JP5581564B2 - Preform for plastic bottle molding - Google Patents

Description

  The present invention relates to a plastic bottle molding preform, and more particularly to a plastic bottle molding preform having a capacity of 600 ml or less that can reduce the amount of resin used and reduce the weight.

In general, plastic bottles made of polyester, polypropylene, nylon or the like are known. As this type of plastic bottle molding preform, a 2000 ml bottle molding preform (Parison) is known (for example, see Patent Document 1). Also, a preform with a parallel part under the support ring (thin part under the support ring) of 2.68 mm was used as a blow molding preform for a 500 ml plastic bottle, and heat setting was performed after the primary blow molding. In addition, it is known that blow molding of a bottle having a weight of 26 g and excellent heat resistance is performed by performing secondary molding (see Patent Document 2).
However, when reducing the weight of plastic bottles, the maximum thickness of the preform must be reduced. When the maximum thickness of the preform is reduced, the maximum thickness portion of the preform is easily stretched during blow molding, and the bottle body is thin. Therefore, when the weight of the preform is reduced without changing the outer shape of the preform, the shape of the thin part of the bottom and bottom of the support ring under the support ring of the preform that is easily stretched even when the preform is thin is required. It is done. This is particularly required when the weight is further reduced from 26 g.
JP 2002-240136 A JP2003-53823, paragraph 0042

  An object of the present invention is to provide a plastic bottle molding preform having a resin weight of 25.0 or less and a capacity of 600 ml or less.

  Invention of Claim 1 solves said subject, It is a plastic bottle molding preform provided with the bottom part which obstruct | occludes the stopper part, a support ring, a trunk | drum, and the edge part of a trunk | drum, Comprising: Resin weight 25.0 g or less, and a lower thin part of the support ring having a length of 5.0 to 10.0 mm consisting of the smallest thin part is provided under the support ring, and the bottom part gradually becomes thinner toward the gate part. The gist is a preform for molding a plastic bottle characterized by the above.

  According to the present invention, the stretchability of the thin portion under the support ring is improved, the thickness of the bottle body can be increased, and the physical properties of the bottle can be improved. By setting the length to 5.0 to 10.0 mm, the wall thickness of the shoulder portion of the bottle can be kept in a range that does not affect the physical properties of the bottle.

      In the present invention, based on the thickness of the thin part under the support ring, the thickness of the trunk part is 1.19 to 1.9 times the thickness of the thin part under the support ring. The wall thickness is desirably 0.85 to 1.19 times the wall thickness of the thin part under the support ring.

  The preform for molding a plastic bottle of the present invention is a preform for molding a plastic bottle having a stopper, a support ring, a body part, and a bottom part that closes an end part of the body part, and the resin weight is 25.0 g or less. There is a support ring lower thin part with a length of 5.0 to 10.0 mm consisting of the smallest thin part under the support ring, and the bottom part is characterized by gradually decreasing the thickness toward the gate part. The length of the thin part under the support ring is 5.0-10.0 mm, and the bottom part is directed toward the gate part, and the thickness is gradually reduced. In addition to being able to increase the thickness of the bottle body, the physical properties of the bottle can be improved, and the length of the thin part under the support ring is set to 5.0 to 10.0 mm. Yo , It can be kept to a range that also the wall thickness of the shoulder portion of the bottle does not affect the bottle physical properties.

  FIG. 1 shows a preform for molding a plastic bottle of the present invention.

  As shown in FIG. 1, a plastic bottle molding preform 1 according to the present invention has a cap portion 2, a support ring 3, a trunk portion 5, and a bottom portion 6 that closes an end portion of the trunk portion 5, and a plastic having a capacity of 600 ml or less. A preform for bottle molding having a resin weight of 25.0 g or less, a support ring lower thin portion 4 having a length of 5.0 to 10.0 mm consisting of a minimum thin portion under the support ring 3, and a bottom portion 6 is gradually formed thinner toward the gate portion.

  The support ring lower thin portion 4 is preferably formed to have a length of 7 to 8 mm, and particularly preferably 7.5 mm. When the length of the support ring lower thin part 4 is smaller than 7 mm, sufficient stretchability of the support ring lower thin part 4 is not obtained, and the maximum thickness part of the preform is easily stretched, and the thin bottle body A part will be formed. On the other hand, when the length of the support ring lower thin portion 4 is larger than 8 mm, the bottle shoulder portion becomes too thin.

  The thickness of the gate part below the bottom part 6 is 0.85 to 1.19 times the thickness of the thin part of the lower part of the support ring in the case of a plastic bottle molding preform having a capacity of 600 ml or less which is normally used. 8 to 2.5 mm is desirable. When the thickness of the gate portion is thinner than 1.8 mm, the flow of the resin is deteriorated at the time of injection molding, and there is a high possibility that problems such as molding failure occur. In addition, when the thickness of the gate portion is larger than 2.5 mm, the difference from the thickness of the barrel portion becomes smaller, the gate portion of the preform becomes difficult to be stretched, and a thin bottle barrel portion is formed.

  The thickness of the body portion 5 is desirably 2.5 to 4.0 mm, which is 1.19 to 1.9 times the thickness of the lower thickness portion of the support ring, and is particularly preferably 3.0 to 3.5 mm. desirable. If the thickness is less than 2.5 mm, sufficient stretchability of the lower thickness portion 4 of the support ring cannot be obtained, and the maximum thickness portion of the preform becomes easy to be stretched, so that an extremely thin bottle body portion is formed. When the thickness is larger than 4.0 mm, a temperature difference between the inner surface and the outer surface of the preform is likely to occur during preheating of blow molding, and the physical properties and appearance of the bottle are adversely affected because the temperature of the inner surface of the preform is low.

  The general height excluding the stopper portion of a plastic bottle of 600 ml or less is about 190 mm. The length under the support ring of the preform is desirably 63.0 to 95.0 mm because the longitudinal stretch ratio with respect to the plastic bottle is desirably 2.0 to 3.0 times.

The general body diameter of a plastic bottle of 600 ml or less is about 66 mm. The drawing taper starting position diameter f is preferably set to 13.0 to 26.0 mm because the transverse draw ratio with respect to the plastic bottle is preferably 2.5 to 5.0 times.
However, it is desirable to set the punching taper starting position diameter f to 14.0 to 26.0 mm on the mold when the preform is injection-molded.
Further, in order to prevent the preforms from overlapping and moving when the preform is conveyed, it is desirable that the punching taper starting position diameter f is 0.4 mm or more larger than the inner diameter of the stopper portion of the preform.

  The angle of the taper taper is required when taking out the molded bottle from the injection mold, and is preferably 0.2 to 0.5 °.

  It is desirable that the length from the bottom of the support ring to the starting position of the taper taper is determined so as to correspond to the shoulder of the plastic bottle. Therefore, it is desirable that the length from the bottom of the support ring to the punching taper start position is 12.5 to 15.0 mm.

  The preform shown in FIG. 1 shows an example of a preform for molding a plastic bottle of a total length of 92.5 mm and 600 ml or less. In FIG. 1, a indicates the length of the thin part of the support ring lower wall = 7.5 mm. , B represents the thickness of the thin portion under the support ring = 2.1 mm, c represents the length from the bottom of the support ring to the punch taper start position = 14.4 mm, and d represents the thickness of the body = 3.0 mm, e indicates the thickness of the gate portion = 2.3 mm, f indicates the diameter of the taper taper starting position = 24.0 mm, and g indicates the length under the support ring.

  In the plastic bottle molding preform 1 of the present invention, the length of the support ring lower thin part 4 is set to 5.0 to 10.0 mm, and the thickness is gradually reduced with the bottom 6 directed toward the gate part. The stretchability of the lower support ring thin part 4 is improved, the thickness of the bottle body can be increased, and the physical properties of the bottle can be improved. By setting the thickness to 5.0 to 10.0 mm, the thickness of the shoulder portion of the bottle can be kept within a range that does not affect the physical properties of the bottle.

  Examples of the thermoplastic resin constituting the preform 1 for molding a plastic bottle of the present invention include thermoplastic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, and copolymers thereof, and the like. Resins or blends with other resins are suitable, and ethylene terephthalate-based thermoplastic polyesters such as polyethylene terephthalate can be suitably used. Moreover, an acrylonitrile resin, a polypropylene, a propylene-ethylene copolymer, etc. can also be used. Various additives such as a colorant, an ultraviolet absorber, a release agent, a lubricant, a nucleating agent, an antioxidant, an antistatic agent and the like are blended with the above-described resin within a range that does not impair the quality of the molded product. be able to.

  As the ethylene terephthalate thermoplastic resin constituting the preform 1, an ethylene terephthalate unit occupies most of the ester repeating portion, generally 70 mol% or more, and has a glass transition point (Tg) of 50 to 90 ° C. Those having a melting point (Tm) in the range of 200 to 275 ° C. are preferred. In addition, as an ethylene terephthalate thermoplastic polyester, polyethylene terephthalate is particularly excellent in terms of pressure resistance, but in addition to the ethylene terephthalate unit, an ester comprising a dibasic acid such as isophthalic acid or naphthalenedicarboxylic acid and a diol such as propylene glycol Copolyesters containing a small amount of units can also be used.

  The preform 1 can also be composed of two or more thermoplastic polyester layers. Furthermore, when the preform 1 is composed of two or more thermoplastic polyester layers, an intermediate layer such as a barrier layer or an oxygen absorbing layer can be provided between the layers. As the oxygen absorbing layer, a combination of an oxidizable organic component and a transition metal catalyst, or a layer containing a gas barrier resin that does not substantially oxidize can be used.

  Next, the present invention will be described with reference to examples and comparative examples.

A preform having the following dimensions was manufactured in the shape shown in FIG. 1 by injection molding of polyethylene terephthalate.
Total length 92.5mm
The length of the thin part under the support ring 7.5mm
Thickness of thin part under support ring 2.1mm
Length from under support ring to taper start position 14.4mm
Body thickness 3.0mm
Gate thickness 2.3mm
Preform weight 22.8g

  The preform was preheated, blow-molded by a known biaxial stretch blow molding machine, and formed into a plastic bottle 7 having the shape shown in FIG. The obtained plastic bottle 7 had sufficient strength with a barrel thickness of 0.31 mm.

A preform having the following dimensions was manufactured in the shape shown in FIG. 1 by injection molding of polyethylene terephthalate.
Total length 92.5mm
The length of the thin part under the support ring 7.5mm
Thickness of thin part under support ring 2.1mm
Length from under support ring to taper start position 14.4mm
Body thickness 2.9mm
Gate thickness 2.3mm
Preform weight 22.4g

  The preform was preheated, blow-molded by a known biaxial stretch blow molding machine, and formed into a plastic bottle 7 having the shape shown in FIG. The obtained plastic bottle 7 had sufficient strength with a barrel thickness of 0.30 mm.

A preform having the following dimensions was manufactured in the shape shown in FIG. 1 by injection molding of polyethylene terephthalate.
Total length 92.5mm
The length of the thin part under the support ring 7.5mm
Thickness of thin part under support ring 2.1mm
Length from under support ring to taper start position 14.4mm
Body thickness 2.8mm
Gate thickness 2.3mm
Preform weight 22.0g

  The preform was preheated, blow-molded by a known biaxial stretch blow molding machine, and formed into a plastic bottle 7 having the shape shown in FIG. The obtained plastic bottle 7 had sufficient strength with a wall thickness of 0.29 mm.

A preform having the following dimensions was manufactured in the shape shown in FIG. 1 by injection molding of polyethylene terephthalate.
Total length 92.5mm
The length of the thin part under the support ring 5.0 mm
Thickness of thin part under support ring 2.1mm
Length from under support ring to taper start position 14.4mm
Body thickness 3.0mm
Gate thickness 2.3mm
Preform weight 22.9g

  The preform was preheated, blow-molded by a known biaxial stretch blow molding machine, and formed into a plastic bottle 7 having the shape shown in FIG. The obtained plastic bottle 7 had sufficient strength with a thickness of the barrel portion of 0.30 mm.

A preform having the following dimensions was manufactured in the shape shown in FIG. 1 by injection molding of polyethylene terephthalate.
Total length 92.5mm
The length of the thin part under the support ring 10.0mm
Thickness of thin part under support ring 2.1mm
Length from under support ring to taper start position 14.4mm
Body thickness 3.20mm
Gate thickness 2.35mm
Preform weight 22.7g

  The above preform was preheated, blow-molded with a known biaxial stretch blow meter, and formed into a plastic bottle having the shape shown in FIG. The obtained plastic bottle 7 had sufficient strength with a thickness of the barrel portion of 0.30 mm.

[Comparative Example 1]
A preform having the following dimensions was manufactured in the shape shown in FIG. 1 by injection molding of polyethylene terephthalate.
Total length 92.5mm
The length of the thin part under the support ring
Thickness of thin part under support ring 2.1mm
Length from under support ring to taper start position 14.4mm
Body thickness 3.0mm
Gate thickness 2.3mm
Preform weight 23.0g

  The preform was preheated, blow-molded by a known biaxial stretch blow molding machine, and formed into a plastic bottle 7 having the shape shown in FIG. As for the obtained plastic bottle 7, sufficient stretchability of the thin part under the support ring is not obtained, and as a result, a stretch load is applied to the part that becomes the bottle body, and the thickness of the body becomes 0.24 mm, A bottle with sufficient strength could not be obtained.

[Comparative Example 2]
A preform having the following dimensions was manufactured in the shape shown in FIG. 1 by injection molding of polyethylene terephthalate.
Total length 92.5mm
Length of thin part of support ring 12.0mm
Thickness of thin part under support ring 2.1mm
Length from under support ring to taper start position 14.4mm
Body thickness 3.20mm
Gate thickness 2.35mm
Preform weight 22.6g

  The above preform was preheated, blow-molded with a known biaxial stretch blow meter, and formed into a plastic bottle having the shape shown in FIG. In the obtained plastic bottle, the bottle shoulder was too thin, and a plastic bottle having sufficient strength could not be obtained.

  According to the preform for molding a plastic bottle of the present invention, a plastic bottle that is lighter than a conventional plastic bottle having a capacity of 600 ml or less can be manufactured.

It is a partial cross section illustration side view of the preform for plastic bottle fabrication of the present invention. It is a side view of an example of the plastic bottle shape | molded using the preform for plastic bottle shaping | molding of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Preform 2 Mouth part 3 Support ring 4 Lower thin part of support ring 5 Body 6 Bottom part a Length of thin thin part of support ring b Thickness of thin thin part of support ring c From under support ring to the taper start position Length d Body thickness e Gate wall thickness f Diameter of taper starting position g Length under support ring 7 Plastic bottle

Claims (2)

In a preform for molding a plastic bottle comprising a mouthpiece, a support ring, a trunk, and a bottom that closes an end of the trunk
A plastic bottle molding preform having a resin weight of 25.0 g or less and a capacity of 600 ml or less,
Furthermore, under the support ring, the length from the bottom of the support ring to the taper start position (corresponding to the shoulder of the plastic bottle), the length consisting of the smallest thin portion of 12.5 to 15.0 mm A support ring lower thin part having a thickness of 5.0 to 10.0 mm is provided,
And the thickness of the trunk is formed in the range of 2.8 to 4.0 mm, which is 1.33 to 1.9 times the thickness of the thin part under the support ring,
Further, the thickness of the bottom portion gradually decreases toward the gate portion, and the thickness of the gate portion below the bottom portion is 0.85 to 1. A preform for molding a plastic bottle characterized by being formed in a range of 1.8 to 2.5 mm, which is 19 times. The preform for molding a plastic bottle according to claim 1, wherein the thickness of the body portion is 3.0 to 3.5 mm.

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