JPH1086212A - Stretchable blow bottle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a crystallization tendency constant and improve heat resistance and gas barrier properties after hot filling of the content by molding a stretchable blow bottle of a blend of ethylene terephthalate crystalline polyester and ethylenenaphthalate polyester. SOLUTION: Ethyleneterephthalate polyester based on an ethyleneterephthalate unit and crystalline polyester are used. A blend used for molding this stretchable blow bottle has the content of 0.5-25mol% of a naphthalene dicarboxylic acid component per total dibasic carboxylic acid component. The blend is heat-crystallized for the mouth part 2 at the density of 1.34g/cm<3> or more and orientation-crystallized for the body part 4 at the density of 1.35g/cm<3> or more, within the range of 1-6% of ester exchange rate E of 1-6% as shown by formula. In the formula, Hu is the amount of fusion heat(J/mol) of crystalline polyester; R is a gas constant of 8.314(J/(mol.K)); Tm is the melting point(K) of the blend; and Tmo is the melting point(K) of crystalline polyester.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretch blow bottle, and more particularly, to a stretch blow bottle formed from a specific blend of an ethylene terephthalate-based polyester and an ethylene naphthalate-based polyester, and having excellent heat resistance,
The present invention relates to a stretch blow bottle having both thermal crystallization performance and gas barrier properties.

[0002]

2. Description of the Related Art Stretch blow bottles made of thermoplastic polyester are excellent in transparency, impact resistance, flavor retention and the like, and are widely used as packaging containers for various beverages and seasonings. In addition, polyethylene-2,6-naphthalate has excellent gas barrier properties, heat resistance, transparency,
As a material with excellent strength, it has also attracted attention in the field of packaging.

It has already been proposed to produce a hollow container from polyethylene-2,6-naphthalate, and JP-A-52-45466 discloses a method for producing a hollow container having a limiting viscosity of 0.1.
In a hollow container made of four or more aromatic polyesters, the material is polyethylene-2,6-naphthalate, and the body and / or bottom of the container has the formula N = n · λ / d. In the formula, n: the number of interference fringes due to birefringence observed with a polarizing microscope, λ: the wavelength of the light source used for the measurement of n, d: the thickness of the sample used for the measurement, and the N value defined by A hollow container characterized by being 0.01 or more is described.

Japanese Patent Application Laid-Open No. Hei 2-233341 discloses that the X-ray interference intensity distribution curve at a plurality of locations on the periphery of the center portion of the bottle body is made of polyethylene naphthalate resin with a probability of at least 80% or more. A stretched bottle made of a polyethylene naphthalate resin is described in which a maximum value is observed in both ranges of the angle 0 ° ± 20 ′ and the β angle 90 ° ± 20 ′.

It is already known to manufacture containers by combining an ethylene naphthalate-based polyester with another polyester, for example, an ethylene terephthalate-based polyester. For example, JP-A-50-62286 discloses a polyalkylene terephthalate. A laminated polyester molded product obtained by laminating a molded product and a molded product made of a mixed polyester obtained by blending polyalkylene terephthalate and polyalkylene naphthalate is described.

Japanese Patent Application Laid-Open No. 50-74652 discloses that a film obtained from a blend of 53 to 99% by weight of polyethylene terephthalate and 1 to 45% by weight of polyethylene 2,6-naphthalate is heated under vacuum or air. A method for producing a polyester molded article characterized by molding is described.

Japanese Unexamined Patent Publication No. 4-239624 discloses that the material constituting the container wall is mainly composed of ethylene terephthalate units and ethylene naphthalene dicarboxylate units, and based on the total weight of both units, 99.8 ethylene terephthalate units. -90% by weight and 0.2-10% by weight of ethylene naphthalenedicarboxylate unit
A food packaging container having excellent ultraviolet blocking properties, characterized in that it is a copolymerized polyester or a mixed polyester.

Similarly, Japanese Patent Application Laid-Open No. 8-34910 discloses that polyethylene terephthalate-containing resins 90.0 to 9
9.5% by weight of polyethylene naphthalate-containing resin
A UV-shielding transparent hollow molded article characterized by containing 5 to 5.0% by weight.

Further, Japanese Patent Application Laid-Open No. 8-47979 discloses that
[A] 95 to 60 parts by weight of polyethylene terephthalate and [B] 40 to 5 parts by weight of polyethylene naphthalate (the total of [A] and [B] is 100 parts by weight). A refillable polyester biaxially stretched bottle having a size of 12 times or less and a body thickness of 600 to 900 μm is described.

[0010]

Although containers made of polyethylene naphthalate are certainly excellent in heat resistance and ultraviolet ray blocking properties, they still have difficulties in molding into bottles, and the walls of bottles are not fluorescent. However, there is also a problem that the material cost tends to be slightly opaque and the material cost is much higher than that of polyethylene terephthalate (PET).

[0011] The conventional proposal of using polyethylene terephthalate and polyethylene naphthalate in the form of a blend in the form of a blend has been to enjoy the advantages inherent in polyethylene terephthalate and the advantages inherent in polyethylene naphthalate, and While trying to curb the rise in costs, it turned out that the following difficulties still exist.

That is, a blend of polyethylene terephthalate and polyethylene naphthalate has a different tendency to crystallize. For example, in a preform manufacturing stage or a biaxial stretch blow molding stage, thermal crystallization causes whitening of the vessel wall. In some cases, or when it is significant, stretch blow molding may be difficult. On the other hand, in the case of a heat-resistant bottle, it is generally performed to heat-set the bottle after stretch blow molding,
Also in this case, the orientation crystallization is not sufficiently performed,
In some cases, a sufficient crystallization speed cannot be obtained.

Further, the heat resistance of the bottle to be formed may still be insufficient. For example, in order to impart heat resistance to the sealing mouth, the mouth is often thermally crystallized. However, it has also been found that the mouth portion made of the above-mentioned blend is thermally deformed during heating for thermal crystallization, so that there is a problem that desired dimensional accuracy cannot be obtained.

Further, a bottle comprising the above blend is
In some cases, the gas barrier properties against oxygen and the like are still insufficient, and it has been found that the gas barrier properties are considerably reduced particularly when the contents are hot-filled.

Therefore, an object of the present invention is to form a blend of polyethylene terephthalate and polyethylene naphthalate, which has a constant crystallization tendency similar to that of polyethylene terephthalate, has excellent heat resistance, and has a high heat resistance. It is an object of the present invention to provide a stretch blow bottle having excellent gas barrier properties after filling.

Another object of the present invention is to form a blend of polyethylene terephthalate and polyethylene naphthalate so that the thermal crystallization of the mouth is sufficiently performed with high dimensional accuracy and the body is oriented and crystallized. An object of the present invention is to provide a stretch-blow heat-fixed bottle that is sufficiently performed, has excellent heat resistance and heat pressure resistance, and also has excellent gas barrier properties after hot filling.

[0017]

According to the present invention, an ethylene terephthalate-based crystalline polyester (A) mainly containing ethylene terephthalate units and an ethylene naphthalate-based polyester (B) mainly containing ethylene naphthalate units are used. Is formed from a blend containing the naphthalenedicarboxylic acid component in a content of 0.5 to 25 mol% based on the total dibasic carboxylic acid component, and the following formula (1): E = 100 · [1-exp {(Hu / R) · (1 / Tm ₀ −1 / Tm)}] (1) where: Hu: heat of fusion of crystalline polyester mainly composed of ethylene terephthalate units (J / mol) R: gas constant 8.314 (J / (mol · K )) Tm: melting point of the blend (K) Tm _0: crystalline polyester composed mainly of ethylene terephthalate units melting point K), in defining esters exchange ratio (E) is stretched blow bottle, characterized in that in the range of 1 to 6% is provided.

According to the present invention, there is also provided a bottle formed by biaxial stretch blow molding of a thermoplastic polyester and having a body, a closed bottom, a shoulder, and a mouth, wherein ethylene terephthalate mainly composed of ethylene terephthalate units is used. The polyester-based polyester (A) and the ethylene-naphthalate-based crystalline polyester (B) mainly composed of ethylene-naphthalate units have a naphthalenedicarboxylic acid component content of 0.5 to 25 mol per total dibasic carboxylic acid component. %
The following formula (1) is formed from a blend containing: E = 100 · [1-exp {(Hu / R) · (1 / Tm ₀ −1 / Tm)}] (1) Hu: heat of fusion of crystalline polyester mainly composed of ethylene terephthalate units (J / mol) R: gas constant 8.314 (J / (mol · K)) Tm: melting point of blend (K) Tm ₀ : ethylene The transesterification rate (E) defined by the melting point (K) of the crystalline polyester mainly composed of terephthalate units is in the range of 1 to 6%, and the density of the mouth is 1.34 g / cm ³ or more. Heat crystallized and the body has a density of 1.35 g / cm
There is provided a stretch blow-molded heat-set bottle characterized in that the bottle is oriented and crystallized to have ³ or more.

The bottle according to the present invention has a nuclear magnetic resonance (N)
The transesterification rate (E ₂ ) measured by MR) is 5 to 70.
%.

The stretch blow bottle of the present invention comprises a blend of an ethylene terephthalate polyester (A) and an ethylene naphthalate polyester (B).
It is important that the above components are contained so that the content of the naphthalenedicarboxylic acid component per dibasic carboxylic acid component is 0.5 to 25 mol%.

When the content of the naphthalenedicarboxylic acid component falls below the above range, the gas barrier properties and heat resistance are not sufficiently improved as compared with the case where the naphthalenedicarboxylic acid component is within the range of the present invention. When the content of the naphthalenedicarboxylic acid component exceeds the above range, uniform stretch molding becomes difficult, and the blend does not show a clear melting point, and the heat resistance also decreases. For this reason, with a blend in which the naphthalenedicarboxylic acid component exceeds the above range, a blowout may occur during blow molding, and thermal crystallization or oriented crystallization cannot be performed satisfactorily.

In the present invention, the component (A) in the above-mentioned blend, that is, the transesterification rate (E) of the ethylene terephthalate-based crystalline polyester shown in the above formula (1) is 1 to 1.
It is characterized by being in the range of 6%.

The above formula (1) for determining the transesterification rate is as follows:
It is based on the commonly known Flory's formula, and there is a certain relationship between the degree of transesterification in the blend and the melting point drop of the crystalline polyester (A) mainly composed of ethylene terephthalate. Is required based on That is, when the melting point of the polyester (A) does not decrease at all, 1 / Tm _{0 on the} left side of the formula (1) is obtained.
The value of −1 / Tm is 0, and the transesterification rate E is zero%.
Becomes As the degree of melting point drop increases, 1 / Tm ₀ −
The value of 1 / Tm is negative and its absolute value becomes large, and the transesterification ratio E becomes a large value.

The fact that the ester exchange rate (E) is in the range of 1 to 6% means that a certain amount of ester is present between the ethylene terephthalate polyester (A) and the ethylene naphthalate polyester (B) in the blend. Although exchange has occurred, this shows that ethylene terephthalate-based blocks and ethylene naphthalate-based blocks remain in this blend.

According to the present invention, the above-mentioned transesterification rate is in the range of 1 to 6%. (1) The crystallization tendency is made to be constant, similar to that of polyethylene terephthalate,
(2) improving heat resistance, and (3) gas barrier properties,
It is particularly important for improving the gas barrier properties after hot filling.

When the transesterification rate is less than 1%, the inherent incompatibility of polyethylene terephthalate and polyethylene naphthalate appears, which tends to cause whitening.
Such preforms cannot be used for producing stretch blow bottles. Further, even if stretch blow can be performed by adjusting the production conditions of the preform, uniform stretch molding becomes difficult, and there is a tendency that transparency is reduced and impact resistance is reduced. Further, heat resistance is reduced due to distortion remaining in the container wall, and uniform molecular orientation cannot be performed, so that the gas barrier property, particularly the gas barrier property after hot filling is reduced.

On the other hand, when the transesterification rate exceeds 6%, the tendency of crystallization is reduced as compared with those in which the transesterification rate is within the range of the present invention. The degree of oriented crystallization that can be achieved is lower than that of the present invention. This tendency is also observed during thermal crystallization of the mouth. When the transesterification ratio exceeds 6%, the heat resistance of the molded product is insufficient, and the thermal deformation of the mouth of the preform or the bottle causes thermal deformation of the mouth. A fatal drawback is loss of precision. Further, when the bottle after the heat setting is hot-filled, the gas barrier property tends to be greatly reduced.

In contrast, according to the present invention, by maintaining the transesterification rate in the blend in the range of 1 to 6%, the crystallization tendency can be maintained in an appropriate range similar to that of polyethylene terephthalate, and the whitening In addition to the production of a preform free of the problem, a uniform stretch blow molding can be performed, and a bottle having excellent transparency and impact resistance can be produced. In addition, oriented crystallization of the body and thermal crystallization of the mouth sufficiently proceed, and a container having excellent heat resistance and heat pressure resistance is formed. Furthermore, even if hot filling is performed after heat setting, a surprising result that the gas barrier property of the vessel wall does not decrease is obtained.

The present invention is particularly useful as a heat-resistant or heat-resistant stretch-blow heat-set bottle, which is thermally crystallized so that the mouth has a density of 1.34 g / cm ³ or more.
In addition, there is a feature that the body is oriented and crystallized so that the density becomes 1.35 g / cm ³ or more. That is, when the density of the mouth portion is less than the above range, the sealing accuracy at the time of hot filling is deteriorated, and when the density of the body portion is less than the above range, the creep resistance and heat resistance are low, and the hot filling of the contents and Insufficient heat sterilization of contents having autogenous pressure, but in the bottle of the present invention, by performing thermal crystallization or oriented crystallization within the above range, the sealing accuracy at the time of hot filling. And the creep resistance and heat resistance can be improved.

The transesterification rate includes the transesterification (E) obtained from the above-mentioned formula (1) based on the heat of fusion and the following formula (3) obtained from the expanded magnetic resonance (NMR). Although the value itself is considerably different, the transesterification rate by NMR of the blend in the present invention is equivalent to 5 to 70%.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 (side view) showing an example of a biaxially stretched blow bottle of the present invention, this biaxially stretched polyester bottle 1 has an unstretched nozzle portion (mouth) 2, a frusto-conical shape. , A cylindrical body 4 and a closed bottom 5. Although not shown, the body 4 may have a well-known panel-rib structure for absorbing reduced-pressure deformation or a rib structure for reinforcement. Further, the bottom portion 5 may be formed with an upwardly-facing dome structure or a petaloid-shaped valley-foot structure known per se for providing self-standing stability.

The bottle 1 of the present invention comprises an ethylene terephthalate-based polyester (A) mainly composed of ethylene terephthalate units and an ethylene naphthalate-based polyester (B) mainly composed of ethylene naphthalate units, which are all dibasic carboxylic acids. The amount of the naphthalenedicarboxylic acid component per acid component is 0.5 to 25 mol%, particularly 5 to 15 mol%, and the transesterification amount (E) is in the range of 1 to 6%.

In the case of a heat-resistant bottle or a heat-resistant bottle, the mouth 2 has a density of 1.34 g / cm ³ or more, particularly 1.35 g / cm ³ or more.
It is thermally crystallized to 1.45 g / cm ³ , and the body 4 has a density of 1.35 g / cm ³ or more, especially 1.36 to
It is preferable that the crystal is oriented and crystallized to have a weight of 1.50 g / cm ³ .

(Ethylene Terephthalate Crystalline Polyester) The ethylene terephthalate crystalline polyester used in the present invention is one in which ethylene terephthalate units occupy most, preferably 80 mol% or more, of the ester repeating units. Point (Tg) 50 to 90
Crystalline polyesters having a melting point (Tm) of from 220 to 260 ° C, especially from 240 to 260 ° C, at 70 ° C, in particular from 70 to 90 ° C, are preferred. Homopolyethylene terephthalate is preferred in terms of heat resistance, but a copolymerized polyester containing a small amount of an ester unit other than the ethylene terephthalate unit may be used. Whether or not the polyester is crystalline can be confirmed by showing a clear crystal melting peak in differential thermal analysis.

Examples of dibasic acids other than terephthalic acid include isophthalic acid, orthophthalic acid, P-β-oxyethoxybenzoic acid, naphthalene 2,6-dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, Preferred is at least one dibasic acid selected from the group consisting of sodium sulfoisophthalic acid, hexahydroterephthalic acid, adipic acid, sebacic acid, trimellitic acid, and pyromellitic acid. Further, it contains a polybasic carboxylic acid such as pyromellitic acid, trimellitic acid, 3,4,3 ', 4'-biphenyltetracarboxylic acid or its anhydride in an amount of 40 mol% or less. Is also good.

The diol component is preferably composed only of ethylene glycol, but other diol components such as propylene glycol, 1,4-butanediol, diethylene glycol, and the like may be used within a range not to impair the essence of the present invention. , 6-hexylene glycol, cyclohexane dimethanol, bisphenol A ethylene oxide adduct or the like, or two or more thereof may be contained. Further, a trivalent or higher alcohol component such as trimethylolethane, trimethylolpropane, trimethylolmethane, pentaerythritol and the like may be contained in an amount of 40 mol% or less.

As the ethylene terephthalate crystalline polyester to be used, those having an intrinsic viscosity (IV) of generally 0.4 to 1.5, especially 0.6 to 1.0 are suitable. The measurement of the intrinsic viscosity is performed by a method described later.

(Ethylene naphthalate polyester)
The ethylene naphthalate-based polyester used in the present invention contains most of the ester repeating units, preferably at least 80 mol%, of ethylene naphthalate units, particularly ethylene-2,6.
A glass transition point (Tg) of from 100 to 140 ° C., especially from 110 to 130,
At a melting point (Tm) of 240 to 300 ° C., especially 250
Crystalline polyesters at temperatures between 280 ° C and 280 ° C are preferred.
Homopolyethylene naphthalate is preferred in terms of heat resistance, but a copolyester containing a small amount of ester units other than ethylene naphthalate units may also be used.

Examples of dibasic acids other than naphthalene-2,6-dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, P-β-oxyethoxybenzoic acid, naphthalene 2,5-dicarboxylic acid, and naphthalene 2,7- A dibasic acid selected from the group consisting of dicarboxylic acid, diphenoxyethane-4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, adipic acid, sebacic acid, trimellitic acid and pyromellitic acid At least one is preferred. Further, it contains a polybasic carboxylic acid such as pyromellitic acid, trimellitic acid, 3,4,3 ', 4'-biphenyltetracarboxylic acid or its anhydride in an amount of 40 mol% or less. Is also good.

The diol component is preferably composed of only ethylene glycol, but other diol components such as propylene glycol, 1,4-butanediol, diethylene glycol, and the like may be used within a range not to impair the essence of the present invention. , 6-hexylene glycol, cyclohexane dimethanol, bisphenol A ethylene oxide adduct or the like, or two or more thereof may be contained. Further, a trivalent or higher alcohol component such as trimethylolethane, trimethylolpropane, trimethylolmethane, pentaerythritol and the like may be contained in an amount of 40 mol% or less.

The ethylene naphthalate-based polyester used is generally from 0.3 to 1.0, especially from 0.4 to 0.6.
Those having an intrinsic viscosity (IV) of Also,
When the content of the diethylene glycol component (DEG) is 1.0
Those having a weight percentage of not more than 10% are preferred.

(Polyester Composition) In the present invention, the ethylene terephthalate-based polyester (A) and the ethylene naphthalate-based polyester (B) are mixed with the naphthalenedicarboxylic acid component in an amount of 0.5 per total dibasic carboxylic acid component. ２５25 mol%, particularly preferably 5 to 15 mol%.

In a blend of a crystalline polyester resin mainly composed of ethylene terephthalate units and a crystalline polyester resin mainly composed of ethylene naphthalate units, a method for controlling the transesterification ratio (E) in the above-mentioned range is as follows. In the pre-process of the extruder, a method of blending resin chips in advance and kneading while controlling the resin temperature, reaction time, humidity, etc. to control the ester exchange rate (E), or directly extruding the raw material chips There is a method of controlling the resin temperature in the extruder by putting it in, the residence time, etc., any method may be used, but the temperature during kneading,
Time is a very important parameter in transesterification reactions.

The temperature at the time of kneading the polyester resin is generally from 280 ° C. to 310 ° C. If the temperature is high, the transesterification reaction proceeds easily, but on the contrary, thermal decomposition starts,
As a result, the molecular weight decreases. Further, the longer the kneading time, the higher the transesterification rate (E).

The mixing or kneading operation can be performed by performing dry mixing using a blender, a Henschel mixer, or the like, and then performing melt kneading using a kneading apparatus for an injection machine. In this case, a predetermined transesterification rate (E) can be obtained by adjusting the injection cycle.

(Molding of Bottle) The bottle of the present invention is produced by subjecting the above-mentioned polyester blend preform to biaxial stretching blow molding and, if necessary, heat fixing. The preform is heated to a stretching temperature of 90 to 140 ° C., and the preform is biaxially stretched and blow-molded at a circumferential stretching speed of 350% / sec or more so as to have an area magnification of 4 to 20 times.

In FIG. 2 showing an example of a preform with a bottom used in the present invention, this preform 10 has a mouth 11 corresponding to a mouth of a container, a test tubular body 12 and a bottom 1.
3 but below the neck of the preform 1
In the molded container, the thickness of the thick portion under the neck is set to be 2 to 10 times the maximum thickness d1 of the body in the molded container. This is suitable for uniformly reducing the thickness through a step portion.

The bottomed preform used for the stretch blow molding is produced by any method known per se, for example, an injection molding method. In this method, molten polyester is injected to produce a preform having a bottom having an opening corresponding to a final container in an amorphous state.

In injection molding, the polyester composition is melt-injected into a cooled injection mold. As the injection machine, a known injection machine equipped with an injection plunger or a screw is used, and the polyester composition is injected into an injection mold through a nozzle, a sprue, and a gate.
As a result, the polyester composition flows into the injection mold cavity and is solidified to form an amorphous preform for stretch blow molding. As the injection mold, one having a cavity corresponding to the neck shape of the container is used, but a one-gate or multi-gate injection mold is preferably used. The injection temperature is preferably 280 to 310 ° C., and the pressure is preferably about 100 to 1500 kg / cm ² .

For stretch blow molding from a preform,
A method in which a preform in a supercooled state is once manufactured, and the preform is heated to a stretching temperature to perform stretch molding (a cold parison method), or heat given to the preform to be molded, that is, utilizing residual heat. Then, a method of performing a stretch molding after the preliminary molding (hot parison method) or the like is employed. The former method is preferred.

The heating temperature for stretching is 90 to 130.
It is preferably in the range of ° C. That is, when the temperature is lower than the above temperature range, it is difficult to perform a smooth stretch molding operation, and the occurrence of microvoids and the like becomes remarkable.On the other hand, when the temperature is higher than the above range, uneven thickness occurs during stretching, Whitening occurs due to thermal crystallization of the body. In this sense, the heating temperature for stretching should be in the above range.

In the case of a heat-resistant bottle or a heat-resistant pressure bottle, it is important to carry out thermal crystallization in order to improve the heat resistance and rigidity of the container mouth. The thermal crystallization of the mouth of the container can be performed after forming into a bottle, but it is generally preferable to perform the pre-heating, pre-heating, or after pre-heating of the preform prior to stretch blowing.

The degree of thermal crystallization at the mouth is for giving the above-mentioned density.
The heating is preferably performed at a temperature of 50 to 200 ° C. for 40 to 200 seconds. Infrared radiators are particularly suitable as heat sources.

The biaxial stretch blow molding into a bottle or the like can be performed by a one-step method or a two-step method. First, the preform at the stretching temperature is stretched and stretched in the axial direction in a blow molding die or without using a blow molding die, and is expanded and stretched in a circumferential direction by blowing a fluid. The stretching ratio is 4 to 20 times the area stretching ratio (based on the outer surface area of the container / the outer surface area of the preform), particularly 8 to 20 times.
Should be doubled.

In order to enable the above-described high stretching at a relatively low temperature, it is also effective to set the stretching speed in the circumferential direction to 350% / sec or more to utilize the internal frictional heat generation. still,
When performing pre-blow with a low-pressure fluid prior to blowing by blowing high-pressure gas, the stretching speed is determined on the basis of the pre-blow-stretched fluid.

In order to enable high-speed stretching, the pressure of the pressurized fluid used is preferably as high as possible, and it depends on the capacity of the final container and the thickness of the preform. , 30 kg / cm ² or more, particularly preferably in the range of 35 to 60 kg / cm ² . The pressure applied in the preform does not need to be uniform during molding, but may be any as long as a high pressure is initially applied. Such a state in which the stretching speed is different between the initial stage and the final stage during blow molding can be achieved by utilizing a pressure drop accompanying expansion of the preform and an increase in stress accompanying molecular orientation. In the present invention, as the pressurizing fluid, unheated air or inert gas may be used, or heated air or inert gas may be used. A remarkable advantage. This is because, under the stretch blow molding conditions used in the present invention, since the intramolecular heat is generated by high-speed stretching and the preform itself is at a high temperature, the temperature drop of the preform due to the blowing of fluid can be ignored.

In the case of heat-resistant bottles and heat-resistant pressure bottles, it is important to carry out orientational crystallization in order to improve the heat resistance and creep resistance of the body of the container.
Heat setting is performed at any stage of bottle molding. The degree of oriented crystallization is such as to provide the density described above.

In the case of the one-step method, the blow-molding mold is maintained at a temperature of 120 to 180 ° C., and the bottle being formed is brought into contact with the high-temperature mold to perform heat setting. Appropriate processing time is about 1 to 10 seconds.

In the case of the two-stage method, since it is particularly important to set heating conditions according to the degree of crystallization, the heating conditions may differ greatly depending on the heating means. For example, in the case of using an infrared radiator, the molded article obtained by the first-stage stretch blow molding is generally heated to a temperature of 130 to 200 ° C. for 1 hour.
For 0 second, for example, when using hot air from an oven or the like, the temperature is kept in this temperature range for several minutes to 1 hour to remove distortion and heat fix. At this heat treatment stage, the molded product shrinks, but the molded product after the heat treatment is put into a final blow mold and blow-molded to obtain a final bottle. In this heat treatment stage, in order to prevent excessive thermal deformation of the molded article, gas can be sealed inside the molded article, and under heat treatment conditions such that excessive thermal deformation is suppressed,
The inside of the molded article may be kept at atmospheric pressure. Furthermore, if free blow is used for the first-stage blow molding, only one mold needs to be used, and the bottom can be efficiently stretched.

The haze of the body 4 of the bottle of the present invention (Haz)
e) is suppressed to 1% or less, is free from lamellarization of polyester and fluorescence specific to polyethylene-2,6-naphthalate, and is excellent in transparency and appearance characteristics.

The biaxially stretch blow-molded container of the present invention is biaxially stretched at a high draw ratio. In this connection, in the following formula Δn = n ₁ -n ₂ , n ₁ is the thickness direction. Is a refractive index, and n ₂ is a refractive index in a higher direction in a plane direction.
n) is 0.05 or more, especially 0.1 to 0.3 in the body.

[0062]

Next, the present invention will be further described with reference to examples.

1) Sample Polyethylene terephthalate having an intrinsic viscosity (IV) of 0.7 and polyethylene naphthalate having an intrinsic viscosity (IV) of 0.55 were used. For comparison, polyethylene terephthalate in which a naphthalate component was copolymerized by 12 mol% was used. These resins were dried at 130 ° C. for 5 hours before molding as shown in 2).

2) Molding NN75JS Hipersho manufactured by Niigata Iron Works, Ltd.
Screw temperature 300 ° C using t7000 type injection molding machine
Dry blending, injection molding, thickness 5mm, outer shape 25
mm and a preform having a length of 130 mm were obtained. afterwards,
After the inner and outer surfaces of the preform were reheated by an infrared heater, biaxial stretching was performed to obtain a self-standing bottle having an inner volume of 1.5 liter.

3) Evaluation 3-1) Intrinsic viscosity 200 mg of a sample was added to 20 ml of a phenol / 1,1,2,2-tetrachloroethane mixed solvent having a weight ratio of 1: 1.
It was dissolved by stirring at a temperature of 50 ° C. for 20 minutes. Then, the solution viscosity was measured with an Uperode viscometer using a 30 ° C. constant temperature water bath, and then converted to an intrinsic viscosity. The conversion formula used is shown below.

[0066]

(Equation 1)

3-2) Ester exchange rate 3-2-1) Melting point Measurement was performed at a heating rate of 5 ° C./min using a UNIX-DSC7 differential scanning calorimeter manufactured by Perkin Elmer. The transesterification rate was calculated from the value using the formula (1).

3-2-2) NMR Using an EX270MHZ NMR apparatus manufactured by JEOL, the glycol moiety was selectively measured by IH-NMR. The conditions are as follows. Observation frequency width 2000H Border point 65536 Number of times of accumulation 32 Solvent Trifluoroacetic acid: chloroform = 1: 1 Assignment is ethylene glycol proton derived from PEN 4.89 ppm Ethylene glycol proton derived from PET 4.80 ppm Ethylene glycol proton derived from transesterification component 4.85 ppm It was calculated from the respective molar ratios of PEN and PET using the formula (2). Based on the 100% transesterification mole number (Lcal) as a reference, the transesterification rate (TE) was determined from the transesterification mole number (Lobs) in the obtained NMR spectrum using the formula (3). Lcal = 2N (1-N) (2) Formula N: mole number of PEN 1-N: mole number of PET TE = (Lobs / Lcal) * 100 Formula (3) Lobs is the peak at 4.89 ppm. When the molar fraction corresponding to the peak at 4.80 ppm is B, and the molar fraction corresponding to the peak at 4.85 ppm is C, the molar fraction corresponding to A is given by C / (A + B + C).

3-3) Gas Barrier (Oxygen Permeability) The oxygen permeation amount was measured at 25 ° C., RH 80%, and 1 atm using an oxygen permeation tester OX-TRAN 2/20 manufactured by Mocon Corporation. Thereafter, the oxygen permeability coefficient (cc · mm / m ² · day · atm) was determined by converting the average thickness.

3-4) Density A flat plate portion and a mouth portion of the final molded product were cut into 3 * 3 mm and measured at 20 ° C. in a density gradient tube made of carbon tetrachloride and n-heptane.

3-5) Haze S & M Color Computer manufactured by Suga Test Instruments Co., Ltd.
It was measured using r Model / SM14.

Example 1 Polyethylene terephthalate (A) having an intrinsic viscosity (IV) of 0.7 and polyethylene naphthalate (B) having a intrinsic viscosity (IV) of 0.55 were mixed at a molar ratio of 88:12 by NN75JS manufactured by Niigata Ironworks Co., Ltd.
Dry blending and injection molding with a screw temperature of 300 ° C., a resin pressure of 166 kg / cm ² , and a molding cycle of 56 seconds using a Hypershot 7000 type injection molding machine.
5 g of a preform were obtained. The mouth of the preform is crystallized under known polyethylene terephthalate conditions.
The mixture was reheated to 20 ° C., biaxially stretch-blown using a PET bottle molding die, and heat-set at 140 ° C. for 3 seconds to produce a self-standing bottle having a diameter of 28φ and an inner volume of 1.5 liter. The flat portion of the body was cut out, the oxygen gas barrier was measured, and the ester exchange rate (H
The value of u differs depending on the type of resin, but in the following example, Hu
= 9200 (J / mol) was used. ) Was measured. Table 1 shows the values of the oxygen gas permeability, the transesterification rate, the state of the crystallization at the mouth, and the density of the flat plate portion (“density after heat setting”). In particular, the oxygen gas permeability was determined for a sample immersed in hot water at 85 ° C. for 60 seconds in consideration of hot fill.

Example 2 Molding was carried out in the same manner as in Example 1, except that the blend ratio of polyethylene terephthalate (A) and polyethylene naphthalate (B) was 80:20.

Example 3 Polyethylene terephthalate (A) and polyethylene naphthalate (B) were dry-blended at a blend ratio of 80:20, a screw temperature of 300 ° C. and a resin pressure of 166 kg.
Injection molding was performed in a molding cycle of 70 cm / cm ² and a molding cycle of 70 seconds. The transesterification amount of Example 3 was 4.11 mol% (DSC), 50.1 mol
1% (NMR).

Comparative Example 1 Molding was carried out in the same manner as in Example 1, except that the blend ratio of polyethylene terephthalate (A) and polyethylene naphthalate (B) was 70:30. The molded preform collapsed when performing blow molding, and blow molding was impossible.

Comparative Example 2 Dry blending was carried out at a blend ratio of polyethylene terephthalate (A) and polyethylene naphthalate (B) of 88:12, a screw temperature of 300 ° C. and a resin pressure of 166 kg.
Injection molding was performed at a molding cycle of 35 seconds / cm ² . The molded preform was entirely whitened, and blow molding was impossible. The transesterification amount of this comparative example is 0.8 mol
% (DSC) and 5 mol% (NMR), and it was judged that this whitening phenomenon was caused by an insufficient transesterification amount of polyethylene naphthalate and polyethylene terephthalate which were originally incompatible.

Comparative Example 3 For comparison, 12 mol of polyethylene naphthalate component
% IV IV. A molding test was performed using the polyethylene terephthalate resin of Example 7 under the same conditions as the molding described above, and the transesterification rate of this comparative example was 6.83 mol% (DS
C), 99.9 mol% (NMR). Table 1 shows the results.

[0078]

[Table 1]

The composition ratio of (B) in the resin composition comprising polyethylene terephthalate (A) and polyethylene naphthalate (B) was 25 as compared with those in Examples 1, 2 and Comparative Example 1.
It has been found that stretch blow molding can be favorably performed at a mol% or less, particularly at 20 mol% or less.

Further, from Example 1 and Comparative Example 2, even if the resin composition ratio of (A) and (B) is the same, if the transesterification amount is 1 mol% (DSC) and 5% (NMR) or less. It was found that the injection molded product was whitened and that stretch blow molding was impossible. Further, even when the resin composition ratios of (A) and (B) are the same as in Comparative Example 3, the transesterification rate is 6.8.
When it was 3 mol% (DSC) and 99.9% (NMR), crystallization of the mouth was difficult.

Further, when comparing the densities of Example 1 and Comparative Example 3 which were subjected to heat setting for 3 seconds and a short time, the density of Example 1 was larger than that of Comparative Example 3; The resin which had reduced blockiness and left blockability was more easily crystallized than the resin obtained by random copolymerization.

The oxygen permeability after hot-fill of Comparative Example 3 was 1.772, which is lower than 1.650 before hot-fill. However, in Example 1, 1.631 before hot-fill and 1.635 after that. And had maintained.

From the above, when blending polyethylene terephthalate (A) and polyethylene naphthalate (B), Comparative Example 3 in which the transesterification amount was increased and the terephthalate component and the naphthalate component were completely randomized.
Example 1 in which the blockability of the terephthalate component and the naphthalate component is left can be more easily crystallized in the mouth, and the oxygen gas barrier property is further improved by heat setting, and the oxygen gas barrier property is maintained even after hot filling. Had been maintained.

[0084]

According to the present invention, the ethylene terephthalate-based polyester and the ethylene naphthalate-based polyester are blended in a specific ratio, and the ester exchange rate in the blend is maintained in the range of 1 to 6%. In addition to maintaining the crystallization tendency in an appropriate range similar to that of polyethylene terephthalate, preforms without whitening can be manufactured, and uniform stretch blow molding is possible, making it possible to manufacture bottles with excellent transparency and impact resistance. It becomes possible. In addition, oriented crystallization of the body and thermal crystallization of the mouth sufficiently proceed, and a container having excellent heat resistance and heat pressure resistance is formed. Furthermore, even if hot filling is performed after heat setting, a surprising result that the gas barrier property of the vessel wall does not decrease is obtained.

The present invention is particularly useful as a heat-resistant or heat-resistant stretch-blow heat-set bottle. The bottle is thermally crystallized to have a density of 1.34 g / cm ³ or more. Since the part is oriented and crystallized to have a density of 1.35 g / cm ³ or more, the sealing accuracy of the mouth at the time of hot filling is improved, and the creep resistance and heat resistance of the container body are improved. It becomes possible.

[Brief description of the drawings]

FIG. 1 is a side view showing an example of a biaxially stretched blow bottle of the present invention.

FIG. 2 is a side view showing an example of a bottomed preform used in the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Biaxially stretched polyester bottle 2 Unstretched nozzle part (mouth part) 3 Truncated cone-shaped shoulder part 4 Cylindrical body part 5 Closed bottom part 10 Preform 11 Mouth part corresponding to mouth of container 12 Test tube Body 13 bottom 14 lower part of neck

Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 22:00

Claims (7)

[Claims] 1. An ethylene terephthalate-based crystalline polyester (A) having an ethylene terephthalate unit as a main component.
And an ethylene naphthalate-based polyester (B) mainly composed of ethylene naphthalate units, so that the content of the naphthalenedicarboxylic acid component relative to the total dibasic carboxylic acid component is 0.5 to 25 mol%. It is formed from a blend, and has the following formula (1): E = 100 · [1-exp {(Hu / R) · (1 / Tm ₀ −1 / Tm)}] (1) where Hu: ethylene terephthalate unit Heat of fusion (J / mol) of crystalline polyester mainly composed of R: gas constant 8.314 (J / (mol · K)) Tm: melting point of blend (K) Tm ₀ : mainly ethylene terephthalate unit A stretch blow-molded container, wherein the transesterification amount (E) defined by the melting point (K) of the crystalline polyester is in the range of 1 to 6%. 2. The nuclear magnetic resonance (N
2. The stretch blow bottle according to claim 1, wherein the transesterification rate measured by MR) is in the range of 5 to 70%. 3. An ethylene terephthalate crystalline polyester having a melting point of 220 to 300.degree.
The stretch blow bottle according to claim 1 or 2, having an intrinsic viscosity of 4. 4. The stretch blow bottle according to claim 1, wherein the ethylene naphthalate polyester has a melting point of 230 to 300 ° C. and an intrinsic viscosity of 0.3 to 0.9. 5. The stretch blow bottle according to claim 1, wherein the mouth of the container is thermally crystallized. 6. The stretch blow bottle according to claim 1, wherein the body of the container is biaxially stretched and oriented and crystallized to have a density of 1.35 g / cm ³ or more. 7. In a bottle formed by biaxial stretch blow molding of a thermoplastic polyester and having a body, a closed bottom, a shoulder and a mouth, an ethylene terephthalate-based crystalline polyester mainly composed of ethylene terephthalate units A) and an ethylene naphthalate-based polyester (B) mainly composed of ethylene naphthalate units, so that the content of the naphthalenedicarboxylic acid component per total dibasic carboxylic acid component is 0.5 to 25 mol%. The following formula (1) is formed from the containing blend, and E = 100 · [1-exp {(Hu / R) · (1 / Tm ₀ −1 / Tm)}] (1) where Hu: ethylene Heat of fusion of crystalline polyester mainly composed of terephthalate units (J / mol) R: gas constant 8.314 (J / (mol · K)) Tm: melting point of blend K) Tm _0: melting point of the crystalline polyester composed mainly of ethylene terephthalate units (K), in located in being defined range transesterified amount (E) is 1 to 6%, the mouth portion density 1.34 g / It is thermally crystallized to have a cm ³ or more, and the body portion is density of 1.35 g / cm
A stretch blow-molded heat-set bottle, which is oriented and crystallized so as to have a particle size of ³ or more.