JPS5818230A - Method of heat treatment of stretched and blown vessel - Google Patents

Abstract

PURPOSE:To improve the heat resistance of the titled container, by performing preheating, stretching and blowing, and heat treatment of a parison under respective specified conditions. CONSTITUTION:A thermoplastic polyester consisting mainly of ethylene terephthalate is injection molded or extrusion molded into a parison, and after the parison is heated to a temperature suitable for stretching, it is introduced into a split mold that has been heated to a temperature stipulated by the expression: Tg<T1<=Tg+80 deg.C (wherein Tg represents the glass transition temperature of the polyester and; T1 represents the temperature of the mold to which it is heated), and a compressed fluid A having a temperature stipulated by the expression: Tg-60<=T2<=Tg+30 deg.C (wherein T2 represnts the temperature of the compressed fluid A) is blown into the parison to stretch and blow it. Then the compressed fluid A is replaed by a compressed fluid B having a temperature stipulated by the expression Tg+80<=T3<=Tg+170 deg.C (wherein T3 represents the temperature of the compressed fluid B), and the stretched and blown vessel is subjected to the heat treatment thereby, then the fluid B is replaced with the fluid A, and after the vessel is cooled, it is removed from the split mold.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for heat treating a stretched blown container made of thermoplastic polyester containing ethylene terephthalate as a main component. This aims to improve the heat resistance of the container.

The vine stretch p-molding process, in which a parison injection or extrusion molded from a thermoplastic polyester, especially polyethylene terephthalate, is then oriented substantially biaxially is a molding process that has developed in recent years. Stretch blow molded containers have excellent mechanical properties, gas barrier properties, chemical resistance, aroma retention,
Due to its transparency, it is widely used for food such as carbonated drinks, sauces, and dressings, cosmetics such as liquids and emulsions, and containers for chemicals such as insecticides, disinfectants, solvents, and medicines. There is.

On the other hand, sake, beer fruit juice drinks, milk drinks, etc. are #lba60.
Containers are filled with high-temperature liquids at temperatures above °C, but for example, in the case of polyethylene terephthalate containers, shrinkage occurs during or after filling, and the container is deformed, which is a fatal drawback. Application range is 4PIIl
! :I is the current situation.

Many proposals have been made to overcome this drawback, that is, to improve heat resistance. For example, special 111185
No. 5-264, JP-A No. 55-2171, 4ISS 1973
No. 4-71, 4111 No. 54-48381, JP-A-5
4-8455? In the method described in JP-A No. 54-90265, JP-A No. 54-135545, British Patent No. 1474044, etc., a stretched polyethylene terephthalate container is heated at 70 to 220°C in the same shape as the container. Heat treatment is performed in a mold heated to . However, among these methods, when the mold temperature is set at a relatively low temperature of 70 to 140"C, the temperature of the liquid that can be filled into the heat treatment container is at most 75"C, and the temperature of the liquid that can be filled into the heat treatment container is at most 75℃, which is not suitable for sake, fruit juice drinks, etc. 75～
It could not withstand use for liquids that were to be filled at 95°C. On the other hand, if the mold temperature is set to a high temperature range of 140 to 220°C, the heat resistance will improve slightly, but in order to cool the container after heat treatment, the heated mold will have a capacity of 11 it-mold until it is cooled. This causes problems such as a long time of 2 to 6 minutes for the container to cool down, a tendency for the container to become cloudy, and a significant decrease in productivity. occured. That is, since the temperature range of 140 to 220°C is the crystallization temperature range of polyethylene terephthalate, the crystallization rate is high (if the holding time is increased to t★, cloudiness will occur in the container due to the generation and growth of spherulites). The problem of putting it away arises.

For example, l/Ij
The methods disclosed in JP-A-55-264, JP-A-55-2171, JP-A-53-78267, JP-A-53-78268, etc. are methods in which a container held in a cooled metal container is , heat treatment is carried out by blowing high-temperature heated gas around 200°C. In this method, when high-temperature heated gas is injected, the heat container (specific heat) of the gas is small and the mold is at a low temperature of about room temperature, so the container is heated to the temperature of the supplied heated gas. It takes a long time (S minutes to 5 minutes) to
During that time, a problem arose in which cloudiness appeared in @6. This is because during the heat treatment, a temperature gradient occurs between the outer wall of the container and the layer of the inner wall where the gas is exposed, and the spherulites pass through the crystallization temperature region during the heating process. This is because it occurs and becomes cloudy.

As is clear from the above, the inadequacies of the prior art can be summarized as follows. The relatively low temperature heating mold method of 70 to 140°C has a heat resistance of only 75°C at most due to the low temperature.

In the heating mold method at a relatively high temperature of 140 to 220° C., clouding occurs because it takes a long time to cool the mold before taking out the container.

On the other hand, in the method of blowing relatively high-temperature heated gas of around 200° C. into the container, clouding occurs because the heat capacity of the gas is small and it takes a long time to heat the container. As described above, the current situation is that containers that are transparent and have sufficient heat resistance have not been obtained by the methods proposed so far.

After filling a container with a high-temperature liquid up to 95°C, the inventors sealed the container, lowered the temperature to room temperature, and
We conducted extensive studies with the aim of developing a heat-resistant container whose volumetric capacity, when left for 4 hours, is α5 cm or less relative to the volume before filling. This target value is a fairly strict level, so we began our investigation by understanding the basic thermal phenomena of thermoplastic polyester. Heat shrinkage rate KI of polyester
The effects of heat treatment temperature and time are not equivalent; for example, in the case of polyethylene terephthalate in a relatively low-temperature region, no matter how long the heat treatment is held at 70 to 140 degrees Celsius under fixed conditions, the temperature and time effects of heat treatment will not exceed 150 degrees Celsius. The heat shrinkage rate cannot be lower than that obtained when heat treated for a short time at a high temperature region. That is, it has been found that temperature is primarily responsible for the thermal shrinkage rate.

From this result, in order to achieve the above objective *1-, in the case of polyester whose main component is ethylene terephthalate, it is necessary to raise the temperature of (7g+80) to ('TK+170)'C (T is the glass transition #IAIIIL of polyester) However, in the case of polyethylene terephthalate, the maximum growth rate of spherulites occurs around 180°C. There is. Of course -120~140℃
, even in the temperature range of 200 to 240°C, the rate is slow, but if the heat treatment time is prolonged, spherulites are generated. As mentioned above, in order to reduce the heat shrinkage rate, (7g + 80) ~ (Tg +
Applying a high temperature of 170)°C is an essential condition, but if the temperature is kept in such a high temperature range for a certain period of time or more, then on the one hand, it is necessary to stop the occurrence of clouding due to the generation and growth of spherulites. must be solved. As a result of studies by the present inventors, when a polyester stretch-blow container V containing ethylene terephthalate as a main component is kept in a high temperature range of (7g+80) to (Tg+170)°C, the generation of spherulites can be prevented within 3 minutes. I found out something.

Therefore, a method of applying high temperature that satisfies the conditions of (7g+80) to (Tg+170)'C and within 3 minutes was intensively studied. As a result, it was found that the heating mold method was not desirable. This is because, although it is necessary to cool down the heating mold before taking out the container from the heating mold, it takes a long time due to the large heat content, and spherulites are likely to occur during this time. In addition, if we try to keep the high temperature application within S minutes using the heating mold method, (TI+80) ~ (
Holding at Tg+170)'C requires at most 1 minute and cooling of the mold must be started immediately, but this results in insufficient time for heat treatment of the container.

As a result of the study, it was found that a heating fluid is suitable as a means for applying a high temperature of (7g+80) to (1g+170)'C and within 5 minutes. This is because if heating fluid is used, the container can be cooled quickly by replacing the heating fluid with cooling fluid before taking the container out.

In the method of the present invention, the primary application of high temperature is carried out using a heating fluid.
Applying heat for up to 3 minutes at ~(Tg+lO)'C using only the heating fluid, the resulting container has a filling temperature of j[9
It was found that heat resistance with a volumetric shrinkage rate of α5ts or less at 5°C could not be achieved. One way to solve this is (T
This is a method of applying heated fluid at a temperature higher than sr + 170)°C, and although this method was considered, it was still impossible to reduce the volumetric shrinkage rate to (L5% or less. Also, due to the mechanical The properties (tensile strength and elongation f of the sample cut out from the body of the container) deteriorated considerably.

Another method is to rely on a heating fluid to provide the primary heat, and to supplement this with a heating mold that is insufficient in heat.

In this case, if the 11AJf of the heating mold is too high above a certain level, clouding will occur due to the generation and growth of spherulites, so it was found that the appropriate heating mold temperature is Tjr~(7g+80)℃. . In this way, (7g+80) ~ (Tg+1
70)"C relatively high temperature heating fluid and Tg ~ (T, +
It has been found that by a method of jointly using heated gold 11 at a relatively low temperature of 80)°C, it is possible to obtain heat resistance performance that cannot be achieved by using each individual heat application means. The main reason for such good results is the temperature gradient within the polymer layer between the outer and inner walls of the container. According to the experimental results of the present inventors, in the case of polyester whose main component is ethylene terephthalate, one side of the container wall membrane is heated to a temperature below Tg -45℃, and the other side is heated to a temperature above (7g+50)''C for more than 2 minutes. Then,
It was found that the generation of spherulites was promoted. Therefore, in the actual process, introducing hot fluid into a container in which the cooling metal is removed does not give good results. In order to reduce the heat shrinkage rate, the highest value is (Tg 180) ~ (T + 170)"C
It was found that suppressing the simultaneous XaZ gradient was an essential condition. By doing so, a synergistic effect of supplementing the heat deficiency and suppressing the temperature gradient is exhibited for the first time, and an effect that cannot be exhibited when each individual heat application means is used is exhibited. It turned out that.

In this way, in order to meet the strict heat resistance target value of 0.5% or less heat shrinkage with filling liquid at 95℃,
Since the effects of AI degree and time are contradictory on the heat shrinkage rate and the growth of spherulites, it is important to devise a way to carry out the process from stretch blowing to injection in a shorter cycle. For this reason, stretch glow molding was also performed in a heated mold at Tg to (Tg + 80) °C, which was removed from the temperature at which spherulite generation and growth rate was high, and the mold temperature was maintained during the subsequent (heat treatment), and the final The cooling for removal of the container is under pressure mtitt.
The heating mold maintains the above temperature even during cooling, and holding the heating mold at a constant temperature during the stretch blowing and cooling removal of the heating mold, which has a large heat capacity, shortens the time cycle and improves heat resistance. It was found to be effective in improving the spherulites and suppressing the generation and growth of spherulites.

Book: One of the characteristics of Akira's method is that it uses a reinforcing metal of 'rg~(Tg+80)''C even in the stretch blowing step before heat treatment, but during stretch blow molding, Tg~ (Tg+80) It has been found that if the temperature and the application time are appropriately combined, there is no problem in using the mold as a heated mold especially during stretch blow molding of parisons.

As detailed above, the thermal shrinkage rate of thermoplastic polynisder whose main component is ethylene terephthalate, the occurrence of spherulites,
The present invention was arrived at from a study of thermal properties related to growth.

That is, the method of the present invention involves preheating a parison injection- or extrusion-molded from a thermoplastic polyester containing ethylene prephthalate as a main component to an appropriate temperature for stretching, and then supplying the parison to a split mold to create a stretch-blow-molded container. In the method of heat treatment in a plating chamber, after preheating the parison to the appropriate temperature for stretching,
Tsr<Tt≦Tg+80°C (Tg is the glass transition temperature of polynisder, °C, T is the heated mold temperature, °C), and is supplied to a split mold heated to the temperature specified by Tg-
60≦T2≦'rg+-go°C (Tt is the temperature of compressed fluid A, °C) is blown into the compressed fluid and stretch-blow molded, and then inside the stretch-blow container in the split mold. , the compressed fluid.

Tg+80≦Ts≦Tg+170°C (Ten 1 is compressed fluid B
The container is heat-treated by replacing it with compressed fluid B heated to a temperature specified at 100° C., then the compressed fluid B is replaced again with the compressed fluid A, the scissor container is cooled, and then molded into an armpit split mold. This is a method for heat treatment of a stretch-blown container, in which t% of the material is deposited from the container.

The heating mold temperature T1 when supplying the parison to the split mold is T
g (T weight≦Tg+80℃, preferably 7g+30≦T
.

≦Tg+70°C. When TI≦TK, the auxiliary role of the heating mold in the heat treatment is insufficient, and a volumetric shrinkage rate of α5ts or less cannot be achieved at a liquid filling temperature of 95°C. On the other hand, when Tt>Tf+80°C, the mold temperature is too high, causing clouding or drawdown at the bottom during the expansion.

Temperature T of the compressed fluid ram during stretch blow molding of the parison
.

is Tg-60≦T! ≦Tf+lO℃ better Ha, TK-
40≦T, ≦Tg+10°C. ! ■<jg-60℃
In this case, when the above-mentioned mold temperature is used, clouding occurs at the shoulders and bottom of the container during stretch molding. Tt>TI+
At 5 o C, the mechanical properties (breaking strength and elongation and creep properties) of the resulting container tend to deteriorate significantly.

After stretch blow molding under the above conditions, the temperature [T
s is Tg+80≦T, ≦Tg+170°C, preferably,
Tg+110≦T, ≦Tg+150°C. Temperature T is the primary heat application for reducing the thermal shrinkage rate, and T
If s<Tg+80, no matter how long the hot part is, the temperature will reach 95
At the filling temperature of the liquid 71 at .degree. C., a volumetric shrinkage rate of less than .alpha.5 is not achieved. On the other hand, when Tm>Tg+170°C, the mechanical properties (breaking strength and elongation and creep properties) of the resulting container deteriorate, and areas where molecular chain orientation is relatively low, such as the shoulders and bottom of the container, become cloudy. or drawdown at the bottom.

After the heat treatment is performed by the synergistic effect of the combination of the heated compressed fluid B and the heating mold, when the container is immediately taken out using the split mold,
Part of the container shrinks due to thermal stress and cannot be used as a product.

Cooling after the heat treatment is carried out by replacing the heating and compressing body B with a compressed fluid inside the container before opening the heating split mold. At this time, the temperature of the compressed fluid is Tg-60≦T≦Tg+! 0
It is ℃.

T, (Tg - 60°C, the container becomes cloudy.

If T,>Tg+50℃, the cooling effect of the container is low;
After all, clouding is likely to occur.

To cool the container after heat treatment, in addition to replacing compressed fluid B with M, during cooling, the temperature of the heating mold! Ti1t's
≦Tg within the range of 180℃, for example, Tg<Ts≦Tg+
Gold W may be cooled slightly to 50°C, but cooling the mold takes much longer than the heat capacity, so Sagi Shinpu maintains Tg<Ts≦ throughout the entire process of heat treatment and cooling. 'rg
It is preferable to maintain a constant temperature fK within the range of +ao°C.

In the present invention, 5Tg (°C) is the glass transition temperature of the thermoplastic polyester raw material used. , this temperature is poly! It is the boundary temperature between the freezing state of - and the start of local motion of the polymer main chain, and it is said that it is closely related to the stretching temperature, orientation crystallization hot zone temperature, and morphology freezing temperature in Sagi stretching plastic forming. understood. The method for measuring glass transition temperature is DEC.

Collected amount of raw material 15 da, comparative substance α-muj, 0.1
5 da, heating rate ℃/min, sensitivity range 2.5% ca
Scanning is started from room temperature (20° C.) at t/see and chart speed of 40 μ/min, and the end point of transition on the chart is defined as Tg ('C).

The heat treatment of the container from stretch blow molding and the cooling of the container from the heat treatment involve replacing B with a compressed fluid. It can be operated automatically by switching.

For example, the fluid can be introduced through the gap between the stretching rod and the inner wall of the container at the upper part of the mouth, and the fluid can be exhausted by providing a hole at the tip of the stretching rod and passing through the stretching red. When switching fluids, a pressure above a certain level must be applied so that the container does not shrink due to thermal stress, but this is easy electrically and mechanically.

The pressurized body referred to in the present invention may be any kind of gas, water vapor, or donated body, but air is preferable.

It is also preferable that the compressed fluid A is air and the compressed fluid B is nitrogen.

The thermoplastic polyester containing ethylene terephthalate as a main component in the present invention means that 80 moles or more of the acid component, preferably 90 moles or more, is terephthalic acid, and 80 moles of the glycol component, preferably 90 means a polyester in which one or more of the seven radicals is ethylene glycol. Of course, this does not mean that 100-polyethylene terephthalate is excluded. Other acid components include isophthalic acid,
Phthalic acid, naphthalene 1,4- or 2,6-dicarboxylic acid, diphenyl ether 4,4'-dicarboxylic acid, di:
Aromatic dicarboxylic acids such as enyl dicarboxylic acids, diphenoxyethane diethanedicarboxylic acids, etc., adipine, cepatine, azetuic acid, decane 1,10-
Examples include fatty acid dicarboxylic acids such as dicarboxylic acids, alicyclic dicarboxylic acids such as cyclohexane dicarboxylic acids, and the like.
It can contain less than 20 moles of these acid components. Other glycol components include aliphatic glycols such as propylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, hexamethylene glycol, dodecamethylene glycol, neopentyl glycol, and cyclohexane. Examples include alicyclic glycols such as dimetatool, 2,2-bis(4'-β-hydroxyethoxyphenyl)propane, and other aromatic diols, and among these glycol components, 20 It can contain less than mol. In addition to the ethylene terephthalate component, less than 20 moles of oxyacids such as p-hydroxyethoxybenzoic acid, p-oxybenzoic acid, and S-oxycabrenic acid can be contained.

The polyester may contain 5%, preferably less than 391, of polyfunctional components such as trimethylolpropane, pentaerythritol, trimellitic acid, trimesic acid. Additives such as colorants, heat or antioxidants, ultraviolet inhibitors, antistatic agents, antibacterial agents, lubricants, fillers (organic or inorganic), and additives for improving gas barrier properties are also required. It can be contained in an appropriate amount depending on the situation.

The thermoplastic polyester of the present invention has (1) a viscosity (L5 or more, preferably α55 or more, more preferably α63-t
4't- is used.

As mentioned above, the container obtained by the method of the present invention has a high degree of heat resistance. It can be reduced to α5- or less, at least 196 or less, and does not cause clouding, deformation of the container, or drawdown. In addition, a slight improvement in #lt nests after lightening and carbon dioxide gas barrier properties was also observed.

The container obtained by the method of the present invention can be used for soft drinks such as carbonated drinks and fruit juice drinks, milk drinks, alpour drinks such as vinegar, cooking oil, soy sauce, beer, draft beer, sake, whiskey, and wine.
It can be used for a wide range of applications, including food products such as detergents, toiletries such as detergents, cosmetics, liquid, aerosol, or granular chemicals and pharmaceuticals.

Examples of the method of the present invention are shown below, but of course the method of the present invention is not limited by these examples.

Examples 1 to 7 and Comparative Examples 1 to 7 After drying polyethylene terephthalate pellets with an intrinsic viscosity of α76 under reduced pressure to a moisture content of α005- or less, using an injection molding machine manufactured by Nippon Steel Corporation, the cylinder temperature was tc12.
50, C, 280, Cs280℃, injection pressure 45kl/
cm Yuki G, metal melting temperature 15℃, injection/cooling cycle J 5
A bottomed parison with an opening at the upper end was molded using 1@@ and 25-.C. The total length of the parison is 1801111. The outer diameter of the parallel part of the cylinder is 2711 m, and the inner diameter is 22 mm.

After preheating the obtained parison at 115 to 125°C with a temperature gradient using an infrared heater,
A stretch blow molding machine with a partially modified JL B-5 model (installation of a pulp system that allows for replacement of compressed fluid, and heating of the split mold by circulating heating oil) is used to make a stretch blow molding machine. molding,
After hot burying and cooling, the container was taken out. Compressed fluid (air) pressure: 50 kfl/m - Here, the compressed air is air A and BY with two temperatures, set at temperatures f'r and i, respectively, and subjected to stretching process and heat treatment. TI'C's compressed air is used for post-processing cooling, and 11°C compressed air is introduced and exhausted during post-heat treatment for Sagi Shinpu.
±2ψ-1t was maintained. The gold was heated mt through a metalwork @ of drawing, heat treatment, and cooling, and the temperature was set to tx'CK.

The time from the start of introducing compressed air B for the heat treatment to the start of introducing compressed air B for heat treatment is 5 minutes.
sec, the time from the start of introduction of compressed air B for heat treatment to the start of introduction of compressed air A for cooling is 90 ■C1 The time from the start of introduction of compressed air A for cooling to the split mold The time until opening was set to 30s@e.

The obtained container was in the shape of a peel bottle and had a total length of 300 mm.
fi, the outer diameter of the parallel portion of the body 95 - the inner volume 1.51.

The heat resistance of these containers is determined by the volume shrinkage S (%) of the volume before filling after filling with 95°C hot water, immediately sealing the container, and leaving it in a room at 20°C for 24 hours.
It was evaluated by The volume ve(il) before filling is calculated by filling a container with 20°C water, sealing it tightly, and then gently submerging it into a cylindrical pipe filled with 20°C water, and then calculating the weight of the overflow water WO ( Ii) Weigh Vo=Wa/Pto(P
IO was determined from the density of water at 20°C/am”.9
The volume V (wJ) after filling hot water at 5°C and leaving it in a room at 20°C for 24 hours is the weight W ( L)
It was determined from V=w/Pn. Volumetric contraction amount Sma(-)
is calculated from 8v=100 (Vo -V)/Vs.

The glass transition temperature Tg ('C) of the polyethylene terephthalate used was D8C (D-20B) manufactured by Takashi Seisakusho.
os15■, heating rate 10℃/min, sensitivity range 2.5m
eal/s@@, chart speed was 40 m/min, and the transition end point vTt was determined. (TI-4&5°C).

The obtained container was visually observed and the transparency of the container was evaluated using a λ range.

An O mark indicates that there was no clouding at all, and an x mark indicates that a part or all of the container became cloudy.

Stretch blowing, heat treatment, and cooling are carried out at a temperature of T1℃ and
Table 1 shows the volumetric shrinkage (-) and transparency of containers manufactured by changing the compressed air temperature T8 and the temperature T8 of the compressed air.

In Comparative Examples 1, 2 and 3, the mold temperature was 1, in Comparative Examples 4 and 5 the temperature of the compressed air was T, and in Comparative Examples 6 and 7, the temperature of the compressed air was T. In case you are not satisfied. Examples 1 to 7 are cases where the temperature 〒1 and T@s 7s all satisfy the method of the present invention. In case of Comparative Examples 1 to 7, +3 body volume shrinkage amount is greater than 8 m1- or 95°C
Filling with hot water caused the container to become cloudy, deform, and draw down at the bottom, making it unusable as a product.

In the case of Examples 1 to 7, the volume shrinkage was 8 mm or less (L5- or less), and it was completely transparent without deformation or drawdown, and was satisfactory as a heat-resistant container.

Procedural Amendment (Voluntary) November 1981, PA 4 IWIF Agency Director Haruki Shimada Incident! ! 1981 4I Kine Application No. 114388 2 Name of the invention Heat treatment method for stretch blow containers 5 Relationship with the case of the person making the amendment Representative patent applicant Tokyo @ 3-35-58 Sakashita, Itabashi-ku 4 Specification subject to the amendment Column for “Detailed Description of the Invention” Contents of amendment (1) “・・・・・・・・・” in page 5, line 8 of the specification
・Thermal container......" should be changed to "...
・・・Heat capacity...4...'' is corrected.

(2) On page 7, line 1, 'sjP' says "Heat heating...
・・・・・・"O description is changed to ``thermoplastic・・・・・・・・・''
(3) In the 8th line of the same page, “・・・・・・-・
...Supporting......-" should be changed to r.
・・・・・・Dominating・・・−−J Correct.

(4) In line 5 of the 12th Shinki, “Until the ejection...
The description of ri is corrected to r until extraction...j.

(5) “・・・・・・・・・” on the 24th purchase line 1
"Air B and introduction..." should be changed to "...
...Introduce air B... Correct as 1.

Thank you for your understanding as the above is a summary.

Claims (1)

[Claims] A parison made by injection or extrusion molding from a thermoplastic polyester containing ethylene terephthalate as a main component is preheated to an appropriate temperature for stretching, and then supplied to a split mold to be stretched and molded.
V. In the method of subsequently heat-treating the parison in a cough metal mold, after preheating the parison to an appropriate temperature for stretching, 'rg (T157g+8
0°C (Tg is the glass transition temperature of the polyester, "C%
? , is the heating metal temperature specified in °C), and is supplied to a split mold heated by IEK, and Tt-60≦Ttatami≦TI+
A compressed fluid at a temperature specified by 50°C (T: the temperature of the compressed fluid, °C) is injected and stretch-blow-molded, and then the compression is carried out inside a vine-stretched container in a cough splitter. fluid t', T
g+80≦'rs≦Tg+170°C (temperature of Titt compressed fluid B, °C) is replaced with compressed fluid B heated to a temperature specified by Titt, the container is heat-treated, and then the compressed fluid B is replaced with the compressed fluid B again. , a method for heat treating a stretch-blown container, the method comprising cooling the armpit container and then taking it out from the armpit splitter.