JP2007069914A - Stretch-formed container and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stretch-formed container formed of a polyester resin in which the strain hardening effectively occurs, and having both the excellent heat resistance attributable to high-temperature stretching and the stretching balance attributable to the strain hardening even when the mechanical stretching rate reaches a limit. <P>SOLUTION: The stretch-formed container has a layer comprising a blend of an ethylene terephthalate type polyester resin and another polyester resin of different kind. The layer comprising the blend has an island-in-sea dispersion structure composed of a continuous phase comprising the ethylene terephthalate type polyester resin and a dispersed phase comprising the polyester resin of different kind. At least a container body part has a tanδ maximum temperature of ≤115°C in a dynamic viscoelasticity measurement. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a stretch-molded container made of a polyester resin and a method for producing the same. More specifically, the present invention relates to a stretch-molded container with reduced residual strain in a stretch-molded container made of a polyester resin and excellent stretch balance. And a manufacturing method thereof.

Stretch-molded containers of thermoplastic polyester resins such as polyethylene terephthalate have excellent transparency and surface gloss, as well as impact resistance, rigidity, and gas barrier properties required for containers such as bottles and cups. It is used as a container for beverages and foods.
However, stretch-molded containers made of polyester resin have the disadvantage of poor heat resistance and cause heat deformation and shrinkage deformation in volume when the contents are hot filled. (Heat setting) is being performed.

Further, when the stretch-molded container is molded by the one-stage blow molding method, the stretch-molded container having a small residual strain and excellent heat resistance is formed by heating and stretching the preform at a high temperature. Can be molded.
For example, in the one-stage blow molding method, the preform temperature is set as high as possible, and further, heat generation due to internal friction or heat generation due to crystallization at the time of stretching at a high speed is used, and stretch molding and heat setting are simultaneously performed, A method for obtaining a stretch blow bottle made of a polyester resin having high heat resistance has been proposed (see Patent Document 1).

Japanese Patent No. 1767894

However, when stretching at a high temperature, a strain hardening phenomenon is unlikely to occur. Therefore, unless the stretching speed is extremely high, stretching does not propagate to the entire molded product, and a stretch-molded container having a uniform thickness cannot be obtained. . For this reason, conventionally, when there is a limit to the mechanical stretching speed, the stretching temperature is lowered, and the stretching balance is obtained at the expense of heat resistance, which is a merit of high-temperature stretching.
Therefore, the object of the present invention is to effectively produce strain hardening even when the mechanical stretching speed is limited, and from a polyester resin that has both excellent heat resistance by high temperature stretching and stretching balance by strain hardening. It is intended to provide a stretch-molded container.
Another object of the present invention is to provide a production method capable of producing a stretch-molded container made of a polyester resin having a good stretch balance by strain hardening regardless of the stretch speed even in stretch blow molding under high temperature conditions. That is.

  According to the present invention, in a polyester stretch-molded container having a layer composed of a blend of an ethylene terephthalate-based polyester resin and a different polyester resin, the layer composed of the blend is a continuous layer composed of the ethylene terephthalate-based polyester resin. A stretched island having a sea-island dispersive structure comprising a phase and a disperse phase composed of the above-mentioned different polyester resin, and having a tan δ maximum temperature of 115 ° C. or less in at least the dynamic viscoelasticity measured value of the container body A container is provided.

In the stretch-molded container of the present invention,
1. The dissimilar polyester resin contains naphthalene dicarboxylic acid as a constituent monomer;
2. The dissimilar polyester resin contains cyclohexanedimethanol as a constituent monomer;
3. The glass transition temperature Tg (m) of the ethylene terephthalate-based polyester resin and the glass transition temperature Tg (d) of the different polyester resin satisfy the relationship of Tg (d) -Tg (m) ≧ 10 (° C.),
4). The sea-island dispersion structure is such that a disperse phase having a major axis of 0.4 to 10 μm is present at a ratio of 60 to 100% in the unstretched portion.
5. The sea-island dispersion structure is such that in the stretched portion, the continuous phase around the dispersed phase is highly stretched and oriented as compared to other continuous phases.
6). The blend is a blend of different types of polyester resins in an amount of 0.5 to 15% by weight,
7). The shrinkage rate at 200 ° C. by the TMA measurement of the container body is 10% or less,
8). The polyester stretch-molded container is heat-set under a temperature condition of 150 to 230 ° C.,
Is preferred.

According to the present invention, it is also composed of a blend of an ethylene terephthalate polyester resin and a different polyester resin, comprising a continuous phase composed of the ethylene terephthalate polyester resin and a dispersed phase composed of the different polyester resin. There is provided a method for producing a stretch-molded container, which comprises subjecting a preform having a blend layer in which a sea-island dispersion structure is formed, to stretch-blow molding at a stretch temperature of 110 to 120 ° C.
In the production method of the stretch-molded container of the present invention,
1. The blend is a blend of different types of polyester resins in an amount of 0.5 to 15% by weight,
2. Next to stretch blow molding, heat setting is performed at a temperature of 150 to 230 ° C.
Is preferred.

According to the stretch-molded container of the present invention, a polyester stretch container having very little residual strain and excellent stretch balance by strain hardening can be obtained, and in particular, a stretch container having excellent heat resistance and stretch balance by strain hardening. be able to.
In addition, according to the method for producing a stretch-molded container of the present invention, the strain hardening phenomenon can be effectively used regardless of the stretching speed under a high temperature condition of 110 to 120 ° C. A stretch-molded container having both a reduction and a good stretch balance can be produced.

In the stretch-molded container of the present invention, in the polyester stretch-molded container having a layer composed of a blend of an ethylene terephthalate-based polyester resin and a different polyester resin, the layer composed of the blend is the ethylene terephthalate-based polyester resin. It is a first important feature that it has a sea-island dispersion structure composed of a continuous phase composed of the above and a dispersed phase composed of the above-described different polyester resin.
That is, in the stretch-molded container of the present invention, the blend layer forms a sea-island dispersed structure, and the dispersed phase (island part) in the sea-island dispersed structure is less deformed by stretching, and the dispersed phase is a continuous phase (sea part). Only the continuous phase around the film is locally overstretched, resulting in strain hardening similar to that of high-speed stretching, and as a result, such local overstretching contributes effectively to necking propagation, under high temperature conditions. Thus, it is possible to have the same stretching balance (thickness distribution uniformity) as in the case of high-speed stretching.

FIG. 1 is a diagram schematically showing a transmission micrograph of the phase structure of the blend layer at the bottom (unstretched portion) of the stretch-molded container of the present invention. As is apparent from FIG. 1, the blend layer In Japan, a sea-island dispersion structure is formed. In this sea-island dispersion structure, it is particularly preferable that a dispersed phase having a major axis of 0.4 to 10 μm is present at a ratio of 60 to 100%.
FIG. 2 is a diagram schematically showing a transmission polarization micrograph of the phase structure of the blend layer in the body (stretched portion) of the stretch-molded container of the present invention, and FIG. 3 is a view around one dispersed phase. FIG. 2 and FIG. 3 clearly show the degree of stretch orientation of the continuous phase, and in the stretch-molded container of the present invention, as shown in FIG. It is understood that the continuous phase 2 in the vicinity of the dispersed phase 1 is smaller and more highly oriented than the surrounding continuous phase 3.
However, in the transmission polarization micrograph in FIG. 2, the distribution of the degree of stretching orientation is observed as a difference in color tone.

  Such operational effects of the stretch-molded container of the present invention are also apparent from the results of Examples described later. That is, even when a blend of polyethylene terephthalate and a different kind of polyester is blended, when a sea-island dispersion structure is not formed (Comparative Examples 5 to 7), it was excellent under low-temperature stretching conditions. Even if a stretch-molded container having a stretch balance can be molded, the stretch balance deteriorates under high-temperature stretch conditions, and a good stretch balance is obtained as in the case of a polyester stretch-molded container made only of polyethylene terephthalate (Comparative Example 3). I can't. On the other hand, in the stretch-molded container of the present invention in which the sea-island dispersion structure is formed, an excellent stretch balance is obtained not only under low-temperature stretch conditions but also under high-temperature stretch conditions (Example 1). ~ 5).

In the stretch-molded container of the present invention, the second important feature is that the tan δ maximum temperature is 115 ° C. or less in the measured dynamic viscoelasticity of at least the container body, that is, the stretched portion. The small tan δ maximum temperature in the dynamic viscoelasticity measurement value means that the glass transition temperature of the amorphous part is close to the glass transition temperature in the unconstrained state, that is, the polymer caused by residual strain. This means that there is little chain tension and restraint, and this makes it possible to suppress shrinkage deformation accompanying strain relaxation during container heat treatment.
This is also clear from the results of Examples described later. That is, in the stretch molded container having a tan δ maximum temperature higher than 115 ° C. in the measured dynamic viscoelasticity of the container body, a large residual strain remains (Comparative Examples 4 and 8), whereas the container body It is clear that the residual strain is extremely reduced in the stretch-molded container having a tan δ maximum temperature of 115 ° C. or lower in the measured dynamic viscoelasticity (Examples 1 to 5).

[Blend layer]
As described above, the stretch-molded container of the present invention has at least a layer composed of a blend of an ethylene terephthalate-based polyester resin and a polyester resin of a different kind, and the blend layer contains an ethylene terephthalate-based polyester resin as a continuous phase. It is important to form a sea-island dispersion structure in which the dispersed phase (island part) is a (sea part) and a dissimilar polyester resin. In order to form such a sea-island dispersion structure, a polyester resin described later is blended. Can be formed more satisfactorily.

(Ethylene terephthalate polyester resin)
In the stretch-molded container of the present invention, the ethylene terephthalate-based polyester resin constituting the continuous phase (sea portion) of the blend layer has a dicarboxylic acid component of 50% or more, particularly 80% or more of the dicarboxylic acid component. As the diol component, a polyester resin in which 50% or more, particularly 80% or more of the diol component is ethylene glycol is used. Such an ethylene terephthalate-based polyester resin satisfies mechanical properties, thermal properties, and molding processability in a well-balanced manner among polyester resins.

Of course, it can also contain carboxylic acid components other than terephthalic acid. Examples of carboxylic acid components other than terephthalic acid include isophthalic acid, naphthalenedicarboxylic acid, p-β-oxyethoxybenzoic acid, and biphenyl-4,4′-dicarboxylic acid. , Diphenoxyethane-4,4′-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, adipic acid, sebacic acid and the like.
As the diol component, 50% or more, particularly 80% or more of the diol component is preferably ethylene glycol in view of mechanical properties and thermal properties. As diol components other than ethylene glycol, 1,4-butanediol, Examples include propylene glycol, neopentyl glycol, 1,6-hexylene glycol, diethylene glycol, triethylene glycol, cyclohexane dimethanol, ethylene oxide adduct of bisphenol A, glycerol, and trimethylolpropane.

  Further, the dicarboxylic acid component and the diol component may contain a tribasic or higher polybasic acid and a polyhydric alcohol. For example, trimellitic acid, pyromellitic acid, hemimellitic acid, 1,1,2,2 -Ethanetetracarboxylic acid, 1,1,2-ethanetricarboxylic acid, 1,3,5-pentanetricarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, biphenyl-3,4,3 ', 4 Polybasic acids such as' -tetracarboxylic acid and polyvalent acids such as pentaerythritol, glycerol, trimethylolpropane, 1,2,6-hexanetriol, sorbitol, 1,1,4,4-tetrakis (hydroxymethyl) cyclohexane Mention may be made of alcohol.

(Different polyester resin)
In the stretch-molded container of the present invention, the polyester resin constituting the dispersed phase (island portion) of the blend layer is different from the above-described ethylene terephthalate-based polyester resin and is dispersed in the continuous phase of the ethylene terephthalate-based polyester resin. As long as it can exist as a polyester resin composed of the above-described dicarboxylic acid component and diol component, it is necessary to form a sea-island dispersion structure, so an ethylene terephthalate polyester resin that forms a continuous phase It is important that they are incompatible with each other.

Further, in order for the continuous phase around the dispersed phase in the stretched portion described above to be highly stretched and oriented as compared to other continuous phases, the glass is 10 ° C. or higher than the glass transition temperature Tg (m) of the ethylene terephthalate-based polyester resin. It is particularly preferable to use a polyester resin having a high transition temperature Tg (d). Since such a high Tg polyester resin is more elastic than the ethylene terephthalate polyester resin constituting the continuous phase, it is less likely to be stretched than the continuous phase, and as a result, the continuous phase around the dispersed phase is not continuous. It is in a state of being over-stretched locally compared to the phase, and as described above, the same strain hardening as in the case of high-speed stretching under high-temperature conditions can be obtained, and a stretch-molded container excellent in stretching balance can be obtained. It becomes.
Examples of such a polyester resin include a polyester resin containing naphthalenedicarboxylic acid as a constituent monomer and a polyester resin containing cyclohexane dimethanol as a constituent monomer. Moreover, in order to raise incompatibility with the ethylene terephthalate type polyester resin which forms a continuous phase, it is important that there is much content of these structural monomers.

  As the polyester resin containing naphthalenedicarboxylic acid as a constituent monomer, a polyester resin in which 95 mol% or more of the dicarboxylic acid component is naphthalenedicarboxylic acid is preferable, and homopolyethylene naphthalate is preferable. It is known that the polyester resin containing a large amount of naphthalenedicarboxylic acid has a glass transition temperature in the range of 100 to 120 ° C. Ethylene terephthalate-based polyester resin and polyethylene naphthalate are easily transesterified, and when the amount of transesterification increases, a clear phase structure separation cannot be formed, local overstretching does not occur, and the effects of the present invention cannot be obtained. In addition, as the crystallization rate decreases, the efficiency of heat setting decreases and the heat resistance deteriorates. Therefore, the kneading time and kneading temperature can be adjusted so as to suppress transesterification during blending. preferable. In view of the decrease in Tg due to the transesterification reaction, it is preferable to use a polyester resin having a glass transition temperature Tg (d) higher by 20 ° C. or more than Tg (m).

  The polyester resin containing cyclohexane dimethanol as a constituent monomer is preferably a polyester resin in which 60 mol% or more of the diol component is cyclohexane dimethanol. It is known that the polyester resin containing a large amount of cyclohexanedimethanol has a glass transition temperature in the range of 80 to 100 ° C. Since the ethylene terephthalate-based polyester resin and the cyclohexanedimethanol-containing polyester resin are difficult to transesterify, it is preferable to use a polyester resin having a glass transition temperature Tg (d) higher by 10 ° C. or more than Tg (m) during blending.

(Sea-island dispersion structure)
The blend layer of the present invention is formed by blending the above-mentioned ethylene terephthalate polyester resin and a different polyester resin, and in the unstretched portion, a dispersed phase having a major axis of 0.4 to 10 μm is formed. In the stretched portion, a sea-island dispersion structure is formed in which the continuous phase around the dispersed phase is highly stretched and oriented as compared with other continuous phases.
In order to form such a sea-island dispersion structure, the melt viscosity, the blending ratio, and the composition of the ethylene terephthalate-based polyester resin that forms the continuous phase and the different polyester resins that form the dispersed phase are important.
The melt viscosity preferably has a relatively high melt viscosity relative to the ethylene terephthalate polyester resin in which the dissimilar polyester resin forming the dispersed phase forms the continuous phase.

In the melt mixing as described above, generally, a large amount of component tends to be a continuous phase and a small amount of component tends to be a dispersed phase. Therefore, in order to achieve the target sea-island structure, it is necessary to consider the balance between the above-mentioned melt viscosity and composition, but in the present invention, 85% by weight or more of an ethylene terephthalate-based polyester resin that forms a continuous phase is used. Is suitable for forming the above-described sea-island dispersion structure. Preferably, the blending ratio of the ethylene terephthalate-based polyester resin and the polyester resin different from this is generally 85:15 to 99.5 by weight. : 0.5, particularly in the range of 88:12 to 95: 5.
In particular, when polyethylene naphthalate or cyclohexanedimethanol-containing polyester resin is used as the dissimilar polyester resin, it is preferably used in an amount of 0.5 to 15% by weight. When the amount is larger than the above range, there is a possibility that a mutual network structure is formed instead of the sea-island dispersion structure, the stretching stress is increased, the residual strain is increased, and it is difficult to obtain good heat resistance.

  The stretched container of the present invention has a feature that the shrinkage rate at 200 ° C. by TMA measurement (thermomechanical measurement) of the container body is 10% or less. TMA measurement is a method of measuring deformation such as expansion and contraction in a sample as a function of temperature, and in particular, the shrinkage behavior of a stretched molded product at 200 ° C. is dominated by residual strain regardless of its crystallinity. . Therefore, a small shrinkage rate when the stretched molded product is exposed to a high temperature means that the amount of residual strain present in the molded product is small. A small amount of residual strain leads to an increase in heat resistance as it is, and particularly when performing heat setting, a small amount of residual strain to be removed is effective in obtaining excellent heat resistance. .

[Layer structure]
The stretch-molded container of the present invention only needs to have at least one blend layer as described above, and can be a single layer container of the blend layer, or another thermoplastic resin layer can be combined with the blend layer. A container having a multilayer structure can also be used.
In the case of a container having a multilayer structure, it is particularly preferable that the polyester resin constitutes the inner and outer layers. Although the thickness of the blended material layer and the layer provided as necessary cannot be generally defined by the layer structure or the like, it can be set similarly to a conventionally known polyester stretch-molded container.

  As the thermoplastic resin other than the above-mentioned polyester resin, any resin that can be stretch blow molded can be used, and is not limited thereto, but is not limited to this, and olefin resins such as ethylene-vinyl alcohol copolymer and cyclic olefin polymer. And a polyamide resin such as a xylylene group-containing polyamide. Also, an oxygen-absorbing gas barrier resin composition in which a xylene group-containing polyamide is mixed with a diene compound and a transition metal catalyst, recycled polyester (PCR (resin that recycles used bottles), SCR (resin generated in a production plant) ) Or a mixture thereof) or the like. These recycled polyester resins preferably have an intrinsic viscosity (IV) measured by the method described above in the range of 0.65 to 0.75 dL / g.

Moreover, in order to adhere | attach an inner layer or an outer layer, and an intermediate | middle layer, adhesive resin can also be interposed. As the adhesive resin, an acid-modified olefin resin or polyester resin obtained by graft polymerization of maleic acid or the like, or an amorphous polyester resin or polyamide resin can be used.
The polyester resin or thermoplastic resin other than the polyester resin used in the present invention has various additives such as a colorant and an ultraviolet absorber as long as the quality of the biaxially stretched container as the final molded product is not impaired. , Mold release agents, lubricants, nucleating agents, inorganic layered compounds for increasing gas barrier properties, and the like.

[Production method]
The stretch-molded container of the present invention comprises a blend of an ethylene terephthalate polyester resin and a different polyester resin, and comprises a continuous phase made of the ethylene terephthalate polyester resin and a dispersed phase made of the different polyester resin. A preform having a blend layer in which a sea-island dispersion structure is formed can be manufactured by stretch blow molding under the condition of a stretching temperature of 110 to 120 ° C., whereby the stretch molding having the above-described characteristics. The container can be suitably manufactured regardless of the stretching speed.

  As described above, under high-temperature stretching conditions that can impart excellent heat resistance of the stretched molded product, the stretching balance will deteriorate unless high-speed stretching is performed, but there is a limit to increasing the stretching speed, Conventionally, stretch molding is performed at a low temperature (95 to 105 ° C.) at the expense of the merit of high-temperature stretching such as low residual strain. On the other hand, in the manufacturing method of the stretch-molded container of the present invention, when the preform having the blend layer in which the sea-island dispersion structure is formed is used, stretching is performed under a high temperature condition of 110 to 120 ° C. In addition, it is possible to obtain a stretch-formed container having an excellent stretch balance by using a conventional stretch molding apparatus without increasing the stretching speed as much as possible.

The preform used for forming the stretch-molded container of the present invention is formed by a conventionally known method such as injection molding or compression molding using the aforementioned blend.
In the present invention, in the stretch blow molding, it is important to stretch the molded preform by heating to a stretching temperature of 110 to 120 ° C., preferably 115 to 120 ° C., and the stretching temperature is in the above range. By being in such a high temperature region, it becomes possible to reduce residual strain. Here, the heating temperature of the preform, that is, the stretching temperature is the outer surface temperature of the preform immediately before the stretch blow molding, and can be measured by a radiation thermometer, a thermal image measuring instrument, or the like.
In order to heat the preform uniformly and at high speed to the above temperature, it is necessary to heat the preform from inside and outside of the preform by means such as hot air, infrared heater, high frequency induction heated iron core internal insertion, etc. preferable.

The preform is supplied into a publicly known stretch blow molding machine, set in a mold, stretched and stretched in the axial direction by pushing a stretch rod, and stretched and molded in the circumferential direction by blowing blow air. In order to efficiently perform stretch molding at a high temperature in the method of the present invention, it is preferable to blow hot air at 100 to 150 ° C. as blow air.
In the present invention, it is possible to obtain the same stretching balance as when stretching at a higher speed than the set speed, regardless of the stretching speed.
Further, the effect of achieving both the low residual strain and the stretch balance obtained in the present invention can be obtained regardless of the heat setting conditions, but in particular, when heat resistance is required, heat setting is performed. Is preferred.
Further, in the present invention, since stretch blow molding is performed at a temperature higher than usual, there is a risk of oligomer precipitation due to high temperature stretching. Therefore, in order to prevent this, it is preferable to use a surface-treated mold. Further, in order to increase the releasability and suppress deformation after molding, it is preferable to circulate room temperature or cooling air in the blow bottle as cooling air at the time of releasing to reliably cool the molded product.
The stretch ratio in the biaxially stretched container is suitably 1.5 to 25 times in terms of area ratio. Among these, the axial stretch ratio is 1.2 to 6 times, and the circumferential stretch ratio is 1.2 to 4.5. It is preferable to double.

According to the method for producing a stretch-molded container of the present invention, the strain hardening phenomenon can be effectively utilized regardless of the stretching speed under a high temperature condition of 110 to 120 ° C. It becomes possible to form a stretch-molded container having a good stretch balance.
In addition, as a result of the examination so far, it has a good stretching balance, and the shrinkage rate at 200 ° C. in the TMA measurement of the container body is 10% or less. It is clear that it contributes to That is, the heat resistance of the stretching container of the present invention has a relatively high heat resistance as compared with a stretching container formed by the conventional method under the same heat setting conditions.
For example, high heat resistance is not required as in an aseptic filling container, but in order to impart heat resistance to the processing heat during container sterilization, it was necessary to perform heat fixation at about 120 ° C. in the conventional method. In the stretching container of the invention, it is not necessary to perform heat fixing or the heat fixing temperature can be lowered, and the energy required for heat fixing can be reduced.
In addition, when medium heat resistance is required, such as heat resistant (hot filling) applications and heat and pressure application containers, the stretching container of the present invention can lower the heat fixing temperature, and can be used for heat fixing. The energy required can be reduced.
Furthermore, in applications that require high heat resistance such as boiling and retort treatment that requires heat sterilization exceeding 100 ° C., the conventional method can be achieved by heat-setting the stretching container of the present invention at a high temperature. It becomes possible to make a stretch-molded container having high heat resistance that has not been obtained, and in particular, the advantages of the stretch container of the present invention and the production method thereof can be effectively utilized.

In the present invention, as described above, in order to obtain high heat resistance in applications where heat sterilization exceeding 100 ° C. such as boil and retort treatment is performed, 150 to 230 ° C., preferably 150 to 180 ° C. after stretch molding. It is preferable to heat-fix at the temperature. The heat setting can be performed by means known per se, and can also be performed by a one-mold method performed in a blow mold, or a two-mold performed in a heat mold separate from the blow mold. It can also be done by law.
From the viewpoint of handling properties, it is desirable to cool with cold air when taking out from the mold after heat setting.
The present invention also relates to a method for improving the heat resistance of the stretch blow container where the stretch processing is performed. In a portion where the stretch processing is not performed due to a molding method such as a container mouth, the thickness is set to be thick. Alternatively, heat resistance can be improved by heat crystallization before blow molding.

I. Materials The main material is polyethylene terephthalate resin [Homo PET] (RT543CTHP: Nihon Unipet Co., Ltd.), and the blend polyester type is polyethylene naphthalate resin [Homo PEN] (TN8065S: Teijin Chemicals Ltd.), isophthalic acid modified. 1,4-cyclohexanedimethylene terephthalate resin [IA modified PCT] (Thermex 13319: Eastman Chemical), polybutylene terephthalate resin [Homo PBT] (Duranex 500FP: Polyplastics Co., Ltd.), amorphous cyclohexane di Using methanol-containing polyethylene terephthalate resin [amorphous CHDM-modified PET] (S2008: SK Chemical) or polyethylene naphthalate-polyethylene terephthalate copolymer [PEN-PET copolymer] (TN8756: Teijin Chemicals Ltd.) Various blends are made by dry blending the material and each blended polyester in a pellet state at a specified mixing ratio. Dedicated to In addition, each resin was dried before mixing.

II. Molding of stretch blow bottles The above resin pellets, dry blended at a specified ratio, are supplied to the hopper of an injection molding machine (NN75JS: Niigata Engineering Co., Ltd.) with a barrel set temperature of 280 ° C and a cycle time of 30 seconds. Then, a bottle preform having a weight of 28 g and a diameter of 28 mm was formed by injection molding. After that, the body of the preform, whose mouth has been whitened by heating in advance, is heated to a predetermined surface temperature by a heated iron core from the inside with an infrared heater from the outside, and then stretched by biaxial stretching and blowing. The stretched blow bottle shown in FIG. 4 having a capacity of 500 ml with a magnification of 3 times in length, 3 times in width, and 9 times in area was molded. The mold temperature was set to room temperature (25 ° C.), 150 ° C. and 180 ° C. In addition, room temperature (25 ° C.) cooling air was introduced into the container at the time of mold release.

III. Measurement 1. Measurement of Glass Transition Temperature [Tg (d) -Tg (m)] The sample (10 mg) cut out from the material pellet was measured using a differential scanning calorimeter (DSC7: manufactured by PERKIN ELMER). The measurement temperature profile was performed in the following order.
(1) Temperature rise from 25 ° C to 290 ° C at 10 ° C / min (2) Hold at 290 ° C for 5 minutes (3) Temperature drop from 290 ° C to 25 ° C at 300 ° C / min (4) Temperature rise from 25 ° C to 290 ° C 3. Temperature rise at 10 ° C./min (5) Hold at 290 ° C. for 5 minutes (6) Temperature drop from 290 ° C. to 25 ° C. at 10 ° C./min. The glass transition temperature was measured in the temperature rise profile.
The glass transition temperature of Homo PET corresponding to Tg (m) was 78.6 ° C.

2. Tan δ in dynamic viscoelasticity measurement
A test piece having a size of 10 mm × 30 mm was cut from the bottle body so that the long side direction was the bottle height direction, and the measurement was performed using a viscoelasticity spectrometer (EXSTAR6000DMS: Seiko Instruments Inc.). The measurement conditions are shown below.
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. From the obtained tan δ curve, a temperature at which tan δ becomes maximum (tan δ maximum temperature) was derived.

3. Observation of phase structure (1) Preparation of observation sample A microtome (REICHERT ULTRACUTS: equipped with a glass knife) was cut out from the lower part of the neck ring, which is the unstretched part of the molded stretch blow bottle, and from the center part of the body wall, which is the stretch part. Leica Co.) was used to cut an observation sample having a thickness of 5 μm at a cutting speed of 1.0 mm / sec under liquid nitrogen cooling. At this time, the observation surface was set to be horizontal with the bottle ground contact surface. This cut piece was placed on a slide glass, immersed in an immersion liquid (Biolite: Koken Co., Ltd.), covered with a cover glass, and subjected to various microscope observations.

(2) Measurement of phase structure of unstretched part and 0.4-10 μm domain existence ratio (%) About the sample cut out from the neck ring lower part, which is the unstretched part of the stretch blow bottle, up to 1000 times with a transmission light microscope The phase structure was enlarged and observed. Moreover, the ratio of the number of discontinuous phases having a major axis of 0.4 to 10 μm was calculated from the 1000-fold magnified photograph (observation range 88 × 70 μm ² ) using the following formula. Here, the discontinuous phase is in a state where it can be confirmed by visual observation that it is clearly surrounded by the continuous phase.
Domain existence ratio (%) = major axis 0.4-10μm number of discontinuous phases / total number of discontinuous phases x 100

(3) Determination of presence of local overstretched part in stretched part About the sample cut out from the center part of the body wall of the stretched blow bottle, the phase structure was enlarged up to 1000 times using a polarizing microscope in which polarizing plates were arranged in crossed Nicols. Observations were made. At this time, the observation sample was arranged in the diagonal direction between the crossed Nicols. From the observed image, it was judged that there was no local overstretching when the entire sample showed a uniform color tone. Further, in the sample, when unevenness in color tone showing the orientation degree distribution as shown in FIG. 3 was observed, it was judged that there was local overstretching.

4). Determination of Stretch Balance Biaxial stretch blow was performed in advance by placing dots at 10 mm intervals from the neck ring toward the bottom of the preform body with an oil-based magic. In this blow bottle, those having uniform hit point intervals in the trunk were determined to have good stretching balance.

5. 200 ° C. Shrinkage in TMA Measurement A test piece 10 mm × 30 mm larger from the bottle body is cut out so that the long side direction is the bottle height direction, and measured using a viscoelastic spectrometer (EXSTAR6000DMS: Seiko Instruments Inc.). Went. The measurement conditions are shown below.
Measurement mode: F control mode Test piece initial gauge distance: 20mm
Stress profile: unweighted Temperature rise profile: From the shrinkage amount curve obtained by raising the temperature from 25 ° C. to 210 ° C. at 2 ° C./min, a shrinkage rate curve was calculated using the following equation.
S (shrinkage rate:%) = X / L × 100
X: Shrinkage at each temperature (mm)
L: Initial gauge distance (mm) = 20 mm
The amount of shrinkage at the start of measurement was set to 0, and the shrinkage rate when the temperature reached 200 ° C. (shrinkage rate at 200 ° C.) was derived from the calculated shrinkage rate curve.

Example 1
Polyethylene terephthalate resin (RT543CTHP: Nihon Unipet Co., Ltd.) is used as the main material, and polyethylene naphthalate resin [Homo PEN] (TN8065S: Teijin Kasei Co., Ltd.) is used as the blend polyester species. Blend polyester type = 95: 5 was dry blended and supplied to an injection molding machine hopper, and a preform for a bottle having a diameter of 28 mm was injection molded under the conditions of a set temperature of 280 ° C. and a cycle time of 30 seconds.
The preform mouth was crystallized in advance and then biaxially stretched to form a stretch blow bottle having a capacity of 500 ml and capable of aseptic filling. At this time, the heating temperature of the preform, that is, the stretching temperature was set to 115 ° C., and the temperature of the blow mold was set to room temperature (25 ° C.).
Each part of this bottle was cut out and the above measurements were performed.

(Example 2)
A stretch blow bottle corresponding to aseptic filling was prepared in the same manner as in Example 1 except that the material was dry blended in a ratio by weight of main material: blended polyester type = 90: 10 and supplied to the injection molding machine hopper. Each measurement of was performed.

(Example 3)
A stretch blow bottle compatible with aseptic filling was prepared in the same manner as in Example 1 except that the material was dry blended at a weight ratio of main material: blend polyester type = 85: 15 and supplied to the injection molding machine hopper. Each measurement of was performed.

Example 4
A stretched blow bottle was prepared in the same manner as in Example 2 except that the heat setting temperature of the blow mold was set to 180 ° C. to give heat resistance, and the above measurements were performed.

(Example 5)
A stretch blow bottle with heat resistance was prepared in the same manner as in Example 4 except that isophthalic acid-modified 1,4-cyclohexanedimethylene terephthalate resin (Thermex 13319: Eastman Chemical) was used as the blend polyester species. Each of the above measurements was performed.

(Example 6)
Except that the heat setting temperature of the blow mold was set to 150 ° C., a stretch blow bottle imparted with heat resistance was prepared in the same manner as in Example 5 and the above measurements were performed.

(Comparative Example 1)
A stretch blow bottle for aseptic filling was prepared in the same manner as in Example 1 except that only the polyethylene terephthalate resin (RT543CTHP: Nippon Unipet Co., Ltd.) was used as the material, and the heating temperature of the preform was set to 100 ° C. Each of the above measurements was performed.

(Comparative Example 2)
A stretch blow bottle was prepared in the same manner as in Comparative Example 1 except that the heat setting temperature of the blow mold was set to 180 ° C. and heat resistance was imparted, and the above measurements were performed.

(Comparative Example 3)
Except that the preform heating temperature was set to 115 ° C., a stretch blow bottle corresponding to aseptic filling was prepared in the same manner as in Comparative Example 1, and the above measurements were performed.

(Comparative Example 4)
A stretch blow bottle corresponding to aseptic filling was prepared in the same manner as in Example 1 except that the material was dry blended at a ratio of main material: blend polyester type = 70: 30 and supplied to the injection molding machine hopper, as in Example 1. Each measurement of was performed.

(Comparative Example 5)
A stretch blow bottle imparted with heat resistance was prepared in the same manner as in Example 4 except that polybutylene terephthalate resin [Homo PBT] (Duranex 500FP: Polyplastics Co., Ltd.) was used as the blended polyester species. Each measurement of was performed.

(Comparative Example 6)
A stretch blow bottle imparted with heat resistance in the same manner as in Example 4 except that an amorphous cyclohexanedimethanol-containing polyethylene terephthalate resin [amorphous CHDM-modified PET] (S2008: SK Chemical) was used as the blend polyester species. It made and performed each said measurement.

(Comparative Example 7)
A stretch blow bottle imparted with heat resistance in the same manner as in Example 4 except that polyethylene naphthalate-polyethylene terephthalate copolymer [PEN-PET copolymer] (TN8756: Teijin Chemicals Ltd.) was used as the blend polyester species. And the above measurements were performed.

(Comparative Example 8)
Except that the preform heating temperature was set to 105 ° C., a stretch blow bottle with heat resistance was prepared in the same manner as in Example 5 and the above measurements were performed.
Table 1 shows the results of the above measurements.

It is a figure which represents typically the transmission micrograph of the blend layer of the bottom part of the stretch-molded container of this invention. It is a figure which represents typically the transmission polarized light micrograph of the blend layer of the trunk | drum of the stretch-molded container of this invention. It is a figure which represents typically the extent of the extending | stretching orientation of the continuous phase around one dispersed phase of the blend layer of a trunk | drum. It is a reference drawing of the biaxial stretch blow bottle created in the example.

Claims (12)

In a stretch-molded container having a layer composed of a blend of an ethylene terephthalate-based polyester resin and a different polyester resin,
The layer composed of the blend has a sea-island dispersion structure composed of a continuous phase composed of the ethylene terephthalate-based polyester resin and a dispersed phase composed of the dissimilar polyester resin, and at least a dynamic viscoelasticity measurement value of the container body. A stretch-molded container having a tan δ maximum temperature of 115 ° C. or lower.   The stretch-molded container according to claim 1, wherein the dissimilar polyester resin contains naphthalenedicarboxylic acid as a constituent monomer.   The stretch-molded container according to claim 1, wherein the dissimilar polyester resin contains cyclohexanedimethanol as a constituent monomer.   The glass transition temperature Tg (m) of the ethylene terephthalate-based polyester resin and the glass transition temperature Tg (d) of a different polyester resin satisfy a relationship of Tg (d)-Tg (m) ≥ 10 (° C). The stretch-molded container according to any one of 1 to 3.   The stretch-molded container according to any one of claims 1 to 4, wherein in the sea-island dispersion structure, a disperse phase having a major axis of 0.4 to 10 µm is present at a ratio of 60 to 100% in an unstretched portion. .   The stretch-molded container according to any one of claims 1 to 5, wherein the sea-island dispersion structure has a stretched portion in which a continuous phase around the dispersed phase is highly stretched and oriented as compared with other continuous phases.   The stretch-molded container according to any one of claims 1 to 6, wherein the blend is a mixture of different types of polyester resins in an amount of 0.5 to 15% by weight.   The stretch-molded container according to any one of claims 1 to 7, wherein a shrinkage rate at 200 ° C as measured by TMA of the container body is 10% or less.   A stretching container in which the stretch-molded container according to claim 1 is heat-set under a temperature condition of 150 to 230 ° C.   This is composed of a blend of an ethylene terephthalate-based polyester resin and a different type of polyester resin, and a sea-island dispersion structure is formed which comprises a continuous phase made of the ethylene terephthalate-based polyester resin and a dispersed phase made of the different type of polyester resin. A method for producing a stretch-molded container, comprising subjecting a preform having a blend layer to stretch-blow molding at a stretch temperature of 110 to 120 ° C.   The method for producing a stretch-molded container according to claim 10, wherein the blend is a mixture of different kinds of polyester resins in an amount of 0.5 to 15% by weight.   The method for producing a stretch-molded container according to claim 10 or 11, wherein, after the stretch blow molding, heat setting is performed under a temperature condition of 150 to 230 ° C.

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