the outer surface of the side wall is preferably 0.5 to 89.5 ° from the viewpoint of moldability.
FIG. 14 shows a cross section of the blow molding preform when the taper angle is 0.8 °, and FIG. 15 shows a cross section of the blow molding preform when the taper angle is 45 °.
The wall thickness of the side wall portion 65 and the bottom portion 66 may be uniform except for the inclined portion 67 described above, and may vary in thickness. For example, the side wall portion is thicker toward the bottom portion. It may have a distribution that increases.
[0082]
The above preform can be used for stretch blow molding as it is, and in order to give heat resistance and rigidity to the mouth part of the preform, the mouth part may be crystallized by heat treatment and whitened at the stage of the preform. Alternatively, after the preform is formed into a bottle by biaxial stretch blow molding described later, the mouth portion of the obtained plastic bottle may be crystallized and whitened.
[0083]
[Stretch blow molding]
The preform is heated to a stretching temperature, and the preform is pulled and stretched in the axial direction and blown and stretched in the circumferential direction to produce a bottle.
It should be noted that the preform molding and its stretch blow molding can be carried out by the cold parison method and can also be applied to the hot parison method in which the stretch blow molding is performed without completely cooling the preform by compression molding. It should be.
[0084]
Prior to stretch blow molding, if necessary, the preform is preheated to a stretchable temperature by means of hot air, an infrared heater, high frequency induction heating or the like. In the case of polyester, the temperature range is 85 to 120 ° C., particularly 95 to 110 ° C.
[0085]
This preform is supplied into a publicly known stretch blow molding machine, set in a mold, stretched in the axial direction by pushing a stretching rod, and blow stretched in the circumferential direction by blowing fluid. .
[0086]
The draw ratio in the final bottle is suitably 1.5 to 25 times in terms of area magnification, and among these, the draw ratio in the axial direction is 1.2 to 6 times, and the draw ratio in the circumferential direction is 1.2 to 4.5. It is better to double.
[0087]
The stretch blow molded bottle can be heat-set by a means known per se. The heat setting can be performed by a one mold method in a blow molding die, or can be performed by a two mold method in a heat fixing die separate from the blow molding die. The temperature for heat setting is suitably in the range of 100 to 200 ° C.
[0088]
【Example】
The invention is further illustrated by the following examples.
[Manufacture of containers]
A container was manufactured in the following manner and subjected to the following experiment.
[0089]
(1) Preform compression molding
Crane which rotates polyethylene terephthalate resin EFS-7H manufactured by Kanebo Synthetic Co., Ltd. with a dryer and extrudes vertically from a nozzle with a diameter of 22 mm using an extruder with a diameter of 65 mm and L / D of 27 and rotates horizontally. The molten resin is cut horizontally to form a molten mass with a weight of 20 g, immediately transported, and dropped vertically onto the female mold in the molding machine rotating in synchronization with the cutter rotation, and the mold is moved at high speed. At the same time, it is compressed while discharging residual air in the mold, and after cooling and solidifying for about 12 seconds while applying a force of about 700 Kgf, the mold is opened, the diameter is 38 mm, the height is 63 mm, the average thickness is 3 mm, and the weight is 20 g A preform for blow molding was obtained.
[0090]
(2) Preform injection molding
Using an injection molding machine (FE-160, Nissei Plastic Industry Co., Ltd.)
Temperature setting: C1 / C2 / C3 / RS nozzle / nozzle / HR = 275/285/285/285/290/290
Cycle time: 25.9 seconds
A preform was molded in the same manner as described above except that the molding was performed.
[0091]
(3) Stretch blow molding of bottles
After heating these preforms to 110 ° C. with a stretch blow machine, the preforms are stretched longitudinally in a blow mold and then blow-molded with high-pressure air of 35 atm. The height is 140 mm, the trunk diameter is 67.5 mm, A bottle with an internal volume of 380 ml was obtained.
[0092]
[Test method]
(1) Storage test
Ten thermoplastic polyester biaxially stretched blow bottles were kept empty for 3 weeks under conditions of 30 ° C. and 90% RH. After storage, the center of the bottom of the bottle was visually observed for the occurrence of crazing and whitening. The result was expressed by the number of occurrences of crazing and whitening.
(2) Axial load measurement
Use a TENSILON (UCT-5T) (manufactured by Orientec Co., Ltd.) for the axial load strength of the bottle in which 350 ml of water was filled in a thermoplastic polyester biaxially stretched blow bottle and sealed with a cap. Measured at a crosshead speed of 50.0 mm / min to determine the yield point strength.
(3) X-ray measurement
The center portion of the bottom of the thermoplastic polyester biaxially stretched blow bottle was cut into a thickness of 1 mm, and the diffraction peak was measured using micro X-ray diffraction (PSPC-150C) (manufactured by Rigaku Corporation). The direction of the sample was set such that the bottom thickness direction was the height direction of the measurement surface.
Measurement conditions are tube voltage 30 KV, tube current 100 mA, collimator 100 μm, measurement time 1000 seconds, and the measurement location is 100 μm away from the inner and outer surfaces, and three points from the inner and outer surfaces as the measurement center. Measurements were made. After the measurement, integral intensity calculation was performed in the range of 10.071 degrees to 30.071 degrees to obtain the peak position and the half width.
[0093]
[Example 1]
A preform with a basis weight of 20 g was formed by compression molding. The thickness distribution in the circumferential direction of the body of the preform was uniform (maximum thickness−minimum thickness = 0.07 mm or less), and this was biaxially stretch blow molded to obtain a bottle. The difference in thickness (maximum thickness−minimum thickness) in the circumferential direction of the body portion of the bottle was about 0.06 mm or less. When this bottle was subjected to a storage test, no crazing or whitening occurred in all of the ten bottles, and the appearance was the same as before the storage test. Moreover, in the axial load measurement, the yield point strength was 46.0 kgf, satisfying the performance as a beverage bottle.
[0094]
[Example 2]
A preform with a basis weight of 20 g was formed by compression molding and injection molding.
Preforms manufactured by compression molding have a uniform thickness distribution in the circumferential direction of the body (maximum thickness-minimum thickness = 0.07 mm or less) and non-uniformity (maximum thickness-minimum thickness = 0.0). 08-0.15 mm). All preforms manufactured by injection molding had a uniform wall thickness distribution in the circumferential direction. These preforms were biaxially stretch blow molded to obtain bottles.
A bottle manufactured from a preform manufactured by compression molding and having a nonuniform distribution of thickness in the circumferential direction of the trunk part has a difference in thickness in the circumferential direction of the trunk part (maximum thickness-minimum thickness). It was 0.15-0.06 mm, and the difference in the wall thickness in the circumferential direction of the body of the bottle obtained from the other preforms was about 0.06 mm or less.
X-ray measurements of these bottles were performed. The results are shown in Table 1 below.
[0095]
[Table 1]

[0096]
[Comparative Example 1]
A preform with a basis weight of 20 g was formed by injection molding. The obtained preform was biaxially stretch blow molded to obtain a bottle. When the obtained bottle was subjected to a storage test, a craze of about 2 mm occurred at the center of the bottom of the four bottles, and whitening of about φ10 mm occurred on the other three bottles.
[0097]
[Comparative Example 2]
A preform with a basis weight of 20 g was formed by compression molding. The thickness distribution in the circumferential direction of this preform was non-uniform (maximum thickness−minimum thickness = 0.08 to 0.15 mm). This was biaxially stretch blow molded to obtain a bottle. The obtained bottle had a difference in wall thickness in the circumferential direction (maximum wall thickness-minimum wall thickness) of 0.15 to 0.06 mm.
When this bottle was subjected to a storage test, no crazing or whitening occurred in all of the ten bottles, and the appearance was the same as before the storage test. However, the yield point strength in the axial load measurement was 30.2 kgf, which did not satisfy the performance as a beverage bottle. The results of the storage test and the axial load measurement are shown in Table 2 below.
[0098]
[Table 2]

[0099]
【The invention's effect】
According to the present invention, the preform is formed by compression molding of a thermoplastic resin, in particular, one-stage compression molding, so that the flow orientation strain at the center of the bottle bottom is successfully detected and the fluid orientation strain is substantially not generated. By biaxial stretching blow molding of this preform, the bottom is stretched uniformly and uniformly, and there is little flow orientation distortion at the bottom, resulting in improved impact resistance and buckling strength of the bottom. In addition, it has become possible to produce a bottle that is excellent in environmental crack resistance at the center of the bottom, does not cause crazing and whitening during storage, and has excellent appearance characteristics.
[Brief description of the drawings]
FIG. 1 is a side view showing an example of a bottle of the present invention.
FIG. 2 is an explanatory diagram showing a sample used for X-ray diffraction.
FIG. 3 is an explanatory diagram showing a method of X-ray diffraction.
FIG. 4 is an explanatory diagram showing how to obtain a peak position and a half-value width in X-ray diffuse scattering.
FIG. 5 is a graph showing the relationship between the peak position and the half width at various bottle bottoms.
FIG. 6 is a graph showing the relationship between the difference in peak position (B-A) and the difference in half-value width (C-D) at various bottle bottoms.
FIG. 7 is a plan view showing the overall arrangement of the apparatus used in the one-stage compression molding method.
8 is a side view of the apparatus of FIG.
FIG. 9 is a plan view of an apparatus for cutting and supplying molten mass.
10 is a side view showing each stage of the apparatus of FIG. 9;
FIG. 11 is a side sectional view for explaining each stage of the compression molding process.
FIG. 12 is a side sectional view for explaining each stage of a preform removing process after compression molding.
FIG. 13 is a cross-sectional view of an example of a blow molding preform used in the present invention.
FIG. 14 is a cross-sectional view of another blow molding preform used in the present invention.
FIG. 15 is a cross-sectional view of another blow molding preform used in the present invention.

Claims (4)

Is formed by biaxial stretch blow molding of preforms formed by compression molding of a thermoplastic resin, the mouth portion, a shoulder portion, in a bottle having a body portion and a bottom portion, the preform the temperature drop of the lower portion is suppressed The bottle is formed by compression-molding the molten mass, and the center of the bottom portion is substantially outside the influence of residual strain due to flow orientation. The preform is formed by compression-molding a molten lump having a cylindrical shape or a shape close to a cylinder, which is supplied to the mold by holding a portion above the center of gravity of the molten lump with a holding member. The bottle according to claim 1. The bottle according to claim 1 or 2, wherein the preform is a preform having a difference (tmax-tmin) between a maximum thickness and a minimum thickness in a circumferential direction of the body portion of 0.07 mm or less.   Made of polyester resin, the center of the bottom of the bottle has a diffuse scattering peak at 2θ = 19.55 to 20.50 ° as measured by incident X-rays (Cu-α) in the wall thickness direction, The peak position (A) of the outer surface side portion of the bottom center portion is lower than the peak position (B) of the inner surface portion of the bottom center portion, and the difference (B−A) is 0.15 degrees or more. Moreover, the half width (C) of the X-ray diffuse scattering peak at the outer surface side portion of the bottom center portion is larger than the half width (D) of the X-ray diffuse scattering peak at the inner surface portion of the bottom center portion, and The bottle according to any one of claims 1 to 3, wherein the difference (C-D) is 0.10 degrees or more.

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