JP2006056518A - Packaging container, manufacturing method of resin composition, and manufacturing method of highly transparent recyclable resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging container which is obtained by molding a blended material including terephthalate-based polyester resin and naphthalate-based polyester resin, does not contain a coloring agent such as a pigment, has shielding properties to the visible light, and is excellent in recyclability. <P>SOLUTION: The packaging container has a blended material layer including terephthalate-based polyester resin and naphthalate-based polyester resin as a container wall constituting layer. In a non-drawn portion of the container, the blended material layer has a sea-island structure consisting of a continuous phase of the terephthalate-based polyester resin and a discontinuous phase of the naphthalate-based polyester resin and has a presence ratio of the discontinuous phase with a longer diameter of 0.4-10 μm in a range of 50-100%, and a haze of the barrel of the container is 40% or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an opaque packaging container excellent in recyclability and a method for producing a recycled resin using the packaging container. More specifically, the present invention uses a blend of a terephthalate polyester resin and a naphthalate polyester resin. The present invention relates to an opaque packaging container formed and a method for producing a recycled resin using the container.

  Currently, polyester-based packaging containers represented by polyethylene terephthalate (PET) are excellent in properties such as transparency, heat resistance, and gas barrier properties, and are widely used in various applications.

  Recently, a packaging container formed using a blend of polyethylene naphthalate (PEN) with PET has also been proposed (Patent Document 1). That is, PEN is more expensive than PET, but has a high glass transition point (Tg), and the combined use of PEN improves properties such as heat resistance and gas barrier properties. In addition, PET and PEN are inherently incompatible, but a copolymer component between PET and PEN is generated by transesterification by melt-kneading, and as a result, the affinity between the two is enhanced and excellent. Since the transparency can be maintained, the packaging container made of such a blend is excellent in transparency.

  On the other hand, in recent years, the reuse of resources has been strongly demanded, and with respect to the polyester container as described above, a used container is collected and reused for various purposes as a recycled resin.

  By the way, as for the contents stored in the packaging container, those that are easily altered by light, for example, certain beverages, pharmaceuticals, cosmetics, etc., are molded using a resin composition in which a colorant such as a pigment is blended in a resin. Provided in a colored container or an opaque container. However, from the viewpoint of resource reuse, it is not desirable to add a colorant (it would be difficult to ensure transparency in the recycled resin). For this reason, the use of a transparent container is required. Therefore, it is necessary to improve the recyclability of colored containers or opaque containers suitable for accommodating photo-denatured contents.

Regarding the blend of PET and PEN described above, Patent Document 2 discloses a blend of a polyethylene terephthalate resin and a polyethylene naphthalate resin, and has a transesterification rate of 3 to 30% or less. And a container molded using such a resin material is disclosed to have a pearly luster.
Patent No. 2723140 Japanese Patent Laid-Open No. 11-80374

  That is, the container having the pearly gloss disclosed in Patent Document 2 suppresses the transesterification rate between PET and PEN and disperses them in an incompatible state, thereby producing a pearly gloss due to multiple reflections. To do.

  However, the container of Patent Document 2 described above has not reached a level that can be applied to a photo-altering content in terms of visible light blocking property (opacity). In addition, even if visible light blocking properties can be imparted by increasing the thickness of the container wall, it is necessary to add a large amount of expensive PEN resin in order to form the phase structure necessary to develop pearly luster. Yes, not economical.

Therefore, the object of the present invention is obtained by molding a blend of a terephthalate-based polyester resin and a naphthalate-based polyester resin, and is efficient with respect to the amount of blended PEN without containing a colorant such as a pigment. An object of the present invention is to provide a packaging container having good visible light blocking properties and excellent recyclability.
The other object of this invention is to provide the resin composition used for manufacture of the said packaging container.
Still another object of the present invention is to provide a method for producing a recycled resin using the packaging container.

  According to the present invention, a packaging container having a blend layer of terephthalate-based polyester resin and naphthalate-based polyester resin as a container wall constituting layer, and in the unstretched portion of the container, the blend layer is a terephthalate-based polyester. It has a sea-island structure composed of a continuous phase of resin and a discontinuous phase of naphthalate-based polyester resin, and the proportion of discontinuous phases having a major axis of 0.4 to 10 μm is in the range of 50 to 100%. The packaging container is characterized in that the container body has a haze of 40% or more.

In the above packaging container,
(1) The blend layer has a transesterification rate of 20% or less between the terephthalate-based polyester resin and the naphthalate-based polyester resin.
(2) The visible light transmittance of 400 to 520 nm is 30% or less in the body part,
Is preferred.

According to the present invention, 100 parts by weight of terephthalate polyester resin and 0.01 to 50 parts by weight of naphthalate polyester resin having a melt viscosity of 5 times or more with respect to the terephthalate polyester resin are 270 to 300 ° C. A method for producing a resin composition excellent in visible light blocking property, characterized by melting and kneading so that the transesterification rate does not exceed 20% at a temperature of 5 ° C., is provided.
The above packaging container can be manufactured using the resin composition thus obtained. The melt viscosity is a value at each melt kneading temperature (270 to 300 ° C.) and a shear rate of 91.2 sec ⁻¹ .

  According to the present invention, there is also provided a method for producing a recycled resin excellent in transparency, characterized in that the packaging container is crushed and melt-extruded so that the transesterification rate is 12% or more.

  The packaging container of the present invention has a layer made of a blend of a terephthalate polyester resin typified by PET and a naphthalate polyester resin typified by PEN in the vessel wall. By forming a uniform sea-island dispersion structure, the container has a very high haze of 40% or more without blending colorants such as pigments, has a visible light blocking property, and has excellent recyclability. is there.

  Please refer to FIGS. 1 and 2 of the accompanying drawings. FIG. 1 is a diagram conceptually showing the relationship between the composition of PEN and haze in a blend of PET and PEN in a state where no transesterification reaction has been performed, and FIG. 2 shows the present invention. It is a figure which shows the dispersion structure of the blend layer in the unstretched part in the packaging container of.

  As can be seen from FIG. 1, as the PEN content increases, the haze increases and the visible light blocking property increases. However, when the amount exceeds a certain amount, the haze decreases and the visible light blocking property decreases (ie, the visible light blocking property decreases). Transparency increases). That is, when PEN is less than a certain amount, a sea-island dispersion structure is formed in which PET is a matrix (continuous phase) and PEN is an island (discontinuous phase). It is considered that the haze increases as the size of becomes closer to the wavelength size of visible light. On the other hand, as the PEN increases, the sea-island dispersion structure as described above becomes a dispersion structure in which a continuous phase or discontinuous phase of PET and a continuous phase or discontinuous phase of PEN are mixed, and when the PEN increases, A mutual network dispersion structure in which the continuous phase and the continuous phase of PEN are intertwined with each other, and the haze decreases. In other words, when the dispersion structure changes from the mixed region to the mutual network structure, the dispersion structure exceeds the visible light wavelength size, so that the light scattering effect is reduced, and the transparency gradually increases with the appearance of pearly luster. It is done.

  However, in the present invention, since the dispersion structure is adjusted in the region surrounded by ◯ in FIG. 1, high haze is ensured without blending of a colorant such as a pigment. That is, in the packaging container of the present invention, in the unstretched portion, as shown in FIG. 2, the blend layer has a sea-island structure composed of a continuous phase A of terephthalate-based polyester resin and a discontinuous phase B of naphthalate-based polyester resin. And the ratio of the discontinuous phase B having a major axis of 0.4 to 10 μm is in the range of 50 to 100%. By such a sea-island dispersion structure, the haze of the container body is 40% or more, and an extremely high visible light blocking property can be obtained, so that it can be effectively applied as a container for contents that are degenerate to visible light. It is. In order to obtain the maximum visible light blocking effect in the present invention, it is preferable that the ratio of the discontinuous phase B is 95% or more, particularly 100%.

  The sea-island dispersion structure as described above is calculated by cutting the unstretched portion of the container, observing the cut surface with a microscope, and determining the number ratio of discontinuous phases of a predetermined size per unit area. Is done.

  Further, the unstretched part of the container means the neck or bottom center part of the container, and the sea-island dispersion structure is specified in such a part because the container body is stretched, so it is discontinuous. This is because it is difficult to accurately measure the size and the like.

  Moreover, since the packaging container of the present invention having the visible light blocking property as described above does not use a colorant such as a pigment, it is excellent in recycling suitability and can easily produce a recycled resin having transparency. Has advantages. That is, in order to form the sea-island dispersion structure, the transesterification rate between the terephthalate-based polyester resin and the naphthalate-based polyester resin is suppressed to 20% or less. When the transesterification rate is high, the compatibility of both polyester resins increases, and it becomes difficult to form the sea-island dispersion structure as described above. At the same time, even if the sea-island dispersion structure is formed, the phase interface becomes unclear and visible light is visible. This is because the transmittance increases. Therefore, in order to produce a recycled resin using the packaging container of the present invention, the packaging container may be pulverized and the transesterification rate increased by melt extrusion, which makes it easy to achieve transparency. Moreover, as is clear from FIG. 1 described above, the sea-island dispersion structure in the packaging container of the present invention is present in the most mixed region or region close to the mutual network structure, and terephthalate polyester per unit weight of naphthalate polyester resin. Since the interfacial area with the resin is large, the transesterification reaction of both proceeds rapidly, and the transparency can be achieved quickly.

[Production of raw resin composition]
As a raw material resin composition used for manufacturing the packaging container of the present invention, a blend of a terephthalate polyester resin and a naphthalate polyester resin is used.

1. Terephthalate-based polyester resin The terephthalate-based polyester resin is a polyester resin containing a dibasic carboxylic acid unit mainly composed of terephthalic acid, and the ethylene terephthalate unit occupies most of the ester repeating units, preferably 80 mol% or more. Ethylene terephthalate-based crystalline polyester is desirable, and those having a glass transition point (Tg) of 50 to 90 ° C. and a melting point (Tm) of 220 to 260 ° C. are preferred, and their intrinsic viscosity (IV) Is generally in the range of 0.4 to 1.5, in particular 0.6 to 1.0. In particular, homopolyethylene terephthalate is preferable from the viewpoint of heat resistance, but a copolyester containing a small amount of ester units other than ethylene terephthalate units can also be suitably 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, Pp-β-oxyethoxybenzoic acid, naphthalene 2,6-dicarboxylic acid, diphenoxyethane-4,4′-dicarboxylic acid, and 5-sodium sulfoisophthalate. Examples thereof include at least one of acid, hexahydroterephthalic acid, adipic acid, sebacic acid, and the like. Furthermore, polybasic carboxylic acids such as pyromellitic acid, trimellitic acid, 3,4,3 ′, 4′-biphenyltetracarboxylic acid or its anhydride can also be used.

  As the diol component, it is preferable to use only ethylene glycol. However, other diol components such as propylene glycol, 1, 4 are used as long as the excellent properties such as heat resistance of the ethylene terephthalate crystalline polyester are not impaired. -Butanediol, diethylene glycol, 1,6-hexylene glycol, cyclohexanedimethanol, ethylene oxide adduct of bisphenol A, etc. may be used in combination. Further, trihydric or higher alcohol components such as trimethylolmethane, trimethylolethane, trimethylolpropane, pentaerythritol and the like can be used in combination.

2. Naphthalate-based polyester resin The naphthalate-based polyester resin is a polyester resin containing a dibasic carboxylic acid unit mainly composed of ethylene-2,6-dicarboxylic acid, and particularly most of the ester repeating units, preferably 80 mol% or more. Is preferably an ethylene naphthalate-based crystalline polyester having an ethylene naphthalate unit, and preferably has a glass transition point (Tg) of 100 to 140 ° C. and a melting point (Tm) of 240 to 300 ° C. And its intrinsic viscosity (IV) should generally be in the range of 0.3 to 1.0, in particular 0.4 to 0.68. In particular, homopolyethylene naphthalate is preferable from the viewpoint of heat resistance, but a copolyester containing a small amount of ester units other than ethylene naphthalate units can also be preferably used.

  Examples of dibasic acids other than naphthalene-2,6-dicarboxylic acid include terephthalic acid, isophthalic acid, orthophthalic acid, Pp-β-oxyethoxybenzoic acid, naphthalene 2,6-dicarboxylic acid, naphthalene 2,7-dicarboxylic acid, Examples thereof include at least one of diphenoxyethane-4,4′-dicarboxylic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, adipic acid, sebacic acid, and the like. Furthermore, polybasic carboxylic acids such as pyromellitic acid, trimellitic acid, 3,4,3 ′, 4′-biphenyltetracarboxylic acid or its anhydride can also be used.

  As the diol component, it is preferable to use only ethylene glycol. However, other diol components such as propylene are used as long as the excellent properties (for example, high glass transition point) of the ethylene naphthalate crystalline polyester are not impaired. At least one of glycol, 1,4-butanediol, diethylene glycol, 1,6-hexylene glycol, cyclohexanedimethanol, an ethylene oxide adduct of bisphenol A, and the like may be used in combination. Further, trihydric or higher alcohol components such as trimethylolmethane, trimethylolethane, trimethylolpropane, pentaerythritol and the like can be used in combination.

[Melting and kneading]
In the present invention, the target blend is produced by melt-kneading the terephthalate-based polyester resin and the naphthalate-based polyester resin, but the sea-island dispersion structure as shown in FIGS. 1 and 2 is formed. To do
(1) Mixing ratio (2) Melt viscosity ratio at melt kneading temperature (3) It is necessary to consider suppression of the transesterification rate.

  As for the mixing ratio of (1), the naphthalate polyester resin is used in an amount of 0.01 to 50 parts by weight, particularly 1 to 20 parts by weight per 100 parts by weight of the terephthalate polyester resin. If the amount of the naphthalate-based polyester resin is outside the above range, the sea-island dispersion structure does not become the region surrounded by the circles in FIG. 1, and it becomes impossible to obtain a container having high haze and excellent visible light blocking properties.

  Regarding the melt viscosity ratio of (2), at the melt kneading temperature, the melt viscosity (ηb) of the naphthalate polyester resin is 5 times or more, particularly 6 to 15 times the melt viscosity (ηa) of the terephthalate polyester resin. Thus, it is necessary to select and combine a terephthalate polyester resin and a naphthalate polyester resin. That is, as described in (1) above, by adjusting the quantity ratio between the terephthalate polyester resin and the naphthalate polyester resin, and simultaneously selecting a naphthalate polyester resin having a higher melt viscosity than the terephthalate polyester resin, A dispersion structure as shown in FIG. 2 can be formed with the terephthalate resin as a matrix (continuous phase) and the naphthalate polyester resin as an island (negative continuous phase). For example, when the melt viscosities of both are very similar, the dispersion structure shown as the mixed region in FIG. 1 and further the mutual network structure are formed, resulting in a decrease in haze.

  Regarding the transesterification rate of (3), it is necessary to carry out melt-kneading so that the transesterification rate between the terephthalate polyester resin and the naphthalate polyester resin is 20% or less, preferably 12% or less. That is, if the transesterification reaction is promoted by this melt-kneading, the compatibility of both polyester resins is improved, so the sea-island dispersion structure as shown in FIGS. 1 and 2 is not formed, and the haze is lowered. Rather, transparency is enhanced. In order to suppress the transesterification rate within the above range, it is necessary to set the melt kneading temperature in the range of 270 to 300 ° C. and control the kneading time according to the melt kneading temperature. For example, if the melt kneading temperature is higher than the above range, the transesterification rate may exceed the above range, and if the melt kneading temperature is lower than the above range, it becomes difficult to perform kneading effectively. . Further, since the transesterification rate increases as the melt kneading time increases, the melt kneading time should be a short time depending on the melt kneading temperature.

  Incidentally, the transesterification rate is measured using, for example, an NMR apparatus as shown in the examples described later, ethylene glycol protons derived from naphthalate polyester resins, ethylene glycol protons derived from terephthalate polyester resins, and esters. It can be calculated by measuring the ethylene glycol proton derived from the exchange component.

  The melt kneading described above can be performed using, for example, an extruder or a kneader for an injection machine after dry-mixing (dry blending) both polyester resins using a blender, a Henschel mixer, or the like. When using a kneader for an injection machine, it is necessary to adjust the injection cycle so that the transesterification rate does not increase.

  The container-forming resin composition prepared as described above can be blended with antioxidants, fillers, lubricants, and the like, if necessary. It is desirable not to add compounding agents, particularly inorganic powder-based compounding agents.

[Molding of packaging container]
The container of the present invention obtained by using the above-described resin composition (hereinafter sometimes referred to as a polyester blend) is manufactured by biaxially stretching blow-molding a preform of this polyester blend and heat-setting if necessary. Is done.

  The preform used for stretch blow molding is produced by any molding means known per se, such as an injection molding method. For example, molten polyester is injected, and a bottomed preform having a mouth corresponding to the final container is manufactured in an amorphous state. For example, it is manufactured by compression molding. For example, a bottomed preform having a mouth corresponding to the final container is manufactured in an amorphous state by extruding molten polyester into a certain molten resin mass and compressing it with a mold.

In injection molding, the polyester blend is melt-injected into a cooled injection mold. As the injection machine, a known one having an injection plunger or screw is used, and the polyester blend is passed through a nozzle, a sprue, and a gate. The blend is injected into an injection mold. As a result, the polyester blend flows into the injection mold cavity and solidifies into an amorphous preform for stretch blow molding. As the injection mold, a mold 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 pressure is usually about 100 to 1500 kg / cm ² , and the injection temperature is 270 to 300 ° C., similar to the melt kneading temperature described above, and the injection cycle is such that the transesterification rate does not exceed 20%. Set.

  For stretch blow molding from a preform, a preform in a supercooled state is once manufactured, and the preform is heated to a stretching temperature to perform stretch molding (cold parison method) or applied to the preform to be molded. A method of performing stretch molding following pre-molding using the generated heat, that is, residual heat (hot parison method) or the like is employed, but the former method is preferred.

  In the stretch blow molding of the preform obtained above, the packaging container, for example, a bottle of the present invention is obtained by heating the preform to a stretching temperature of 90 to 140 ° C. and biaxial stretching blow molding. When the stretching temperature is lower than the above range, it becomes difficult to perform a smooth stretch molding operation, the occurrence of microvoids becomes significant, while when 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.

  The shape of this container is shown in FIG. That is, in FIG. 3, the container (bottle) indicated by 1 as a whole is closed with the unstretched nozzle part (mouth part) 2, the frustoconical shoulder part 3, the cylindrical body part 4, and the body part 4. The bottom 5 is formed. The center of the bottom part 5 is usually an unstretched part as with the mouth part 2.

  In addition, biaxial stretch blow molding to a bottle etc. can be performed by a one-stage method or a two-stage method. First, a preform at a 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 the circumferential direction by blowing fluid. The draw ratio should be 4 to 20 times, particularly 8 to 20 times, and the thickness of the body part 4 is generally in the range of about 50 to 5000 μm. To do.

  In order to enable the above-described high stretching at a relatively low temperature, it is also effective to use internal frictional heat generation at a circumferential stretching speed of 350% / sec or more. In addition, when performing pre-blow with a low-pressure fluid prior to blowing by blowing high-pressure gas, the stretching speed is determined based on the stretch after the pre-blow.

Furthermore, in order to enable high-speed stretching, the pressure of the pressurized fluid used is preferably as high as possible and varies depending on the capacity of the final container and the thickness of the preform. It is preferably 30 kg / cm ² or more, particularly in the range of 35 to 60 kg / cm ² . Further, the pressure applied in the preform may not be uniform during the molding. As the pressurizing fluid, unheated air or inert gas, or heated air or inert gas can be used.

In the case of a heat-resistant bottle or a heat-resistant pressure bottle, it is important to perform thermal crystallization in order to improve the heat resistance and rigidity of the container mouth 2. The thermal crystallization of the container mouth portion 2 is performed, for example, to a density of 1.34 g / cm ² or more, and can be performed after forming into a bottle. It is preferably performed before heating, during preheating, or after preheating.

  The degree of thermal crystallization of the mouth portion 2 is to give the above-mentioned density, and as the thermal crystallization condition, it is preferable to perform heating at a temperature of 150 to 200 ° C. for 40 to 200 seconds. An infrared emitter is particularly suitable as a heat source.

Further, in the case of a heat-resistant bottle or a heat-resistant pressure bottle, it is important to crystallize in order to improve the heat resistance and creep resistance of the container body 4. At this stage, heat fixation is performed. The degree of orientation crystallization is such that the density of the body portion 4 is 1.35 g / cm ² or more.

  In the case of the one-stage method, heat setting is performed by maintaining the blow mold at a temperature of 120 to 180 ° C. and bringing the bottle being molded into contact with the hot mold. A processing time of about 1 to 10 seconds is appropriate.

  In the case of the two-stage method, since it is particularly important to set the heating conditions according to the degree of crystallization, the heating conditions may vary greatly depending on the heating means. For example, in the case of using an infrared radiator, a molded product obtained by the first stretch blow molding is generally held at a temperature of 130 to 200 ° C. for 10 seconds, and for example, in the case of hot air such as an oven, this temperature range Hold for about several minutes to 1 hour to remove distortion and heat-set. In this heat treatment stage, the molded product shrinks, but the molded product after the heat treatment is put in 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 product, gas can be contained inside the molded product, and under the heat treatment conditions in which excessive thermal deformation is suppressed, The inside may be kept at atmospheric pressure. Furthermore, if free blow is used for the first-stage blow molding, only one mold may be used, and the bottom 5 can be efficiently stretched.

[Packaging container]
In the packaging container of the present invention thus obtained, the container wall is formed by the blend layer composed of the polyester blend described above, and when viewed at the unstretched part (for example, the central part of the container mouth part 2 or the bottom part 5), FIG. The sea-island dispersal structure as shown in Fig. 2 can be confirmed. That is, in such a sea-island dispersion structure, the terephthalate polyester resin is the continuous phase A, the naphthalate polyester resin is the discontinuous phase B, and the ratio of the discontinuous phase B having a major axis of 0.4 to 10 μm is 50 to It is in the range of 100%, preferably 95-100%. The haze at the container body 4 in which the blend layer having such a sea-island dispersion structure is stretched is 40% or more, particularly 60% or more, and exhibits extremely high visible light blocking properties. For example, the visible light transmittance of 400 to 520 nm is 30% or less, particularly 20% or less in such a barrel part 4, and can be effectively applied as a container for contents that are degenerate to visible light. is there.

  In addition, although the manufacturing conditions of the packaging container of the present invention described above and the like have been described by taking as an example the case where the blend layer composed of a polyester blend is a single layer and constitutes the container wall, the container wall is made of such a blend. Of course, it is also possible to have a laminated structure of a layer and a gas barrier layer or a moisture-resistant resin layer. Even in such a container having a laminated structure, the haze and visible light transmittance in the container body 4 are within the above range because the blend layer exhibits high visible light blocking properties. (In terms of recyclability, the container wall is most preferably a single layer of the aforementioned polyester blend.)

  Examples of the gas barrier layer forming resin include an ethylene / vinyl alcohol copolymer and a polyamide resin. Examples of polyamide resins include nylon 6, nylon 6-6, nylon 6-10, nylon 11, nylon 12, nylon 13, and xylylene group-containing polyamide. In terms of gas barrier properties, xylylene group-containing polyamide, specifically, Polyamide obtained by reacting a xylylenediamine component obtained by adding a small amount of paraxylylenediamine to metaxylylenediamine or metaxylylenediamine and an aliphatic dicarboxylic acid component such as adipic acid or sebacic acid is preferable. Furthermore, an oxygen-absorbing component can also be added in order to impart oxygen scavenging performance to these gas barrier layer forming resins. Examples of the moisture resistant resin include low density polyethylene, high density polyethylene, polypropylene, poly 1-butene, poly 4-methyl-1-pentene, ethylene, propylene, 1-butene, 4-methyl-1-pentene, and the like. Examples thereof include polyolefins such as random or block copolymers of α-olefins and the polyesters described above. Such a gas barrier layer-forming resin layer and a moisture-resistant resin layer can be appropriately provided at a position to be an outer surface, an inner surface, or an intermediate layer of a vessel wall according to the function. Further, such a container having a laminated structure is manufactured by molding a corresponding preform having a laminated structure by co-injection or co-compression and performing biaxial stretch blow molding in the same manner as described above.

[Manufacture of recycled resin]
According to the present invention, the above-described container (for example, a used container) is pulverized, and melt-extruded using an extruder or the like to be pelletized so that the transesterification rate is 12% or more, particularly 15% or more. A recycled resin having excellent transparency can be obtained. That is, in this recycled resin, the transesterification reaction of the polyester blend described above is promoted, and the terephthalate-based polyester resin and the naphthalate-based polyester resin are compatible with each other. Therefore, the recycled resin is extremely transparent. For example, the recycled resin pellet is used. When a sheet having a thickness of 3 mm is molded at a set temperature of 290 ° C. with an injection molding machine, the haze of this sheet is 5% or less, particularly 3% or less, and the transparency is extremely high.

  In order to increase the transesterification rate to the above range, as described above, the factors relating to the melt extrusion temperature and the residence time, for example, the extrusion conditions such as the screw rotation speed and the discharge amount may be adjusted. As the temperature is higher, the transesterification rate can be increased in a shorter time. For example, the extrusion temperature (barrel temperature in the extruder) is preferably set to 270 ° C. or higher, particularly about 280 to 300 ° C. Moreover, in the packaging container of the present invention described above, the sea-island dispersion structure of the blend layer is set in a region very close to the mixed region of the terephthalate-based polyester resin and the naphthalate-based polyester resin (see FIG. 1). The interfacial area of the polyester resin is large, and therefore the contact frequency of both polyester resins is high, and the transesterification reaction can be promoted quickly.

  Thus, by using the opaque container of the present invention having the blend layer in which the transesterification rate is suppressed within a predetermined range in the container wall, a recycled resin having good transparency can be easily obtained. Since the recycled resin has excellent transparency, it can be applied to a wide range of uses without deteriorating the commercial value.

1. Materials HomoPET resin [RT543CTHP: Nihon Unipet Co., Ltd.] as the terephthalate polyester resin, and three types of HomoPEN resins [(TN8065S: Teijin Kasei Co., Ltd., PN510: Toyobo Co., Ltd., FS005) as the naphthalate polyester resin These resins were in the form of pellets, and before molding and measurement, the PET resin was dried at 150 ° C. for 4 hours and the PEN resin was dried at 160 ° C. for 5 hours.

2. Molding of stretch blow bottle The dry blend of the above resin pellets at a predetermined ratio is supplied to the hopper of an injection molding machine (NN75JS: Niigata Iron Works), and at a predetermined barrel set temperature and cycle time. Then, a bottle preform having a diameter of 28 mm was formed by injection molding. Thereafter, the preform was heated to a surface temperature of 100 to 130 ° C. with an infrared heater and biaxially stretched and blown in a mold to form a stretch blow bottle having a capacity of 500 ml. The mold temperature was room temperature (25 ° C.).

3. Measurement (1) Intrinsic viscosity (IV)
200 mg of the resin sample was added to 20 ml of the measurement solvent, and dissolved by stirring for 10 minutes while heating at 130 ° C. The measurement solvent is a mixed solvent of phenol: 1,1,2,2-tetrachloroethane = 1: 1 (weight ratio) for PET, and p-chlorophenol: 1,1,2,2-tetrachloroethane = for PEN. A mixed solvent of 3: 1 (weight ratio) was used. Thereafter, the flow-down time was measured using a Ubbelohde type viscosity tube in a constant temperature water bath at 30 ° C., and IV (intrinsic viscosity) was calculated using the following formula.
ηrel (relative viscosity) = T / T0
ηsp (specific viscosity) = ηrel-1
[Η] (Intrinsic viscosity) = {-1+ (1 + 4 · k · ηsp) ^1/2 } / (2 · k · c)
T: Measurement solution flow time (sec) T0: Blank flow time (sec)
k: Huggins constant (PET 0.33, PEN 0.44) c: Solution concentration (g / dl)

(2) Melt viscosity The melt viscosity of the resin sample was measured using a capillograph [Toyo Seiki Co., Ltd.]. The set temperature was 280 to 300 ° C., the piston speed was 0.5 to 500 mm / min, and the capillary L / D = 10/1 was used. The melt viscosities shown in the table are values at each molding temperature and shear rate of 91.2 sec ⁻¹ .

(3) Haze
The center of the body of the formed stretch blow bottle was cut out and measured using a color computer [SM-4: Suga Test Instruments Co., Ltd.]. The measured value was an average value of three arbitrary points.

(4) Visible light average transmittance of 400 to 520 nm The center of the body of the formed stretch blow bottle was cut out, and the transmitted light spectrum was measured using a spectrophotometer [UV3100PC: Shimadzu Corporation]. The wavelength range of 400 to 520 nm was scanned in 0.5 nm steps, the transmittance at each wavelength was measured, and the average value thereof was calculated.

(5) Transesterification rate Cut under the neck ring of the molded stretch blow bottle and dissolve in a mixed solvent of deuterated trifluoroacetic acid: deuterated chloroform = 1: 1 (volume ratio), and the ¹ HNMR spectrum was measured with an NMR apparatus [EX270: JEOL Datum Co., Ltd.]. Among the obtained spectra, the transesterification rate was calculated from the integral value of the peak corresponding to the number of protons at the ethylene glycol moiety using the following formula. At this time, the peak top was attributed to the vicinity of 4.8 ppm from PET, the vicinity of 4.9 ppm from PEN, and the vicinity of 4.85 ppm from the transesterification reaction. If the peaks overlap, the waveform separation program [NM-GXCFT:
JEOL Datum Co., Ltd.] was used for peak separation. The composition distribution when 100% transesterification progressed was assumed to be a random copolymer based on Bernoulli statistics.
NEN: PEN-derived peak integral value
TET: PET-derived peak integral value
TEN: PET-derived peak integral value
Lobs ＝ TEN / (TET + TEN + NEN)… Measured value of proton abundance ratio from transesterification
N = (NEN + TEN / 2) / (TET + TEN + NEN) ... Measured value of PEN content
Lcal = 2N (1-N): Calculated value of the abundance ratio of protons derived from transesterification when 100% transesterification proceeds
TE = (Lobs / Lcal) x 100 ... transesterification rate (%)

(6) Observation of phase structure Cut out under the neck ring, which is the unstretched part of the molded stretch blow bottle, and use a microtome equipped with a glass knife [REICHERT ULTRACUTS: Leica Co., Ltd.] under liquid nitrogen cooling, 1.0 mm / sec. An observation sample having a thickness of 5 μm was cut at a cutting speed of 5 μm. 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, covered with a cover glass, and used for observation under a microscope. The observation of the phase structure was performed up to 1000 times with a transmission light microscope. Further, 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 (%) = existence number of discontinuous phases having a major axis of 0.4 to 10 μm / total number of discontinuous phases × 100

Example 1
As a terephthalate-based polyester resin, 100 parts by weight of HomoPET resin [RT543CTHP: Nippon Unipet Co., Ltd.] with an IV of 0.75, and a HomoPEN resin with a IV of 0.77 as a naphthalate-based polyester resin [TN8065S: Teijin Chemicals ( Co., Ltd.] 3.1 parts by weight (PET: PEN = 97: 3 weight ratio) was dry blended and supplied to an injection molding machine hopper. A preform for a bottle with a diameter of 28 mm under the conditions of a set temperature of 280 ° C. and a cycle time of 30 sec. Was molded. The preform appearance was milky white.
Further, when the preform was biaxially stretched and blown to form a stretched blow bottle having a capacity of 500 ml and a barrel central part thickness of 0.15 mm, the appearance of the bottle was milky white.

(Example 2)
Except that 5.3 parts by weight of naphthalate polyester resin (PET: PEN = 95: 5 weight ratio) was used, a preform and a stretch blow bottle were molded in the same manner as in Example 1. It was milky white.

(Example 3)
Except that 11.1 parts by weight of naphthalate polyester resin (PET: PEN = 90: 10 weight ratio) was used, a preform and a stretch blow bottle were molded in the same manner as in Example 1. It was milky white.

Example 4
Except that 17.6 parts by weight of naphthalate-based polyester resin (PET: PEN = 90: 10 weight ratio) was used, a preform and a stretch blow bottle were molded in the same manner as in Example 1. It was milky white.

(Example 5)
Except that 42.9 parts by weight of naphthalate-based polyester resin (PET: PEN = 70: 30 weight ratio) was used, a preform and a stretch blow bottle were molded in the same manner as in Example 1. It was milky white.

(Example 6)
As the preform, the preform and the stretch blow bottle were used in the same manner as in Example 1 except that a preform whose thickness was set so that the thickness of the center portion of the trunk portion was 0.3 mm in the stretch blow bottle state was used. When molded, the preform appearance and the bottle appearance were milky white.

(Example 7)
As a preform, the preform and the stretch blow bottle were used in the same manner as in Example 2 except that a preform whose thickness was set to be 0.3 mm in the stretch blow bottle state was used. When molded, the preform appearance was milky white and the bottle appearance was milky white.

(Example 8)
As a preform, a preform and a stretch blow bottle were used in the same manner as in Example 3 except that a preform whose thickness was set to be 0.3 mm in the stretch blow bottle state was used. When molded, the preform appearance and the bottle appearance were milky white.

(Comparative Example 1)
Except that 100 parts by weight of naphthalate polyester resin (PET: PEN = 50: 50 weight ratio) was used, a preform and a stretch blow bottle were molded in the same manner as in Example 1. As a result, the appearance of the preform was determined by the incident light angle. Showed a changing pearly luster, and the bottle appearance was milky white.

(Comparative Example 2)
The same as Example 1 except that 42.9 parts by weight (PET: PEN = 70: 30 weight ratio) of HomoPEN resin [PN510: Toyobo Co., Ltd.] with an IV of 0.59 was used as the naphthalate-based polyester resin. When a preform and a stretch blow bottle were molded, the preform appearance and the bottle appearance were both almost transparent.

(Comparative Example 3)
As naphthalate-based polyester resin, the same as Example 1 except that 42.9 parts by weight (PET: PEN = 70: 30 weight ratio) of HomoPEN resin [FS005: Mitsubishi Chemical Corporation] with an IV of 0.55 was used. When a preform and a stretch blow bottle were molded, the preform appearance and the bottle appearance were both almost transparent.

(Comparative Example 4)
Except that the conditions of the injection molding were set at a set temperature of 300 ° C. and a cycle time of 30 sec, a preform and a stretch blow bottle were molded in the same manner as in Example 3. As a result, both the preform appearance and the bottle appearance were almost transparent.

(Comparative Example 5)
A preform and stretch blow bottle were molded in the same manner as in Example 3 except that the conditions for injection molding were set at a set temperature of 300 ° C. and a cycle time of 60 sec. Both the preform appearance and the bottle appearance were almost transparent.

  Table 1 shows the material characteristics, molding conditions, and mixing ratio in the above-described Examples and Comparative Examples, and Table 2 shows the measurement results.

[Recycled resin pellets]
Each of the stretch blow bottles prepared in Examples 1 to 9 was pulverized with a plastic pulverizer [Horai Co., Ltd.]. The mesh size was 8 mm. These flakes are melt extruded into a strand shape with a vacuum vent type twin screw extruder [TEM35B: Toshiba Machine Co., Ltd.], and amorphous recycled resin pellets are obtained using granulation equipment consisting of a cooling water tank, a cooling conveyor and a cutter. After that, the transesterification rate of the pellet was measured.
Next, the pellets were heated and dried for 4 hours at 150 ° C. under vacuum in a stirring type vacuum dryer [45 MV heating type: Dalton Co., Ltd.], and then subjected to crystallization, and then an injection molding machine equipped with a sheet mold The sheet was supplied to a hopper, and a 3 mm thick sheet was molded under the conditions of a set temperature of 290 ° C. and a cycle time of 30 sec.
As a result, when the extrusion molding conditions were set so that the transesterification rate was 12% or more in the pellet state, the pellet was transparent, and the obtained injection-molded sheet had a Haze of 5% or less and was transparent. In contrast, when the extrusion molding conditions were set so that the transesterification rate was less than 12%, the pellets were white and the obtained sheet was cloudy.

Illustratively, after the stretch blow bottle prepared in Example 3 was pulverized by a plastic pulverizer, the biaxial extrusion conditions were as follows: screen mesh # 100, vacuum 1.3 × 10 ⁻⁴ MPa (1 Torr), extruder rotation speed 100 rpm, set temperature 290 ° C., discharge rate 5 kg / hour, the recycled resin pellet in the amorphous state is transparent and the transesterification rate is 13.3%. The sheet obtained by the above method had a haze of 2.2%.
On the other hand, under the twin-screw extrusion molding conditions, when the rotational speed of the extruder is 50 rpm, the set temperature is 280 ° C., and the discharge rate is 15 kg / hour, the amorphous recycled resin pellet is white and the transesterification rate is 3.1. The haze of the sheet obtained by molding from this pellet by the above method becomes cloudy at 22.5%.

It is a figure which shows notionally the relationship between the composition of PEN and a haze (Haze) in the blend of PET and PEN in the state where transesterification is not performed. It is a figure which shows the dispersion structure of the blend layer in the unstretched part in the packaging container of this invention. It is a figure which shows an example of the shape of the packaging container of this invention.

Explanation of symbols

1: Container (bottle)
2: Container neck (mouth)
3: Shoulder 4: Torso 5: Bottom

Claims (5)

  A packaging container having a blend layer of a terephthalate-based polyester resin and a naphthalate-based polyester resin as a container wall constituting layer, and in the unstretched portion of the container, the blend layer is composed of a continuous phase of terephthalate-based polyester resin and naphthalate The discontinuous phase having a sea-island structure composed of a discontinuous phase of a polyester resin and having a major axis of 0.4 to 10 μm is in the range of 50 to 100%. A packaging container having a haze of 40% or more.   The packaging container according to claim 1, wherein the blend layer has a transesterification rate of 20% or less between the terephthalate polyester resin and the naphthalate polyester resin.   The packaging container according to claim 1 or 2, wherein a visible light transmittance of 400 to 520 nm is 30% or less in the body portion.   Transesterification rate of 100 parts by weight of a terephthalate polyester resin and 0.01 to 50 parts by weight of a naphthalate polyester resin having a melt viscosity of 5 times or more with respect to the terephthalate polyester resin at a temperature of 270 to 300 ° C. Melt-kneading so that it may not exceed 20%, The manufacturing method of the resin composition excellent in visible light blocking | blocking property characterized by the above-mentioned.   A method for producing a recycled resin excellent in transparency, characterized in that the packaging container according to any one of claims 1 to 3 is pulverized and melt-extruded so that the transesterification rate is 12% or more.

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