JPH07132923A - Heat resistant biaxially stretch blow molded bottle and method for producing the same - Google Patents

Abstract

(57) [Abstract] [Purpose] A heat-resistant biaxial stretch blow-molded bottle having a mouth and a transition part having excellent heat resistance and dimensional accuracy, and a support ring having high strength, and such a heat-resistant biaxial bottle. Provided is a method of making a stretch blow molded bottle. [Structure] A mouth portion 1 having a support ring 11 at a lower end,
The transition part 2 following the mouth part 1, the shoulder part 3, the body part 4, and the bottom part 5
And a mouth portion 1 and a transition portion 2 other than the support ring 11.
Is a heat-resistant biaxially stretch blow-molded bottle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant biaxially stretch blow-molded bottle having a crystallized (whitened) mouth portion and transition portion, and a method for producing the same, particularly because the mouth portion other than the support ring is crystallized. The present invention relates to a heat resistant biaxially stretch blow molded bottle having excellent heat resistance and good dimensional accuracy, and a support ring having high strength, and a method for producing the same.

[0002]

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

However, in a polyester bottle obtained by ordinary biaxially stretch blow molding, the mouth portion is left unstretched and the transition portion is also low stretched, so that heat resistance cannot be imparted by stretching or heat setting. , Cannot be used for filling liquid at 80-95 ℃. In particular, it is difficult to continuously use under severe hot fill conditions of 90 ° C or higher. Also, 65-80
When pasteurizing with a hot shower at ℃ is performed for a long time, the amount of deformation is large especially in the transition portion of low stretching due to heat and internal pressure.

Therefore, a method of crystallizing the polyester and improving the heat resistance is performed by subjecting the mouth of the bottle to a heat treatment after the parison stage or after the biaxially stretch blow molding. However, this method has a problem that the dimension of the mouth portion is likely to change due to the crystallization of the polyester during the heat treatment, and the shrinkage is likely to occur particularly at the opening end portion. Further, the crystallized support ring has a problem that it is liable to be broken when filling or transferring the contents.

Therefore, an object of the present invention is to provide a heat-resistant biaxially stretch-blown bottle having a mouth portion and a transition portion having excellent heat resistance and dimensional accuracy, and a support ring having high strength, and the heat resistance. It is to provide a method of manufacturing a biaxially stretch blow molded bottle.

[0006]

As a result of earnest research in view of the above-mentioned object, the present inventor has found that the mouth portion and the transition portion are heated from the inside and then supported after the bison stretch blow molding of the parison stage or the parison. If the mouth is heated from the outside while the ring is held in the cooling mold, the mouth and transition part other than the support ring are crystallized without being substantially deformed and have sufficient heat resistance against hot fill and hot shower. The inventors have found that a biaxially stretch blow-molded bottle can be obtained, and have arrived at the present invention.

That is, the heat-resistant biaxially stretch blow-molded bottle of the present invention has a mouth portion having a support ring at the lower end, a transition portion continuing to the mouth portion, a shoulder portion, a body portion, and a bottom portion. Yes, the mouth portion and the transition portion other than the support ring are crystallized.

The first method of the present invention for producing the heat-resistant biaxially stretch blow-molded bottle is as follows: (a) a mouth part having a support ring at the lower end, a transition part following the mouth part, and a body part. And a bottomed cylindrical parison having a bottom and
(b) The mouth and the transition part are heated and crystallized from the inside by a heater inserted inside the mouth, and (c) the mouth is heated from the outside while the support ring is held in a cooling mold. The outside of the mouth portion other than the support ring is crystallized, and (d) the parison is then biaxially stretch blow molded.

The second method of the present invention for producing the heat-resistant biaxially stretch blow-molded bottle is (a) a mouth portion having a support ring at the lower end, a transition portion continuing to the mouth portion, and a body portion,
Forming a cylindrical parison with a bottom and a bottom, (b) biaxially stretch blow molding the parison, (c) by a heater inserted inside the mouth of the resulting biaxially stretch blow molded bottle The mouth and the transition part are heated and crystallized from the inside,
(d) The mouth of the bottle is heated from the outside while the support ring of the bottle is held by a cooling mold to crystallize the outside of the mouth other than the support ring.

The third method of the present invention for producing the above heat-resistant biaxially stretch blow-molded bottle is (a) a mouth portion having a support ring at the lower end, a transition portion continuing to the mouth portion, and a body portion,
A bottomed cylindrical parison having a bottom portion is formed, and (b) the mouth portion and the transition portion are heated from the inside by a heater inserted inside the mouth portion, and the inside of the mouth portion and the transition portion are heated. And (c) subsequently biaxially stretch blow molding the parison, (d) holding the support ring of the obtained biaxially stretch blow molded bottle in a cooling mold, and opening the mouth of the bottle outside. It is characterized in that the outside of the mouth portion other than the support ring is crystallized by further heating.

[0011]

The present invention will be described in detail below. [A] Structure of Bottle Mouth Portion The heat-resistant biaxially stretch blow-molded bottle of the present invention is made of polyester resin, and as shown in FIG. Transition part 2
And a shoulder portion 3, a body portion 4, and a bottom portion 5. In the present specification, the transitional portion is a portion located slightly below the mouth portion 1 and is hardly stretched by the biaxial stretching blow, and is located between the mouth portion and the shoulder portion in a bottle state. Further, the “heat resistance” in the present specification includes both heat resistance and heat resistance / pressure resistance. Note that the shoulder portion 3, the body portion 4, and the bottom portion 5 of the bottle are not limited to the shape shown in FIG. 1, and may be appropriately changed to various shapes found in conventional plastic bottles. Further, it goes without saying that the sealing form of the mouth portion 1 can be appropriately selected from shapes other than screws.

As shown in FIGS. 1 and 2, the polyester resin in the mouth portion 1 other than the support ring 11 is a crystallized layer.
It has 12a and has excellent heat resistance. The polyester resin 12b in the support ring 11 is not crystallized,
It is in an amorphous state. As described above, since the polyester resin in the support ring 11 is not crystallized, it is not deformed by its own weight during heating during the crystallization process and has good impact resistance.

The transition portion 2 has a first crystallized region 2a immediately below the support ring 11 and a second crystallized region 2b below the first crystallized region 2a. The first crystallized region 2a is crystallized uniformly on the inside and the outside, but the second crystallized region 2b gradually decreases from the outer side toward the shoulder portion 3.

The first crystallized region 2a and the second crystallized region
In the transition section 2 having 2b, even when the high temperature contents are filled, the inside of the transition section in contact with the contents is crystallized, so that the heat resistance is excellent and deformation or the like does not occur. Also,
When the transition portion 2 is crystallized as described above at the parison stage, the non-crystallized portion outside the second crystallized region 2b may be stretched / formed into an arbitrary shape during the subsequent blow molding. it can. At this time, if the thickness of the transition portion and the thickness of the shoulder portion are gently changed, excellent physical properties and a beautiful appearance can be obtained.

Therefore, in the transitional portion 2 as shown in FIG. 2, there is more freedom in shape as compared with the case where the entire transitional portion is crystallized, and when the transitional portion once crystallized is forcibly formed. It is possible to prevent the resulting deformation, cracking, or a step difference in wall thickness that is likely to occur between the crystallized transition portion and the uncrystallized portion below the transition portion.

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

[B] Method for Manufacturing Bottle [0110] The mouth 1 other than the support ring 11 is crystallized by heat treatment. The heat crystallization treatment is performed by the following three methods,
That is, (1) heat crystallization treatment at the parison stage, (2) heat crystallization treatment after blow molding, and (3) heat crystallization only at the inner side at the parison stage, and then the outer side after blow molding. There is a method of heat crystallization treatment.
Hereinafter, each method will be described.

(1) Heat crystallization treatment is performed at the parison stage.
To a method will be described first parison production. As shown in Fig. 3 (a), the mouth part mold 71 and the injection cavity mold
A parison is manufactured by an ordinary injection molding method using an injection molding die 7 composed of 72 and an injection core mold 73.

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

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

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

Next, the mouth die 71 is removed from the parison 6, and the support ring 11 is held by the support ring die 21 as shown in FIG. In this state, the mouth portion 1 is heated from the outside by the ring heater 10, but other hot air heaters, infrared heaters or the like may be used. The heating temperature is 100 as above.
It may be about 190 ° C. Further, the heating time may be a time sufficient for crystallization of the uncrystallized polyester resin in the outer layer of the mouth, but specifically, it is preferably 0.5 to 3 minutes. At this time, the support ring mold 21 is preferably cooled to a temperature lower than the crystallization temperature of the polyester resin. Specifically, the cooling temperature of the support ring 11 is preferably 10 to 40 ° C.

By heating the mouth portion 1 by such a method, the polyester resin in the support ring 11 remains amorphous, and the other mouth portion 1 is crystallized, and the transition portion 2 has the first crystallization region. 2a and the second crystallized region 2b are formed. In the method of the present invention, the heat treatment is performed without inserting a supporting means such as a jig into the inside of the mouth 1. However, since the inner portion of the mouth 1 is crystallized, the heating crystallization temperature is also good. It retains heat resistance, so that the mouth portion 1 is hardly deformed.

When the support ring 11 is softened by heating, it is easily deformed by its own weight. However, since the support ring 11 is held by the support ring mold 21, the support ring 11 can be prevented from being deformed. Since the support ring 11 that remains amorphous has good impact resistance, it does not break even when it receives an impact.

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

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

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

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

Next, the mouth mold is released from the bottle, and the support ring of the bottle is gripped by the support ring mold. In this state, the mouth is heated from the outside to crystallize the uncrystallized polyester resin in the outer layer of the mouth. Heat crystallization conditions are (1)
The method may be the same as that of.

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

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

After the biaxial stretch blow molding is performed using the parison, the support ring of the bottle is held by the support ring type. In this state, the mouth is heated from the outside to crystallize the uncrystallized polyester resin in the outer layer of the mouth. The heat crystallization conditions may be the same as in the method (1).

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

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

In the polyester resin used in the present invention, stabilizers, pigments, and
Additives such as antioxidants, heat deterioration preventing agents, ultraviolet deterioration preventing agents, antistatic agents, antibacterial agents, and other resins can be added in appropriate amounts.

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

The present invention will be described in more detail with reference to the following specific examples. Example 1 Polyester terephthalate (NEH-2050 manufactured by Unitika Ltd.) was used as a polyester resin, and a parison having a mouth shape shown in FIG. 6 was molded by injection molding.
Dimensions A to H of each part of the obtained parison (A: screw thread diameter, B: screw root diameter, C: mouth inner diameter (maximum), D: mouth inner diameter (minimum), E: tightening ring diameter, F: Lower diameter of winding tightening ring,
G: support ring diameter, H: support ring height) were measured.

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

Next, while holding the support ring with a support ring type cooled at 20 ° C., the opening of the parison was heated from the outside by a ring heater at 150 ° C. for 1 minute to uncrystallize the outer layer of the opening. The polyester resin was crystallized.

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

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

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

Next, while holding the support ring with a support ring type cooled at 20 ° C., the mouth of the bottle is heated from the outside by a ring heater at 150 ° C. for 1 minute to uncrystallize the outer layer of the mouth. The polyester resin was crystallized.

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

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

The above parison was biaxially stretch blow-molded by a usual method, and while the support ring of the obtained bottle was being held by a support ring type cooled at 20 ° C., the mouth of the bottle was opened from the outside by a ring heater. The uncrystallized polyester resin in the outer layer of the mouth was crystallized by heating at 150 ° C. for 1 minute.

The dimensions A to H of the respective parts of the obtained bottle were measured, and the shrinkage ratio due to the heat crystallization was calculated. I found it wasn't.

Comparative Example 1 Using the same raw material as in Example 1, a parison having the mouth shape shown in FIG. 6 was molded, and the dimensions A to H of each part were measured. Then, the mouth of the parison was heated from the outside by a ring heater at 150 ° C. for 2 minutes for crystallization.

The dimensions A to H of the respective parts of the obtained parison were measured, and the shrinkage rate due to heat crystallization was calculated. The results are shown in Fig. 7. As is clear from FIG. 7, deformation was observed in the mouth of the parison, and in particular, the amount of deformation of the mouth inner diameter and the height of the support ring was large.

[0050]

As described above, according to the present invention,
Before and / or after biaxial stretch blow molding, the mouth and transition are heated from the inside, and then the mouth is heated from the outside while the support ring is held by the cooling mold. A bottle with good dimensional accuracy can be obtained with substantially no deformation due to heat crystallization. Also, since the support ring is not crystallized, the impact resistance of that portion is good, and it will not be damaged even if an impact is applied during handling or filling of the bottle.

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

[Brief description of drawings]

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

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

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

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

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Mouth part 11 ... Support ring 12a ... Crystallized polyester resin 12b ... Uncrystallized polyester resin 2 ... Transition part 2a ... 1st crystallization area 2b ... 2nd Crystallization region 3 ... Shoulder part 4 ... Body part 5 ... Bottom part 6 ... Parison 7 ... Injection mold 71 ... Mouth mold 72 ... Injection cavity mold 73 ... Injection core type 8 ... Cooling type 9 ... Rod heater 10 ... Ring heater 21 ... Support ring type

Claims (5)

[Claims] 1. A mouth portion having a support ring at a lower end,
A heat-resistant biaxially stretch blow-molded bottle having a transition part following the mouth part, a shoulder part, a body part, and a bottom part, wherein the mouth part and the transition part other than the support ring are crystallized. A heat resistant biaxially stretch blow molded bottle characterized by: 2. The heat resistant biaxially stretch blow molded bottle according to claim 1, wherein the transition portion has a uniform crystallization region immediately below the support ring, and the crystallization region faces the shoulder portion. Heat-resistant biaxially stretch blow-molded bottle characterized by gradually decreasing from the outside. 3. The method for producing a heat-resistant biaxially stretch blow-molded bottle according to claim 1, wherein (a) a mouth portion having a support ring at a lower end, and a transition portion continuing to the mouth portion,
Forming a cylindrical parison with a bottom having a body and a bottom, (b) heating and crystallizing the mouth and the transition from the inside by a heater inserted inside the mouth, (c) the support It is characterized in that the mouth is heated from the outside in a state where the ring is held in a cooling mold to crystallize the outside of the mouth other than the support ring, and (d) subsequently, the parison is biaxially stretch blow molded. Method. 4. The method for producing a heat-resistant biaxially stretch blow-molded bottle according to claim 1 or 2, wherein (a) a mouth portion having a support ring at a lower end thereof, and a transition portion continuing to the mouth portion,
Forming a bottomed cylindrical parison having a body portion and a bottom portion, (b) biaxially stretch blow molding the parison, and (c) inserting inside the mouth portion of the obtained biaxially stretch blow molded bottle. The mouth part and the transition part are heated and crystallized from the inside by the heater, (d) the mouth part is heated from the outside while the support ring of the bottle is held in a cooling mold, and the mouth part other than the support ring is heated. A method characterized by crystallizing the outside. 5. The method for producing a heat-resistant biaxially stretch blow-molded bottle according to claim 1 or 2, wherein (a) a mouth portion having a support ring at a lower end thereof, and a transition portion continuing to the mouth portion,
Forming a bottomed cylindrical parison having a body and a bottom, and (b) heating the mouth and the transition from the inside by a heater inserted inside the mouth, the inside of the mouth And crystallizing the transition part, (c) subsequently biaxially stretch blow molding the parison, (d) in a state where the support ring of the obtained biaxially stretch blow molded bottle is held in a cooling mold,
A method of heating the mouth of the bottle from the outside to crystallize the outside of the mouth other than the support ring.