JPH07125053A - Heat-resistant biaxially stretched blow molded bottle and production thereof - Google Patents

Abstract

PURPOSE:To provide a mouth part having excellent heat resistance and good dimensional accuracy. CONSTITUTION:A heat-resistant biaxially stretched blow molded bottle has a mouth part 1 having a support ring 11 provided to the lower end thereof, the transfer part 2 continued to the mouth part 1, a shoulder part 3, a body part 4 and a bottom part 5. The mouth part 1 has a multilayered structure consisting of a polyester layer 14 and a heat-resistant resin layer 13 and the polyester layer 14 in the mouth part 1 and the transfer part 2 is crystallized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant biaxially stretched blow-molded bottle in which the mouth and the transition are crystallized (whitened) and a method for producing the same, and particularly because the mouth and the transition are crystallized. The present invention relates to a heat-resistant biaxially stretch blow-molded bottle having excellent heat resistance and good dimensional accuracy, and a method for producing the same.

[0002]

2. Description of the Related Art In recent years,
So-called hot fill, which fills a polyester bottle with a liquid at 80 to 95 ° C, and pasteurizing with a hot shower for bottles filled with carbonic acid-containing fruit juice, lactic acid bacteria beverages, etc., will be performed especially near the mouth. Excellent heat resistance is now required. For hot fill, the mouth is first exposed to a hot liquid, and also for pasteurizing with a hot shower,
This is because it is common to pour the hot shower from above the bottle.

However, in a polyester bottle obtained by ordinary biaxially stretch blow molding, the mouth portion is left unstretched and the transition portion is also low stretched, so that heat resistance cannot be imparted by stretching or heat setting. , Cannot be used for filling liquid at 80-95 ℃.

Therefore, various methods have been attempted for producing a biaxially stretch blow molded bottle from a parison having a multi-layered structure including a heat resistant resin and a polyester resin in the mouth. However, even in that method, when pasteurizing with a hot shower at 65 to 80 ° C. for a long time is performed on a bottle for a carbon dioxide-containing beverage or the like, the amount of deformation becomes large especially at the transition portion of low stretching due to heat and internal pressure. Further, it is difficult to obtain heat resistance capable of continuous use under severe hot fill conditions of 90 ° C or higher.

Further, a method of crystallizing the polyester to improve the heat resistance by subjecting the mouth of the bottle to a heat treatment after the parison stage or after the biaxial stretch blow molding has been carried out. However, in this method, with the crystallization of the polyester when subjected to heat treatment,
There is a problem that the size of the mouth portion is likely to change, and contraction is likely to occur especially at the opening end portion.

Therefore, an object of the present invention is to provide a heat resistant biaxially stretch blow molded bottle having a mouth portion having excellent heat resistance and good dimensional accuracy, and a method for producing such a heat resistant biaxially stretch blow molded bottle. Is to provide.

[0007]

As a result of earnest research in view of the above object, the present inventor produced a parison having a multilayer structure in the mouth by co-injecting a polyester resin and a heat-resistant resin. After the step or the parison is biaxially stretch blow molded, the mouth and the transition are heated from the inside, and then the mouth is heated from the outside, the polyester layer in the mouth and the transition is crystallized without substantial deformation. It was found that a biaxially stretched blow molded bottle having sufficient heat resistance against hot fill and hot shower can be obtained, and the present invention has been conceived.

That is, the heat-resistant biaxially stretch blow-molded bottle of the present invention has a mouth portion having a support ring at the lower end, a transition portion continuing to the mouth portion, a shoulder portion, a body portion, and a bottom portion, The mouth portion has a multi-layered structure including a polyester layer and a heat resistant resin layer, and the polyester layer in the mouth portion and the transition portion is crystallized.

The first method of the present invention for producing the heat-resistant biaxially stretch blow-molded bottle is (a) having a multilayer structure consisting of a polyester layer and a heat-resistant resin layer, and having a support ring at the lower end. A mouth portion, a transition portion that follows the mouth portion,
Forming a bottomed cylindrical parison having a body portion and a bottom portion, (b) by a heater inserted inside the mouth portion, the mouth portion and the transition portion are heated from the inside and the inside of the mouth portion is formed. And after crystallizing the polyester layer in the transition part, (c) heating the mouth portion from the outside to crystallize the polyester layer in the mouth portion and the transition portion, (d) subsequently biaxially the parison. It is characterized by stretch blow molding.

The second method of the present invention for producing the heat-resistant biaxially stretch blow-molded bottle is as follows: (a) A mouth part having a multilayer structure consisting of a polyester layer and a heat-resistant resin layer and having a support ring at the lower end. And forming a bottomed cylindrical parison having a transition part following the mouth part, a body part, and a bottom part,
(b) biaxially stretch blow molding the parison, (c) by a heater inserted inside the mouth of the resulting biaxially stretch blow molded bottle, the mouth and the transition part are heated from the inside to After crystallizing the polyester layer at the inside of the mouth and at the transition, (d) heating the mouth from the outside to crystallize the polyester layer at the mouth and the transition.

The third method of the present invention for producing the heat-resistant biaxially stretch blow-molded bottle is (a) a mouth part having a multilayer structure comprising a polyester layer and a heat-resistant resin layer and having a support ring at the lower end. And forming a bottomed cylindrical parison having a transition part following the mouth part, a body part, and a bottom part,
(b) heating the mouth portion and the transition portion from the inside by a heater inserted inside the mouth portion to crystallize the polyester layer at the inside of the mouth portion and the transition portion, and (c) subsequently the parison. Biaxially stretch blow molded, (d) heating the mouth of the resulting biaxially stretch blow molded bottle from the outside,
It is characterized in that the polyester layer on the outside of the mouth portion and on the transition portion is crystallized.

[0012]

The present invention will be described in detail below. [A] Structure of Bottle Portion The heat-resistant biaxially stretch blow-molded bottle of the present invention has a mouth portion 1 having a support ring 11 at the lower end, as illustrated in FIG.
And a transition portion 2 following the mouth portion 1, a shoulder portion 3, a body portion 4, and a bottom portion 5. In the present specification, the transition portion is the mouth portion 1
It is located slightly below and is hardly stretched by biaxial stretching blow, and is located between the mouth and the shoulder in the bottle state. In addition, in this specification, heat resistance means including both heat resistance and heat resistance / pressure resistance. Note that the shoulder portion 3, the body portion 4, and the bottom portion 5 of the bottle are not limited to the shape shown in FIG. 1, and may be appropriately changed to various shapes found in conventional plastic bottles. Further, it goes without saying that the sealing form of the mouth portion 1 can be appropriately selected from shapes other than screws.

The mouth portion 1 comprises a screw portion 12 and a support ring 11. The mouth portion 1 having such a shape has a heat-resistant resin layer 13
And a polyester layer 14 are alternately formed. In the example shown in FIG. 2, the heat resistant resin layer 13 has three layers (13a-
13c), and the outermost heat-resistant resin layer 13a may be continuous to the upper surface of the support ring 11. On the other hand, the polyester layers 14a and 14b are present between the heat resistant resin layers 13a to 13c. The heat resistant resin layer 13 is not limited to three layers,
It can have any number of layers.

The thickness of the heat-resistant resin layers 13a to 13c is not particularly limited, but the heat-resistant resin layer 13 occupies a larger proportion toward the opening end, and the opening end portion is almost entirely made of the heat-resistant resin. It is preferable that

As shown in FIGS. 1 and 2, the polyester layer 14 in the mouth portion 1 is crystallized. Also, the transition section 2
Has a uniform crystallization region 2a immediately below the support ring 3 and a tilted crystallization region 2b below it. The uniform crystallized region 2a is crystallized uniformly on the inside and the outside, but the inclined crystallized region 2b gradually decreases from the outside toward the shoulder portion 3.

The uniform crystallization region 2a and the inclined crystallization region
In the transition section 2 having 2b, even when filling the high-temperature content, the inside of the transition section in contact with the content is crystallized, so that deformation or the like does not occur. When the transition part 2 is crystallized as described above at the parison stage, the non-crystallized portion outside the tilted crystallized region 2b is stretched / formed into an arbitrary shape in the subsequent blow molding. You can At this time, if the thickness of the transition portion and the thickness of the shoulder portion are gently changed, excellent physical properties and a beautiful appearance can be obtained.

Therefore, compared to the case where the entire transitional portion is crystallized, the shape is more flexible, and the deformation, cracking, or crystallized transitional portion which occurs when the once crystallized transitional portion is forcibly formed. It is possible to prevent a thickness difference or the like, which is likely to occur between the non-crystallized portion and the lower portion.

The bottle of the present invention described above has a temperature of 80 to 95 ° C.
It has good heat resistance enough to withstand hot filling for filling the liquid and hot pasteurizing at 70-80 ° C for about 30 minutes from the top of the bottle.

[B] Bottle Manufacturing Method The mouth portion 1 and the transition portion 2 are crystallized by a heat treatment. The heat crystallization treatment includes the following three methods:
(1) Heat crystallization at the parison stage, (2)
There are a method of performing heat crystallization treatment after blow molding, and a method of (3) heat crystallization of only the inner side at the stage of parison, and then heat crystallization treatment of the outer side after blow molding. Hereinafter, each method will be described.

(1) Heat crystallization treatment is performed at the parison stage.
To a method will be described first parison production. As shown in Fig. 3 (a), the mouth part mold 71 and the injection cavity mold
The parison is manufactured using the injection molding die 7 including the 72 and the injection core die 73. The mouth portion 1 of the parison 6 in the present invention has a multi-layer structure composed of the heat-resistant resin layer 13 and the polyester resin layer 14, and therefore is disclosed in, for example, Japanese Patent Laid-Open No.
By the co-injection method of a polyester resin and a heat-resistant resin shown in No. 294025, it is possible to manufacture a parison having the above-mentioned multilayer structure, but in addition, a heat-resistant resin from the mouth side, from the bottom side It can also be manufactured by a so-called two-gate co-injection molding method or the like in which each polyester resin is injected.

When the molded parison 6 is cooled to a temperature lower than the glass transition temperature, the injection core mold 73 and the injection cavity mold 72 are released. At this time, as shown in FIG. 3 (b), the mouth die 71 holds the mouth portion 1 of the parison 6 still.

Next, as shown in FIG. 4, it is preferable to put the parison 6 held by the mouth die 71 into the cooling die 8. At this time, it is preferable to cool not only the mouth die 71 but also the body and bottom of the parison 6. The cooling temperature may be lower than the crystallization temperature of the polyester resin, specifically, 10
It is preferable to cool to about 50 ° C.

With the parison 6 being cooled from the outside as described above, the rod heater 9 is inserted from the mouth portion 1 of the parison 6 as shown in FIG. 4, and the mouth portion 1 and the transition portion 2 are heated from the inside, The polyester layer 14 in that portion is partially crystallized, that is, only the inner portion is crystallized. At this time, it is preferable to heat the parison so that the surface temperature of the parison is 100 to 190 ° C. If the surface temperature of the parison is less than 100 ° C, the polyester resin will not crystallize, and if it exceeds 190 ° C, the crystallization of the polyester layer will be slow and the parison will be easily softened and deformed. Further, the heating time is set so as to cause partial crystallization of the polyester layer 14, but specifically, it is set to 0.
5 to 3 minutes is preferable.

Next, the mouth die 71 is removed from the parison 6 and the mouth 1 is opened from the outside as shown in FIG.
However, other hot air heaters, infrared heaters or the like may be used. At this time, it is preferable to put it in the cooling mold 20 so as not to heat the lower part of the transition part 2 and the body part. The heating temperature may be about 100 to 190 ° C. as described above. Further, the heating time may be a time sufficient for the uncrystallized polyester layer 14 in the outer layer of the mouth to be crystallized, but specifically 0.5
~ 3 minutes is preferred.

By heating the mouth portion 1 by such a method, the polyester layer 14 of the mouth portion 1 is crystallized and the transition portion 2
A uniform crystallized region 2a and a tilted crystallized region 2b are formed on the surface. In the method of the present invention, the heat treatment is performed without inserting a supporting means such as a jig into the inside of the mouth 1. However, since the inner portion of the mouth 1 is crystallized, the heating crystallization temperature is also good. It retains heat resistance, so that the mouth portion 1 is hardly deformed.

The parison 6 thus obtained is biaxially stretch-blow-molded by a usual method, but at that time, a steep thickness difference from the transition portion 2 to the shoulder portion 3 does not occur.

A two-step blow molding method may be used as the biaxial stretch blow molding method. In the case of the two-stage blow molding method, in the first stage, blow molding is performed to a size slightly larger than the final shape of the desired bottle to produce a pre-bottle. The pre-bottle is heat-shrinked at a temperature not lower than the crystallization temperature of the crystalline plastic and lower than the melting point, and again subjected to biaxial stretch blow molding to obtain a bottle having a desired shape. By such a biaxial stretch blow molding method, it is possible to prevent the whitening phenomenon of the bottle body and the like and prevent the occurrence of irregular distortion on the bottle surface. Further, since the internal stress can be relaxed and the density can be improved, a bottle having further excellent heat resistance can be obtained.

(2) Perform heat crystallization treatment after blow molding
Method In this method, the parison is not subjected to the heat crystallization treatment, but is subjected to the biaxial stretch blow molding in the same manner as described above to mold the bottle, and then the mouth heat crystallization treatment is performed.

After the biaxially stretch blow molding, the bottle is taken out from the mold while being held by the mouth mold, and the following heat crystallization treatment is performed. In the heating crystallization process, the bottle held by the mouth mold is put in the cooling mold, and a heater is inserted from the mouth of the bottle to heat the mouth and the transition part from the inside in the same manner as in the method (1). Crystallize the polyester layer in parts. The heat crystallization conditions may be the same as in the method (1).

Next, the mouth mold is released from the bottle and the mouth is heated from the outside to crystallize the uncrystallized polyester layer in the outer layer of the mouth. The heat crystallization conditions may be the same as in the method (1).

(3) Heat crystallization of only the inside at the stage of parison
Treated, then heat-crystallized on the outside after blow molding
Method According to this method, the mouth portion and the transitional portion are heat-crystallized from the inside at the stage of parison, and then the mouth portion is heat-crystallized from the outside after blow molding.

After the parison is manufactured, the injection core mold and the injection cavity mold are removed while the parison is gripped by the mouth mold, and the mouth part and the transition part are heated from the inside to crystallize the polyester layer in the part. The heat crystallization conditions may be the same as in the method (1).

After biaxial stretch blow molding is performed using the parison, the mouth portion is heated from the outside to crystallize the uncrystallized polyester layer in the outer layer of the mouth portion. The heat crystallization conditions are
The method of (1) may be the same.

[C] Material The polyester layer 14 of the heat resistant biaxially stretch blow molded bottle of the present invention can be formed of a polyester resin composed of a saturated dicarboxylic acid and a saturated dihydric alcohol.
Saturated dicarboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, naphthalene-1,4- or 2,6-dicarboxylic acid, diphenyl ether-4,4'-dicarboxylic acid, diphenyldicarboxylic acids, diphenoxyethanediethanedicarboxylic acids And the like, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, decane-1,10-dicarboxylic acid and the like, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and the like can be used. As the saturated dihydric alcohol, aliphatic glycols such as ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, dodecamethylene glycol and neopentyl glycol are used. Glycols, alicyclic glycols such as cyclohexanedimethanol, 2,2-bis (4'-β-hydroxyethoxyphenyl) propane, and other aromatic diols can be used. As the polyester resin composed of such a saturated dicarboxylic acid and a saturated dihydric alcohol, it is preferable to use polyethylene terephthalate composed of terephthalic acid and ethylene glycol.

The above polyester resin has an intrinsic viscosity of 0.5.
Has a value in the range from .about.1.5, preferably 0.55 to 0.85. Also, such polyesters are produced by melt polymerization, 1
Those that have been subjected to reduced pressure treatment or heat treatment in an inert gas atmosphere at a temperature of 80 to 250 ° C., or those that have reduced the content of oligomers and acetaldehyde, which are low molecular weight polymers by solid-state polymerization, are suitable.

As the heat resistant resin, polycarbonate, polyarylate, polyethylene naphthalate, polyacetal, polysulfone, polyether ether ketone, polyether sulfone, polyether imide, polyphenylene sulfide and blends of these resins with polyethylene terephthalate. Polymers, blend polymers between the above heat resistant resins, further blend polymers of two or more resins of the above heat resistant resins with polyethylene terephthalate, U polymers (manufactured by Unitika, blend polymers of polyarylate and polyethylene terephthalate), etc. Can be used. Among these, especially polycarbonate, polyarylate, and U
Polymers (blended polymers of polyarylate and polyethylene terephthalate) are preferred.

In the polyester resin and heat-resistant resin used in the present invention, stabilizers, pigments, antioxidants, heat deterioration inhibitors, ultraviolet light deterioration inhibitors, antistatic agents are included within the range not impairing the object of the present invention. An appropriate amount of additives such as antibacterial agents and other resins can be added.

The present invention has been described above with reference to the accompanying drawings. However, the present invention is not limited to this, and various modifications can be made without departing from the idea of the present invention.

The present invention will be described in more detail with reference to the following specific examples. Example 1 Polycarbonate as a heat-resistant resin (Mitsubishi Kasei Co., Ltd.)
Manufactured by NOVAREX 7022A) and co-injection molding with polyethylene terephthalate (NEH-2050 manufactured by Unitika Ltd.) to form a parison having a multilayer structure shown in FIG. Dimensions A to H of each part of the obtained parison (A: screw thread diameter, B: screw root diameter, C: mouth inner diameter (maximum), D: mouth inner diameter (minimum), E: tightening ring diameter, F: winding clamp ring lower diameter, G: support ring diameter, H: support ring height) were measured.

While holding the parison with the mouth mold, it was placed in a cooling mold cooled to 20 ° C. In this state, a rod heater was inserted from the mouth of the parison, and the mouth and transition part of the parison were heated from the inside at 150 ° C. for 1 minute to crystallize the polyester layer in that part.

Next, the mouth of the parison was heated from the outside by a ring heater at 150 ° C. for 1 minute to crystallize the uncrystallized polyester layer in the outer layer of the mouth.

Dimension A of each part of the parison after heat crystallization
.About.H was measured, and the shrinkage rate due to heat crystallization was calculated. The results are shown in Fig. 7. As is clear from the graph of FIG. 7, the mouth of the parison subjected to the heat crystallization treatment by the method of the present invention showed almost no deformation due to the heat crystallization.

Example 2 Using the same raw material as in Example 1, a parison having a multilayer structure shown in FIG. 6 was molded and biaxially stretch blow molded by a usual method. Dimension A of each part of the obtained bottle
~ H was measured.

While holding the bottle with the mouth mold, the bottle was put into a cooling mold cooled to 20 ° C. In this state, a rod heater was inserted from the mouth of the bottle, and the mouth and transition part of the bottle were heated from the inside at 150 ° C. for 1 minute to crystallize the polyester layer in that part.

Next, the mouth of the bottle was heated from the outside by a ring heater at 150 ° C. for 1 minute to crystallize the uncrystallized polyester layer in the outer layer of the mouth.

The dimensions A to H of the respective parts of the obtained bottle were measured, and the shrinkage rate due to the heat crystallization was calculated. As a result, the mouth of the biaxially stretch blow-molded bottle showed almost no deformation due to the heat crystallization. I understood.

Example 3 Using the same raw material as in Example 1, a parison having a multi-layer structure shown in FIG. 6 was molded, and the dimensions A to H of each part were measured. Next, the parison was held in the mouth mold and put into a cooling mold cooled to 20 ° C. In this state, a rod heater was inserted from the mouth of the parison, and the mouth and transition part of the parison were heated from the inside at 150 ° C. for 1 minute to crystallize the polyester layer in that part.

The above parison was biaxially stretch blow-molded by a conventional method, and the mouth of the obtained bottle was heated from the outside by a ring heater at 150 ° C. for 1 minute to crystallize the uncrystallized polyester layer in the outer layer of the mouth. Turned into

The dimensions A to H of the respective parts of the obtained bottle were measured, and the shrinkage ratio due to heat crystallization was calculated. As a result, the mouth of the biaxially stretch blow-molded bottle was hardly deformed due to heat crystallization. I understood.

[0050]

As described above, according to the present invention,
Before and / or after biaxially stretch blow molding, the mouth and transition of the multilayer structure containing the heat resistant resin layer are heated from the inside,
Next, since the mouth is heated from the outside, the mouth of the bottle is substantially free from deformation due to heat crystallization, and a bottle having good dimensional accuracy and excellent heat resistance can be obtained.

The heat-resistant biaxially stretch blow-molded bottle of the present invention having such characteristics is suitable for applying pastelizing by hot fill or hot shower, and has good handleability.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a heat resistant biaxially stretch blow molded bottle of the present invention.

FIG. 2 is an enlarged view of the mouth portion of FIG.

FIG. 3 is a schematic view showing a part of the manufacturing process of the heat resistant biaxially stretch blow molded bottle of the present invention.

FIG. 4 is a schematic view showing a part of the manufacturing process of the heat resistant biaxially stretch blow molded bottle of the present invention.

FIG. 5 is a schematic view showing a part of the manufacturing process of the heat resistant biaxially stretch blow molded bottle of the present invention.

FIG. 6 is a sectional view showing the mouth of the parison obtained in the example.

FIG. 7 is a graph showing the contraction rate in each part of the mouth of the parison obtained in Example 1.

[Explanation of symbols]

 1 ... Mouth 11 ... Support Ring 12 ... Screw 13 ... Heat Resistant Resin Layer 14 ... Polyester Layer 2 ... Transition 2a ... Uniform Crystallization Region 2b ... Gradient crystallization region 3 ... Shoulder part 4 ... Body part 5 ... Bottom part 6 ... Parison 7 ... Injection mold 71 ... Mouth part mold 72 ... Injection cavity mold 73 ...・ Injection core type 8 ・ ・ ・ Cooling type 9 ・ ・ ・ Rod heater 10 ・ ・ ・ Ring heater 20 ・ ・ ・ Cooling type

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Claims (5)

[Claims] 1. A mouth portion having a support ring at a lower end,
A heat-resistant biaxially stretched blow-molded bottle having a transition part following the mouth part, a shoulder part, a body part, and a bottom part, and the mouth part having a multilayer structure consisting of a polyester layer and a heat-resistant resin layer. A heat-resistant biaxially stretch blow-molded bottle, wherein the polyester layer in the mouth portion and the transition portion is crystallized. 2. The heat resistant biaxially stretch blow molded bottle according to claim 1, wherein the transition portion has a uniform crystallization region immediately below the support ring, and the crystallization region faces the shoulder portion. Heat-resistant biaxially stretch blow-molded bottle characterized by gradually decreasing from the outside. 3. The method for producing a heat-resistant biaxially stretch blow-molded bottle according to claim 1 or 2, wherein the support ring has a multilayer structure comprising (a) a polyester layer and a heat-resistant resin layer. A mouth part having, a transition part following the mouth part, a body part, and a bottomed cylindrical parison having a bottom part are formed, (b) by a heater inserted inside the mouth part,
After heating the mouth portion and the transition portion from the inside to crystallize the polyester layer in the mouth portion and the transition portion, (c) heating the mouth portion from the outside, the mouth portion and the transition Part of the polyester layer is crystallized, and (d) subsequently, the parison is biaxially stretch blow molded. 4. The method for producing a heat-resistant biaxially stretch blow-molded bottle according to claim 1, wherein the support ring has a multi-layered structure comprising (a) a polyester layer and a heat-resistant resin layer, and a support ring at the lower end. Forming a bottomed cylindrical parison having a mouth part having a transition part following the mouth part, a body part, and a bottom part, (b) biaxially stretch blow molding the parison, and (c)
After crystallizing the polyester layer on the inside of the mouth and the transition part by heating the mouth part and the transition part from the inside by a heater inserted inside the mouth part of the obtained biaxially stretched blow molded bottle. And (d) heating the mouth portion from the outside to crystallize the polyester layer in the mouth portion and the transition portion. 5. The method for producing a heat-resistant biaxially stretch blow-molded bottle according to claim 1, wherein the support ring has a multi-layered structure comprising (a) a polyester layer and a heat-resistant resin layer. Forming a bottomed cylindrical parison having a mouth part having, a transition part following the mouth part, a body part, and a bottom part, and (b) the mouth part by a heater inserted inside the mouth part and The transition part is heated from the inside to crystallize the polyester layer in the inside of the mouth part and the transition part,
(c) Then biaxially stretch blow molding the parison, (d)
A method of heating the mouth portion of the obtained biaxially stretch blow molded bottle from the outside to crystallize the polyester layer outside the mouth portion and at the transition portion.