JPH02269638A - Heat-resistant plastic bottle - Google Patents

Abstract

PURPOSE:To enhance the manufacturing efficiency and heat-resistance by utilizing a polyester resin of naphthalenedicarboxylic acid/ethylene glycol for an opening of a bottle. CONSTITUTION:Polyester resin of naphthalenedicarboxylic acid/ethylene glycor is used for the opening, or the bottom if required, of a plastic bottle mainly made of only polyethylene terephthalate resin. Polyethylene terephtharate resin which is a chief material of the bottle, can be applied by a resin wherein a unit of terephthalic acid for instance is converted to into isophthalic acid unit. In this way, a manufacturing efficiency and heat resistant property can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat-resistant plastic bottle suitable for use as a container for contents that require heat sterilization during filling, such as fruit juice drinks.

More specifically, the present invention relates to a heat-resistant plastic bottle that has reinforced parts that require heat resistance, such as a spout, and particularly relates to a heat-resistant plastic bottle that is useful as a bottle container for fruit juice drinks and carbonated drinks.

[Prior art] Biaxially stretched blow bottles made of polyethylene terephthalate have excellent properties such as hygienic properties, aroma retention, pressure resistance, and lightness, so they are used for carbonated beverages, draft beer, seasonings, and cosmetics. It is used extremely widely.

However, the glass transition temperature of polyethylene terephthalate resin is around 70°C, and the distortion caused by blow molding remains, so the heat resistance of polyethylene terephthalate resin is low, and if it is used at temperatures above 65°C, it cannot be used during heat sterilization. Alternatively, a defective product may be produced in which the plug portion is deformed during blow molding, making it impossible to seal with the plug.

To solve this problem, it is widely practiced to mold the bottle body while heat-treating it at high temperatures, and increase the degree of crystallinity of the spout to increase the heat resistance of this part.

Another method is to improve the heat resistance of the spout by attaching a heat-resistant ring to the spout and performing biaxial stretch blow molding (Japanese Unexamined Patent Publication No. 63-41) )and so on.

On the other hand, since the stretching ratio of the bottom of the bottle is low, it cannot be strengthened by crystallization treatment through biaxial stretching like the body of the bottle, so heat resistance and pressure resistance can be improved by creating a rib structure or increasing the wall thickness. method is being done.

[Problems to be Solved by the Invention] However, although the crystallization treatment of the spout certainly improves the heat resistance under normal pressure, it is difficult to maintain the dimensional accuracy of the spout of the bottle. It becomes difficult to fit the plug or to hold the spout during blow molding.

In addition, crystallization treatment that is maintained at high temperatures for a long time requires a long molding cycle and has low productivity, and also has the disadvantage that it is weak in heat treatment under pressure such as in the case of carbonated beverage bottles in terms of physical properties.

On the other hand, the method of applying a heat-resistant ring to the spout and performing biaxial stretch blow molding requires a complicated operation of pre-forming the heat-resistant ring and inserting it into the mold, and the molding cycle is also complicated. It also has the disadvantage that the ring body is longer and the adhesion between the ring body and the main body is not good.

An object of the present invention is to provide a container with good manufacturing efficiency and excellent heat resistance.

Another object of the present invention is to provide a lightweight bottle in which the heat resistance of the bottom part, which has a low draw ratio, is improved by a simple structure without a rib structure, if desired.

[Means to Solve the Problem] In order to improve the heat resistance of the spout under such circumstances, the inventors of the present invention have conducted intensive research and have determined that the main materials used in the pre-blow molding stage of the bottle are as follows: We manufactured a preform for blow molding by injecting resin with excellent heat resistance that is compatible with the resin only in the necessary areas, and used this to manufacture bottles by blow molding and improve the heat resistance of mouthpieces etc. Successful.

That is, the present invention provides a heat-resistant plastic bottle mainly made of polyethylene terephthalate resin, characterized in that a 7-thalene dicarboxylic acid/ethylene glycol-based polyester resin is used in the mouth and optionally the bottom of the bottle. A plastic version is provided.

The polyethylene terephthalate resin, which is the main material of the bottle of the present invention, is not particularly limited, and has a structure in which a part of the constituent units of the homopolymer of polyethylene terephthalate and a polyethylene terephthalate polymer structure are replaced, for example, a part of the terephthalic acid unit is replaced with isophthalate. Polyethylene terephthalate resins such as those substituted with acid units can be used as appropriate.

The naphthalene dicarboxylic acid/ethylene glycol-based polyester resin used in the present invention is a polyester resin whose constitutional units are mainly naphthalene dicarboxylic acid units and ethylene glycol units, and at least 70 mol% of the acid component of the constitutional units is naphthalene. Dicarboxylic acids such as terephthalic acid, 7-thalic acid, isophthalic acid, hexahydrophthalic acid, naphthalene dicarboxylic acid, succinic acid, adipic acid, sebacic acid, etc. are preferably used as dicarboxylic acids, and in an amount of less than 30 mol% of the total acid components. Acids, polyhydric carboxylic acids such as trimellitic acid, pyromellitic acid, etc. can be used as the acid component.

In addition, the alcohol component of the structural unit of the polyethylene terephthalate resin is at least 70 mol%.
is preferably ethylene glycol, and in a range of less than 30 mol% of the total alcohol component, cyclohexane dimetatool, 1.2-7" lobanediol, 113-propanediol, 1,4-butanediol, 1,6 - It is also possible to use glycols such as hexanediol, neopentyl glycol, diethylene glycol, polyhydric alcohols such as trimethylolpropane, trimethylolpropane, pentaerythritol.

As the naphthalene dicarboxylic acid, 2.6-naphthalene dicarboxylic acid is usually used, but 2.7 monomer, 1.5
The monomer, 1.4-isomer and mixtures of these isomers can also be used.

In the present invention, a polyester resin based on 7-thalene dicarboxylic acid/engineered ethylene glycol and other polyester resins can be blended and used as an injection material for reinforced parts such as spout parts.

Although the mixing ratio in this case is arbitrarily selected, the naphthalene dicarboxylic acid content of the entire acid component must be 50 mol % or more, preferably 70 mol % or more.

Such polyester resins can be manufactured by various known methods used for polyethylene terephthalate.

For example, an esterification reaction is performed using naphthalene dicarboxylic acid and ethylene glycol, or a transesterification reaction is performed using an ester of naphthalene dicarboxylic acid, such as naphthalene dicarboxylic acid dimethyl ester, and ethylene glycol, and then the resulting reaction product is It can be produced by further polycondensation.

The intrinsic viscosity of the polyester resin used in the bottle of the present invention [value measured at 30'0 using a mixed solvent of phenol 10-dichlorobenzene (weight ratio 60/40)] is 0.4 to 1.
．． 5, preferably from the range of 0.55 to 1.0.

In the polycondensation reaction of polyester of the present invention, an esterification catalyst, a transesterification catalyst, a polycondensation catalyst, a stabilizer, etc. can be used.

As the transesterification catalyst, one or more known compounds such as calcium, manganese, zinc and sodium, and lithium compounds can be used, but manganese compounds are particularly preferred from the viewpoint of transparency.

Although any known transesterification catalyst can be used, the reaction can proceed without using one.

As the polymerization catalyst, known titanium, tin, antimony,
One or more of germanium and cobalt compounds can be used, but preferably titanium compounds can be used.

In addition, these polyester resins used in the bottles of the present invention may be added with known additives, such as short fiber glass fibers, antioxidants, ultraviolet absorbers, optical brighteners, mold release agents, antistatic agents, Colorants such as dispersants and dyes and pigments may be added at any stage during polyester production, or may be added in a so-called masterbatch formulation before molding.

The method for molding a heat-resistant plastic bottle according to the present invention includes:
Two types of resins are plasticized separately using two injection molding machines, and reinforcing resins containing polyethylene terephthalate resin and 7-tale dicarboxylic acid/ethylene glycol-based polyester resin are placed in the same mold cavity. Two types of resins are used as injection materials, and the parts are sequentially injected, and the mouth part or the bottom part, if desired, is made of 7thalene dicarboxylic acid/ethylene glycol-based polyester* fat, and the other part is made of polyethylene terephthalate resin. The preform can be molded and biaxially stretch blow molded to make bottles from it.

In the present invention, it is preferable that the entire spout is made of naphthalene dicarboxylic acid/ethylene glycol-based polyester resin; The heat-resistant effect of the present invention is also achieved when mixed with other materials to form various forms of multi-layered structures, and bottles having such multi-layered spouts are also suitably used as heat-resistant plastic bottles of the present invention. be able to.

In this case, since the flow of the resin within the cavity is complicated, the structure often does not have a simple two-layer or three-layer structure, but four or more layers.

In addition, in the case of such a mixed layer, it is effective as an embodiment of the present invention that the inner core in the spout part is made of 7tale dicarboxylic acid/ethylene glycol based polyester resin and the outer part is made of pure polyethylene terephthalate resin.

Furthermore, if naphthalene dicarboxylic acid/ethylene glycol-based polyester resin is used for the bottle bottom, not only will the heat resistance of the bottle bottom be improved, but it will also prevent retention in the hot runner during injection molding. The material for the next shot can be a naphthalene dicarboxylic acid/ethylene glycol polyester resin, so the ratio of naphthalene dicarboxylic acid/ethylene glycol polyester resin at the spout can be adjusted without mixing the polyethylene terephthalate resin. can be increased.

[Examples] The present invention will be explained in more detail by Examples below.
The present invention is not limited to the following examples.

Example 1 Multilayer biaxial stretching blowing machine A S manufactured by Nissin NSP Co., Ltd.
B50TH was used, and the main cylinder was made of polyethylene terephthalate resin [RT543C (trade name) manufactured by Nippon Unipet Co., Ltd.] with an intrinsic viscosity of 0.75, and the secondary cylinder was made of polyethylene terephthalate resin with an acid component of 2,6-naphthalene dicarboxylic acid. Yes, the glycol component is ethylene glycol, and the naphthalene dicarboxylic acid/ethylene glycol type polyester resin is used for the spout and bottom, and the other parts are A test-tube-shaped preform with a uniform thickness of the plate part made of polyethylene terephthalate resin was molded, and then biaxial stretch blow molding was performed in a blow mold at a temperature of 105°C using the same machine. A bottle with a structure without ribs on the bottom, shaped like a cider bottle, and weighing 6
09, a heat-resistant layer with an internal capacity of 1.5Q was obtained.

The resulting heat-resistant layer is heated to 85°C, which is comparable to filling heat sterilization treatment.
After filling 1.5 sections with hot water and applying an aluminum cap using a capping machine, the bottle was turned over and left to cool, and the fitting condition of the cap was examined and found that there was no deformation of the spout or bottom. No leakage of contents was observed.

Comparative Example 1 Example 1 using the same molding machine as Example 1 with only the main cylinder
A bottle made entirely of the same polyethylene terephthalate resin was molded and evaluated.

The resulting bottle had a deformed spout and bottom, and leakage of the contents was observed.

Comparative Example 2 Polycarbonate resin [manufactured by Mitsubishi Kasei Corporation: Novarenx 7025A] was used instead of the naphthalene dicarboxylic acid/ethylene glycol-based polyester resin of the secondary cylinder.
Weight 609, contents! Same as Example 1 except that product name) was used. A heat-resistant layer of 1.511 was obtained.

The obtained heat-resistant layer was evaluated in the same manner as in Example 1, but it was found that the adhesion between the polyethylene terephthalate resin and the polycarbonate resin was poor at the spout, and peeling was observed when the cap was tightened.

[Effects of the Invention] According to the present invention, a plastic bottle with excellent heat resistance can be obtained, so that it can be used, for example, as a bottle for juice that requires high-temperature sterilization or a bottle for carbonated drinks that is subject to pressure. In addition to being sufficiently heat resistant, it has the advantages of a simple manufacturing method, a short container molding cycle, and very high manufacturing efficiency, so it can be widely used and useful in this field of containers.

Claims (1)

[Scope of Claims] 1. A heat-resistant plastic bottle mainly made of polyethylene terephthalate resin, characterized in that a naphthalene dicarboxylic acid/ethylene glycol-based polyester resin is used for the spout of the bottle. 2. A heat-resistant plastic bottle mainly made of polyethylene terephthalate resin, characterized in that naphthalene dicarboxylic acid/ethylene glycol-based polyester resin is used in the mouth and bottom of the bottle.