JP2016013664A - Preform - Google Patents
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- JP2016013664A JP2016013664A JP2014137534A JP2014137534A JP2016013664A JP 2016013664 A JP2016013664 A JP 2016013664A JP 2014137534 A JP2014137534 A JP 2014137534A JP 2014137534 A JP2014137534 A JP 2014137534A JP 2016013664 A JP2016013664 A JP 2016013664A
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本発明は、ブロー成形により合成樹脂製ボトルを製造する際に用いるプリフォームに関する。 The present invention relates to a preform used when producing a synthetic resin bottle by blow molding.
飲料等の液状内容物を収容するポリエチレンテレフタレート製ボトル等の合成樹脂製ボトルは、加熱されたプリフォームを金型に装着して二軸延伸ブロー成形を行うことにより形成される。 A synthetic resin bottle such as a polyethylene terephthalate bottle containing liquid content such as a beverage is formed by mounting a heated preform on a mold and performing biaxial stretch blow molding.
プリフォームは、射出成形により形成され、円筒状の口部と、口部に連続する円筒状の肩部形成部と、肩部形成部に連続する円筒状の胴部形成部と、胴部形成部を閉塞する半球状の底部形成部とを備えている（例えば特許文献１参照）。 The preform is formed by injection molding, and has a cylindrical mouth portion, a cylindrical shoulder forming portion continuous with the mouth portion, a cylindrical trunk forming portion continuous with the shoulder forming portion, and a trunk forming And a hemispherical bottom forming portion that closes the portion (see, for example, Patent Document 1).
更に、肩部形成部は、内径が下方に向かって僅かに小径となりながら下方に延びる内径略ストレート部と、内径略ストレート部の下端から次第に縮径して胴部形成部の内面に連なる内径テーパ部とを備えている。 Further, the shoulder forming portion includes an inner diameter substantially straight portion that extends downward while the inner diameter is slightly smaller, and an inner diameter taper that gradually decreases from the lower end of the inner diameter substantially straight portion and continues to the inner surface of the body forming portion. Department.
口部には、外周にキャップを螺着するためのネジ山が形成されていると共に下端外周に鍔状のサポートリングが形成されている。肩部形成部は、ブロー成形によりにサポートリングの下部から次第に拡径するボトル肩部となる。胴部形成部及び底部形成部は、ブロー成形により伸展してボトル胴部及びボトル底部となる。 The mouth portion is formed with a screw thread for screwing the cap on the outer periphery, and a hook-shaped support ring is formed on the outer periphery of the lower end. The shoulder forming portion becomes a bottle shoulder that gradually increases in diameter from the lower portion of the support ring by blow molding. The body part forming part and the bottom part forming part are extended by blow molding to become a bottle body part and a bottle bottom part.
プリフォームによりボトルを形成するときには、射出成形金型から払い出されたプリフォームを加熱装置により加熱する。このとき加熱装置は、プリフォームの口部を除く部分を加熱して軟化させる。 When forming a bottle from a preform, the preform dispensed from the injection mold is heated by a heating device. At this time, the heating device heats and softens the portion excluding the mouth portion of the preform.
次いで、加熱装置により軟化されたプリフォームをブロー成形金型の上部に形成された装着孔を介してブロー成形金型内部に挿入する。このとき、ブロー成形金型の装着孔にはプリフォームの軟化していないサポートリングが掛止され、口部がブロー成形金型から露出した状態で装着孔が閉塞される。 Next, the preform softened by the heating device is inserted into the blow mold through an attachment hole formed in the upper part of the blow mold. At this time, the support hole in which the preform is not softened is hooked on the mounting hole of the blow molding die, and the mounting hole is closed with the mouth portion exposed from the blow molding die.
続いて、プリフォームの口部からストレッチロッドを挿入し、プリフォームの底部形成部に突き当て、胴部形成部をその軸線方向に延伸しつつプリフォームの口部から胴部形成部内にブローエアを導入する。これにより、プリフォームの肩部形成部、胴部形成部、及び底部形成部が伸展し、ブロー成形金型のキャビティ形状に対応する形状のボトルが形成される。 Subsequently, a stretch rod is inserted from the mouth of the preform, abuts against the bottom forming part of the preform, and blow air is blown from the mouth of the preform into the body forming part while extending the body forming part in the axial direction. Introduce. Thereby, the shoulder part forming part, the body part forming part, and the bottom part forming part of the preform are extended, and a bottle having a shape corresponding to the cavity shape of the blow molding die is formed.
プリフォームは、ブロー成形後のボトルにおいて所定の肉厚分布が得られるように各部の寸法が設定されている。ボトルの好ましいとされる肉厚分布を挙げると、ボトル肩部は口部側からボトル胴部側にかけて次第に肉厚が小さくなっており、ボトル胴部はその軸線方向全長にわたって均一に薄肉とされ、ボトル底部はボトル胴部よりも肉厚が大となっている。このような肉厚分布を採用することにより、肉薄でしかも強度のあるボトルとなる。そして、このような肉厚分布のボトルは、ブロー成形金型に対して最適となる形状に形成されたプリフォームによって得ることができる。 The dimensions of each part of the preform are set so that a predetermined thickness distribution can be obtained in the bottle after blow molding. When the preferable thickness distribution of the bottle is given, the bottle shoulder is gradually reduced in thickness from the mouth side to the bottle body side, and the bottle body is uniformly thin over its entire length in the axial direction. The bottom of the bottle is thicker than the bottle body. By adopting such a thickness distribution, the bottle is thin and strong. And a bottle with such a wall thickness distribution can be obtained by a preform formed in a shape optimal for a blow molding die.
具体的には、内容量６００ｍＬ以下のボトルをブロー成形するためのブロー成形金型においては、樹脂重量２３ｇであり、肩部形成部の外径が胴部形成部の外径よりも大とされ、胴部形成部の内径が口部の内径よりも小とされ、肩部形成部の内径略ストレート部の肉厚が、胴部形成部の肉厚の５３〜８４％とされ且つ底部形成部の肉厚の７５〜１００％とされているプリフォームを用いるのが適しており、周知である（例えば、特許文献２参照）。 Specifically, in a blow molding die for blow molding a bottle having an internal capacity of 600 mL or less, the resin weight is 23 g, and the outer diameter of the shoulder forming portion is larger than the outer diameter of the trunk forming portion. The inner diameter of the trunk forming portion is smaller than the inner diameter of the mouth portion, the thickness of the substantially straight inner diameter of the shoulder forming portion is 53 to 84% of the thickness of the trunk forming portion, and the bottom forming portion It is suitable to use a preform having a thickness of 75 to 100% of the thickness of the film (see, for example, Patent Document 2).
また、ブロー成形金型から加熱装置を経てブロー成形金型に至るプリフォームの搬送経路には、各プリフォームを連続搬送する搬送装置が設けられている。この搬送装置は、搬送位置に応じてプリフォームの最適部位を保持する複数種の保持手段やプリフォームの胴部形成部に当接して案内する案内路を備えており、これらの保持手段や案内路は、ブロー成形金型に投入されるプリフォームの形状に対応したものが用いられる。 In addition, a transport device for continuously transporting each preform is provided in the transport route of the preform from the blow mold to the blow mold through a heating device. This transport device is provided with a plurality of types of holding means for holding the optimal part of the preform according to the transport position and a guide path for contacting and guiding the preform body forming portion. A path corresponding to the shape of the preform to be put into the blow molding die is used.
即ち、所望のボトルの形状に対応したブロー成形金型が設けられると、このブロー成形金型によりブロー成形されるボトルにおいて所望の肉厚分布が得られるように各部の寸法が設定されたプリフォームを成形する射出成形金型が設けられ、この射出成形金型によって形成されたプリフォームの形状に対応した搬送装置が設けられる。 That is, when a blow molding die corresponding to a desired bottle shape is provided, a preform in which dimensions of each part are set so that a desired thickness distribution is obtained in a bottle blow-molded by this blow molding die An injection mold for molding is provided, and a conveying device corresponding to the shape of the preform formed by the injection mold is provided.
ところで、近年、ボトルの形状を変更することなく、材料コストを低減するために、プリフォームに使用する樹脂量を削減させる軽量化が望まれている。 By the way, in recent years, in order to reduce the material cost without changing the shape of the bottle, it is desired to reduce the weight of the resin used for the preform.
ブロー成形後のボトル形状を変更することなくプリフォームの軽量化を行うためには、射出成形金型におけるプリフォームの内部形状に対応するコアの外径を大きくして、プリフォームの内径を、軽量化前のプリフォームよりも大とすることが考えられる。これによれば、プリフォームの軸線方向の全長や各部の外径は軽量化前のプリフォームと同一寸法に維持されるので、射出成形金型の前記コアの交換が必要となるだけで、軽量化前のプリフォームに対応した搬送装置やブロー成形金型を用いることができる。 In order to reduce the weight of the preform without changing the bottle shape after blow molding, the outer diameter of the core corresponding to the inner shape of the preform in the injection mold is increased, and the inner diameter of the preform is increased. It can be considered to be larger than the preform before weight reduction. According to this, since the overall length in the axial direction of the preform and the outer diameter of each part are maintained at the same dimensions as the preform before weight reduction, it is only necessary to replace the core of the injection mold. A conveying device or a blow mold corresponding to the preform before conversion can be used.
しかし、ボトルの形状を変更することなくプリフォームを軽量化する場合には、当該ボトルの口部に嵌着させるキャップも変更されないため、軽量化前のプリフォームと同一の口部形状が維持されている必要がある。しかも、プリフォームにおいては、射出成形金型のコアの円滑な離形性を確保するために、口部よりも大径の内径部分を設けることができず、肩部形成部の内径略ストレート部の内径を口部の内径より大きく形成することはできない。なお、内径略ストレート部も殆どストレート状であるが、コアの抜き取りのために正確な寸法では僅かにテーパ状に形成されている。 However, when reducing the weight of the preform without changing the shape of the bottle, the cap that is fitted to the mouth of the bottle is not changed, so the same mouth shape as the preform before weight reduction is maintained. Need to be. Moreover, in the preform, in order to ensure smooth releasability of the core of the injection mold, it is not possible to provide an inner diameter part larger in diameter than the mouth part, and the shoulder part forming part has a substantially straight inner part. The inner diameter cannot be made larger than the inner diameter of the mouth. The substantially straight portion of the inner diameter is also almost straight, but is formed in a slightly tapered shape with an accurate dimension for extracting the core.
このことから、プリフォームにおいて、内径を大きくすることによって薄肉化が可能となるのは、胴部形成部、底部形成部、及び肩部形成部の内径テーパ部のみとなる。なお、肩部形成部の内径テーパ部においては内径が上下方向に均等に大径とされるのではなく、上端側は内径略ストレート部の内径と同径であって、内径が大とされた胴部形成部に連続させた分、肉薄となる。 For this reason, in the preform, it is possible to reduce the thickness by increasing the inner diameter only in the inner diameter taper portion of the body portion forming portion, the bottom portion forming portion, and the shoulder portion forming portion. In the inner diameter taper portion of the shoulder forming portion, the inner diameter is not increased uniformly in the vertical direction, but the upper end is the same diameter as the inner diameter of the substantially straight portion, and the inner diameter is increased. It becomes thin as much as it continues to the body forming part.
しかし、発明者の知見によれば、内容量６００ｍＬ以下のボトルの形成においては、肩部形成部の内径テーパ部、胴部形成部、及び底部形成部を薄肉化したプリフォームを用いてブロー成形を行うと、ボトル胴部の肉厚が不均一となったり、ボトル底部が十分な肉厚にならず、所望の肉厚分布を有するボトルを得ることができなくなる不都合があった。 However, according to the inventor's knowledge, in forming a bottle having an internal volume of 600 mL or less, blow molding is performed using a preform in which the inner diameter tapered portion, the trunk portion forming portion, and the bottom portion forming portion of the shoulder forming portion are thinned. However, there is a problem in that the thickness of the bottle body is not uniform, the bottle bottom is not sufficiently thick, and a bottle having a desired thickness distribution cannot be obtained.
そこで、軽量化前のプリフォームに比べて軸線方向の全長を短くすることによりプリフォームを軽量化することが考えられる。これによれば、軽量化前のプリフォームと同一の肉厚を維持することができ、所望の肉厚分布を有するボトルを得ることができる。 Therefore, it is conceivable to reduce the weight of the preform by shortening the total length in the axial direction as compared with the preform before weight reduction. According to this, the same wall thickness as the preform before weight reduction can be maintained, and the bottle which has desired wall thickness distribution can be obtained.
しかし、軽量化前のプリフォームに比べて軸線方向の全長が短い軽量化プリフォームを形成するためには、射出成形金型においてコアだけでなくキャビティ形状（キャビティ内の長さ等）も変更する必要がある。更に、射出成形金型とブロー成形金型との間の搬送装置においては、軽量化したプリフォームの全長に対応する保持手段や案内路に交換する必要がある。このため、軽量化前のプリフォームに比べて軸線方向の全長を短くしてプリフォームの軽量化を図った場合には、設備の変更にかかるコストが増加する不都合がある。 However, in order to form a lightweight preform with a shorter overall length in the axial direction compared to the preform before weight reduction, not only the core but also the cavity shape (length in the cavity, etc.) is changed in the injection mold. There is a need. Furthermore, in the transfer device between the injection mold and the blow mold, it is necessary to replace the holding means and the guide path corresponding to the total length of the weight-reduced preform. For this reason, when the weight of the preform is reduced by shortening the total length in the axial direction as compared with the preform before weight reduction, there is a disadvantage that the cost for changing the equipment increases.
上記の点に鑑み、本発明は、内容量６００ｍＬ以下の合成樹脂製ボトルを形成するのに好適な形状の樹脂重量２３ｇのプリフォームを基準としたとき、基準プリフォームよりも樹脂重量を小とし、しかも、基準プリフォーム用の搬送装置等の設備を変更することなくブロー成形が行えて設備変更にかかるコスト増加を抑えることができ、基準プリフォームと同等の肉厚分布を有するボトルを得ることができるプリフォームを提供することを目的とする。 In view of the above points, when the present invention is based on a preform having a resin weight of 23 g having a shape suitable for forming a synthetic resin bottle having an internal volume of 600 mL or less, the resin weight is smaller than that of the reference preform. Moreover, blow molding can be performed without changing the equipment such as the transport device for the reference preform, and the increase in cost for the equipment change can be suppressed, and a bottle having a wall thickness distribution equivalent to that of the reference preform can be obtained. An object is to provide a preform that can be used.
かかる目的を達成するために、本発明は、ブロー成形により内容量６００ｍＬ以下の合成樹脂製ボトルを形成するプリフォームであって、外周にキャップを螺着するためのネジ山が形成されていると共に下端外周に鍔状のサポートリングが形成された円筒状の口部と、該口部の下端に連設されてブロー成形後に前記サポートリングの下部から次第に拡径するボトル肩部となる円筒状の肩部形成部と、該肩部形成部の下端に連設されてブロー成形後にボトル胴部となる円筒状の胴部形成部と、該胴部形成部の下端に連設されてブロー成形後にボトル胴部の下端を閉塞するボトル底部となる半球状の底部形成部とを備えて射出成形により形成されるプリフォームにおいて、樹脂重量２３ｇであり、前記肩部形成部の外径が前記胴部形成部の外径よりも大とされ、前記胴部形成部の内径が前記口部の内径よりも小とされ、前記肩部形成部は、内径が下方に向かって僅かに小径となりながら下方に延びる内径略ストレート部と、該内径略ストレート部の下端から次第に縮径して前記胴部形成部の内面に連なる内径テーパ部とを備え、前記肩部形成部の内径略ストレート部の肉厚が、前記胴部形成部の肉厚の５３〜８４％であり且つ前記底部形成部の肉厚の７５〜１００％とされていて、ブロー成形により内容量６００ｍＬ以下のボトルを形成するためのプリフォームを基準プリフォームとしたとき、口部の上端から底部形成部の下端までの上下方向の長さ、口部の上端からサポートリングの下面までの外周面形状、口部の内径、肩部形成部の内径略ストレート部の内径、胴部形成部の外径、及び底部形成部の外側半球面形状を前記基準プリフォームと同一とし、肩部形成部の外径を前記基準プリフォームの肩部形成部の外径より小とし、肩部形成部の内径略ストレート部の内径を超えない範囲で胴部形成部の内径を前記基準プリフォームの胴部形成部の内径より大とし、底部形成部の内側半球面形状を前記基準プリフォームの底部形成部の内側半球面形状より大とし、肩部形成部の内径略ストレート部の肉厚が、胴部形成部の肉厚の５３〜８４％であり且つ底部形成部の肉厚の７５〜１００％である関係を維持して、肩部形成部と胴部形成部と底部形成部との肉厚を前記基準プリフォームよりも小とすることにより、前記基準プリフォームよりも樹脂重量を小としたことを特徴とする。 In order to achieve this object, the present invention is a preform for forming a synthetic resin bottle having an internal volume of 600 mL or less by blow molding, and a thread for screwing a cap around the outer periphery is formed. A cylindrical mouth portion having a bowl-shaped support ring formed on the outer periphery of the lower end, and a cylindrical mouth portion that is connected to the lower end of the mouth portion and becomes a bottle shoulder portion that gradually expands from the lower portion of the support ring after blow molding. A shoulder-forming part, a cylindrical body-forming part that is connected to the lower end of the shoulder-forming part and becomes a bottle body after blow molding, and a blow-molding that is connected to the lower end of the body-forming part A preform formed by injection molding with a hemispherical bottom forming part that becomes a bottle bottom that closes the lower end of the bottle body, the resin weight is 23 g, and the outer diameter of the shoulder forming part is the body The outer diameter of the forming part An inner diameter of the trunk portion forming portion is smaller than an inner diameter of the mouth portion, and the shoulder portion forming portion has a substantially straight inner diameter portion extending downward while the inner diameter is slightly smaller toward the lower side. An inner diameter taper portion that is gradually reduced in diameter from the lower end of the inner diameter substantially straight portion and continues to the inner surface of the trunk portion forming portion, and the thickness of the shoulder portion forming portion is substantially the inner diameter of the trunk portion forming portion. The preform for forming a bottle having an inner volume of 600 mL or less by blow molding is used as a reference preform. The length in the vertical direction from the upper end of the mouth part to the lower end of the bottom part, the shape of the outer peripheral surface from the upper part of the mouth part to the lower surface of the support ring, the inner diameter of the mouth part, the inner diameter of the shoulder part, Inner diameter, outer diameter of the body forming part, The outer hemispherical shape of the bottom forming portion is the same as that of the reference preform, the outer diameter of the shoulder forming portion is smaller than the outer diameter of the shoulder forming portion of the reference preform, and the inner diameter of the shoulder forming portion is substantially straight. The inner diameter of the body forming portion is larger than the inner diameter of the body forming portion of the reference preform within a range not exceeding the inner diameter of the portion, and the inner hemispherical shape of the bottom forming portion is the inner hemisphere of the bottom forming portion of the reference preform. The thickness is larger than the surface shape, and the thickness of the substantially straight inner diameter of the shoulder forming portion is 53 to 84% of the thickness of the trunk forming portion and 75 to 100% of the thickness of the bottom forming portion. Maintaining the thickness of the shoulder forming portion, the trunk forming portion, and the bottom forming portion smaller than the reference preform, thereby reducing the resin weight than the reference preform. To do.
内容量６００ｍＬ以下のボトルをブロー成形する際に用いられる樹脂重量２３ｇのプリフォームは、前述した通り、従来より、肩部形成部の外径が胴部形成部の外径よりも大とされ、胴部形成部の内径が口部の内径よりも小とされ、肩部形成部は、内径が下方に向かって僅かに小径となりながら下方に延びる内径略ストレート部と、内径略ストレート部の下端から次第に縮径して胴部形成部の内面に連なる内径テーパ部とを備えている。そして、このプリフォームを射出成形金型やブロー成形金型までの搬送装置は、このプリフォームの各部の形状に対応して構成される。更に、このプリフォームは、ブロー成形時に生じる肉延びの偏向やブロー成形後のボトルの肉厚分布の不良を防止し、所望の肉厚分布を有するボトルを得るために、肩部形成部の内径略ストレート部の肉厚が、胴部形成部の肉厚の５３〜８４％であり且つ底部形成部の肉厚の７５〜１００％とされている。 As described above, the preform having a resin weight of 23 g used for blow molding a bottle having an internal volume of 600 mL or less, as described above, the outer diameter of the shoulder forming portion is larger than the outer diameter of the trunk forming portion. The inner diameter of the body forming portion is smaller than the inner diameter of the mouth portion, and the shoulder forming portion has an inner diameter substantially straight portion that extends downward while the inner diameter is slightly smaller toward the lower side, and a lower end of the inner diameter substantially straight portion. The inner diameter taper part which is gradually reduced in diameter and continues to the inner surface of the body part forming part is provided. And the conveying apparatus from this preform to an injection mold or a blow mold is configured corresponding to the shape of each part of this preform. In addition, this preform prevents the deflection of the wall thickness that occurs during blow molding and the poor thickness distribution of the bottle after blow molding, and in order to obtain a bottle having the desired thickness distribution, the inner diameter of the shoulder forming portion The thickness of the substantially straight portion is 53 to 84% of the thickness of the trunk portion forming portion and 75 to 100% of the thickness of the bottom portion forming portion.
本発明においては、先ず、上記形状のプリフォームを基準プリフォームとする。一方、本発明のプリフォームは、基準プリフォームの樹脂重量を削減して軽量化したものである。 In the present invention, first, the preform having the above shape is used as a reference preform. On the other hand, the preform of the present invention is reduced in weight by reducing the resin weight of the reference preform.
基準プリフォームの樹脂重量を削減して軽量化を図る場合に、基準プリフォームと同一のキャップを口部に装着するために口部の形状を変更することはできない。しかも、肩部形成部の内径テーパ部、胴部形成部、及び底部形成部を肉薄化した場合には、射出成形金型のコアの交換のみで対応できるが、基準プリフォームと同等の良好な肉厚分布を有するボトルを得ることができず、また、肉厚や外径を変更せずに全長のみを短くすると、基準プリフォーム用の搬送装置が使用できない不都合が生じることは前述した通りである。 When reducing the resin weight of the reference preform and reducing the weight, the shape of the mouth cannot be changed in order to attach the same cap as the reference preform to the mouth. Moreover, when the inner diameter taper portion, the trunk portion forming portion, and the bottom portion forming portion of the shoulder forming portion are thinned, it can be dealt with only by replacing the core of the injection mold, but it is as good as the standard preform. As described above, bottles having a wall thickness distribution cannot be obtained, and if only the entire length is shortened without changing the wall thickness or outer diameter, the transport device for the reference preform cannot be used. is there.
そこで、本発明のプリフォームは、口部の上端から底部形成部の下端までの上下方向の長さ（全長）、肩部形成部の内径略ストレート部の内径、胴部形成部の外径、及び底部形成部の外側半球面形状を基準プリフォームと同一とした。これにより、基準プリフォーム用の搬送装置が使用でき、設備変更にかかるコスト増加を抑えることができる。 Therefore, the preform of the present invention has a vertical length (full length) from the upper end of the mouth portion to the lower end of the bottom forming portion, the inner diameter of the shoulder forming portion, the inner diameter of the substantially straight portion, the outer diameter of the trunk forming portion, In addition, the outer hemispherical shape of the bottom forming portion was the same as the reference preform. Thereby, the conveyance apparatus for reference | standard preform can be used, and the cost increase concerning an equipment change can be suppressed.
また、発明者は、試行錯誤の結果、肩部形成部の内径略ストレート部の肉厚が、胴部形成部の肉厚の５３〜８４％であり且つ底部形成部の肉厚の７５〜１００％であるという関係を維持すれば、肩部形成部の内径テーパ部、胴部形成部、及び底部形成部を基準プリフォームよりも肉薄としても、基準プリフォームを用いた場合と同等の肉厚分布を有するボトルが得られることを知見した。 Further, as a result of trial and error, the inventor found that the thickness of the substantially straight inner diameter portion of the shoulder forming portion is 53 to 84% of the thickness of the trunk forming portion and 75 to 100 of the thickness of the bottom forming portion. %, If the inner diameter taper portion, the trunk portion forming portion, and the bottom portion forming portion of the shoulder forming portion are thinner than the reference preform, the thickness is the same as when using the reference preform. It has been found that bottles with a distribution can be obtained.
そこで、本発明のプリフォームにおいては、肩部形成部と胴部形成部と底部形成部との肉厚を基準プリフォームよりも小とすることにより樹脂重量を大幅に削減した。このとき、肩部形成部の内径略ストレート部の内径を超えない範囲で胴部形成部の内径を大とすることで、射出成形金型のコアの離形性を確保する。その上で、上記知見に基づき、肩部形成部の内径略ストレート部の肉厚が、胴部形成部の肉厚の５３〜８４％であり且つ底部形成部の肉厚の７５〜１００％であるという関係を維持すべく、肩部形成部の外径を前記基準プリフォームの肩部形成部の外径より小とした。 Therefore, in the preform of the present invention, the resin weight is significantly reduced by making the thicknesses of the shoulder forming portion, the trunk forming portion, and the bottom forming portion smaller than those of the reference preform. At this time, by increasing the inner diameter of the body forming portion within a range not exceeding the inner diameter of the substantially straight portion of the shoulder forming portion, the releasability of the core of the injection mold is ensured. In addition, based on the above knowledge, the thickness of the substantially straight inner diameter of the shoulder forming portion is 53 to 84% of the thickness of the trunk forming portion and 75 to 100% of the thickness of the bottom forming portion. In order to maintain the relationship, the outer diameter of the shoulder forming portion was made smaller than the outer diameter of the shoulder forming portion of the reference preform.
このように、本発明のプリフォームは、基準プリフォーム用の搬送装置による搬送を阻害するおそれのある部分の形状を基準プリフォームと同一として、基準プリフォーム用の搬送装置の変更を不要とし、しかも、肩部形成部の内径略ストレート部の肉厚が、胴部形成部の肉厚の５３〜８４％であり且つ底部形成部の肉厚の７５〜１００％であるという関係が維持されるので、基準プリフォームと同等の肉厚分布を有するボトルを得ることができる。よって、基準プリフォームよりも樹脂重量を小とし、しかも設備変更にかかるコスト増加を抑えることができるプリフォームを提供することができる。 Thus, the preform of the present invention has the same shape as the reference preform with the shape of the portion that may hinder the conveyance by the conveyance device for the reference preform, and does not require the change of the conveyance device for the reference preform. In addition, the relationship that the thickness of the substantially straight portion of the inner diameter of the shoulder forming portion is 53 to 84% of the thickness of the trunk forming portion and 75 to 100% of the thickness of the bottom forming portion is maintained. Therefore, a bottle having a wall thickness distribution equivalent to that of the reference preform can be obtained. Therefore, it is possible to provide a preform in which the resin weight is smaller than that of the reference preform, and the increase in cost required for equipment change can be suppressed.
ところで、基準プリフォームを用いてブロー成形を行うためのブロー成形金型の上部には、基準プリフォームの肩部形成部を装着させる装着孔が形成されている。この装着孔は、基準プリフォームの肩部形成部の外径に対応する内径を有しているが、肩部形成部の外径が基準プリフォームの肩部形成部の外径より小となっているプリフォームをブロー成形金型の装着孔に装着すると、装着孔と肩部形成部との間には、基準プリフォームを装着したときに比べて大きな間隙が形成される。この間隙は、サポートリングの下面によって閉塞されてブロー成形金型の内部の気密性は確保されるものの、装着孔の軸心と肩部形成部の軸心とに位置ずれが生じるおそれがある。 By the way, a mounting hole for mounting the shoulder forming portion of the reference preform is formed in the upper part of the blow molding die for performing blow molding using the reference preform. The mounting hole has an inner diameter corresponding to the outer diameter of the shoulder forming portion of the reference preform, but the outer diameter of the shoulder forming portion is smaller than the outer diameter of the shoulder forming portion of the reference preform. When the preform is mounted in the mounting hole of the blow molding die, a larger gap is formed between the mounting hole and the shoulder forming portion than when the reference preform is mounted. Although this gap is closed by the lower surface of the support ring and airtightness inside the blow molding die is secured, there is a possibility that a positional deviation occurs between the shaft center of the mounting hole and the shaft center of the shoulder forming portion.
そこで、本発明のプリフォームにおいては、前記サポートリングの下面と前記肩部形成部の外面との境界部分に、前記基準プリフォームの肩部形成部の外面に相当する位置を通って次第に縮径しつつ下方に向かって延びる傾斜面を設けることが好ましい。 Therefore, in the preform of the present invention, the diameter gradually decreases through a position corresponding to the outer surface of the shoulder forming portion of the reference preform at the boundary portion between the lower surface of the support ring and the outer surface of the shoulder forming portion. However, it is preferable to provide an inclined surface extending downward.
これによれば、本発明のプリフォームをブロー成形金型の装着孔に装着したとき、前記傾斜面が装着孔に当接し、装着孔の軸心と肩部形成部の軸心との位置ずれを抑えることができる。 According to this, when the preform of the present invention is mounted in the mounting hole of the blow molding die, the inclined surface comes into contact with the mounting hole, and the misalignment between the axis of the mounting hole and the axis of the shoulder forming portion Can be suppressed.
本発明の実施形態を図面に基づいて説明する。図１に示す本実施形態のプリフォームＡは、二軸延伸ブロー成形を施すことにより内容量６００ｍＬ以下の合成樹脂製ボトルを形成するものである。このボトルは、図示しないが、キャップを装着するボトル口部と、ボトル口部の下端から外方に拡径するボトル肩部と、ボトル肩部から下方に延びる中空のボトル胴部と、ボトル胴部の下端を閉塞するボトル底部とで構成され、内部に飲料等が収容される。 Embodiments of the present invention will be described with reference to the drawings. The preform A of this embodiment shown in FIG. 1 forms a synthetic resin bottle having an internal volume of 600 mL or less by performing biaxial stretch blow molding. Although this bottle is not shown, a bottle mouth portion to which a cap is attached, a bottle shoulder portion that expands outward from the lower end of the bottle mouth portion, a hollow bottle trunk portion that extends downward from the bottle shoulder portion, and a bottle barrel The bottle bottom portion closes the lower end of the portion, and contains beverages and the like.
本実施形態のプリフォームＡは、図２に示すプリフォームＢを基準として、この基準プリフォームＢよりも樹脂重量を小とすることにより軽量化を施したものである。以下の説明においては、図２に示す基準プリフォームＢに対し、図１に示す本発明の実施形態のプリフォームＡを、便宜上、軽量化プリフォームＡと言う。 The preform A of the present embodiment is lightened by making the resin weight smaller than that of the reference preform B with the preform B shown in FIG. In the following description, the preform A of the embodiment of the present invention shown in FIG. 1 is referred to as a weight-reduced preform A for the sake of convenience with respect to the reference preform B shown in FIG.
基準プリフォームＢと軽量化プリフォームＡとは、共に同一形状のボトルを形成するものである。軽量化プリフォームＡと基準プリフォームＢとは、何れもポリエチレンテレフタレート等の合成樹脂を材料とする射出成形により形成され、図１及び図２に示すように、口部１と、肩部形成部２と、胴部形成部３と、底部形成部４とにより構成されている。口部１、肩部形成部２、及び胴部形成部３は連続する円筒状に形成されており、底部形成部４は半球状に形成されている。 Both the reference preform B and the light weight preform A form a bottle having the same shape. Each of the lightweight preform A and the reference preform B is formed by injection molding using a synthetic resin such as polyethylene terephthalate, and as shown in FIGS. 1 and 2, the mouth 1 and the shoulder forming part 2, a trunk portion forming portion 3, and a bottom portion forming portion 4. The mouth part 1, the shoulder part forming part 2, and the body part forming part 3 are formed in a continuous cylindrical shape, and the bottom part forming part 4 is formed in a hemispherical shape.
口部１の外周には、キャップを螺着するためのネジ山５と、下端外周から外方に鍔状に張り出すサポートリング６とが形成されている。 A thread 5 for screwing the cap and a support ring 6 projecting outward from the outer periphery of the lower end are formed on the outer periphery of the mouth portion 1.
肩部形成部２は、内径が下方に向かって僅かに小径となりながら下方に延びる内径略ストレート部７と、内径略ストレート部７の下端から次第に縮径して胴部形成部３の内面に連なる内径テーパ部８とで構成されている。 The shoulder portion forming portion 2 has a substantially straight inner diameter portion 7 that extends downward while the inner diameter becomes slightly smaller in the downward direction, and is gradually reduced in diameter from the lower end of the inner diameter substantially straight portion 7 and continues to the inner surface of the trunk portion forming portion 3. It is comprised by the internal diameter taper part 8. FIG.
肩部形成部２の内径略ストレート部７は、その上端内径と下端内径の差が極度に小さく、そのテーパ状の度合いは僅かである。肩部形成部２の内径テーパ部８は、内径略ストレート部７よりもテーパ状の度合いが大きい。肩部形成部２の内径略ストレート部７と内径テーパ部８とは、そのテーパ状の度合から境界位置が明確である。一方、内径略ストレート部７の外周面と内径テーパ部８の外周面とは、その境界が肩部形成部２の外周面に現れておらず、滑らかに連続する面となっている。 The substantially straight portion 7 with an inner diameter of the shoulder forming portion 2 has an extremely small difference between the inner diameter at the upper end and the inner diameter at the lower end, and the degree of taper is slight. The inner diameter taper portion 8 of the shoulder forming portion 2 is more tapered than the inner diameter substantially straight portion 7. The boundary position between the substantially straight inner diameter portion 7 and the inner diameter tapered portion 8 of the shoulder forming portion 2 is clear from the degree of taper. On the other hand, the boundary between the outer peripheral surface of the substantially straight inner diameter portion 7 and the outer peripheral surface of the inner diameter tapered portion 8 does not appear on the outer peripheral surface of the shoulder forming portion 2 but is a smoothly continuous surface.
なお、肩部形成部２の外周面は、胴部形成部３に向かって次第に縮径するテーパ状に形成されているが、内径略ストレート部７の外周面はテーパ状の度合いが僅かであり、内径テーパ部８の外周面はテーパ状の度合いが比較的大きい。 The outer peripheral surface of the shoulder forming portion 2 is formed in a tapered shape that gradually decreases in diameter toward the body forming portion 3, but the outer peripheral surface of the substantially straight inner diameter portion 7 has a slight taper degree. The outer peripheral surface of the inner diameter tapered portion 8 has a relatively large degree of taper.
口部１は、ブロー成形されないことにより形状は殆ど変化せず、ボトル口部となる。肩部形成部２、胴部形成部３、及び底部形成部４は、ブロー成形により伸展され、夫々、ボトル肩部、ボトル胴部、及びボトル底部となる。 Since the mouth part 1 is not blow-molded, the shape hardly changes and becomes a bottle mouth part. The shoulder forming part 2, the body forming part 3, and the bottom forming part 4 are extended by blow molding, and become a bottle shoulder, a bottle trunk, and a bottle bottom, respectively.
基準プリフォームＢは、内容量６００ｍＬ以下のボトルを形成するためのブロー成形金型（図示せず）によってブロー成形が良好に行えるように設計された従前のものである。 The reference preform B is a conventional one designed so that blow molding can be favorably performed by a blow molding die (not shown) for forming a bottle having an internal volume of 600 mL or less.
ブロー成形金型に基準プリフォームＢを搬送するための搬送装置も基準プリフォームＢの形状及び各部の寸法に合わせたものが用いられる。即ち、搬送装置は、図３に模式的に示すように、例えば、基準プリフォームＢの胴部形成部３を収容して保持する管状の保持部材９を備えている。この保持部材９は、内部の形状が基準プリフォームＢの胴部形成部３に対応しており、保持部材９に接続された図示しない吸引手段の吸引力により基準プリフォームＢの保持状態を維持するようになっている。また、図示しないが、射出成形金型から基準プリフォームＢを取り出す際にも基準プリフォームＢの胴部形成部３を収容する管状の保持部材が用いられ、更に、複数の基準プリフォームＢを配列搬送する際の案内路も基準プリフォームＢの胴部形成部３の外径に対応する幅で搬送方向に延びている。このように、ブロー成形金型に基準プリフォームＢを搬送する搬送装置が備えている保持部材９や案内路は、基準プリフォームＢの口部１の上端から底部形成部４の下端までの上下方向の長さ（以下全長という）、及び、胴部形成部３の外径に合致するものが用いられている。 A transport device for transporting the reference preform B to the blow molding die is also used in accordance with the shape of the reference preform B and the dimensions of each part. That is, as schematically shown in FIG. 3, the transport device includes, for example, a tubular holding member 9 that houses and holds the body forming portion 3 of the reference preform B. The holding member 9 has an internal shape corresponding to the body forming portion 3 of the reference preform B, and maintains the holding state of the reference preform B by the suction force of suction means (not shown) connected to the holding member 9. It is supposed to be. Although not shown, a tubular holding member that accommodates the body forming portion 3 of the reference preform B is also used when taking out the reference preform B from the injection mold. The guide path for the array conveyance also extends in the conveyance direction with a width corresponding to the outer diameter of the body forming portion 3 of the reference preform B. As described above, the holding member 9 and the guide path provided in the conveying device that conveys the reference preform B to the blow molding die are vertically moved from the upper end of the mouth portion 1 of the reference preform B to the lower end of the bottom forming portion 4. The one that matches the length in the direction (hereinafter referred to as the full length) and the outer diameter of the body portion forming portion 3 is used.
このため、基準プリフォームＢと全長が異なっていたり、胴部形成部３の外径が異なっている他のプリフォームを搬送する場合には、保持部材９や案内路を構成する部品が使用できず、他のプリフォームに合致したものに交換しなければならず、多大な作業工数とコスト増加が生じることとなる。 For this reason, when transporting other preforms that are different in total length from the reference preform B or different in outer diameter of the body portion forming portion 3, the components constituting the holding member 9 and the guide path can be used. First, it must be exchanged for one that matches another preform, resulting in a significant man-hour and cost increase.
本実施形態の軽量化プリフォームＡの基準として用いる基準プリフォームＢは、図２に示すように、肩部形成部２の外径が胴部形成部３の外径よりも大とされ、胴部形成部３の内径が口部１の内径よりも小とされている。 As shown in FIG. 2, the reference preform B used as a reference for the lightweight preform A of the present embodiment has an outer diameter of the shoulder forming portion 2 larger than an outer diameter of the trunk forming portion 3. The inner diameter of the part forming part 3 is smaller than the inner diameter of the mouth part 1.
基準プリフォームＢの各部の具体的な寸法（誤差記載省略）は、
全長ａが８５．０２ｍｍ、
肩部形成部２の内径略ストレート部７の外径ｂが２５．８ｍｍ、
胴部形成部３の上端外径ｃが２４．３ｍｍ、
胴部形成部３の下端外径ｄが２３．８ｍｍ、
口部１の上端内径ｅが２１．７４ｍｍ、
肩部形成部２の内径略ストレート部７の上端内径ｆが２１．５６ｍｍ、
肩部形成部２の内径略ストレート部７の下端内径ｇが２１．２４ｍｍ、
胴部形成部３の上端内径ｈが１７．２０５ｍｍ、
胴部形成部３の下端内径ｉが１６．７２７ｍｍ、
肩部形成部２の内径略ストレート部７の肉厚ｊが２．２１ｍｍ、
胴部形成部３の肉厚ｋが３．５５ｍｍ、
底部形成部４の肉厚ｎが２．５９２ｍｍ
となっている。
Specific dimensions (error description omitted) of each part of the reference preform B are as follows:
Total length a is 85.02 mm,
The outer diameter b of the inner diameter substantially straight portion 7 of the shoulder forming portion 2 is 25.8 mm,
The upper end outer diameter c of the body forming part 3 is 24.3 mm,
The lower end outer diameter d of the body portion forming portion 3 is 23.8 mm,
The upper end inner diameter e of the mouth part 1 is 21.74 mm,
The upper end inner diameter f of the inner diameter substantially straight part 7 of the shoulder forming part 2 is 21.56 mm,
The lower end inner diameter g of the inner diameter substantially straight portion 7 of the shoulder forming portion 2 is 21.24 mm,
The upper end inner diameter h of the trunk portion forming portion 3 is 17.205 mm,
The inner diameter i of the lower end of the body portion forming portion 3 is 16.727 mm,
The wall thickness j of the inner diameter substantially straight portion 7 of the shoulder forming portion 2 is 2.21 mm,
The thickness k of the body forming part 3 is 3.55 mm,
The thickness n of the bottom forming part 4 is 2.592 mm.
It has become.
肩部形成部２、胴部形成部３、及び底部形成部４の寸法は、良好な肉厚分布を有するボトルをブロー成形することができる条件として、肩部形成部２の内径略ストレート部７の肉厚ｊが、胴部形成部３の肉厚ｋの５３〜８４％となり、底部形成部４の肉厚ｎの７５〜１００％となるように設定される。そして、基準プリフォームＢもこの条件を満たし、肩部形成部２の内径略ストレート部７の肉厚ｊは、胴部形成部３の肉厚ｋの約６２％、底部形成部４の肉厚ｎの約８５％となっている。 The dimensions of the shoulder forming part 2, the trunk forming part 3, and the bottom forming part 4 are such that the inner diameter of the shoulder forming part 2 is substantially straight as a condition that a bottle having a good thickness distribution can be blow-molded. Is set to be 53 to 84% of the thickness k of the body forming portion 3 and 75 to 100% of the thickness n of the bottom forming portion 4. The reference preform B also satisfies this condition, and the thickness j of the substantially straight inner portion 7 of the shoulder forming portion 2 is about 62% of the thickness k of the trunk forming portion 3 and the thickness of the bottom forming portion 4. It is about 85% of n.
次に、図１に示す軽量化プリフォームＡの各部の具体的な寸法（誤差記載省略）は、
全長ａが８５．０２ｍｍ、
肩部形成部２の内径略ストレート部７の外径ｂが２５．２ｍｍ、
胴部形成部３の上端外径ｃが２４．３ｍｍ、
胴部形成部３の下端外径ｄが２３．８ｍｍ、
口部１の上端内径ｅが２１．７４ｍｍ、
肩部形成部２の内径略ストレート部７の上端内径ｆが２１．５６ｍｍ、
肩部形成部２の内径略ストレート部７の下端内径ｇが２１．２４ｍｍ、
胴部形成部３の上端内径ｈが１８．３８５ｍｍ、
胴部形成部３の下端内径ｉが１７．９０４ｍｍ、
肩部形成部２の内径略ストレート部７の肉厚ｊが１．８２ｍｍ、
胴部形成部３の肉厚ｋが２．９６ｍｍ、
底部形成部４の肉厚ｎが２．３６８ｍｍ
となっている。
Next, the specific dimensions (error description omitted) of each part of the light weight preform A shown in FIG.
Total length a is 85.02 mm,
The outer diameter b of the inner diameter substantially straight portion 7 of the shoulder forming portion 2 is 25.2 mm,
The upper end outer diameter c of the body forming part 3 is 24.3 mm,
The lower end outer diameter d of the body portion forming portion 3 is 23.8 mm,
The upper end inner diameter e of the mouth part 1 is 21.74 mm,
The upper end inner diameter f of the inner diameter substantially straight part 7 of the shoulder forming part 2 is 21.56 mm,
The lower end inner diameter g of the inner diameter substantially straight portion 7 of the shoulder forming portion 2 is 21.24 mm,
The upper end inner diameter h of the trunk portion forming portion 3 is 18.385 mm,
The lower end inner diameter i of the trunk portion forming portion 3 is 17.904 mm,
The wall thickness j of the inner diameter substantially straight portion 7 of the shoulder forming portion 2 is 1.82 mm,
The thickness k of the body forming part 3 is 2.96 mm,
The thickness n of the bottom forming part 4 is 2.368 mm.
It has become.
図１に示す軽量化プリフォームＡと図２に示す基準プリフォームＢとを比較すれば明らかなように、軽量化プリフォームＡの全長ａ、口部１の形状、肩部形成部２の内径略ストレート部７の内径ｆ，ｇ、胴部形成部３の外径ｃ，ｄ、及び底部形成部４の外面形状は、基準プリフォームＢと同一である。 As is clear from the comparison between the lightweight preform A shown in FIG. 1 and the reference preform B shown in FIG. 2, the overall length a of the lightweight preform A, the shape of the mouth portion 1, and the inner diameter of the shoulder forming portion 2. The inner diameters f and g of the substantially straight portion 7, the outer diameters c and d of the body portion forming portion 3, and the outer surface shape of the bottom portion forming portion 4 are the same as those of the reference preform B.
軽量化プリフォームＡの口部１の形状を基準プリフォームＢと同一としたことにより、基準プリフォームＢと共通のキャップが使用でき、キャップの設計変更が不要となる。また、肩部形成部２の内径略ストレート部７の内径ｆ，ｇも基準プリフォームＢと同一であるが、これは口部１の形状を基準プリフォームＢと同一としたことに伴うものである。そして、口部１の上端から肩部形成部２の内径略ストレート部７の下端までの内周面を連続した平滑なテーパ面とすることができるので、射出成形金型のコアを円滑に離形させることができる。 By making the shape of the mouth portion 1 of the lightweight preform A the same as that of the reference preform B, a cap common to the reference preform B can be used, and the design change of the cap becomes unnecessary. Also, the inner diameters f and g of the substantially straight portion 7 of the shoulder forming portion 2 are the same as the reference preform B. This is because the shape of the mouth portion 1 is the same as that of the reference preform B. is there. And since the inner peripheral surface from the upper end of the mouth part 1 to the lower end of the inner diameter substantially straight part 7 of the shoulder forming part 2 can be made into a continuous and smooth tapered surface, the core of the injection mold can be separated smoothly. Can be shaped.
軽量化プリフォームＡの全長ａ、胴部形成部３の外径ｃ、ｄ、及び底部形成部４の外面形状を基準プリフォームＢと同一としたことにより、図３に示す基準プリフォームＢ用の搬送装置の保持部材９や案内路を使用することができ、部品交換等のコスト増加を防止することができる。 For the reference preform B shown in FIG. 3, the overall length a of the lightweight preform A, the outer diameters c and d of the body forming portion 3 and the outer shape of the bottom forming portion 4 are the same as those of the reference preform B. The holding member 9 and the guide path of the transfer device can be used, and an increase in cost such as component replacement can be prevented.
一方、軽量化プリフォームＡにおいては、胴部形成部３の内径ｈ，ｉが基準プリフォームＢの胴部形成部３の内径ｈ，ｉより大きく、底部形成部４の内側半球面形状が基準プリフォームＢの底部形成部４の内側半球面形状より大きい。これにより、胴部形成部３の外径ｈ，ｉ、及び底部形成部４の外面形状を基準プリフォームＢと同一として胴部形成部３及び底部形成部４の肉厚ｋ，ｎを薄くすることができる。なお、胴部形成部３の内径ｈ，ｉは、肩部形成部２の内径略ストレート部７の内径ｆ，ｇよりも小さいため、射出成形金型のコアの円滑な離形性が確保されている。 On the other hand, in the light weight preform A, the inner diameters h and i of the body forming part 3 are larger than the inner diameters h and i of the body forming part 3 of the reference preform B, and the inner hemispherical shape of the bottom forming part 4 is the reference. It is larger than the inner hemispherical shape of the bottom forming part 4 of the preform B. As a result, the outer diameters h and i of the body part forming part 3 and the outer surface shape of the bottom part forming part 4 are made the same as those of the reference preform B, and the thicknesses k and n of the body part forming part 3 and the bottom part forming part 4 are reduced. be able to. The inner diameters h and i of the body forming portion 3 are smaller than the inner diameters f and g of the substantially straight portion 7 of the shoulder forming portion 2, so that the smooth mold releasability of the core of the injection mold is ensured. ing.
そして更に、軽量化プリフォームＡにおいては、肩部形成部２の外径が基準プリフォームＢの肩部形成部２の外径より小とされている。具体的には、肩部形成部２の内径略ストレート部７の外径ｂを２５．２ｍｍとすることで、肩部形成部２の内径略ストレート部７の肉厚ｊを１．８２ｍｍとした。これにより、肩部形成部２の内径略ストレート部７の肉厚ｊが、胴部形成部３の肉厚ｋの約６１．５％、底部形成部４の肉厚ｎの約７７％となって、良好な肉厚分布を有するボトルをブロー成形することができる条件、即ち、肩部形成部２の内径略ストレート部７の肉厚ｊが胴部形成部３の肉厚ｋの５３〜８４％であり且つ底部形成部４の肉厚ｎの７５〜１００％であることを満たすことができる。 Further, in the lightweight preform A, the outer diameter of the shoulder forming portion 2 is smaller than the outer diameter of the shoulder forming portion 2 of the reference preform B. Specifically, by setting the outer diameter b of the inner diameter substantially straight portion 7 of the shoulder forming portion 2 to 25.2 mm, the thickness j of the inner diameter substantially straight portion 7 of the shoulder forming portion 2 is set to 1.82 mm. . As a result, the thickness j of the substantially straight inner diameter portion 7 of the shoulder forming portion 2 is about 61.5% of the thickness k of the body forming portion 3 and about 77% of the thickness n of the bottom forming portion 4. Thus, the conditions under which a bottle having a good thickness distribution can be blow-molded, that is, the thickness j of the substantially straight inner portion 7 of the shoulder forming portion 2 is 53 to 84 of the thickness k of the barrel forming portion 3. % And 75 to 100% of the thickness n of the bottom forming portion 4 can be satisfied.
軽量化プリフォームＡは、以上の寸法を採用したとき、樹脂重量が約２０ｇとなり、樹脂重量が２３ｇの基準プリフォームＢよりも１０％以上の軽量化が可能となる。なお、軽量化プリフォームＡの上記各部の寸法は好ましい一例であって、これに限るものではなく、基準プリフォームＢの各部の寸法に応じて設定されるものである。 When the weight reduction preform A adopts the above dimensions, the weight of the resin is about 20 g, and the weight can be reduced by 10% or more than the standard preform B having a resin weight of 23 g. In addition, the dimension of each said part of the weight reduction preform A is a preferable example, Comprising: It does not restrict to this, It sets according to the dimension of each part of the reference | standard preform B.
即ち、基準プリフォームＢの各部の寸法から軽量化プリフォームＡの各部の寸法を設定する場合には、全長（口部１の上端から底部形成部４の下端までの上下方向の長さ）ａ、口部１の上端からサポートリング６の下面までの外周面形状、口部１の内径ｅ、肩部形成部２の内径略ストレート部の内径ｆ，ｇ、胴部形成部３の外径ｃ，ｄ、及び底部形成部４の外側半球面形状を基準プリフォームＢと同一とし、肩部形成部２の外径ｂを基準プリフォームＢの肩部形成部２の外径ｂより小とし、肩部形成部２の内径略ストレート部７の内径ｆ，ｇを超えない範囲で胴部形成部３の内径ｈ，ｉを基準プリフォームＢの胴部形成部３の内径ｈ，ｉより大とし、底部形成部４の内側半球面形状を基準プリフォームＢの底部形成部４の内側半球面形状より大とし、肩部形成部２の内径略ストレート部７の肉厚ｊが、胴部形成部３の肉厚ｋの５３〜８４％であり且つ底部形成部４の肉厚ｎの７５〜１００％である関係を維持して、肩部形成部２と胴部形成部３と底部形成部４との肉厚ｊ，ｋ，ｎを基準プリフォームＢよりも小とすればよい。 That is, when the dimensions of each part of the weight reduction preform A are set from the dimensions of each part of the reference preform B, the total length (the length in the vertical direction from the upper end of the mouth part 1 to the lower end of the bottom part forming part 4) a The outer peripheral surface shape from the upper end of the mouth part 1 to the lower surface of the support ring 6, the inner diameter e of the mouth part 1, the inner diameters f and g of the substantially straight part of the shoulder part 2, and the outer diameter c of the body part 3 , D and the outer hemispherical shape of the bottom forming portion 4 are the same as the reference preform B, the outer diameter b of the shoulder forming portion 2 is smaller than the outer diameter b of the shoulder forming portion 2 of the reference preform B, The inner diameters h and i of the body forming part 3 are made larger than the inner diameters h and i of the body forming part 3 of the reference preform B within a range not exceeding the inner diameters f and g of the substantially straight part 7 of the shoulder forming part 2. The inner hemispherical shape of the bottom forming portion 4 is more than the inner hemispherical shape of the bottom forming portion 4 of the reference preform B. The thickness j of the substantially straight portion 7 of the inner diameter of the shoulder forming portion 2 is 53 to 84% of the thickness k of the trunk forming portion 3 and 75 to 100% of the thickness n of the bottom forming portion 4. While maintaining a certain relationship, the thicknesses j, k, and n of the shoulder forming portion 2, the trunk forming portion 3, and the bottom forming portion 4 may be smaller than those of the reference preform B.
ところで、図４に一部を示すように、ブロー成形金型１０の上部には、装着孔１１が形成されている。この装着孔１１には、基準プリフォームＢの肩部形成部２が装着される。しかし、軽量化プリフォームＡは、肩部形成部２の外径が基準プリフォームＢの肩部形成部２の外径より小さいために、肩部形成部２と装着孔１１の内周縁との間の間隙１２が基準プリフォームＢよりも大きくなる。このため、軽量化プリフォームＡの軸心と装着孔１１の軸心とに位置ずれが生じるおそれがある。 Incidentally, as shown in part in FIG. 4, a mounting hole 11 is formed in the upper portion of the blow molding die 10. The shoulder forming portion 2 of the reference preform B is mounted in the mounting hole 11. However, since the outer diameter of the shoulder forming portion 2 is smaller than the outer diameter of the shoulder forming portion 2 of the reference preform B, the weight-reduced preform A is formed between the shoulder forming portion 2 and the inner peripheral edge of the mounting hole 11. The gap 12 therebetween is larger than that of the reference preform B. For this reason, there is a possibility that position shift may occur between the shaft center of the light weight preform A and the shaft center of the mounting hole 11.
そこで、図４に示すように、軽量化プリフォームＡにおいては、サポートリング６の下面と肩部形成部２の外面との境界部分に僅かに湾曲する傾斜面１３を設けている。この傾斜面１３は、基準プリフォームＢの肩部形成部２の外面位置（図中二点鎖線で示す）を通って次第に縮径しつつ下方に向かって延びている。 Therefore, as shown in FIG. 4, in the light weight preform A, an inclined surface 13 that is slightly curved is provided at a boundary portion between the lower surface of the support ring 6 and the outer surface of the shoulder forming portion 2. The inclined surface 13 extends downward while gradually reducing the diameter through the outer surface position (indicated by a two-dot chain line in the drawing) of the shoulder forming portion 2 of the reference preform B.
これにより、軽量化プリフォームＡをブロー成形金型の装着孔１１に装着したときには、傾斜面１３が装着孔１１の内周縁に当接して装着孔１１の軸心に向かって案内されるので、装着孔１１に対する軽量化プリフォームＡの軸心ずれを抑制することができる。 Thereby, when the lightweight preform A is mounted in the mounting hole 11 of the blow molding die, the inclined surface 13 contacts the inner peripheral edge of the mounting hole 11 and is guided toward the axis of the mounting hole 11. A shift in the axis of the lightweight preform A with respect to the mounting hole 11 can be suppressed.
Ａ…軽量化プリフォーム（プリフォーム）、Ｂ…基準プリフォーム、１…口部、２…肩部形成部、３…胴部形成部、４…底部形成部、５…ネジ山、６…サポートリング、７…内径略ストレート部、８…内径テーパ部、１３…傾斜面。 A ... Light weight preform (preform), B ... Reference preform, 1 ... Mouth part, 2 ... Shoulder forming part, 3 ... Body forming part, 4 ... Bottom forming part, 5 ... Screw thread, 6 ... Support Ring, 7 ... Internally substantially straight part, 8 ... Internal diameter taper part, 13 ... Inclined surface.
Claims (2)
外周にキャップを螺着するためのネジ山が形成されていると共に下端外周に鍔状のサポートリングが形成された円筒状の口部と、該口部の下端に連設されてブロー成形後に前記サポートリングの下部から次第に拡径するボトル肩部となる円筒状の肩部形成部と、該肩部形成部の下端に連設されてブロー成形後にボトル胴部となる円筒状の胴部形成部と、該胴部形成部の下端に連設されてブロー成形後にボトル胴部の下端を閉塞するボトル底部となる半球状の底部形成部とを備えて射出成形により形成されるプリフォームにおいて、
樹脂重量２３ｇであり、前記肩部形成部の外径が前記胴部形成部の外径よりも大とされ、前記胴部形成部の内径が前記口部の内径よりも小とされ、前記肩部形成部は、内径が下方に向かって僅かに小径となりながら下方に延びる内径略ストレート部と、該内径略ストレート部の下端から次第に縮径して前記胴部形成部の内面に連なる内径テーパ部とを備え、前記肩部形成部の内径略ストレート部の肉厚が、前記胴部形成部の肉厚の５３〜８４％であり且つ前記底部形成部の肉厚の７５〜１００％とされていて、ブロー成形により内容量６００ｍＬ以下のボトルを形成するためのプリフォームを基準プリフォームとしたとき、
口部の上端から底部形成部の下端までの上下方向の長さ、口部の上端からサポートリングの下面までの外周面形状、口部の内径、肩部形成部の内径略ストレート部の内径、胴部形成部の外径、及び底部形成部の外側半球面形状を前記基準プリフォームと同一とし、肩部形成部の外径を前記基準プリフォームの肩部形成部の外径より小とし、肩部形成部の内径略ストレート部の内径を超えない範囲で胴部形成部の内径を前記基準プリフォームの胴部形成部の内径より大とし、底部形成部の内側半球面形状を前記基準プリフォームの底部形成部の内側半球面形状より大とし、肩部形成部の内径略ストレート部の肉厚が、胴部形成部の肉厚の５３〜８４％であり且つ底部形成部の肉厚の７５〜１００％である関係を維持して、肩部形成部と胴部形成部と底部形成部との肉厚を前記基準プリフォームよりも小とすることにより、前記基準プリフォームよりも樹脂重量を小としたことを特徴とするプリフォーム。 A preform for forming a synthetic resin bottle having an internal volume of 600 mL or less by blow molding,
A cylindrical mouth portion in which a thread for screwing a cap is formed on the outer periphery and a hook-shaped support ring is formed on the outer periphery of the lower end, and the blower after the blow molding is provided continuously to the lower end of the mouth portion. A cylindrical shoulder forming portion that becomes a bottle shoulder that gradually expands from the lower portion of the support ring, and a cylindrical barrel forming portion that is connected to the lower end of the shoulder forming portion and becomes a bottle trunk after blow molding And a preform formed by injection molding with a hemispherical bottom part forming a bottle bottom part that is continuously provided at the lower end of the body part forming part and closes the lower end of the bottle body part after blow molding,
The resin weight is 23 g, the outer diameter of the shoulder portion forming portion is larger than the outer diameter of the trunk portion forming portion, the inner diameter of the trunk portion forming portion is smaller than the inner diameter of the mouth portion, and the shoulder The portion forming portion includes a substantially straight inner diameter portion that extends downward while the inner diameter is slightly smaller toward the bottom, and an inner diameter taper portion that gradually decreases in diameter from the lower end of the substantially straight inner diameter portion and continues to the inner surface of the trunk portion forming portion. The thickness of the substantially straight inner diameter of the shoulder forming portion is 53 to 84% of the thickness of the trunk forming portion and 75 to 100% of the thickness of the bottom forming portion. When a preform for forming a bottle having an internal volume of 600 mL or less by blow molding is used as a reference preform,
The vertical length from the upper end of the mouth part to the lower end of the bottom part forming part, the outer peripheral surface shape from the upper end of the mouth part to the lower surface of the support ring, the inner diameter of the mouth part, the inner diameter of the shoulder part, the inner diameter of the substantially straight part, The outer diameter of the body forming portion and the outer hemispherical shape of the bottom forming portion are the same as the reference preform, the outer diameter of the shoulder forming portion is smaller than the outer diameter of the shoulder forming portion of the reference preform, The inner diameter of the shoulder forming portion is set to be larger than the inner diameter of the trunk forming portion of the reference preform within a range not exceeding the inner diameter of the substantially straight portion, and the inner hemispherical shape of the bottom forming portion is set to the reference profile. The thickness of the reformed bottom forming portion is larger than the inner hemispherical shape, and the thickness of the substantially straight inner diameter of the shoulder forming portion is 53 to 84% of the thickness of the trunk forming portion and the thickness of the bottom forming portion is Maintaining the relationship of 75-100%, shoulder formation and trunk formation And by smaller than the thickness of the bottom forming portion and the reference preform, the preform, characterized in that the resin weight smaller than the reference preform.
前記サポートリングの下面と前記肩部形成部の外面との境界部分に、前記基準プリフォームの肩部形成部の外面に相当する位置を通って次第に縮径しつつ下方に向かって延びる傾斜面を設けたことを特徴とするプリフォーム。 The preform according to claim 1,
An inclined surface extending downward while gradually reducing the diameter through a position corresponding to the outer surface of the shoulder forming portion of the reference preform at the boundary portion between the lower surface of the support ring and the outer surface of the shoulder forming portion. Preform characterized by providing.
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| JP2017007264A (en) * | 2015-06-25 | 2017-01-12 | 大日本印刷株式会社 | Preform, plastic bottle, and method for producing plastic bottle |
| JP2018083335A (en) * | 2016-11-22 | 2018-05-31 | 東洋製罐株式会社 | Preform for biaxial drawing blow molding of synthetic resin heat-resistant container |
| JP2020011421A (en) * | 2018-07-17 | 2020-01-23 | 大日本印刷株式会社 | preform |
| JP2020049779A (en) * | 2018-09-27 | 2020-04-02 | 大日本印刷株式会社 | preform |
| CN113993676A (en) * | 2019-05-31 | 2022-01-28 | 三得利控股株式会社 | Bottle preform and container forming method |
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| JP2017007264A (en) * | 2015-06-25 | 2017-01-12 | 大日本印刷株式会社 | Preform, plastic bottle, and method for producing plastic bottle |
| JP2018083335A (en) * | 2016-11-22 | 2018-05-31 | 東洋製罐株式会社 | Preform for biaxial drawing blow molding of synthetic resin heat-resistant container |
| JP2020011421A (en) * | 2018-07-17 | 2020-01-23 | 大日本印刷株式会社 | preform |
| JP7081359B2 (en) | 2018-07-17 | 2022-06-07 | 大日本印刷株式会社 | preform |
| JP2020049779A (en) * | 2018-09-27 | 2020-04-02 | 大日本印刷株式会社 | preform |
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| CN113993676A (en) * | 2019-05-31 | 2022-01-28 | 三得利控股株式会社 | Bottle preform and container forming method |
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