JP3449634B2 - Heat-resistant biaxially stretch blow-molded bottle and method for producing the same - Google Patents

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 stretched blow-molded bottle having a crystallized (whitened) mouth portion and transition portion, and a method for producing the same, particularly because the inside of the mouth portion and the transition portion are crystallized. Relates to a heat-resistant biaxially stretch blow-molded bottle having excellent heat resistance and good dimensional accuracy, 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 carbon dioxide-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 can be imparted by stretching or heat setting. Therefore, it cannot be used for filling liquid at 80 to 95 ° C.

Therefore, various methods have been attempted for producing a biaxially stretch blow molded bottle from a parison having a multi-layered structure including a heat resistant resin and a polyester resin in the mouth. However, even in that method, when pasteurizing with a hot shower at 65 to 80 ° C. for a long time on a beverage bottle containing carbon dioxide gas or the like, the amount of deformation is large especially at the transition portion of low stretching due to heat and internal pressure. Further, it is difficult to obtain heat resistance capable of continuous use under severe hot fill conditions of 90 ° C or higher.

Further, a method of crystallizing the polyester to improve the heat resistance by subjecting the mouth of the bottle to a heat treatment after the parison stage or after the biaxial stretch blow molding has been carried out. However, in this method, with the crystallization of the polyester when subjected to heat treatment,
There is a problem that the size of the mouth portion is likely to change, and contraction is likely to occur especially 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.

[0007]

As a result of earnest research in view of the above object, the present inventor produced a parison having a multilayer structure in the mouth by co-injecting a polyester resin and a heat-resistant resin. After biaxially stretch blow molding the stage or parison, while gripping the mouth with a cooled mouth mold,
If the mouth and transition are heated from the inside, the polyester layer inside the mouth and transition will crystallize without substantial deformation, and biaxial stretch blow molding with sufficient heat resistance to hot fill and hot shower. The inventors have found that a bottle can be obtained, and have conceived 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, The mouth portion has a multilayer structure composed of a polyester layer and a heat resistant resin layer, the polyester layer inside the mouth portion is crystallized, and the support of the transition portion is formed.
Uniform crystallization of the polyester layer just below the Ottling
Forming a region, the crystallized region facing the shoulder.
It is characterized by gradually decreasing from the outside .

The first method of the present invention for producing the heat-resistant biaxially stretch blow-molded bottle is (a) having a multilayer structure consisting of a polyester layer and a heat-resistant resin layer, and having a support ring at the lower end. A mouth portion, a transition portion that follows the mouth portion,
A body and a bottomed cylindrical parison having a bottom are formed, and (b) while gripping the mouth with a cooled mouth die, the mouth and the heater are inserted inside the mouth. The transition part is heated from the inside to crystallize the polyester layer inside the mouth part and the transition part, and (c) subsequently, the parison is biaxially stretch blow molded.

The second method of the present invention for producing the heat-resistant biaxially stretch blow-molded bottle is as follows: (a) A mouth part having a multilayer structure consisting of a polyester layer and a heat-resistant resin layer and having a support ring at the lower end. And forming a bottomed cylindrical parison having a transition part following the mouth part, a body part, and a bottom part,
(b) biaxially stretch blow molding the parison, (c) while holding the mouth of the obtained biaxially stretch blow molded bottle by a cooled mouth die, by a heater inserted inside the mouth, The mouth portion and the transition portion are heated from the inside to crystallize the polyester layer inside the mouth portion and the transition portion.

[0011]

The present invention will be described in detail below. [A] Structure of Bottle Portion The heat-resistant biaxially stretch blow-molded bottle of the present invention has a mouth portion 1 having a support ring 11 at the lower end, as illustrated in FIG.
And a transition portion 2 following the mouth portion 1, a shoulder portion 3, a body portion 4, and a bottom portion 5. In the present specification, the transition portion is the mouth portion 1
It is located slightly below and is hardly stretched by biaxial stretching blow, and is located between the mouth and the shoulder in the bottle state. Further, the “heat resistance” in the present specification includes both heat resistance and heat resistance / pressure resistance. In addition, the shoulder portion 3, the body portion 4 and the bottom portion 5 of the bottle
1 is 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.

The mouth portion 1 comprises a screw portion 12 and a support ring 11. The mouth portion 1 having such a shape has a heat-resistant resin layer 13
And a polyester layer 14 are alternately formed. In the example shown in FIG. 2, the heat resistant resin layer 13 has three layers (13a-
13c), and the outermost heat-resistant resin layer 13a may be continuous to the upper surface of the support ring 11. On the other hand, the polyester layers 14a and 14b are present between the heat resistant resin layers 13a to 13c. The heat resistant resin layer 13 is not limited to three layers,
It can have any number of layers.

The thickness of the heat-resistant resin layers 13a to 13c is not particularly limited, but the proportion of the heat-resistant resin layer 13 increases toward the opening end, and the entire opening end portion is made of the heat-resistant resin. It is preferable that

As shown in FIGS. 1 and 2, the polyester layer 14 inside the mouth portion 1 is a crystallization layer 14a and has excellent heat resistance. The polyester portion 14b outside the mouth portion 1 including the support ring 11 is not crystallized and 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. Since the thread and the thread trough located outside the mouth 1 are not deformed by heating, the dimensional accuracy is good.

Further, the transition portion 2 has a uniform crystallization region 2a directly below the support ring 11 and a tilted crystallization region 2b below the uniform crystallization region 2a. The uniform crystallized region 2a is crystallized uniformly on the inside and the outside, but the inclined crystallized region 2b gradually decreases from the outside toward the shoulder portion 3.

The uniform crystallization region 2a and the inclined crystallization 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 in the parison stage as described above, the non-crystallized portion outside the tilted crystallized region 2b can be stretched / formed into any shape during the subsequent blow molding. . 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] Bottle Manufacturing Method The crystallization of the mouth portion 1 other than the support ring 11 is performed by heat treatment. The heat crystallization treatment includes the following two methods.
That is, there are (1) a method of performing heat crystallization treatment at the parison stage, and (2) a method of performing heat crystallization treatment after blow molding. Hereinafter, each method will be described.

(1) Heat crystallization treatment is performed at the parison stage.
Method First, the production of a parison will be described. As shown in Fig. 3 (a), the mouth part mold 71 and the injection cavity mold
The parison is manufactured using the injection molding die 7 including the 72 and the injection core die 73. The mouth portion 1 of the parison 6 in the present invention has a multi-layer structure composed of the heat-resistant resin layer 13 and the polyester resin layer 14, and therefore is disclosed in, for example, Japanese Patent Laid-Open No.
By the co-injection method of a polyester resin and a heat-resistant resin shown in No. 294025, it is possible to manufacture a parison having the above-mentioned multilayer structure, but in addition, a heat-resistant resin from the mouth side, from the bottom side It can also be manufactured by a so-called two-gate co-injection molding method or the like in which each polyester resin is injected.

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 layer 14 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.

By heating the mouth portion 1 by such a method, the outside of the mouth portion 1 and the polyester layer 14 in the support ring 11 remain amorphous, and the inside of the other mouth portion 1 is crystallized, A uniform crystallization region 2a and a tilted crystallization region 2b are formed in the transition section 2.

When the support ring 11 is softened by heating, it is easily deformed by its own weight, but it can be prevented from being deformed because it is held by the cooled mouth die 71. Since this support ring 11 that remains amorphous retains good impact resistance,
It will not be damaged even when it is shocked. Also, mouth 1
The threads and valleys located on the outside of the can be prevented from being deformed because it is gripped by the similarly cooled mouth die 71,
Good dimensional accuracy can be maintained.

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-step 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, the biaxial stretch blow molding is performed in the same manner as described above to mold the bottle, and then the mouth heat crystallization treatment is performed.

After the biaxially stretch blow molding, the bottle is taken out from 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). Crystallize the polyester layer in parts. The heat crystallization conditions may be the same as in the method (1).

[C] Material The polyester layer 14 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, and 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 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.

As the heat resistant resin, polycarbonate, polyarylate, polyethylene naphthalate, polyacetal, polysulfone, polyether ether ketone, polyether sulfone, polyether imide, polyphenylene sulfide and blends of these resins with polyethylene terephthalate. Polymers, blend polymers between the above heat resistant resins, further blend polymers of two or more resins of the above heat resistant resins with polyethylene terephthalate, U polymers (manufactured by Unitika, blend polymers of polyarylate and polyethylene terephthalate), etc. Can be used. Among these, especially polycarbonate, polyarylate, and U
Polymers (blended polymers of polyarylate and polyethylene terephthalate) are preferred.

In the polyester resin and heat-resistant resin used in the present invention, stabilizers, pigments, antioxidants, heat deterioration inhibitors, ultraviolet light deterioration preventives, antistatic agents are included within a range not impairing the object of the present invention. An appropriate amount of additives such as antibacterial agents and other resins can be added.

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

The present invention will be described in more detail with reference to the following specific examples. Example 1 Polycarbonate as a heat-resistant resin (Mitsubishi Kasei Co., Ltd.)
Manufactured by NOVAREX 7022A) and co-injection molding with polyethylene terephthalate (NEH-2050 manufactured by Unitika Ltd.) to form a parison having a multilayer structure shown in FIG. 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: winding clamp ring lower diameter, 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 part of the parison were heated from the inside at 150 ° C. for 1 minute to crystallize the polyester layer in that part.

After crystallization by heating, the dimension A of each part of the parison was measured.
.About.H was measured, and the shrinkage rate due to heat crystallization was calculated. Results are shown in FIG. As is clear from the graph of FIG. 6, 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 a multilayer structure shown in FIG. 5 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 part of the bottle were heated from the inside at 150 ° C. for 1 minute to crystallize the polyester layer in that part.

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. As a result, the mouth of the biaxially stretch blow-molded bottle showed almost no deformation due to the heat crystallization. I understood.

[0041]

As described above, according to the present invention,
Before or after biaxial stretch blow molding, the mouth and transition part are cooled from the outside and heat crystallized from the inside, so there is virtually no deformation due to heat crystallization at the mouth of the bottle, and dimensional accuracy A good bottle of can be obtained. 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 stretched 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 sectional view showing the mouth of the parison obtained in the example.

FIG. 6 is a graph showing the contraction rate in each part of the mouth of the parison obtained in Example 1.

[Explanation of symbols]

1 ... mouth 11 ・ ・ ・ Support ring 12 ... screw part 13-Heat resistant resin layer 14 ... Polyester layer 14a ... Crystallized polyester layer 14b ... Uncrystallized polyester layer 2 ... Transition area 2a: Uniform crystallization area 2b ... gradient crystallization region 3 ... Shoulder 4 torso 5 ... bottom 6 ... Parison 7 ... Injection mold 71 ・ ・ ・ Mouth type 72 ... Injection cavity type 73 ... Injection core type 8 ... Cooling type 9 ... Rod heater

Claims (3)

(57) [Claims] 1. A mouth portion having a support ring at a lower end,
A heat-resistant biaxially stretched blow-molded bottle having a transition part following the mouth part, a shoulder part, a body part, and a bottom part, and the mouth part having a multilayer structure consisting of a polyester layer and a heat-resistant resin layer. The polyester layer inside the mouth is crystallized and should be placed just below the support ring at the transition.
The polyester layer that forms a uniform crystallization area
The crystallization area gradually decreases from the outside toward the shoulder.
A heat resistant biaxially stretch blow molded bottle characterized by being 2. The method for producing a heat-resistant biaxially stretch blow-molded bottle according to claim 1, wherein the heat-resistant biaxially stretched blow-molded bottle has a multilayer structure comprising (a) a polyester layer and a heat-resistant resin layer, and a support ring at the lower end. Forming a bottomed cylindrical parison having a mouth, a transition section following the mouth, a body, and a bottom,
(b) While gripping the mouth part with a cooled mouth part mold, the heater inserted inside the mouth part heats the mouth part and the transition part from the inside, and the inside of the mouth part and the transition part A method comprising crystallizing a polyester layer, and (c) subsequently biaxially stretch blow molding the parison. 3. The method for producing a heat-resistant biaxially stretch blow-molded bottle according to claim 1, wherein the heat-resistant biaxially stretched blow-molded bottle has a multilayer structure comprising (a) a polyester layer and a heat-resistant resin layer, and a support ring at the lower end. Forming a bottomed cylindrical parison having a mouth, a transition section following the mouth, a body, and a bottom,
(b) biaxially stretch blow molding the parison, (c) while holding the mouth of the obtained biaxially stretch blow molded bottle by a cooled mouth die, by a heater inserted inside the mouth, A method comprising heating the mouth portion and the transition portion from the inside to crystallize the polyester layer inside the mouth portion and the transition portion.