JPH0462028A - 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 by controlling the temperature of only the surface of a preformed body, the cylindrical part of which is made of blend of polyester resin and gas barrier resin, and, after that, secondary stretch blow molding is performed under the condition that the temperature of the whole preformed body. CONSTITUTION:A primary preformed body 10, the cylindrical part of which is produced by injection molding blend of polyester resin and gas barrier resin, is primarily-stretch-blow- molded so as to form a secondary preformed body 20. The primary preformed body 10, which is held with a mouth part outer mold 41 and a mouth part inner mold 42, is installed in a primary forming mold 40 and the temperatures of the body 10 is controlled so as to set the temperatures at a layer 10a near the outer surface of the body 10 and at a layer 10c near its inner surface lower than the temperature of a central layer 10b. Next, primary stretch blow molding is performed by inserting a stretching rod 45 from above in the body so as to press it and, at the same time, blowing off pressurizing air through blow-off holes 47 in order to obtain a secondary preformed body 20. In a temperature Controlling device 60, the temperature of the secondary preformed body 20 is controlled from its inner and outer surfaces up to its suitable temperature so as to stretch-blow-molded in order 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 containers molded by stretch blow molding, and particularly to a method for manufacturing high stretch blow molded containers with a large stretch ratio.

[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 a carbonated beverage or the like, there is a problem in that if carbon dioxide gas is released from inside the container, the product value will be impaired.

Therefore, a gas barrier is added to such stretch-blow molded containers.
Various measures have been devised 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. There are methods such as a method of forming a multilayer structure with a layer having an oxygen barrier property such as coalescence or nylon, or a method of plastic metallizing using a vacuum evaporation method or the like with aluminum having an oxygen barrier property on the surface of the stretch blow molded container.

However, these methods cause delamination, insufficient surface strength, difficulty in recycling, unstable oxygen barrier performance, and reduce product value due to opacity. There are problems such as.

Despite having the disadvantages of the above-mentioned methods, one method for improving gas barrier properties 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.

This method also allows the body of the preform to be made of a mixture of polyester resin and a resin with gas barrier properties, thereby making it possible to obtain a highly stretchable blow-molded container with even better gas barrier properties. I can do it.

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. Is there 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 is generally different for each part, it is necessary to adjust the temperature to the optimum temperature for stretch blowing depending on the part.

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 this time, the density or calorific value of the heater is appropriately changed in the direction along the axis of the preform, or after heating with the heater, low-temperature air is blown onto a predetermined portion of the preform to cool it. 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.

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). Since this method does not require stocking of preforms, it is advantageous in terms of inventory control when producing a wide variety of products in small quantities.

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. It takes a lot of time to adjust the temperature to a suitable temperature for molding, which poses a problem in that productivity decreases.

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 the problem of influence.

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

Therefore, the object of the present invention is to
In order to improve gas barrier properties, etc., the body of the preform is made of a blend of polyester resin and gas barrier resin, and the stretch ratio in stretch blow molding is set high, so that the preform has a thick wall thickness. A high stretch blow molding 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 without whitening the product even when the product has An object of the present invention is to provide a manufacturing method.

[Means to solve the problem]

As a result of intensive research in view of the above object, the present inventor has developed a method for manufacturing a container in which a preform whose body portion is made of a blend of a polyester resin and a gas barrier resin is highly stretch blow molded. The blow molding process is divided into two stages, the temperature of only the surface of the body of the preform is controlled, and the primary stretch blow molding process is performed. When the thickness of the preform has decreased to a certain extent, the preform is finished. By adjusting the overall temperature and performing secondary stretch blow molding once the temperature adjustment has been completed, the preform is precisely adjusted to the appropriate temperature for stretch blow molding, right down to the inside of the preform. They discovered that the time it takes to do this can be shortened, and came up with the present invention.

That is, a thick resin primary molded body is formed by the injection molding method of the present invention, and includes a mouth portion, a body portion, and a bottom portion, and the body portion is made of a blend of polyester resin and gas barrier resin. A method for producing a container by high stretch blow molding includes (a) lowering the temperature of a layer near the surface of the body of the primary uneven molded body which is at a high temperature after injection molding;
(C) forming a secondary preform by performing primary stretch blow molding in a non-uniform temperature distribution state in which the center layer of the primary uneven molded body is at a high temperature and the neighboring layers are at a low temperature; The present invention is characterized in that the temperature distribution of the secondary preformed body is made uniform, and the secondary preformed body is further subjected to secondary stretch blow molding.

[Examples and effects]

First, the resin constituting the body of the preform used in the method of manufacturing a high stretch blow molded container having gas barrier properties according to the present invention will be explained.

As the polyester resin, a thermoplastic resin consisting of a saturated dicarboxylic acid and a saturated dihydric alcohol can be used. 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, and diphenoxyethane diethanedicarboxylic acids. Aromatic dicarboxylic acids such as adipic acid, sepatic acid, azelaic acid, decane-1,1O-
Aliphatic dicarboxylic acids such as dicarboxylic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, etc. can be used. Saturated dihydric alcohols include aliphatic alcohols 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. Glycols, alicyclic glycols such as cyclohexane dimetatool, 2,2-bis(4'
-βhydroxyethoxyphenyl)propane, other aromatic diols, etc. can be used.

A preferred polyester is polyethylene terephthalate consisting of terephthalic acid and ethylene glycol.

Next, barrier resins that have excellent barrier properties against gases such as oxygen and carbon dioxide include ethylene vinyl alcohol copolymer resin, high nitrile resin, polyacrylonitrile, and a copolymer of acrylonitrile, methyl acrylate, and butadiene (product name: Valex). ), polyvinyl chloride, nylon MXD6 made of metaxylylene diamine and adipic acid, polyethylene isophthalate copolymer, copolymer made of isophthalic acid or terephthalic acid, ethylene glycol and 1,3-bis(2-hydroxyethoxy)benzene. Examples include polyester, poly P-phenyleterephthalamide, and various liquid crystal polyesters (trade names: Econol, XYDA, etc.).

In addition, blend resins include LONG LIFB (trade name of Aquanautics), which uses organometallic complexes, PET, MXD6 nylon, and cobalt salt (5
OXBAR (CMB
A mixture of names of famous products from companies and trading companies can also be mentioned.

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 a primary uneven molded body 10).

In the present embodiment, the primary uneven molded body IO 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. body 12 at a position of 1/2 of
The wall thickness W0 is formed to be thicker than the wall thickness of the mouth portion 11 and the wall thickness of the bottom portion 13.

In addition, the stretching length of the primary uneven molded body IO. The average diameter of the trunk 12 at the 1/2 position is φ. The inner surface diameter at the same position is φ. , 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.

φo”(φo1+φ.2)/2 In addition, in this embodiment, the body 1 of the primary uneven molded body 10
2 consists of a layer 10a near the inner surface, a center layer 10b, and a layer 10c near the outer surface.

FIG. 2 is a cross-sectional view showing a preform of a high stretch blow-molded container according to an embodiment of the present invention. (referred to as preformed body 2o).

In this embodiment, the secondary preform 2o includes a mouth portion 11, a body portion 12, and a bottom portion 13.

Further, in this example, the wall thickness of the body portion 12 at the position 172 of the stretching length h1 of the secondary preform 2o is W2, the average diameter at the same position is φ1, and the inner surface diameter at the same position is φ, 1, and the outer surface diameters at the same position are φ and 2, then φ and φ1. The relationship between and φ is expressed by the following equation.

φ,=(φ,1+φ12)/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, the high-stretch blow-molded container 3o includes a mouth portion 11, a body portion 12, and a bottom portion 13.

In addition, in this example, the outer surface diameter at the position 172 of the stretch-forming length h2 of the high-stretch blow-molded container 30 is φ,
It is set at 2.

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 preform 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, the primary preform 10 held by the outer mouth mold 41 and the inner mouth mold 42 (indicated by a broken line in FIG. 4), or the primary preform 10 held in the blow mold 4o. At this time, the temperature of the primary preform 10 shown in FIG. 1 is adjusted in the injection mold, so 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 center layer 10b is low. is getting higher. 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 central layer Job be above the glass transition point temperature and below the crystallization temperature. is preferable. This is because the layers 10c and 510a near the inner and outer surfaces can obtain a stretching orientation effect, can prevent clouding from occurring due to crystallization of the center 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 portion 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, a 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. 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, mold 4 in Figure 4 was prepared without taking the temperature control process shown in Figure 5.
By controlling the temperature of the secondary preform, the secondary preform can be kept in the mold 40 even after the primary stretch blowing, and the temperature of the secondary preform can be controlled, and the process can proceed 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 stretching 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 preform 10 shown in FIG.
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 preform 10, b indicates a position corresponding to the center layer 10b, and C indicates a position corresponding to the layer 10c near the inner surface.

FIG. 8 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the primary preform 10 shown in FIG.

This figure shows the temperature distribution in the cross-sectional thickness direction of .

In FIGS. 7 and 8, a indicates a position corresponding to the layer 10a near the inner surface of the primary preform 10, 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. It shows the temperature distribution in the direction.

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, and the temperature was adjusted in a temperature adjustment device having the structure shown in FIG. It shows the temperature distribution in the cross-sectional thickness direction of the secondary preform 20 immediately after.

7 to 1O, the horizontal axis of the graph indicates the position (0, W
Os W2 indicates the outermost part of the cross section, and Wo and w3 indicate the central part of the cross section. Also, the vertical axis of the graph is the temperature (T
, indicates the appropriate temperature for stretching, and Li++I,T.

1, T, ++3, Lln4 is the lowest temperature, T+++axl
, Traaxt, T□1, T□84 indicate the maximum temperature)
It shows.

Thick primary preformed 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 Twa a x I and T, wa, is quite large.

In FIG. 8, the temperature distribution state of the body of the primary preformed body released from the injection mold immediately before primary stretch blow molding is slightly more uniform than that shown in FIG. 7. However, the difference between Tmax2 and Ll++2 is large. However, the layers near the surface shown in a and C are at a temperature suitable for stretch blow molding, and by performing primary stretch blow molding in this state, the effects of stretch blow molding can be obtained for the layers near the surface.

In FIG. 9, since the wall thickness of the body of the secondary preform is thinner or the primary stretch blow molding is performed in a short time, Tl1
The difference between mX2 and Tyu1ゎ3 is still unresolved.

In FIG. 1O, 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. This allows the wall thickness of the preform to be 5
It is also possible to mold containers using a blend of polyethylene terephthalate resin and barrier resin that exceeds mm.

Furthermore, in this example, 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 embodiment, 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 as well, there are no problems such as whitening, and good effects are exhibited.

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.

Although the blend of the present invention can be made using various resin mixing methods, the gas barrier resin is not homogeneously dispersed at the molecular level;
Non-uniform dispersion with an island structure is more desirable, and therefore a method of melting and mixing in a cylinder during injection molding is preferred.

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.

In this example, the resin constituting the body of the preform is specifically polyethylene terephthalate resin J1.
A mixture of a polyester resin consisting of 35 (manufactured by Mitsui Pet Resin ■) and a copolymerized polyester resin BOIO (manufactured by Mitsui Pet Resin ■) having gas barrier properties (weight ratio 9
:1) was used.

Example 1 112 shown in FIG. 3 = 284 mm, φ2 = 93.
High stretch blow molded container 3 with a diameter of 5 mm and an internal volume of 1.5 f
0, using an ASB 50 type molding machine (manufactured by Nisshin ASB Kikai ■), the weight 50g shown in Figure 1 was used.
ha=110.5mm, Wo=5.5mm, φ
o+=12mm, φ02=23mm, φ0=17
．． A 5 mm primary preform 10 was molded. After an injection cooling time of 23 seconds, the mold was 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 h+=165 mm, W2=3.0 mm, φ, as shown in FIG. 2.
1=19mm, φ, 2=25mm, φ, =22m
A secondary preform 20 of m 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 to bring each part of the secondary preformed body 20 to the desired stretch-blow molding temperature of 95°.
C to 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 ratio h2/ho=2.
6 times, circumferential stretching magnification φ, /φ. = 5.3 times, and the surface area magnification was 13.7 times. In addition, when looking at the stretching ratio on the inner and outer surfaces of the container, it is approximately 20 times on the inner surface and about 1 on the outer surface.
015 times. Furthermore, the molding cycle of the high stretch blow molded container was as short as about 27 seconds, and no whitening occurred in the container.

The oxygen barrier properties of the above-mentioned high stretch blow molded containers were measured. As a result, the oxygen permeation amount per tube per day under the condition of 1 atm was 0.23 cc, and good oxygen barrier properties were obtained.

Example 2 In order to mold a high-stretch blow-molded container 3o similar to that of Example 1, using the same resin and molding machine as that of Example 1, the weight shown in FIG. 1 was 50 g ha''=83 mm, w.

=7, 0mm, φo + = 12mm, φ.

! = 26 mm1 A primary preformed body 10 with φo = 19 mm was molded. After injection molding, the mold was cooled for 26 seconds and released.

This primary uneven molded body lo was inserted into an apparatus having the structure shown in FIG. 4 and stretch-blow molded to obtain h+=200.0 mm, W2: 2.0 mm, as shown in FIG. 2.
φ, , = 24mm, φI 2 = 28mm, φ
A secondary preform 20 having a diameter of 26 mm was molded.

Subsequently, this secondary preform 20 was kept in a temperature-controlled mold shown in FIG. 4, and the temperature was adjusted for about 24 seconds to obtain the desired stretch-blow molding temperature for each part of the secondary preform 20. .

Next, this secondary preform 20 was inserted into an apparatus having the structure shown in FIG. 6 and subjected to stretch blow molding, thereby obtaining the high stretch blow molded container 3o.

In this example, the axial stretching ratio h2/ho=3.
4 times, circumferential stretching magnification φ, /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 31
seconds, and no whitening occurred in the container. .

The oxygen barrier properties of the containers described above were measured. As a result, 1
The amount of oxygen permeated per bottle per day under atmospheric pressure conditions is 0.21c.
c, and even better oxygen barrier properties than in Example 1 were obtained.

Comparative Example 1 Using the same product container and resin molding material as in Example 1, a similar primary preform was molded, and stretch blow molding was performed without molding a secondary preform. A container with a high draw ratio similar to the above was obtained. The molding cycle at this time was long, about 40 seconds, and if it was shorter than 27 seconds, whitening occurred on the container. In addition, there were some thin parts of the container, and the wall thickness was not stable from shot to shot.

In addition, in this comparative example, the oxygen barrier properties of the above-mentioned high stretch blow-molded container were measured in the same manner as in Example 1. As a result, under the condition of 1 atm, the amount of oxygen permeation per tube per day was 0.
32 cc, and sufficient oxygen barrier properties could not be obtained.

Comparative Example 2 Using the same resin and molding machine as in Example 1, the weight shown in Fig. 1 was 50 g, ho = 137 mm, Wo = 4.0
mm, φ, , = 16.5mm, φ, 2=
A primary preform lO of 24.5 mm, φo = 2o, smm was molded, and high 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/h, =2.
1x, circumferential stretching magnification φ2/φ. = 4.5 times, and the surface area magnification was 9.5 times. The molding cycle was approximately 28 seconds, and no whitening occurred.

Further, in this comparative example, the oxygen barrier properties of the above-mentioned high stretch blow-molded container were measured in the same manner as in Example I. As a result, under the condition of 1 atm, the amount of oxygen permeation per tube per day was 0.
28 cc, and the oxygen barrier property was inferior to that of Example 1.

Comparative Example 3 A molded container with a high stretch ratio as in Example 1 was obtained by molding the same primary preform as in Example 2 and stretch blow molding without molding a secondary preform. . This container became cloudy and the wall thickness was unstable.

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 0.35 cc under the condition of 1 atm, and sufficient oxygen barrier properties were not obtained.

Comparative Example 4 A container was obtained in the same manner as in Example 1 using only J135 resin. The oxygen barrier was 0.32 cc, and the performance of Example 1 could not be obtained.

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. It was possible to obtain a high-stretch blow-molded container with a suitable wall thickness distribution.

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

〔Effect of the invention〕

As detailed above, in the method for manufacturing a high stretch blow molded container of the present invention, the stretch blow molding process of a preform whose body is made of a blend of polyester resin and gas barrier resin is divided into two steps. Then, the temperature is adjusted only on the surface of the preform, and the primary stretch blow molding process is performed.
The structure is such that the temperature of the entire preform is adjusted when the thickness of the preform has decreased to a certain extent, and secondary stretch blow molding is performed when the temperature adjustment is completed.

As a result, in order to improve gas barrier properties, etc., a preform formed from a blend of a polyester resin and a gas barrier resin has a large wall thickness by setting a high stretch ratio in stretch blow molding. Even in this case, it is possible to shorten the time required to precisely adjust the temperature of the preform to the temperature suitable for stretch blow molding, without causing whitening.

[Brief explanation of drawings]

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 a high-stretch blow-molded container; FIG. 7 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the primary preform 10 shown in FIG. 1; , FIG. 8 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the primary preform 10 shown in FIG. 1, and FIG. 9 is a graph showing the cross-sectional thickness of the secondary preform 20 shown in FIG. 10 is a graph qualitatively showing the temperature distribution in the cross-sectional thickness direction of the secondary preform 2o shown in FIG. 2, and FIG. It is a sectional view showing an example of a preform. 1.11... Mouth 2.12... Body 3.13... Bottom 4.45.95... Stretching rod 10. 10a 10b . . 0c 14.24. 20・ ・ ・ 30・ 40・ 41.91・ 42, 92・ 43, 93・ ・ 46.96・ 47.97・ ・ 50・ ・ ・ ・ 51 ・ 60・ 61～65・ 66・ 67・ 71～77・・ ・Primary uneven molded body・Layer near the inner surface・Center layer・Layer near the outer surface・・Central secondary preformed body・Stretch blow molded container・-Blow molding mold・Outer mouth mold・Inner mouth mold・Hole・Tip section・Blowout hole・Temperature adjustment core・Groove・Temperature adjustment device・Temperature adjustment block・・Upper block・・Lower block・・Passages 81 to 85・ 90・・Temperature adjustment heater secondary molding mold

Claims (4)

[Claims] (1) A thick primary preform made of resin is formed by injection molding and consists of a mouth part, a body part, and a bottom part, and the body part is made of a blend of polyester resin and gas barrier resin, and is highly stretched. In a method for producing a blow-molded container, (a) the temperature of a layer near the surface of the body of the primary preform, which is at a high temperature after injection molding, is lowered, and (b) the center layer of the primary preform is (C) forming a secondary preform by performing primary stretch blow molding in a non-uniform temperature distribution state where the temperature is high and the neighboring layer is low; (C) uniformizing the temperature distribution of the secondary preform; A method characterized in that the secondary preform is further subjected to secondary stretch blow molding. (2) In the method for manufacturing a high-stretch blow-molded container according to claim 1, the temperature of the neighboring layer is around the glass transition point temperature, and the temperature of the central layer is above the glass transition point temperature and below the crystallization temperature. A method characterized by carrying out primary stretch blow molding under the following conditions. (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.