WO2018003790A1

WO2018003790A1 - Polyester stretch blow-molded container and manufacturing method therefor

Info

Publication number: WO2018003790A1
Application number: PCT/JP2017/023551
Authority: WO
Inventors: 温小宮; 玲太石井; 大樹安川; 友山崎; 友紀栗原
Original assignee: 東洋製罐株式会社
Priority date: 2016-06-28
Filing date: 2017-06-27
Publication date: 2018-01-04

Abstract

The present invention relates to a polyester stretch blow-molded container, which is thin-walled with an average body section thickness of 280 µm or less and for which deformation that occurs during high temperature filling of contents is effectively limited, and is characterized in that the tanδ peak value and the tanδ peak temperature at said peak value in dynamic viscoelasticity measurements measured in the axial direction of the center portion of the body section satisfy either (i) tanδ peak value is in the range of 0.23-0.29 and the tanδ peak temperature at said peak value is in the range of 111-118°C, or (ii) tanδ peak value is less than 0.25 and the tanδ peak temperature at said peak value is in the range of 119°C or higher.

Description

Polyester stretch blow molded container and method for producing the same

The present invention relates to a thin stretched polyester stretch blow molded container and a method for producing the same, and more particularly, to a lightweight thin stretch polyester stretch blow molded container having heat resistance suitable for high temperature filling and a method for producing the same. About.

Polyester stretch blow molded containers formed by biaxial stretch blow molding of polyester preforms are widely used as containers for various beverages because they are excellent in transparency and light weight.
In recent years, from the viewpoints of resource saving, cost reduction, environmental maintenance, and the like, there is a demand for further thinning of polyester stretch blow molded containers. However, the heat resistant container has a problem that it becomes difficult to maintain heat resistance due to further thinning. In other words, when the contents are filled at a high temperature of 80 ° C. or higher, the container is greatly deformed, and its thinning is limited at present.

That is, as a means for improving heat resistance in a stretch stretch blow molded container made of polyester, generally, a means for heat-treating (heat fixing) the container after blow molding is widely adopted, but the average thickness of the container body is In a thin polyester stretch blow molded container that has been thinned to 280 μm or less, the container may be deformed by heating for heat setting, and it cannot be sufficiently crystallized by heat setting. When the contents were filled at a high temperature, deformation of the container could not be prevented, and as a result, the container body could not be sufficiently thinned.

As a prior art for improving the heat resistance of a stretch blow molded container made of polyester, the following Patent Document 1 discloses that in a dynamic viscoelasticity measurement, a tan δ peak temperature is 113 ° C. or less and a tan δ absolute value in the vertical direction of the container body. A polyester container characterized in that is 0.18 or less has been proposed.
The polyester container exhibits excellent heat distortion resistance by blow stretching and heat setting so as to satisfy certain dynamic viscoelastic properties, for example, heat distortion resistance that can withstand high temperature sterilization treatment (retort treatment). In addition, by satisfying the dynamic viscoelastic characteristics of the container within a certain range, excellent heat distortion resistance that can withstand retort treatment is developed.

However, the technique disclosed in Patent Document 1 is applied to a thick-walled polyester blow container, and the thinned and light-weight polyester blow container is used at the time of molding as described above. Since there exists a possibility that it may deform | transform by heat setting, the technique currently disclosed by patent document 1 was not able to be applied.

JP 2006-306452 A

Accordingly, an object of the present invention is to provide a stretch blow container made of polyester and a method for producing the same, in which the average thickness of the body portion is 280 μm or less, and the deformation that occurs during high temperature filling of the contents is effectively suppressed. is there.

According to the polyester stretch blow container of the first aspect of the present invention, it is a polyester stretch blow container having a trunk average thickness of 280 μm or less, and the dynamic viscoelasticity measurement is performed in the axial direction of the trunk central portion. Is provided with a tan δ peak value of 0.23 to 0.29, and a tan δ peak temperature at the peak value of 111 to 118 ° C.
According to the polyester stretch blow molded container of the second aspect of the present invention, a polyester stretch blow container having a trunk average thickness of 280 μm or less, wherein the dynamic viscoelasticity is measured in the axial direction of the trunk central portion. In the measurement, a polyester stretch blow container characterized in that the tan δ peak value is less than 0.25 and the peak temperature of tan δ at the peak value is 119 ° C. or more is provided.

In the stretch blow molded container made of polyester of the present invention,
1. The degree of crystallinity measured by the density method measured for the central portion of the trunk is in the range of 29 to 38%;
2. For high temperature filling,
Is preferred.

According to the present invention, there is also provided a method for producing a polyester stretch blow molded container according to the second aspect, wherein a polyester preform heated to a stretching temperature is stretched by stretching by a stretch rod and stretching by air blow, In a method for producing a polyester stretch blow container that is heat-set, the stretch temperature is in the range of 100 to 130 ° C., and the air blow uses blow air adjusted to a temperature in the range of 80 to 200 ° C., There is provided a method for producing a polyester stretch blow molded container, wherein the mold temperature in the heat setting is in the range of 130 to 160 ° C.
In the above manufacturing method, the air blow is composed of pre-blow performed simultaneously with stretching by the stretch rod and main blow performed simultaneously with completion of stretching by the stretch rod, and adjusted to a temperature in the range of 80 to 200 ° C. in both the pre-blow and the main blow. Suitably blown air is used.

The stretch blow container made of polyester of the present invention has excellent heat resistance despite the fact that the trunk average thickness is reduced to 280 μm or less, and the content is 80 ° C. or higher, particularly 83 to 87 ° C. Even when a thermal history of filling and then lowering the temperature is received, thermal deformation of the container is effectively prevented.
The stretch blow container made of polyester of the present invention has excellent heat resistance despite the fact that the trunk average thickness is reduced to 280 μm or less, and the content is 80 ° C. or higher, particularly 83 to 87 ° C. Even when a thermal history of filling and then lowering the temperature is received, thermal deformation of the container is effectively prevented.
That is, in the dynamic viscoelasticity measurement described above, the tan δ peak value is 0.23 to 0.29, and the tan δ peak temperature at the peak value is in the range of 111 to 118 ° C. The polyester stretch blow container of the aspect is set so as to positively generate a certain degree of thermal deformation (thermal expansion) when the contents are filled at a high temperature. For this reason, the container contracts due to subsequent decompression by cooling. When (absorption under reduced pressure) is performed, the thermal expansion at high temperature and the absorption under reduced pressure at the time of cooling have an appropriate balance, so that the final deformation of the container can be effectively avoided.
For example, as shown in Experimental Example 1 to be described later, the polyester blow container (empty container) of the first aspect of the present invention is held in an 85 ° C. oven for 5 minutes, and this is brought to room temperature (23 ° C.). When cooled, the rate of change of the container based on the volume of the container before heating in the oven is 0.4 to 0.8%, which is larger than 0.3% or less of the conventional container, and is filled at high temperature. Thermal expansion is easy to occur. Thereafter, the container is cooled, and the amount of contraction due to reduced pressure (the amount of absorption under reduced pressure) is the same as that of the conventional container. The amount of shrinkage is small, the balance between thermal expansion and reduced pressure absorption is good, and deformation of the container after filling is effectively prevented.

Further, in the stretch blow molded container made of polyester of the second aspect of the present invention, the tan δ peak value is less than 0.25 in the dynamic viscoelasticity measurement measured in the axial direction of the central portion of the trunk portion. The crystal part indicates that the molecular chain stress is relaxed. In addition, the peak temperature of tan δ at the peak value is 119 ° C. or higher, which indicates that the ratio of the above-described amorphous portion is small and the degree of crystallization (orientation by stretching) is high. From these, it can be seen that the stretch-molded polyester container of the second aspect of the present invention has excellent heat resistance even in a thinned state.

In the above manufacturing method, by flowing high-temperature blow air from the initial stage of blow molding, the container is heated from the inner surface side to relieve strain on the inner surface side of the container, and promote self-heating of the container. It becomes possible to improve the heat resistance by promoting oriented crystallization. As a result, a polyester stretch blow container having the above-described characteristics can be formed.

The above-described effects of the present invention are also apparent from the results of Experimental Example 2 described later.
That is, a polyester stretch blow molded container formed under the same stretching conditions as in the examples except that blow air that is not heated is used has a tan δ peak temperature of 118 ° C. or lower and a tan δ peak value of 0.25 or higher, Inferior in properties (Comparative Examples 1 to 3). In contrast, polyester stretch blow molded containers formed by using blow air in the range of 80 to 200 ° C. from the time of pre-blow have the tan δ peak temperature and the tan δ peak value in the above-mentioned ranges, and have excellent heat resistance. (Examples 1 to 6).

It is a figure which shows the schematic side view of the stretch blow container made from polyester of this invention. It is a figure which shows the relationship between the blow air temperature with respect to time in the biaxial stretch blow molding process in the manufacturing method of the polyester stretch blow container of the 2nd aspect of this invention, and a blow pressure. It is a figure which shows the result of the dynamic viscoelasticity measurement about the various bottles measured in Experimental example 1. FIG. It is a figure which shows the result of the dynamic viscoelasticity measurement about the various bottles measured in Experimental example 2. FIG.

(Polyester stretch blow container)
As shown in FIG. 1, the polyester stretch blow molded container of the present invention is generally indicated by 10, has a neck portion 1 and a trunk portion 3 connected to the neck portion 1. Is closed by a bottom 5.
The polyester blow container 10 having such a configuration is manufactured by molding a test tube-shaped preform by injection molding or the like, blow-molding the preform, and then heat-setting (heat-setting) it in an appropriate temperature range. However, a detailed manufacturing method will be described later.
The neck portion 1 is an unstretched portion (portion fixed by a mold during blow molding), and a thread 1a is appropriately formed on the outer surface according to the form of the cap attached to the container. A support ring 1b is provided below 1a for supporting and conveying the preform and the container to be molded.
On the other hand, the body portion 3 (and the bottom portion 5) is a portion that is blow-drawn, and is a portion that is stretch-formed by blowing blow fluid in a state where the neck portion 1 of the preform is fixed.
Further, in order to provide the container with reduced pressure absorbability during high temperature filling, as shown in FIG. 1, the bottom portion 5 has a raised bottom shape, and a recess is formed on the bottom surface.

The polyester stretch blow container 10 of the present invention having the above-described form is thinned, and the average thickness of the body portion 3 which is a stretch-formed part is 280 μm or less, preferably 270 to 200 μm, more preferably. Is in the range of 250 to 200 μm, and weight reduction is realized by such thinning.
In the polyester stretch blow container 10 thus thinned, in the present invention, as described above, in the dynamic viscoelasticity measurement (also referred to as DMS or DMA) at the trunk axial direction central portion X, the first In the polyester stretch blow container of the aspect, the tan δ peak value is in the range of 0.23 to 0.29 and the tan δ peak temperature at the peak value is in the range of 111 to 118 ° C., or the polyester stretch blow of the second aspect. In the container, the tan δ peak value is less than 0.25, particularly 0.18 to less than 0.25, particularly 0.22 to less than 0.25, and the peak temperature of tan δ at the peak value is 119 ° C. or more, In particular, it is important to be in the range of 119 to 125 ° C.

Dynamic viscoelasticity measurement measures the mechanical properties of a sample by measuring stress or strain, and tan δ is a parameter called loss tangent, expressed as a ratio of loss elastic modulus / storage elastic modulus. The The loss elastic modulus is a loss due to an amorphous part, and the storage elastic modulus is an elastic modulus due to a crystal part, both of which depend on temperature. The temperature at which tan δ exhibits a peak indicates an apparent glass transition point.
Therefore, the smaller the tan δ peak value, the more crystal parts are present, and the higher the peak temperature indicating this peak value, the higher the glass transition point, which causes deformation of the container at the time of high temperature filling of the contents. It shows that heat resistance is high.

On the other hand, setting the peak value and peak temperature of tan δ, like the stretch blow container made of polyether of the first aspect of the present invention, improves the thermal deformation (thermal expansion) property at the time of high temperature filling of the contents. However, at the same time, the amount of shrinkage required from the pre-filling container due to the temperature drop after cooling at high temperature (cooling to room temperature) can be reduced, and the high temperature filling of the contents by the balance between this thermal deformation (thermal expansion) and shrinkage. The deformation that occurs at the time is effectively suppressed.
That is, in the polyester stretch blow container of the first aspect, when the contents are filled at a high temperature, it is thermally deformed to some extent and expands. And since the conventionally well-known thick heat-resistant polyester blow container (conventional heat-resistant container) is thick, it does not expand at the time of filling more than the blow container of this invention. However, since the amount of vacuum absorption by cooling after filling is the same, the amount of shrinkage from the container before filling is smaller in the blow container of the present invention than in the conventional heat-resistant container. Therefore, the conventional heat-resistant container can withstand deformation under reduced pressure and suppress deformation of the container after high-temperature filling, and the first polyester stretch blow container of the present invention is different from conventional heat-resistant containers in that it has thermal expansion. By properly balancing the vacuum absorption, it is a container that effectively suppresses deformation of the bottle after high temperature filling.

Further, in the thin-walled container as in the present invention, when the peak value or peak temperature of tan δ is outside the above-mentioned range, the balance between the thermal expansion at the time of high temperature filling of the contents and the contraction due to the subsequent temperature drop is lost. As a result, the deformation that occurs during high temperature filling cannot be effectively prevented.

Note that the tan δ peak value and peak temperature described above are prepared by cutting the container body into an appropriate size so as to include the central portion X in the body axial direction, and using a viscoelastic spectrometer. It is measured by applying a load from the axial direction of the container.

In addition, in the stretch blow container made of polyester of the first aspect of the present invention, a certain amount of thermal deformation occurs during high-temperature filling of the contents, so as to ensure form stability when such thermal deformation occurs. As shown in FIG. 1, it is preferable that the bottom portion 5 is raised to have a bottom shape and a recess is formed on the bottom surface. Thereby, when this container is thermally deformed (expanded), the central portion of the bottom portion 5 is lowered, stress due to thermal expansion can be relieved, and the container can be held in an upright state.

The stretch blow container of the present invention described above is formed of a polyester capable of forming a preform by injection molding or compression molding. As such a polyester, polyethylene terephthalate usually formed from terephthalic acid and ethylene glycol is used. (PET) is preferably used.
Such polyethylene terephthalate usually has a glass transition point (Tg) of 50 to 90 ° C., particularly 55 to 80 ° C., and a melting point (Tm) of 200 to 275 ° C., particularly 220 to 270 ° C.

In addition, an ester derived from a dibasic acid other than terephthalic acid or a diol unit other than ethylene glycol, provided that the ethylene terephthalate unit occupies 70 mol% or more, particularly 80 mol% or more in the ester repeating unit. Copolyesters containing units can also be suitably used. Examples of such dibasic acids other than terephthalic acid include aromatic dicarboxylic acids such as isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; succinic acid, adipic acid, sebacic acid, and dodecane. Examples of the diol component other than ethylene glycol include propylene glycol, 1,4-butanediol, diethylene glycol, and 1,6-hexylene glycol. , Cyclohexanedimethanol, and one or more of bisphenol A ethylene oxide adducts.

Such a polyester should have at least a molecular weight sufficient to form a film, and usually has an intrinsic viscosity (IV) of 0.6 to 1.4 dL / g, particularly 0.63 to 1. An injection grade in the range of 3 dL / g is used.

Furthermore, as long as the above-mentioned dynamic viscoelastic properties are maintained, the above-mentioned polyester may be blended with known compounding agents (antioxidants, lubricants, etc.) per se. Such a polyester may be used as an inner and outer layer, and an oxygen barrier layer and an oxygen absorption layer may be provided as an intermediate layer through an adhesive layer.

The oxygen barrier layer having the multilayer structure is formed of an oxygen barrier resin such as an ethylene-vinyl alcohol copolymer or polyamide, so long as the oxygen barrier property is not impaired. The thermoplastic resin may be blended with other thermoplastic resins.
The oxygen absorbing layer is a layer containing an oxidizing polymer and a transition metal catalyst, as described in Japanese Patent Application Laid-Open No. 2002-240813, etc., and the oxidizing polymer is activated by the action of the transition metal catalyst. Is oxidized by oxygen, which absorbs oxygen and blocks the permeation of oxygen. Such an oxidizable polymer and a transition metal catalyst are described in detail in the above Japanese Patent Application Laid-Open No. 2002-240813 and the like. Is an olefin resin having a tertiary carbon atom (for example, polypropylene or polybutene-1, or a copolymer thereof), a thermoplastic polyester or an aliphatic polyamide; a xylylene group-containing polyamide resin; an ethylenically unsaturated group-containing polymer. A polymer (eg, a polymer derived from a polyene such as butadiene); Moreover, as a transition metal type catalyst, the inorganic salt, organic acid salt, or complex salt of transition metals, such as iron, cobalt, and nickel, are typical.
Further, the adhesive resin used for adhesion of each layer is known per se, for example, olefin graft-modified with carboxylic acids such as maleic acid, itaconic acid, fumaric acid or anhydrides thereof, amides, esters, etc. Resins; ethylene-acrylic acid copolymers; ion-crosslinked olefin copolymers; ethylene-vinyl acetate copolymers; and the like are used as adhesive resins.
The thickness of each layer described above may be set to an appropriate thickness as long as the average thickness of the body portion of the container wall after blow molding is in the above-described range (280 μm or less).
Furthermore, it is also possible to provide a regrind layer in which scrap generated when molding a blow container is blended with a polyester virgin resin.

(Production method of stretch blow container made of polyester)
The polyester stretch blow container of the present invention uses a preform molded by injection molding or the like, and is subjected to stretch blow molding and heat setting, so that the above-mentioned average thickness of the body portion is 280 μm or less. However, it is necessary to set various conditions so as to satisfy the dynamic viscoelastic properties described above.
For example, when the draw ratio is high, the tan δ peak value tends to be small and the peak temperature tends to be high, and when the blow air temperature is high, the tan δ peak value tends to be small and the peak temperature tends to be high, and the heat setting temperature is high. And the peak value of tan δ tend to be small and the peak temperature tends to be high. By using this, laboratory experiments are performed in advance so that the dynamic viscoelastic properties (the peak value and the peak temperature of tan δ) are within a predetermined range. Various conditions may be set according to the thickness of the stretch-formed part (corresponding to the body part of the container) of the molded preform.

[preform]
The preform used for molding the stretch blow container made of polyester according to the present invention can be formed into a single layer or a multilayer structure by molding the above-mentioned polyester by a conventionally known method such as injection molding or compression molding. From the viewpoint of heat resistance, it is desirable that the neck portion of this be heated and crystallized.

[Preform heating process]
The molded preform is heated to a stretching temperature before being subjected to stretch blow molding. In the first polyester stretch blow container of the present invention, the outer surface temperature of the preform is in the range of 100 to 140 ° C. In particular, it is desirable to heat so that the temperature is in the range of 120 to 135 ° C and 100 to 130 ° C. In the second polyester stretch blow container of the present invention, the outer surface temperature of the preform is in the range of 100 to 130 ° C. It is desirable to heat as is. When the outer surface temperature of the preform is higher than 140 ° C., the preform may be whitened by thermal crystallization. On the other hand, when the stretching temperature is lower than the above range, in the subsequent biaxial stretch blow molding step There is a possibility that the film cannot be sufficiently stretched.
The preform can be heated by a conventionally known method. In general, the preform is heated at a normal temperature in combination with an infrared heater and an inner surface heater, and cooling due to the conveyance of the preform is taken into consideration. And it heats so that it may become the said temperature range at the time of blow molding.

[Biaxial stretch blow molding process]
In the biaxial stretch blow molding process, a preform heated to the uniform and high temperature under the above-described heating conditions is fixed in the neck and is placed in a blow mold. In addition to stretching in the (longitudinal direction), it is stretched in the circumferential direction (radial direction) by flowing blow air, and the preform comes into contact with the mold surface and is shaped into the shape of the final molded product.
As a means for blow molding, a two-stage blow is known in which an intermediate-shaped molded body is once blow-molded, and then this intermediate-shaped molded body is heated and then subjected to secondary blow molding to obtain a final molded body. However, in order to form the first blow container of the present invention, such a two-stage blow is not suitable, and a normal one-stage blow is applied. This is because, when the container is formed by two-stage blowing, orientation crystallization by blow stretching is promoted, so that it becomes difficult to adjust the peak value and peak temperature of tan δ within the above-described range.

When the polyester stretch blow container of the first aspect of the present invention is molded, the blow air is not particularly limited. However, when the second polyester stretch blow container is molded, it is 80 to 200 ° C., particularly 145. It is preferable to use blow air adjusted to a temperature of ˜200 ° C. As long as blow air in this temperature range is used, it is possible to perform blow molding to the final molded product at the same flow rate without changing the flow rate of blow air even after stretching by the stretch rod. It is desirable to perform pre-blow with a small flow rate until the end of stretching with the rod, and to perform main blow with a greater flow rate than the pre-blow when stretching with the stretch rod is completed.

FIG. 2 is a diagram showing the relationship between the temperature and pressure of blow air over time in an example of a biaxial stretch blow molding process for molding the polyester stretch blow container of the second aspect of the present invention. In general, the blow process shown in FIG. 2 is a pre-blow process (0.02 to 0.6 seconds) in which the flow rate of blow air is small and the blow pressure is in the range of 0.5 to 2 MPa. It consists of a main blow step (0.6 to 3 seconds) in the range of 4 MPa, and a cooling step for cooling the container by injecting cooling air after the completion of the main blow.
In the present invention, blow air adjusted to a temperature of 80 to 200 ° C. is introduced even at the pre-blow stage, so that the temperature of the preform heated to the stretching temperature is not lowered, and the shaft by the stretch rod is used. Direction stretching can be performed uniformly and efficiently. In addition, since high-temperature blow air is used in the main blow, distortion of the inner surface of the container being molded can be alleviated, and heat resistance is further improved in combination with heating from the outer surface by heat fixation described later. It becomes possible to make it. Furthermore, since it flows in at a relatively high pressure while maintaining high-temperature blown air, it is not necessary to lengthen the stretch molding cycle for heat resistance, and the heat resistance is also improved by self-heating of the container.

The stretch ratio in the biaxial stretch blow molding step is a range of 1.8 to 3.4 times in the longitudinal stretch ratio, 2.8 to 3.8 times in the circumferential direction, and 4 to 12 times in the area ratio. It is preferable that it exists in. Thereby, the average thickness of the body portion is reduced to 280 μm or less, and it becomes possible to obtain a final molded product that is reduced in weight.

[Heat setting process]
The container after blow molding is subjected to heat fixation and then cooled to complete the final molded product.
The heat setting is a one-mold method that is performed simultaneously with blow molding using a mold used for blow molding, or a two-mold method in which a blow-molded container is taken out of the blow mold and reheated with a dedicated mold for heat setting. However, in order to manufacture the blow container according to the first aspect of the present invention, the one mold method of forming in a short time is suitable. In the two-mold method, since the blow molded body is heated after being cooled once, the heating time becomes long, and it becomes difficult to set the heating temperature for molding the container of the present invention.

In the heat setting by the one mold method, the heating temperature is set so as to satisfy a predetermined dynamic viscoelastic property (tan δ) according to the stretching temperature (preform temperature) and the stretching ratio described above. In the case of obtaining a stretch blow container made of polyester of one embodiment, the heat setting temperature is 130 ° C. or more and less than 150 ° C., and the heat setting time may be several seconds. For example, the heat setting temperature used when manufacturing a normal thick heat-resistant blow container is 150 ° C. or higher, which is higher than the heat setting temperature employed in the present invention.
On the other hand, when obtaining the polyester stretch blow container of the second aspect of the present invention, the temperature may be higher than that of the stretch blow container of the first aspect. In this case, the heat setting temperature is 130 to 160 ° C. The heat setting time may be several seconds.

The polyester stretch blow container of the present invention thus formed has a crystallinity of 29 to 38% by the density method at the body center portion X as described above, and particularly in the first embodiment. Excellent heat resistance is obtained when the crystallinity is in the range of 30 to 35%, and in the second embodiment, the crystallinity is in the range of 35 to 38%.
The stretch blow container made of polyester of the present invention is very thin, for example, a bottle having a full volume of 500 mL and a weight of 22 g or less, a bottle having a full volume of 2 L and a weight of 49 g or less, Considering that the weight of a commercially available 500 mL PET bottle is 28 g or more and the weight of a normal commercially available 2 L PET bottle is 65 g or more, in the present invention, a considerable weight reduction is realized by thinning.

The invention is illustrated by the following experimental example.
Various measurement methods employed in the following experimental examples are as follows.

(1) Tan δ in dynamic viscoelasticity measurement
Referring to FIG. 1, a 5 mm × 40 mm test piece Y is cut out from the center X of the bottle body so that the long side direction is the bottle height direction, and a viscoelastic spectrometer (EXSTAR6000DMS: Seiko Instruments Inc.) Measurement was performed using The measurement conditions are shown below. From the obtained tan δ curve (temperature plotted on the horizontal axis and tan δ value on the vertical axis), the maximum value of tan δ (tan δ value) and the maximum temperature of tan δ (peak temperature) were derived.
Measurement mode: Tensile sine wave mode Distance between test specimens: 20 mm
Frequency: 1Hz
Minimum tension: 100mN
Temperature rise profile: Temperature rise from 25 ° C. to 210 ° C. at 2 ° C./min (2) Measurement of rate of change The bottle is held in an 85 ° C. oven for 5 minutes and cooled to room temperature (23 ° C.). The volume of the container before heating and after cooling was measured, and the rate of change of the container with respect to the volume before heating was determined.
(3) Average thickness measurement The thickness was measured every 20 mm in the longitudinal direction at 6 points in the circumferential direction of the bottle, and the average was obtained.
(3) Measurement of heat resistance An empty bottle was filled with water heated to 87 ° C., showered at 77 ° C. for 5 minutes, and then naturally cooled. Thereafter, the deformation of the bottle was visually observed.
Small deformation amount: ◎ Medium deformation amount: ○ Large deformation amount: △ Deformation amount cannot be commercialized Level: ×

(Experimental example 1)
The following bottles molded under the conditions shown in Table 1 were measured for dynamic viscoelasticity. The results are shown in FIG. In addition, the crystallinity of the bottle of the present invention is also shown in FIG.

In FIG. 3, ▪, ○, ●, and Δ indicate the next bottles in Table 1 above.
■: Invention bottle (bottle for high temperature filling)
○: Thick heat-resistant bottle (conventional high-temperature filling bottle)
●: Two-stage blow bottle (high-temperature filling bottle blow-molded twice)
Δ: heat-resistant pressure bottle (bottle for carbonated beverages to be heat sterilized after filling, not compatible with high temperature filling)

Moreover, the change rate was measured for the 500 ml bottle of the present invention and the thick heat-resistant bottle. The results are shown in Table 2. In addition, when trying to mold the PF for a bottle of the present invention under the same conditions as a thick heat-resistant bottle, the bottle does not deform due to heat, so that a heat-resistant bottle with a thin wall and dynamic viscoelasticity outside the scope of the present invention could not be molded. .

From this experimental example, the bottle of the first aspect of the present invention has a tan δ peak value of 0.23 to 0.29 and a tan δ peak temperature in the range of 111 to 118 ° C. from dynamic viscoelasticity measurement. Yes, it was confirmed that the bottle is more susceptible to heat shrinkage than the conventional thick heat-resistant bottle. As a result, since the rate of change of the bottle of the present invention is larger than that of the conventional thick heat-resistant bottle, the thermal expansion of the bottle after high-temperature filling at 80 ° C. or higher is greater in the bottle of the present invention, and the reduced pressure after cooling the bottle Since the amount of change due to is the same for bottles of the same capacity, it can be seen that the amount of deformation due to decompression from the bottle before filling is small for the bottle of the present invention. Therefore, the bottle of the present invention can effectively prevent deformation of the bottle even if it is subjected to a heat history such as high temperature filling and subsequent temperature drop, although the bottle is thinned by weight reduction.

(Experimental example 2)
The dynamic viscoelasticity, trunk average thickness, and heat resistance of each bottle (Example, Comparative Example) molded under the bottle size and molding conditions shown in Table 3 were measured. The results are shown in Table 3 and FIG.

As can be seen from the results, the heat resistance is good when the tan δ peak value is in the range of less than 0.25 and the tan δ peak temperature is 119 ° C. or higher, and the heat resistance decreases when the value is away from the value. It was. In particular, when the average wall thickness of the bottle is 250 μm or less, it is more important that the temperature of the blow air is 145 ° C. or more. Further, as can be seen from Comparative Example 4, it can be confirmed that a bottle having an average wall thickness greater than 280 μm does not cause a decrease in heat resistance unlike a thinned bottle.

Since the polyester stretch blow container of the present invention effectively suppresses deformation when the contents are filled at high temperature, a non-carbonated beverage that is filled at a high temperature of 80 ° C. or more, particularly 83 to 87 ° C., for example, It is suitably applied as a container for various fruit juices, water, or various chemical solutions.
Further, since it is thinned to 280 μm or less and lightened, it is possible to save resources and reduce waste, and it can be suitably applied to general-purpose products that are mass-produced.

1: neck, 3: body, 5: bottom, 10: blow container.

Claims

A polyester stretch blow container having an average body thickness of 280 μm or less, wherein the tan δ peak value is 0.23 to 0.29 in the dynamic viscoelasticity measurement measured in the axial direction of the center portion of the body portion. A polyester stretch blow container having a peak temperature of tan δ of 111 to 118 ° C.
It is a polyester stretch blow container having an average trunk thickness of 280 μm or less. In the dynamic viscoelasticity measurement measured in the axial direction of the central part of the trunk, the tan δ peak value is less than 0.25. A polyester stretch blow container having a peak temperature of tan δ of 119 ° C. or higher.
3. The polyester stretch blow container according to claim 1 or 2, wherein the crystallinity measured by the density method measured for the central portion of the trunk is in the range of 29 to 38%.
The polyester stretch blow container according to any one of claims 1 to 3, which is used for high temperature filling.
In a method for producing a polyester stretch blow container, which is obtained by stretching a polyester preform heated to a stretch temperature by stretching by a stretch rod and stretching by air blow, followed by heat setting.
The stretching temperature is in the range of 100 to 130 ° C., the air blow is performed using blow air adjusted to a temperature in the range of 80 to 200 ° C., and the mold temperature in the heat setting is in the range of 130 to 160 ° C. The method for producing a stretch blow molded container made of polyester according to claim 2.
The air blow consists of a pre-blow performed simultaneously with stretching by the stretch rod and a main blow performed simultaneously with the completion of stretching by the stretch rod. Blow air adjusted to a temperature in the range of 80 to 200 ° C. is used in both the pre-blow and the main blow. The manufacturing method of the stretch blow molding container made from polyester of Claim 5 which has.