JPH0462027A - Manufacture of high-stretch-blow-molded container - Google Patents

Abstract

PURPOSE:To enhance the gas barrier properties and the like of the container concerned by a method wherein primary stretch blow molding is performed under the condition that the temperature of only the surface of a preformed body is controlled, and, when the wall thickness decreases by some extent, the temperature of the whole preformed body is controlled so as to perform secondary stretch blow molding at the end of said temperature controlling. CONSTITUTION:A primary preformed body 10, which is held with B mouth part outer mold 41 and a mouth part inner mold 42, is installed in a primary forming mold 40. At this time, the temperatures at a layer 10a near the outer surface of the body 10 and at a layer 10c near its inner surface is lower than the temperature of a central layer 10b. Next, a stretching rod 45 is inserted in the body 10 so as to abut the tip part 46 of the rod against the central part 14 of the bottom part 13 of the body 10, and, at the same time, pressurizing air is blown off through blow-off holes 47 so as to perform primary stretch blow molding in order to obtain a secondary preformed body 20. In a temperature controlling device 60, by controlling the temperatures of temperature controlling cores and of respective temperature controlling heaters 81-85 and the inflow of air, the temperature of the secondary preformed body 20 is controlled from its inner and outer surfaces up to the temperature suitable for stretch blow molding. Finally, the secondary preformed body 20 is stretch-blow-molded so as to form a high-stretch-blow-molded container 30.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a container formed by stretch blow molding, and in particular a method for manufacturing a high stretch blow molded container (with a large stretch ratio). -Related.

[Prior art and problems to be solved by the invention] Resin containers, especially bottles, for enclosing carbonated drinks, fruit juice drinks, etc.
It is manufactured by stretch-blow molding a preformed body made by injection molding polyethylene terephthalate resin or the like.

When enclosing a fruit juice drink or the like in such a stretch-blow-molded container, there is a problem that the properties of the contents change due to the influence of oxygen entering from outside the container, impairing the flavor. Furthermore, when enclosing carbonated drinks or the like, there is a problem in that if carbon dioxide gas is released from the inside of the container, the product value will be impaired.

Therefore, a gas barrier is added to such stretch-blow molded containers.
Various measures have been taken to add gender.

For example, a method of coating the surface of a stretch blow molded container with an inorganic material such as vinylidene chloride or silicon oxide (silica) having oxygen barrier properties, or a method of coating a resin layer such as polyethylene terephthalate forming the stretch blow molded container with an ethylene vinyl alcohol copolymer. By combining or creating a multilayer structure with a layer having oxygen barrier properties such as nylon, or by vacuum deposition of aluminum or the like having oxygen barrier properties on the surface of the stretch blow molded container,
There are methods such as plastic metallization and ising.

However, with these methods, delamination occurs, the surface strength is not sufficient, recycling is difficult, the oxygen barrier performance is not stable, and the product becomes opaque, reducing the product value. There are problems such as causing

A method for improving gas barrier properties without having the disadvantages of the above-mentioned methods is to increase the stretch ratio in stretch blow molding. In this method, the gas barrier properties can be improved as the stretching ratio is increased. Furthermore, by increasing the stretching ratio, the physical properties of the container such as transparency, strength, and rigidity can also be improved.

However, in order to increase the draw ratio, it is necessary to mold a thick preform by injection molding, etc., but it takes a long time to cool it to prevent clouding due to crystallization during molding. There's a problem.

By the way, in order to stretch-blow mold a bottomed cylindrical preformed body consisting of a mouth part l, a body part 2, and a bottom part 3 as shown in FIG. There is a way to do that. In this method, the bottom part 3 of the preform is pressed vertically from the inside with a stretching rod 4, and at the same time, high-temperature pressurized air is blown out from inside the stretching rod to stretch-blow mold the body 2 in the circumferential direction. At that time, since the degree of stretching generally differs between regions, it is necessary to adjust the temperature to the optimum temperature for stretch blowing depending on the region.

There are generally two methods for controlling the temperature of a preform.

One is a method called the cold parison method.

In this method, after injection molding, the preforms are temporarily stored, and the large number of preforms that have reached room temperature are heated by a heater or the like before being moved one after another. in particular,
The preform is moved while rotating around its axis, and passed through a heating area equipped with a heater. At that time, the density or calorific value of the heater is changed appropriately in the direction along the axis of the preform, and a certain U= is heated by the heater and then cooled by blowing low temperature air onto a predetermined part of the preform. do. Thereby, each part of the preform is brought to a temperature suitable for stretch blow molding. This method is suitable for mass production because preforms can be stocked.

However, when heating and temperature controlling a thick-walled preform, such as one with a thickness of 5 mm or more, using this method, the surface layer is overheated and becomes cloudy due to the temperature exceeding the crystallization temperature. It has been implemented.

Another method is a method called the hot parison method. In this method, multiple temperature control molds are stacked, a high-temperature preform immediately after injection molding is installed inside the mold, and each part of the preform corresponding to each temperature control mold is stretch-blow-molded on the outer peripheral surface. This is a method of adjusting the temperature to an appropriate temperature (for example, JP-A-63-1
No. 89225). This method does not require stock of preforms, so it is suitable for high-mix, low-volume production.
This is advantageous in terms of inventory management.

However, when setting a high stretching ratio in order to improve the oxygen barrier properties, transparency, strength, rigidity, etc. of the stretch blow molded container as described above, it is necessary to The temperature must be adjusted to the desired temperature, and the preform is thicker (and shorter) than normal stretch blow molding, so stretch blow molding uniformly balances the temperature difference inside the preform. There is a problem in that a lot of time is required to adjust the temperature to a suitable temperature for molding, which reduces productivity.

Particularly in the hot parison method, in which a high-temperature preform is stretch-blow molded immediately after injection molding, the time it takes to adjust the temperature of the preform to a temperature suitable for stretch-blow molding directly reduces production efficiency. There is an issue of influence.

In addition, thick preforms tend to whiten due to crystallization when the temperature is adjusted to a temperature suitable for stretch blow molding, resulting in a loss of transparency.

Therefore, the object of the present invention is to
In order to improve gas barrier properties, etc., the stretch ratio in stretch blow molding is set high, and even if the preform has a thick wall thickness, the product can be processed without whitening.
It is an object of the present invention to provide a method for manufacturing a high-stretch blow-molded container that can shorten the time required to precisely adjust the temperature of a high-temperature preform immediately after injection molding to a temperature suitable for stretch-blow molding.

[Means to solve the problem]

As a result of intensive research in view of the above objectives, the present inventor divided the stretch blow molding process of the preform into two stages in the manufacturing method of a high stretch blow molded container, and determined that the The layers near the inner and outer surfaces of the meat body that are in contact with the mold are cooled to near the glass transition temperature, while the center layer of the meat body remains at a high temperature above the glass transition temperature and below the crystallization temperature, that is, an uneven temperature distribution. At the point when the temperature of only the surface of the body of the preform is adjusted to a temperature where a stretching effect can be obtained, the primary stretch blow molding process is performed to reduce the wall thickness of the preform and expand the surface area. , the temperature of the entire preform is adjusted, and once the temperature adjustment is completed, secondary stretch blow molding is performed to precisely adjust the temperature of the preform to the appropriate temperature for stretch blow molding, down to the inside of the preform. The inventors have discovered that the time required for this process can be shortened, and that by stretching twice, an extremely high stretching ratio can be achieved, especially for the inner and outer surface layers of the parison, and the present invention has been developed.

That is, the method for producing a container of the present invention involves high-stretch blow molding of a thick-walled resin primary unevenly molded body formed by injection molding, consisting of a mouth, a body, and a bottom. (b) lowering the temperature of a layer near the surface of the trunk of the primary molded body at a high temperature; A secondary preform is formed by primary stretch blow molding in a temperature distribution state, and (c) the temperature distribution of the secondary preform is made uniform, and the secondary preform is further subjected to secondary stretching. It is characterized by blow molding.

[Examples and effects]

FIG. 1 is a sectional view showing a preformed body of a high stretch blow-molded container according to an embodiment of the present invention, which is before primary stretch blow molding (referred to as primary uneven molded body 1o).

In this embodiment, the primary uneven molded body 10 is a cylindrical body with a bottom formed by injection molding, and has a mouth part 11 and a body part 12.
and a bottom portion 13.

In addition, in this embodiment, the mouth portion 11 of the primary molded body 10 is
Excluding stretch molding length. The body 12 at a position of 1/2 of
Thickness W. is formed to be thicker than the mouth portion 11 and the bottom portion 13.

Also, the stretching length of the primary uneven molded body 1o. The average diameter of the trunk 12 at the 1/2 position is φ. The inner surface diameter at the same position is φ. 1, and the outer surface diameter at the same position is φ. 2, φ. andφ. .

andφ. The relationship with 2 is expressed by the following equation.

φ. =(φ.1+φ.2)/2 In addition, in this embodiment, the body portion 1 of the primary uneven molded body 1o
2 consists of a layer 10a near the inner surface, a center layer lob, and a layer 10c near the outer surface.

FIG. 2 is a sectional view showing a preformed body of a high stretch blow molded container according to an embodiment of the present invention, and shows the primary molded body 10 shown in FIG.
(referred to as a secondary preform 20).

In this example, the secondary preformed body 20 (well, the mouth part 11
It consists of a body part 12 and a bottom part 13.

In addition, in this example, the wall thickness of the body portion 12 at position 172 of the stretching length h1 of the secondary preform 20 is set as W2, the average diameter at the same position is set as φ1, and the inner surface diameter at the same position is set as φ11. , If the outer surface diameter at the same position is φ12, the relationship between φ1, φ11, φ, and 2 is expressed by the following equation.

φ1=(φ3.0φ12)/2 FIG. 3 is a sectional view showing a high stretch blow molded container according to an embodiment of the present invention.

In this embodiment, a high-stretch blow-molded container 30 consists of a mouth portion 11, a body portion 12, and a bottom portion 13.

Further, in this embodiment, the surface diameter of the surface of the high-stretch blow-molded container 30 at a position 1/2 of the stretch-formed length h2 is set to φ2□.

FIG. 4 is a schematic cross-sectional view showing the first step in the manufacturing process of a high stretch blow-molded container according to an embodiment of the present invention.

In FIG. 4, an injection molded primary component molded body 10 is shown.
The figure shows a state in which a secondary preform 20 has been formed by primary stretch blow molding.

In this embodiment, a primary molded article 10 (indicated by broken lines in FIG. 4) held by an outer mouth mold 41 and an inner mouth mold 42 is installed in a blow mold 40. However, at this time, since the temperature of the primary molded article 10 shown in FIG. 1 is adjusted in the injection mold, the temperature of the layer 10a near the outer surface and the layer 10c near the inner surface is low, and the temperature of the layer 10a near the outer surface is low, and the temperature of the layer 10c near the inner surface is low. temperature is rising. Specifically, it is preferable that the temperature of the layer 10a near the outer surface and the layer 10c near the inner surface be around the glass transition point temperature, and the temperature of the center layer 10b be above the glass transition point temperature and below the crystallization temperature. is preferable. This is because the layers 10c and 110a near the inner and outer surfaces can obtain a stretching orientation effect, can prevent clouding from occurring due to crystallization of the central layer, and have a hardness that allows the layers near the inner and outer surfaces to be released from the mold.

Next, the stretching rod 45 is inserted from above through the hole 43 of the inner mouth mold 42 . Tip end 46 of stretching rod 45
is in contact with the center portion 14 of the bottom portion 13 of the primary irregular molded body 10 (this state is shown by a broken line in FIG. 4),
While pressing, the plurality of blowout holes 4 of the stretching rod 45
By blowing out pressurized air from 7 and performing primary stretch blow molding, the secondary preform 20 is obtained.

FIG. 5 is a schematic cross-sectional view showing the second step of the manufacturing process of a high stretch blow-molded container according to an embodiment of the present invention.

In FIG. 5, there are a plurality of air vent grooves 5 on the inside of the secondary preform 20 attached to the mouth outer mold 41.
1 is inserted into the temperature regulating device 60. Here, a temperature regulating medium is circulated inside the temperature regulating core 50, and the temperature regulating core 50 is formed into a tapered shape to facilitate mold release.

In this embodiment, the temperature adjustment device 60 has five temperature adjustment blocks 61 to 65, and each temperature adjustment block 61 has five temperature adjustment blocks 61 to 65.
-65 has passages 71-75 on the inside, and band-type temperature adjustment heaters 81-85 on the outside.

Further, in this embodiment, the temperature adjustment device 60 has an upper block 66 and a lower block 67, and the upper block 66 has an upper block 66 and a lower block 67.
6 has a passage 76, and the lower block 67 has a passage 76.
It has 7. Each of the above-mentioned passages is continuous, from the passage 77 of the lower block 67 through the passages 71 to 75 of the temperature adjustment blocks 61 to 65, to the passage 76 of the upper block 66.
It has a structure that allows temperature adjustment air to pass through.

In the temperature adjustment device 60 having such a structure, the secondary preform 20 is adjusted by adjusting the temperature of the temperature adjustment core, the temperature of each temperature adjustment heater 81 to 85, and the amount of air inflow.
Adjust the temperature of the inner and outer surfaces to a temperature suitable for stretch blow molding. Here, by controlling the temperature of the mold 40 shown in FIG. 4 to a desired temperature without taking the temperature control step shown in FIG. You can also move on to the third step.

FIG. 6 is a schematic cross-sectional view showing the third step in the manufacturing process of a high-stretch blow-molded container according to an embodiment of the present invention.

FIG. 6 shows a state in which the secondary preform 20 has been stretch blow molded to form a high stretch blow molded container 30.

In this embodiment, the secondary preform 20 (indicated by broken lines in FIG. 6) held by the outer mouth mold 91 and the inner mouth mold 92 is mounted in the secondary mold 90, and A stretching rod 95 is inserted from above through the hole 93 of the inner mouth mold 92 . Here, the tip end 9 of the extension rod 95
(6) or in contact with the center part 24 of the bottom part 23 of the secondary preform 20 (in FIG. 6, this state is shown by a broken line)
, while pressing, air is blown out from the plurality of blowing holes 97 of the stretching rod 95 to perform secondary stretch blow molding, thereby obtaining the high stretch blow molded container 30.

FIG. 7 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the primary molded body lO shown in FIG. 10
This figure shows the temperature distribution in the cross-sectional thickness direction of .

In FIG. 7, a indicates a position corresponding to the layer 10a near the outer surface of the primary component molded body lO, b indicates a position corresponding to the center layer lOb, and C indicates a position corresponding to the layer 10c near the inner surface of the primary molded body lO. .

FIG. 8 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the primary equipped molded body 10 shown in FIG. This shows the temperature distribution of .

In FIGS. 7 and 8, a indicates a position corresponding to the layer 10a near the inner surface of the primary molded body IO, and b indicates a position corresponding to the center layer 1
A position corresponding to 0b is shown, and C is a position corresponding to the outer surface vicinity layer 10c.

FIG. 9 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the secondary preform 20 shown in FIG. This shows the temperature distribution of .

FIG. 10 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the secondary and secondary shaped body 20 shown in FIG.
This figure shows the temperature distribution in the cross-sectional thickness direction of the secondary preform 20 immediately after temperature adjustment was performed in the temperature adjustment device having the structure shown in the figure.

In FIGS. 7 to 1θ, the horizontal axis of the graph indicates the position (0, w
o and w2 indicate the outermost part of the cross section, and W3 and w3 indicate the central part of the cross section. Also, the vertical axis of the graph is temperature (T,
indicates the appropriate stretching temperature, T1.1, T.

, 2, T1.2, T1.4 are the lowest temperatures, Laxl, T+
++axt, Tmax2, and T*ax4 indicate the maximum temperature).

Thick primary molded body 1 indicated by a and C in FIG.
The layer near the surface of No. 0 was in a low temperature state because it was in contact with the cooled injection mold. Further, the central layer indicated by b almost maintains the high temperature during injection molding.

Therefore, the difference between T1111111'l and Llml is
Quite large.

In FIG. 8, the temperature distribution state of the body of the primary molded article immediately before primary stretch blow molding which has been released from the injection mold is slightly more uniform than that shown in FIG. 7. However, the difference between T□ and T,52 is large. However, a, C
The layer near the surface shown in is at a temperature suitable for stretch blow molding, and by performing primary stretch blow molding in this state, the effect of stretch blow molding can be obtained for the layer near the surface.

In FIG. 9, the wall thickness of the body of the secondary preform is thinner, but because the primary stretch blow molding takes place in a short time, T□0
The difference between Tm1n3 and Tm1n3 remains unresolved.

In FIG. 10, the temperature of the cross section of the entire body is made uniform around the temperature suitable for stretch blow molding.

In this example, compared to the stretch blow molding method in which a thick preform is formed in one go, the time required for the above-mentioned uniformity can be significantly shortened. Therefore, the cycle time of the entire molding process can be shortened, and productivity can be significantly improved.

Further, in this example, since the temperature adjustment is carried out in a short time, the container does not become cloudy with crystals, and good transparency can be obtained. As a result, the wall thickness of the preform is 5
It is also possible to mold containers using homobolymer polyethylene terephthalate resin exceeding mm.

Furthermore, in this embodiment, by making the thin secondary preformed body after the primary stretch blow molding into a cylindrical shape, the shape of the mold for temperature adjustment, etc. can also be simplified.

Furthermore, in this example, the wall thickness of the body of the primary uneven molded body can be applied to stretch blow molding at a high magnification of 10 to 20 times that of the body of the finished container. In this case, there are no problems such as whitening, and the effect is good.

Furthermore, in this example, when forming the secondary preform from the primary uneven mold, the stretching ratio in the axial direction of the preform is set to be larger than the ratio in the circumferential direction, and stretching is performed mainly in the axial direction only. is also possible, and in this case also exhibits a good effect.

In this example, an example was shown in which a high-stretch blow-molded container was molded by the hot parison method, but the method of the present invention exhibits good effects when it is stretch-blow molded with a large stretching ratio.

However, the hot parison method exhibits particularly good effects when molding high-stretch blow-molded containers.

The method for producing a high stretch blow-molded container of the present invention will be explained in detail with reference to the following specific examples.

Example 1 h2 shown in Fig. 3 = 284 mm, φ2 = 93.5
High stretch blow molded container 30 with a diameter of 1.5 mm and an internal volume of 1.51 mm
For molding, polyethylene terephthalate with an IV value of approximately 0.8 is used, and an ASB50 type molding machine (scale
Using a machine manufactured by B Machine ■, the weight 50g ha shown in Figure 1 was used.
"110.5mm, Wo=5.5mm, φo+
= 12mm1 φoz=23mm.

φ. A primary molded body IO having a diameter of 17.5 mm was molded. After an injection cooling time of 22 seconds, the mold was released.

By inserting this primary uneven molded body 10 into an apparatus having the structure shown in FIG. 4 and stretch-blow molding, h+ = 165 mm, W2 = 3.0 mm, as shown in FIG. 2, are obtained.
φ1=19mm, φ, , = 25mm, φ, =2
A 2 mm secondary preform 20 was molded.

Subsequently, this secondary preformed body 20 is kept in a temperature-controlled mold shown in FIG. 4, and the temperature is adjusted for about 19 seconds, so that each part of the secondary preformed body 20 reaches the desired stretch blow molding temperature of 95°C.
~115°C was obtained.

Next, this secondary preform 20 was inserted into an apparatus having the structure shown in FIG. 6, and stretch blow molding was performed to obtain the above-mentioned high stretch blow molding 30.

In this example, the axial stretching magnification h2/fi
.

2.6 times, circumferential stretching ratio φ2/φ. = 5.3 times, and the surface area magnification was 13.7 times. Further, when looking at the stretching ratio on the inner and outer surfaces of the container, it was about 20 times on the inner surface and about 10.5 times on the outer surface. Furthermore, the molding cycle of the high stretch blow molded container was as short as about 26 seconds, and no whitening occurred in the container.

As a result of measuring the oxygen barrier properties of the above-mentioned container, the oxygen permeation amount per container per day was 0°32 CC under the condition of 1 atm, indicating that good oxygen barrier properties were obtained.

Example 2 In order to mold a high-stretch blow-molded container 30 similar to that of Example 1, the same resin and molding machine as those of Example 1 were used, and the weight as shown in FIG. 1 was 50 g ho = g: 3 mm% w.

7, Qmm, φ. +=t2mmqφ. 2=26mm
A primary molded body 10 having a diameter of %φ0 of 19 mm was molded. After injection molding, the mold was cooled for 26 seconds and released.

This primary uneven molded body 10 is inserted into an apparatus having the structure shown in FIG. 4 and subjected to stretch blow molding to obtain tz = 200.0 mm SW, = 2.0 mm as shown in FIG. 2.
φ11 ”' 24m” sφI 2” 28mm
A secondary preform 20 having a diameter of 25 mm was molded.

Subsequently, this secondary preformed body 20 was kept in a temperature-controlled mold shown in FIG. 4, and the temperature was adjusted for about 23 seconds, so that each part of the secondary preformed body 20 obtained the desired stretch-blow molding temperature. .

Next, this secondary preform 20 was inserted into an apparatus having the structure shown in FIG. 6 and stretch blow molded, thereby obtaining the high stretch blow molded container 30.

In this example, the axial stretching ratio is /h0=3.
4 times, circumferential stretching magnification φ2/φ. = 4.9 times, the surface area magnification was 16.8 times, the inner surface was 27 times, and the outer surface was 12 times, which was an even higher stretching ratio compared to Example 1.

In addition, the molding cycle of the high stretch blow molded container is approximately 30
seconds, and no whitening occurred in the container. .

As a result of measuring the oxygen barrier properties of the above-mentioned container, the oxygen permeation amount per container per day was 0.31 cc under the condition of 1 atm, and even better oxygen barrier properties than in Example 1 were obtained.

Comparative Example 1 Using the same product container and resin molding machine as in Example 1, a similar primary molded body was molded, and by stretch blow molding without molding a secondary preform, Example 1 was obtained. A container with a high draw ratio similar to the above was obtained.

The molding cycle at this time was as long as about 40 seconds, and if the molding cycle was shorter than 40 seconds, whitening occurred on the container. In addition, there was a thin wall part in a part of the container, and the wall thickness of the container after stretch blow molding was not stable.

As a result of measuring the oxygen barrier properties of the above-mentioned container, the oxygen permeation amount per container per day was 0.38 CC under the condition of 1 atm, and sufficient oxygen barrier properties were not obtained.

Comparative Example 2 Using the same resin and molding machine as in Example 1, the weight as shown in FIG. 1 was 50 g, Flo=137 mm, Wo=4.
0mm, φ, , = 16.5mm, φ. , =24.5m
A primary molded body 10 with m and φo = 20.5 mm was molded, and stretch blow molding of a product container was performed in the same manner as in Example 1 without molding a secondary preform.

In this comparative example, the axial stretching ratio h2/ho=2.
The stretching ratio in the circumferential direction was 1x, the stretching ratio in the circumferential direction was φ2/φ, = 4.5x, and the surface area ratio was 9.5x. The molding cycle was approximately 26 seconds, and no whitening occurred.

The oxygen barrier properties of the containers described above were also measured.

As a result, the oxygen permeation amount per tube per day was 0.37 cc under the condition of 1 atm, and sufficient oxygen barrier properties were not obtained.

Comparative Example 3 A container with a high stretch ratio as in Example 2 was molded by molding the same primary molded product as in Example 2 and stretch-blow molding without molding a secondary preform. . Even after sufficient cooling time in the injection mold, the preform turned white before entering the stretch-blowing process, resulting in whitening of the container.

The oxygen barrier properties of the containers with the above-mentioned high draw ratio were measured.

As a result, the oxygen permeation amount per tube per day was 0.40 cc under the condition of 1 atm, and sufficient oxygen barrier properties were not obtained. This was because the thick preform could not be temperature controlled to an appropriate temperature, the wall thickness was uneven, and there were thin parts.

As shown above, according to this example, even when using a thick preform and setting a large stretching ratio, the container does not whiten and the variation in wall thickness can be reduced in a short time. We were able to obtain a highly stretchable blow-molded container with an appropriate wall thickness distribution.

Furthermore, by increasing the stretching ratio, a container with excellent gas barrier properties could be obtained.

〔Effect of the invention〕

As described in detail above, in the method for producing a high stretch blow molded container of the present invention, the stretch blow molding process of the preform is divided into two stages, and only the surface of the preform is temperature-controlled. After the stretch blow molding process is performed and the thickness of the preform has decreased to a certain extent, the temperature of the entire preform is adjusted, and when the temperature adjustment is completed, the structure is such that the secondary stretch blow molding is carried out. It has become.

As a result, in order to improve gas barrier properties, etc., the stretching ratio in stretch blow molding is set high, and even if the preform has a large wall thickness, the preform can be heated internally without whitening. It is possible to shorten the time required to strictly adjust the temperature to the appropriate temperature for stretch blow molding.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a preformed body of a high stretch blow molded container according to an embodiment of the present invention, and FIG. 2 is a cross sectional view showing a preformed body of a high stretch blow molded container according to an embodiment of the present invention. FIG. 3 is a sectional view showing a high stretch blow molded container according to an embodiment of the present invention, and FIG. 4 is a first step of the manufacturing process of a high stretch blow molded container according to an embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing the second step of the manufacturing process of a high-stretch blow-molded container according to an embodiment of the present invention, and FIG. FIG. 7 is a schematic cross-sectional view showing the third stage of the manufacturing process of the high-stretch blow-molded container; FIG. 7 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the primary molded body lO shown in FIG. 8 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the primary preformed body 10 shown in FIG. 1, and FIG. 9 is a graph showing the temperature distribution of the secondary preformed body 20 shown in FIG. 10 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the secondary preform 20 shown in FIG. 2; The figure is a sectional view showing an example of a preform. 1.11... Mouth 2.12... Body 3.13... Bottom 4.45.95 10 ・ 0a 0b 0c 14.24 ・ 20 ・ 30 ・ 40 ・41.91 ・ 42.92 ・ 43.93 ・ 46.96 ・ 47.97 ・ 50 ・ 51 ・ 60 ・ 61 ~ 65 ・ 66 ・ 67 ・ Layer near the inner surface of the primary molded body of the stretched rod Central layer Layer near the outer surface Central part Secondary preform Stretch blow molded container Primary mold mouth Outer mold mouth Inner mold hole Tip part Blowout hole Temperature adjustment core Groove Temperature adjustment device Temperature adjustment block Upper block Lower block 71-77 ・ 81-85 ・ 90・ ・Passway/temperature adjustment heater secondary molding mold

Claims (4)

[Claims] (1) In a container manufacturing method in which a thick-walled resin primary preform formed by injection molding is formed by high-stretch blow molding, (a) the container is heated at a high temperature after injection molding. (b) lowering the temperature of a layer near the surface of the body of the primary preform; Forming a secondary preform by stretch blow molding, (c) uniformizing the temperature distribution of the secondary preform, and further performing secondary stretch blow molding of the secondary preform. How to characterize it. (2) In the method for manufacturing a high stretch blow-molded container according to claim 1, a crystalline resin is used so that the temperature of the neighboring layer is around the glass transition point temperature, and the temperature of the central layer is around the glass transition point temperature. A method characterized by performing primary stretch blow molding at a temperature below the crystallization temperature. (3) In the method for manufacturing a high stretch blow molded container according to claim 1 or 2, the thickness of the body of the primary preform is greater than the thickness of the body after the secondary stretch blow molding. ,1
A method characterized in that the magnification is 0 to 20 times. (4) In the method for manufacturing a high-stretch blow-molded container according to any one of claims 1 to 3, during the primary stretch blow-molding, an axial stretching ratio is greater than or equal to a circumferential stretching ratio of the body. , a method characterized by stretching mainly in the axial direction.