JPH0688324B2 - Hollow PET container and method for manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a pressure-resistant and heat-resistant hollow PET container and a method for producing the same, and particularly to a hollow PET container having good heat sterilization efficiency of contents and excellent impact resistance. And the manufacturing method thereof.

[Prior Art] In a pressure-resistant heat-resistant hollow PET container, a bottomed cylindrical parison made of polyethylene terephthalate (hereinafter referred to as PET) is preformed, and this parison is biaxially stretch blow molded to crystallize into a resin material. The pressure resistance and the heat resistance were ensured by causing the orientation and heat setting.

The hollow PET container molded in this way has a drawback that the bottom has a low degree of stretching, the degree of crystallinity is low, or an uncrystallized portion is generated, and heat resistance and pressure resistance are extremely poor. there were.

As a result, when the filling is sterilized by applying hot water or the like from the top of the container, the bottom portion is likely to be deformed by heat and internal pressure.

Therefore, in order to eliminate this deformation, the temperature of the hot water is lowered. However, there is a drawback that the processing time becomes long, and there is a strong desire among those skilled in the art to use hot hot water in a short time. .

In order to solve the problem, it was attempted to thermally crystallize the mouth and neck and the center of the bottom, which are difficult to draw and heat set, at the time of the parison.

However, if the center of the bottom is uniformly heat-crystallized, a container molded using such a parison will crack at the center of the bottom even when the base cup is attached when a drop test is performed. It has drawbacks and cannot be put to practical use.

This is due to the fatal property that the thermally crystallized portion has extremely low impact resistance.

[Problems to be Solved by the Invention] A hollow having high impact resistance and excellent pressure resistance and heat resistance
It is to provide a PET container.

[Means for Solving the Problems] As a result of various studies for solving the problems, the present inventors have found that the thermal crystallinity of the thermally crystallized bottom central part of the hollow PET container is high in the peripheral part and high in the central part. By lowering the part, the high crystallization part of the peripheral part provides heat resistance and pressure resistance effect, and the low crystallization part of the center part provides impact resistance effect, without impairing the pressure resistance and heat resistance of the hollow PET container. The present invention has been completed by succeeding in improving impact resistance.

That is, the present invention provides "1. Hollow container body 1 formed by stretch blow molding"
In a PET container made of resin having a thermal crystallization region in the bottom center part 5 and the mouth / neck part 3, the thermal crystallization degree of the thermal crystallization region of the bottom center part 5 and the peripheral part 7 are thermally crystallized. Hollow PET container with a high temperature of 25 to 50% and a low central portion 6.

2. The hollow PET container according to claim 1, wherein the central portion 6 has a thermal crystallinity of 20% or less.

3. The hollow PET container according to claim 1, wherein the thermal crystallization region provided in the peripheral portion 7 is continuous and the outer periphery thereof is circular.

4. The hollow according to claim 1 or 2, wherein the thermal crystallization region provided in the peripheral portion 7 is continuous and its outer periphery is polygonal.
PET container.

5. The thermal crystallization region provided in the peripheral part 7 is discontinuous, and the non-thermal crystallization part exists between them.
The hollow PET container according to any one of 1.

6. A thermal crystallization area is provided in the bottom central portion 15 and the mouth / neck portion 3, and the thermal crystallization degree of the peripheral portion 17 of the thermal crystallization area of the bottom central portion 15 is high, the central portion 16 is low, and the peripheral portion 17 is Outer diameter D1 of the bottom outer diameter D2 of 15 ~
A method for producing a hollow PET container, characterized in that a tubular parison with a bottom of 95% is biaxially stretch blow-molded and all regions other than the thermal crystallization region are stretched to a high stretch ratio.

7. The parison has its thermally crystallized bottom center part 15 periphery
The hollow PET according to claim 6, wherein the outer diameter D1 of 17 is slightly larger than the outer diameter D3 of the stretch rod for stretch blow molding.
Container manufacturing method.

8. The hollow PET container according to claim 6 or 7, wherein the parison has the curvature of the thermally crystallized bottom center part 15 matched with the curvature of the bottom center part 5 of the completed hollow PET container. Manufacturing method.

9. The parison has its thermal crystallized bottom center part 15 periphery
The hollow PE according to any one of claims 6 to 8, wherein the thickness of 17 is smaller than the thickness of the body 12 of the parison.
Manufacturing method of T container.

10. The hollow PET according to claim 9, wherein the parison is formed by gradually increasing the thickness of the peripheral portion 17 of the thermally crystallized bottom central portion 15 of the peripheral portion 17 adjacent to the outer side toward the outer side. Container manufacturing method. [Operation] In the present invention, the thermal crystallization degree at the center of the bottom, which is the thermal crystallization region at the bottom of the hollow PET container, is high in the peripheral portion and low in the central portion, so that pressure resistance and heat resistance are improved. The impact resistance can be increased without impairing it. This is because by arranging the regions having different thermal crystallinity in the bottom in this way, the center of the bottom, which receives the strongest impact when dropped, is flexible and resistant to impact due to the low thermal crystallinity.

In the present invention, a good effect can be obtained by setting the thermal crystallization degree at the peripheral portion of the thermal crystallization region at the center of the bottom of the hollow container body to 25 to 50%.

If the thermal crystallinity of the peripheral part is less than 25%, the heat resistance is low because the crystallinity is small, and therefore deformation due to heat occurs. If the thermal crystallinity exceeds 50%, the impact resistance deteriorates and the product falls. Cracks occur.

Also, good results are obtained when the thermal crystallinity of the central portion is 20% or less. This is because the central part surrounded by the thermally crystallized peripheral part and having low thermal crystallinity retains more flexibility even after blow molding, so that the impact resistance of the hollow PET container is good. Of.

The outer circumference of the thermally crystallized peripheral portion is usually circular, but may be polygonal such as triangular, square or hexagonal.

When the thermal crystallinity of the center of the bottom is 10% or less, and the region of 10% or less is considerably wide, the thermally crystallized peripheral portion has a circular ring shape or a polygonal ring shape. In such a case, the flexibility at the center of the bottom is extremely good, and the impact resistance is excellent.

In addition, when the peripheral portion of the thermal crystallization region is discontinuous, that is, between the intermittent thermal crystallization portions formed by dots, lines or elongated rectangles, non-thermal crystallization portions exist. In the case where it is present, the central part is also appropriately stretched and crystallized, and the mechanical strength is large and the pressure resistance is extremely excellent.

To manufacture the hollow PET container of the present invention, polyethylene terephthalate (PET) is used to make a cylindrical parison with a bottom by injection molding, etc., and the mouth and neck are thermally crystallized according to the usual method, and then the center of the bottom is followed according to the present invention. The peripheral part of the thermal crystallization region is thermally crystallized to a high thermal crystallinity of, for example, 25 to 50%, and the central part is thermally crystallized to a low thermal crystallinity of, for example, 20% or less. It can be manufactured by molding.

At this time, if the thermal crystallinity of the central portion is set to 10% or less, a hollow PET container having more excellent impact resistance can be obtained. Then, the thermal crystallization portion around it can be formed in an annular shape or a polygonal shape, or can be formed in the shape of dots, lines, elongated rectangles, or the like to be discontinuous.

Further, in the manufacturing method of the present invention, the outer diameter of the peripheral portion of the thermally crystallized region at the center of the thermally crystallized bottom of the parison needs to be 15 to 95% of the outer diameter of the bottom of the parison.

If it is less than 15%, the heat resistance strength of the bottom part becomes low because the crystallization part is too small when stretch blow molding, and if it exceeds 95%,
The crystallized portion becomes too large, and the impact resistance strength decreases.

Further, the outer diameter of the peripheral portion of the thermally crystallized region of the thermally crystallized bottom center of the parison is slightly larger than the outer diameter of the stretch rod for stretch blow molding, and when stretch blow molding is performed, The stretching of the portion adjacent to the outer side of the peripheral portion of the thermal crystallization region at the center of the bottom can be performed extremely uniformly and smoothly.

In addition, by matching the curvature of the thermally crystallized bottom center of the parison with the curvature of the hollow PET container bottom after completion, the stretched crystallization part formed by stretch blow molding and the original heat No distortion occurs between the crystallization part,
A hollow PET container with excellent impact strength can be obtained.

In addition, by making the thickness of the peripheral part of the thermally crystallized region in the center part of the thermally crystallized bottom of the parison smaller than the thickness of the bottom part and body of the parison, the thickness of the center part of the bottom after stretch blow molding The thickness of the container wall can be made equal, distortion does not occur at the boundary, and it helps improve impact resistance.

Further, by gradually increasing the thickness of the portion adjacent to the outer side of the peripheral portion of the thermal crystallized region of the central portion of the thermally crystallized bottom of the parison toward the outer side, after the stretch blow molding, the boundary The change in the thickness of the portion becomes smoother, and the impact resistance can be further improved.

[Examples] Hereinafter, the present invention will be described based on illustrated examples.

FIG. 1 shows one embodiment of the hollow PET container of the present invention, and in the figure, I shows the whole hollow PET container.
The container I is composed of a container body 1 which is hollow inside, and a base cup II which is attached to the bottom surface of the container body 1.

FIG. 2 illustrates the container main body 1. The container main body 1 is made of polyethylene terephthalate (PET), and has a cylindrical body portion 2 and a mouth / neck portion provided on the tip of the body portion 2 by squeezing the upper portion of the body 2 roundly. 3 and a bottom portion 4 continuously provided at the lower end of the body portion 2 and projecting downward in a spherical shell shape.

The mouth / neck portion 3 has a thick-walled cylindrical shape, and the upper edge of the shoulder portion continuously extended from the body portion 2 is joined to the outer edge of the lower end surface of the mouth / neck portion 3. Thermally crystallized to about 45% to improve strength and heat resistance.

That is, the thermally crystallized mouth-neck portion 3 is thermally crystallized at about 100 ° C to 140 ° C, and spherulites are formed to give a milky white color. It retains its morphology.

Further, the bottom portion 4 of the container body 1 is partially crystallized by heat to form a thermal crystallization region bottom central portion 5.

This thermally crystallized thermally crystallized region, that is, the bottom center portion 5
Is composed of a bottom center portion 6 having a low thermal crystallization degree and a high heat crystallization peripheral portion 7 arranged at the periphery thereof, and the peripheral portion 7 has an outer diameter D4 of about 10 mm with the center portion 6 as the center. , Thermal crystallinity is about 45%. The thermal crystallinity decreases from the peripheral portion 7 toward the central portion 6, and the thermal crystallinity of the central portion 6 is 10% or less.

Therefore, the bottom portion 4 of the hollow PET container of the present invention is not deformed by boiling water due to the heat resistance effect of the highly thermally crystallized peripheral portion 7, and the central portion thereof has a low thermal crystallinity. 6 has an excellent impact resistance effect.

Of course, in this case, the peripheral portion 7 of the bottom central portion 5 of the thermal crystallization region is
As shown in FIG. 3 to FIG. 6, heat-crystallized in an annular shape or a polygonal shape and having a thermal crystallinity of 25 to 50%, and the inner portion thereof has a thermal crystallinity of 20% or less, Has almost the same heat and pressure resistance and impact resistance.

Further, as shown in FIG. 7 or FIG. 8, when the thermally crystallized annular or polygonal annular portion is interrupted, an appropriate amount of the inner portion is also stretch-crystallized during stretch molding, which is excellent. Shows mechanical strength and pressure resistance.

Then, the region other than the mouth / neck part 3 and the region other than the bottom center part 5 of the container body 1 are all thinly stretched at a high stretch ratio to be high stretch crystallization regions, and these regions are crystallized. It is highly stretched and crystallized to 10-40%. Therefore,
In the high-stretch crystallization region, the crystal orientation occurs inside the material due to the stretching action. It has high strength and excellent shape retention.

In this example, the heat-set was applied to the highly stretched container, whereby the crystallinity was further increased and the heat resistance was further improved.

The base cup II has a substantially bottomed cylindrical shape, and the diameter of the peripheral wall is substantially the same as the outer diameter of the body portion 2 of the container body I.

An annular pedestal portion that is adhesively fixed to the bottom surface of the container body I is provided on the bottom wall of the base cup II.

On the other hand, the upper end of the peripheral wall of the base cup is locked to the lower edge of the body portion 2 of the container main body I, and the upper end of the peripheral wall has hot water in a space formed between the base cup and the bottom of the container main body. A plurality of through-holes are provided in the circumferential direction to allow the circulation of.

Next, a method for manufacturing the hollow PET container will be described with reference to FIGS. 9 to 12.

First, a stretch molding parison 11 as shown in FIG. 9 is preformed. The parison 11 is a material that is preliminarily molded to perform the biaxial stretch blow molding of the container body 1. The parison 11 is mainly the cylindrical portion 12 that should be the body portion 2 of the container body 1, and the center of the bottom of the container body 1. The bottom center 15 of the parison should be 5,
It is configured by a bottomed cylindrical member including a mouth and neck portion 3 connected to the upper end of the tubular portion 12.

The parison 11 is manufactured by injection molding, for example. That is, the molten resin was injected from the injection nozzle into the closed mold, cooled and cured, and the mold was opened to take out the molded parison 11.

Next, as shown in FIG. 9, the parison 11 was heat-treated at the mouth / neck portion 3 and the bottom center portion 15 which is a part of the center of the bottom.
In the present embodiment, the mouth / neck portion 3 has an overall crystallinity of about 45%.
Thermally crystallized.

Further, with respect to the bottom central portion 15, the peripheral portion 17 is thermally crystallized to have a crystallinity of about 45%, and the crystallinity decreases toward the bottom central portion 16, and the central portion 16 has a crystallinity of 10% or less. did.

At this time, as shown in FIG. 9 or FIG. 10, the outer diameter D1 of the crystallized peripheral portion 17 is equal to the outer diameter D2 of the bottom of the parison (= the body portion 12).
40% of the outer diameter).

In this example, since the bottom outer diameter D2 of the parison was 25 mm, the outer diameter D1 of the peripheral portion 17 was thermally crystallized to be 10 mm.

Further, in the present embodiment, the thermally crystallized bottom central portion 15
As shown in FIG. 11 (a), the curvature was designed to have a radius (r) of 50 mm in accordance with the curvature of the container body bottom 4 after completion.

As a result, the roundness of the bottom 4 of the container body after blow molding was finished uniformly and smoothly, and there was no distortion and excellent impact resistance was exhibited.

In addition, as shown in FIG. 11 (a), the thickness of the peripheral portion 17 of the thermally crystallized region of the thermally crystallized bottom central portion 15 is 2 mm thinner than the thickness 3 mm of the parison body 12 to be 1 mm. And As a result, as shown in (b), the thickness of the container body bottom center portion 5 after blow molding became the same as the thickness of the body portion 2, and there was no distortion, indicating excellent impact resistance.

Further, as shown in FIG. 11 (a), the outer thickness of the peripheral portion 17 of the thermally crystallized region of the thermally crystallized bottom central portion 15 was designed to gradually increase toward the outer side. As a result, as shown in (b), the thickness of the container body bottom portion 4 after the blow molding was smoothly finished to a uniform thickness, and the distortion was further eliminated to show excellent impact resistance.

Next, a molding process for molding the container body 1 by blow molding using the parison 11 described above will be described based on FIGS. 12 (a) and 12 (b).

In the figure, 30 is a mold for blow molding.
Reference numeral 30 includes a split mold 31 for molding the body portion 2 of the container body 1, a bottom mold 32 for molding the bottom central portion 5 of the container body, and a neck mold 33 for holding the mouth / neck portion 3 of the container.

Reference numeral 34 is an extension rod for extending the parison 11 in the axial direction thereof, and is inserted into the parison 11 mounted on the mold 30 by a drive source (not shown) so as to be retractable from the mouth / neck 3 side. The outer diameter D3 of the drawing rod 34 is 9 mm in this embodiment.
Is. A fluid passage 35, through which a fluid such as compressed air passes, is provided in the space between the stretching rod 34 and the inner surface of the parison 11.

Blow molding is performed in the above apparatus as follows. First, the parison 11 heated to a stretching temperature of 70 to 140 ° C., preferably 90 to 120 ° C. is stretched in the axial direction by stretching the stretching rod 34 as shown in FIG. In this state, mainly the cylindrical part of parison 11
12 are stretched in the axial direction.

As described above, the outer diameter D3 of the stretch rod 34 is not the same in this embodiment.
Since it is 9 mm, the outer diameter D1 of the crystallized peripheral portion 17 is set to be 10 mm.

By making D1 slightly larger than D3 in this way, the portion adjacent to the outer side of the peripheral portion 17 can be extremely smoothly stretched.

If the outer diameter D3 of the stretching rod 34 is too large, it will be difficult for air to enter, which is not preferable.

Furthermore, as shown in Fig. 12 (b), compressed air is
Blown under high pressure through 34 fluid passages 35, parison
The tubular portion 12 of 11 bulges outward in the radial direction and comes into close contact with the inner surface of the mold 30. On the other hand, the bottom of the parison spreads outward in the radial direction while being thinned from a portion adjacent to the outside of the peripheral portion 17 of the thermal crystallization region of the bottom central portion 15, and the outer surface thereof adheres to the inner surface of the bottom mold 32. . In this state, the tubular portion 12 of the parison 11 is mainly stretched in the circumferential direction.

In this way, all the regions other than the mouth / neck part 3 and the bottom center part 5 of the container body 1 are thinly stretched at a high stretching ratio to become highly stretched crystallization regions, and these regions are crystallized. It is highly stretched and crystallized to a degree of 10-40%.

To obtain such a high stretch crystallinity, as described above,
This can be achieved by producing a high crystal orientation by stretching at a high stretching ratio in a state of being heated to 70 to 140 ° C, preferably 90 to 120 ° C.

Regarding the bottom of the parison, when the parison is blow-drawn, if the periphery of the peripheral part 17 of the thermal crystallized region of the bottom central part 15 of the parison that is thermally crystallized is continuous, this thermal crystallized part is no longer necessary. Since neither stretching nor shrinking is caused by stretching, the inner central portion surrounded by the peripheral portion 17 is not stretched, and only the outer amorphous portion continuous with the peripheral portion 17 is stretched.

Even when the peripheral portion 17 of the thermally crystallized region of the bottom central portion 15 which is thermally crystallized has an annular shape or a polygonal annular shape as shown in FIGS. 3 to 6, this thermal crystallized portion is Almost no change is caused by the stretching, so that the enclosed inner central portion is not stretched, and only the outer amorphous portion continuous with the peripheral portion 17 is stretched.

That is, in the above case, the inner central portion is low and is either thermally crystallized or uncrystallized.

However, when the peripheral portion 17 which is thermally crystallized is intermittent as shown in FIG. 7 or FIG. 8, the peripheral portion is slightly expanded by stretching, and the central portion is also slightly stretched and crystallized accordingly. It will be.

As a result of the stretch crystallization as described above, the stretch crystallization effect is exerted more than the low heat crystal or the uncrystallized one, and the bottom central portion 5 having high mechanical strength and excellent pressure resistance is formed.

In this way, the amorphous part of the parison 11 other than the thermally crystallized region,
Mainly, the tubular portion 12 is heated and stretched to cause sufficient crystal orientation to form the body portion 2, the shoulder portion and the bottom portion 4 of the container body, and this portion is highly stretched and crystallized.

During stretch blow molding, split mold 31 and bottom mold 32 are
When heated to 0 ° C., the molded container is heat set, and a container having excellent heat resistance can be obtained.

11 (a) and 11 (b) show the stretched state of the parison bottom in stretch blow molding.

That is, the parison bottom shown in (a) is stretch-molded on the bottom of the container body shown in (b) by the gas pressure of compressed air, but the thickness of the center 15 of the parison bottom is made thinner than the thickness of the parison body 12. Further, since the thickness is gradually increased from the peripheral part 17 of the parison bottom toward the outside, and the curvature r of the central part 15 of the parison bottom is made equal to the curvature r of the bottom part of the container main body after completion, the stretch molding is performed. After that, an extremely smooth bottom is formed like the bottom of the container body shown in (b).

In this way, a hollow PET container with excellent pressure resistance, heat resistance and impact resistance can be obtained.

To measure the thermal crystallinity and the stretch crystallinity,
The density of that portion may be measured and converted.

However, D is a density (measured value) When the molding of the container body 1 is completed, the base cup II is attached to the bottom surface of the container body 1 as shown in FIG. 1, and the container is completed by adhesively fixing the base cup II.

Next, a case where the container thus formed is filled with a carbonated drink or the like and the contents are sterilized by heating will be described.

The heat sterilization of the content is performed by filling the content in the container and capping it, and then pouring hot water from the upper part of the container. In this embodiment, hot water of 75 ° C. is poured on the upper part of the container. The hot water flows downward along the outer peripheral surface of the body 2 of the container body 1, and heat-sterilizes the contents through the wall surface of the container body 1.

On the other hand, the hot water that has flowed to the lower end of the body enters the inside of the base cup II through the passage formed in the base cup II, flows along the spherical outer peripheral surface of the bottom surface of the container body 1, and flows downward. On this bottom surface, boiling water is about 65 ° C.

On the other hand, the heating increases the gas pressure inside the container body 1,
Although the container body 1 is exposed to high temperature and high pressure,
The peripheral portion 7 of the thermally crystallized region of the bottom central portion 5 of the above is fully thermally crystallized, and the bottom portion 4 which is adjacent to the peripheral portion 7 and outwardly is a highly stretched portion having a sufficiently crystallographic orientation. Because
There is no possibility of softening even when hot water is poured, heat resistance and pressure resistance are increased, and restrictions due to temperature are reduced.

By the way, the heat-resistant temperature of such crystallization is 80-90.
The temperature and pressure resistance are about 8-10 kg / cm ² . Therefore, sterilization at a higher temperature becomes possible, and the range of use can be expanded.

Moreover, since the thermal crystallization degree of the bottom central portion 5 which is the thermal crystallization region of the bottom of the container body 1 is decreased from the peripheral portion 7 toward the central portion 6, the impact resistance is great, and when falling, etc. The impact resistance effect is extremely excellent.

(Effects of the Invention) The present invention is composed of the above-mentioned constitutions and operations. When the center part of the container bottom and the neck part which are not sufficiently stretched at the time of stretch blow molding are thermally crystallized in advance and stretch blow molding, It solves the disadvantage of the conventional container that the center part of the bottom of the container is broken especially when dropped because the crystallization part is fragile.
Thermal crystallization is performed by 50%, and the thermal crystallization degree is gradually reduced from the peripheral portion 7 to the central portion 6 to 20% or less. In that case, the thermal crystallized peripheral portion 7 is circled if necessary. The heat resistance and pressure resistance of the bottom center part 5 of the container can be enhanced by making the inside of the ring or polygonal ring to have a thermal crystallization degree of 10% or less and intermittently dividing the thermally crystallized peripheral part 7. Since the impact resistance can be remarkably enhanced while maintaining it, it is possible to quickly sterilize the contents with high temperature hot water,
It has become possible to provide a heat-resistant and pressure-resistant container with high versatility that can be used as a container for storing various contents having a high sterilization temperature and that the bottom is not easily broken when dropped.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing the overall structure of a hollow PET container I according to an embodiment of the present invention. FIG. 2 shows a hollow PET container I according to an embodiment of the present invention,
The partially broken front view of the container main body 1 which removed the base cup II is shown. FIG. 3 shows a thermally crystallized annular peripheral portion provided on the bottom of the container body or parison. 4 to 6 show the peripheral portion of a thermally crystallized polygonal ring (triangle, square, hexagon) provided on the bottom of the container body or the parison. FIGS. 7 to 8 show a thermally crystallized intermittent peripheral portion provided on the bottom of the container body or the parison. FIG. 9 shows a partially cutaway front view of the parison used in the present invention. FIG. 10 is an enlarged cross-sectional view of the bottom part to the cylindrical part of the parison and the stretch rod used in the present invention. FIG. 11 (a) is a partial cross-sectional view of the parison in which the bottom center part 15 is thermally crystallized, and (b) is a cross-sectional view of the bottom part of the container body 1 showing the relationship when (a) is stretched. is there. 12 (a) and 12 (b) are schematic vertical cross-sectional views of the blow molding die showing a state in which the container body is blow molded using the parison of FIG. I ... Hollow PET container, II ... Base cup, 1 ... Container body, 2 ... Container body, 3 ... Container body or parison mouth / neck, 4 ... Container bottom, 5 ... ... central part of bottom of container body, 6 ... central part of bottom of container body, 7 ... peripheral part of thermal crystallization region at bottom center part of container body, 11 ... parison, 12 ... cylindrical part of parison, 15 …… Parison bottom central part, 16 …… Parison bottom central part, 17 …… Parison bottom central part peripheral part of thermal crystallization region, 30 …… Mold, 31 …… Split mold, 32 …… Bottom type, 33 …… Neck type, 34 …… Stretching rod, D1…
… Outer diameter of the peripheral part 17 of the thermal crystallization area of the bottom central part 15 of the parison, D2 …… Outer diameter of the bottom of the parison (= outer diameter of the body 12), D3…
... outer diameter of the drawing rod 34, D4 ... outer diameter of the peripheral portion 7 of the thermal crystallization region of the bottom central portion 5 of the container body, r ... curvature (radius).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-57-201631 (JP, A) JP-A-54-155262 (JP, A) Actually open Sho-52-117566 (JP, U) Actual-open Sho-55- 101712 (JP, U)

Claims (10)

[Claims] Claim: What is claimed is: 1. A plastic PET container, comprising a hollow container body 1 formed by stretch blow molding and having thermal crystallization regions in the center 5 of the bottom and the neck 3 of the container. The thermal crystallinity of the area is 25 to 50% in the peripheral portion 7.
Hollow PET container with high and low center 6. 2. The thermal crystallinity of the central portion 6 is 20% or less,
The hollow PET container according to claim 1. 3. The hollow PET container according to claim 1, wherein the thermal crystallization region provided in the peripheral portion 7 is continuous and its outer periphery is circular. 4. The hollow PET container according to claim 1, wherein the thermal crystallization region provided in the peripheral portion 7 is continuous and its outer periphery is polygonal. 5. The hollow PET according to claim 1, wherein the thermally crystallized region provided in the peripheral portion 7 is discontinuous, and the non-thermally crystallized region is present therebetween. container. 6. A thermal crystallization region is provided in the bottom central portion 15 and the mouth / neck portion 3, and the peripheral portion 17 of the thermal crystallization region of the bottom central portion 15 has a high thermal crystallinity and the central portion 16 has a low thermal crystallization degree. The outer diameter D1 of the part 17 is 15 to 95% of the outer diameter D2 of the bottom, and a bottomed cylindrical parison is biaxially stretch blow molded to stretch all regions other than the thermal crystallization region to a high stretch ratio. A method for producing a hollow PET container, which is characterized by: 7. A parison has a thermally crystallized bottom center portion.
7. The method for producing a hollow PET container according to claim 6, wherein the outer diameter D1 of the peripheral portion 17 of 15 is slightly larger than the outer diameter D3 of the stretch rod for stretch blow molding. 8. A parison has a thermally crystallized bottom center portion.
The hollow PE according to claim 6 or 7, wherein the curvature of 15 is matched with the curvature of the bottom central portion 5 of the completed hollow PET container.
Manufacturing method of T container. 9. The parison has a thermally crystallized bottom center portion.
The method for manufacturing a hollow PET container according to any one of claims 6 to 8, wherein the peripheral portion 17 of 15 has a thickness smaller than that of the body 12 of the parison. 10. The parison is formed by gradually increasing the thickness of the peripheral portion 17 of the thermally crystallized bottom central portion 15 of the peripheral portion 17 adjacent to the outer side toward the outer side. For manufacturing a hollow PET container.