JP2022158785A - Polyester container and polyester preform - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester container which is reduced in yellowish color, and in which a bluing agent can be easily removed when mechanically recycled.

SOLUTION: A polyester container comprises a mouth part, a neck part, a shoulder part, a trunk part and a bottom part. The polyester container contains mechanical recycle polyester and a bluing agent. In the polyester container, a content of the bluing agent relative to a content of the mechanical recycle polyester is 0.0001 mass% to 0.00125 mass%, and the bluing agent at 15 mbar includes a dye with an evaporation temperature of 230°C or less. Further, a b^* value of the mechanical recycle polyester in an L^*a^*b^* colorimetric system is +3.0 or higher.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to polyester containers and polyester preforms.

In recent years, attempts have been made to recycle plastic products in order to reduce the burden on the environment. For example, polyester containers such as used PET bottles are being recycled. Recycled polyester obtained by recycling polyester containers is used in various products. Chemically recycled polyesters and mechanically recycled polyesters are known as such recycled polyesters.

Chemically recycled polyester is polyester obtained by chemically decomposing a used polyester container to return it to the monomer unit, purifying it, and repolymerizing it. Therefore, chemically recycled polyester has physical properties and characteristics comparable to virgin polyester. However, chemically recycled polyester has a problem of high recycling cost. Here, the virgin polyester is a polyester produced by a conventional method from a dicarboxylic acid and a diol made from petroleum or the like.

On the other hand, mechanically recycled polyester is obtained by pulverizing and washing used polyester containers to remove contaminants and foreign substances to obtain flakes, which are further treated under high temperature and reduced pressure for a certain period of time to remove contaminants inside the resin. Or, after pelletizing the washed flakes, the pellets are further treated at high temperature and reduced pressure for a certain period of time to remove contaminants inside the resin. It is polyester. In mechanical recycling, recycled polyester can be obtained without undergoing chemical decomposition, so the recycling cost is lower than in chemical recycling. Therefore, from the viewpoint of cost, it is desirable to use mechanically recycled polyester as the recycled polyester.

When flakes and pellets made of mechanically recycled polyester are used to manufacture a polyester container, the molded polyester container may turn yellow due to trace impurities remaining in the flakes and pellets.
In order to reduce the yellowness of the resin due to yellowing as described above and make it transparent, Patent Document 1 discloses that a molded article obtained from a resin composition containing recycled polyester is added with a brightening agent and a blue pigment. It has been proposed to use pigments. Additives such as fluorescent brightening agents and blue pigments that reduce the yellowness of resins to make them transparent are generally called bluing agents (see, for example, Patent Document 2).

JP 2004-359914 A Japanese Patent Application Laid-Open No. 2001-166101

By the way, since flakes and pellets made of mechanically recycled polyester are used in various containers, it is desirable that the additives used in the polyester container before mechanical recycling remain in the flakes and pellets. From this point of view, when a polyester container containing a bluing agent is mechanically recycled, it is desirable that the bluing agent is removed from flakes and pellets made of the obtained mechanically recycled polyester.

The present inventors have recently noticed that the bluing agent cannot be removed when a polyester container containing a pigment as a bluing agent is mechanically recycled.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a polyester container with reduced yellowness and from which a bluing agent can be easily removed when mechanically recycled.
Another object of the invention is to provide a polyester preform for use in making this polyester container.

The present inventors have found that the above problems can be solved by using a specific dye as a bluing agent.

Accordingly, the present invention is a polyester container comprising a mouth, a neck, a shoulder, a body and a bottom, comprising:
including mechanically recycled polyester and a bluing agent,
The content of the bluing agent with respect to the content of the mechanically recycled polyester is 0.0001% by mass or more and 0.00125% by mass or less,
The bluing agent is a dye having a vaporization temperature of 230° C. or less at 15 mbar;
The polyester container, wherein the b ^* value in the L ^* a ^* b ^* color system of the mechanically recycled polyester is +3.0 or more.

In the polyester container according to the present invention, the bluing agent may be an anthraquinone-based bluing agent.

In the polyester container according to the present invention, the content of the mechanically recycled polyester with respect to the entire polyester constituting the polyester container may be 95% by mass or more.

In the polyester container according to the present invention, the body portion may have a thickness of 0.05 mm or more and 0.54 mm or less.

In the polyester container according to the present invention, the content may be a colorless and transparent liquid.

The present invention is a polyester preform used for manufacturing the polyester container.

ADVANTAGE OF THE INVENTION According to this invention, while being a polyester container with reduced yellowness, the polyester container which can remove a bluing agent easily in the case of mechanical recycling can be provided.

According to the present invention, it is possible to provide a polyester preform for use in manufacturing this polyester container.

1 is a schematic half-sectional view showing one embodiment of a polyester container according to the present invention; FIG. 1 is a schematic half-sectional view showing one embodiment of a polyester preform according to the present invention; FIG.

[Polyester container]
A polyester container according to the present invention comprises mechanically recycled polyester and a bluing agent.
As used herein, a "polyester container" is a container containing polyester as a main component. As used herein, "main component" means a component that accounts for more than 50% by mass of the total. The content of polyester in the polyester container is preferably 70% by mass or more, more preferably 90% by mass or more, and still more preferably 99% by mass or more.

As used herein, the term "container" means a molded body that houses an article. Examples of the container include molded articles such as compression molded articles, injection molded articles, blow molded articles and thermoformed articles. Examples of specific containers include bottles, vials, cups, trays and packs.

As used herein, "polyester" means a polymer polymerized by ester bonds. Such polyesters are usually obtained by polycondensation of a dicarboxylic acid compound and a diol compound.
Dicarboxylic acid compounds include, for example, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, eicosandioic acid, pimelic acid, azelaic acid, methylmalonic acid and ethylmalonic acid, adamantane dicarboxylic acid, norbornene dicarboxylic acid, cyclohexanedicarboxylic acid, decalinedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 1, 8-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 5-sodiumsulfoisophthalic acid, phenylendanedicarboxylic acid, anthracenedicarboxylic acid, phenanthenedicarboxylic acid, 9,9'-bis (4-Carboxyphenyl)fluoric acid and their ester derivatives.
Examples of diol compounds include ethylene glycol, 1,2-propanediol, 1,3-propanediol, butanediol, 2-methyl-1,3-propanediol, hexanediol, neopentyl glycol, cyclohexanedimethanol, and cyclohexane. diethanol, decahydronaphthalenedimethanol, decahydronaphthalenediethanol, norbornanedimethanol, norbornanediethanol, tricyclodecanedimethanol, tricyclodecaneethanol, tetracyclododecanedimethanol, tetracyclododecanediethanol, decalindimethanol, decalindiethanol, 5 -methylol-5-ethyl-2-(1,1-dimethyl-2-hydroxyethyl)-1,3-dioxane, cyclohexanediol, bicyclohexyl-4,4'-diol, 2,2-bis(4-hydroxy cyclohexylpropane), 2,2-bis(4-(2-hydroxyethoxy)cyclohexyl)propane, cyclopentanediol, 3-methyl-1,2-cyclopentadiol, 4-cyclopentene-1,3-diol, adamandiol , paraxylene glycol, bisphenol A, bisphenol S, styrene glycol, trimethylolpropane, pentaerythritol and bis-β-hydroxyethyl terephthalate (BHET).
In the polyester container according to the present invention, the polyester is preferably polyethylene terephthalate or modified polyethylene terephthalate obtained by polymerizing a raw material monomer for polyethylene terephthalate and a copolymerization monomer, and particularly preferably polyethylene terephthalate.

The polyester may contain a monomer other than the dicarboxylic acid compound and the diol compound as long as it does not impair the properties of the present invention, but the content thereof is preferably 10 mol% or less with respect to all structural units. , more preferably 5 mol % or less, and still more preferably 3 mol % or less.

The mechanically recycled polyester and bluing agent contained in the polyester container according to the present invention are described below.

<Mechanical recycled polyester>
As used herein, the term "mechanical recycled polyester" means that the used polyester container is pulverized and washed to remove contaminants and foreign matter to obtain flakes, and the flakes are further treated at high temperature and reduced pressure for a certain period of time. It is a polyester obtained by removing contaminants inside the resin and pelletizing, or after pelletizing the washed flakes, the pellets are further treated at high temperature and reduced pressure for a certain period of time to remove the inside of the resin. Polyester obtained by removing contaminants.
The mechanically recycled polyester contained in the polyester container according to the invention is preferably mechanically recycled polyethylene terephthalate.

A small amount of impurities remain in the flakes and pellets made of the mechanically recycled polyester. Such trace impurities are unavoidable impurities that cannot be completely removed even by treatment under high temperature and reduced pressure for a certain period of time. In the manufacture of polyester containers, the flakes and pellets are melted, and if trace impurities are present in the flakes and pellets, the heat during melting causes the polyester to turn yellow. Therefore, the mechanically recycled polyester contained in the polyester container according to the present invention has a yellow tint.
The polyester container according to the present invention can reduce the yellowness of the polyester container by containing the bluing agent described later in a specific range. Such a polyester container with reduced yellowness is particularly suitable when the content is a colorless and transparent liquid. The colorless and transparent liquid is not particularly limited, and examples thereof include drinking water.

In the polyester container according to the present invention, the b ^* value in the L ^* a ^* b ^* color system of the mechanically recycled polyester may be +3.0 or more, +4.0 or more, or +4.5 or more. On the other hand, the b ^* value in the L ^* a ^* b ^* color system of the mechanically recycled polyester may be +20.0 or less, +10.0 or less, or +7.0 or less.
In this specification, the b ^* value in the L ^* a ^* b ^* color system of the mechanically recycled polyester is measured according to JIS Z8722:2009.
Specifically, a mechanically recycled polyester having an arbitrary shape is freeze-pulverized to prepare a powder, and this powder is measured by reflected light using a spectrocolorimeter. The measurement conditions are SCE (exclude specular reflection), 10° field of view, and D65 light source. As a spectral colorimeter, for example, CMS-35SP manufactured by Murakami Color Research Laboratory Co., Ltd. can be used.

In the polyester container according to the present invention, the content of the mechanically recycled polyester with respect to the entire polyester constituting the polyester container is preferably 95% by mass or more, more preferably 97% by mass or more, and still more preferably 99% by mass or more. Yes, particularly preferably 99.9% by mass or more. As a result, a polyester container with a reduced environmental load can be obtained.
The polyester container according to the present invention may contain polyester such as virgin polyester and chemically recycled polyester in addition to mechanically recycled polyester.

<Bluing agent>
As used herein, the term “bluing agent” refers to an additive that absorbs light in the visible light range, for example, light in the wavelength range from orange to yellow, and adjusts the hue.
As used herein, “visible light region” means a region of 380 nm or more and 780 nm or less.

The bluing agent contained in the polyester container according to the invention is a dye with a vaporization temperature of 230° C. or less at 15 mbar. By using such a dye as a bluing agent, the bluing agent can be easily removed when the polyester container is mechanically recycled. This is because, in mechanical recycling, the bluing agent can be easily removed together with contaminants inside the resin when the flakes or pellets are treated under high temperature and reduced pressure for a certain period of time.
From the point of view that the bluing agent can be more easily removed from the flakes or pellets, the vaporization temperature of the dye used as bluing agent is preferably 225° C. or lower, more preferably 220° C. or lower at 15 mbar.
On the other hand, the vaporization temperature of the dye used as the bluing agent is preferably 300° C. or higher, more preferably 350° C. or higher at 1013.25 mbar (atmospheric pressure). By using such a dye having a vaporization temperature or higher, it is possible to reduce the amount of dye released into the atmosphere during the production of the polyester container, and it is possible to easily adjust the content of the bluing agent in the polyester container after molding. .

In the polyester container according to the present invention, the content of the bluing agent with respect to the mechanically recycled polyester is 0.0001% by mass or more and 0.00125% by mass or less. If the content of the bluing agent is in such a range, the yellowness of the polyester container can be reduced and the polyester container can be made transparent. Moreover, by setting the content of the bluing agent in such a range, the bluing agent can be easily removed when the polyester container according to the present invention is mechanically recycled.
The bluing agent content is preferably 0.00025% by mass or more, more preferably 0.0004% by mass or more. On the other hand, the bluing agent content is preferably 0.001% by mass or less, more preferably 0.0008% by mass or less.

The bluing agent contained in the polyester container according to the present invention preferably has a maximum absorption peak in the wavelength region of 500 nm or more and 650 nm or less in the visible light region. By using a bluing agent having a maximum absorption peak in such a wavelength region, the yellowness of the polyester container can be efficiently reduced. The bluing agent more preferably has a maximum absorption peak in the wavelength region of 550 nm or more and 600 nm or less in the visible light region.
In this specification, the maximum absorption peak can be measured by, for example, SPD-M20A (photodiode array detector) manufactured by Shimadzu Corporation. Acetonitrile, for example, can be used as a solvent for dissolving the bluing agent.

Examples of the above bluing agents include dyes such as anthraquinone bluing agents and indigo bluing agents.

で表されるアントラキノン環を含有するブルーイング剤である。アントラキノン系ブルーイング剤として、好ましくは、式（２）：

［式（２）中、Ｘ^１はＯＨ、ＮＨＲ^１又はＮＲ^１Ｒ^２を表し、Ｘ^２はＮＨＲ^３又はＮＲ^３Ｒ^４を表し、Ｒ^１、Ｒ^２、Ｒ^３及びＲ^４は、互いに独立して、炭素数１以上６以下の直鎖状又は分枝状アルキル基、又は、炭素数１以上６以下の直鎖状又は分枝状アルキル基で置換されたフェニル基を表す。］
で表される一般式を有する化合物が挙げられる。式（２）中のＸ^１及びＸ^２は、互いに同一でも、異なってもよい。式（２）で表される化合物は、好ましくは、式中のＸ^１及びＸ^２のうち少なくとも１つが、炭素数１以上６以下の直鎖状又は分枝状アルキル基で置換されたフェニル基を有し、より好ましくは、式中のＸ^１又はＸ^２が炭素数１以上６以下の直鎖状又は分枝状アルキル基で置換されたフェニル基を有する。 The anthraquinone bluing agent has the formula (1):

is a bluing agent containing an anthraquinone ring represented by As an anthraquinone-based bluing agent, preferably the formula (2):

[In formula (2), X ¹ represents OH, NHR ¹ or NR ¹ R ² , X ² represents NHR ³ or NR ³ R ⁴ , R ¹ , R ² , R ³ and R ⁴ are represents a linear or branched alkyl group having 1 to 6 carbon atoms, or a phenyl group substituted with a linear or branched alkyl group having 1 to 6 carbon atoms. ]
A compound having a general formula represented by is mentioned. X ¹ and X ² in formula (2) may be the same or different. In the compound represented by formula (2), at least one of X ¹ and X ² in the formula is preferably a phenyl group substituted with a linear or branched alkyl group having 1 to 6 carbon atoms More preferably, X ¹ or X ² in the formula has a phenyl group substituted with a linear or branched alkyl group having 1 to 6 carbon atoms.

As the anthraquinone-based bluing agent, compounds represented by formulas (3) to (5) are more preferred.

Indigo-based bluing agents are bluing agents containing indoxyl or thioindoxyl.

From the viewpoint of heat resistance and solubility (dispersibility), the bluing agent contained in the polyester container according to the present invention is preferably an anthraquinone-based bluing agent, and more preferably has a structure represented by formula (1). at least one bluing agent having, more preferably at least one bluing agent having a structure represented by formula (2), still more preferably formula (3) to formula (5) is at least one bluing agent selected from the group consisting of compounds represented by the formula (3), and is particularly preferably a bluing agent represented by formula (3).

A bluing agent may be used individually by 1 type, or may use 2 or more types together. Also, during the production of the polyester container according to the present invention, the bluing agent may be used together with the oil component in order to disperse well in the polyester container. Examples of oil components include ester compounds such as glycerol diacetyl monooleate.
In one embodiment, the bluing agent can be added to the polyester container by using a masterbatch that includes the bluing agent and polyester. The masterbatch may contain the above oil component.
In one embodiment, the bluing agent may be added during the process of pelletizing the flakes in mechanical recycling.

Hereinafter, one embodiment of the structure of the polyester container according to the present invention will be described with reference to FIG.

FIG. 1 is a schematic half-sectional view showing one embodiment of a polyester container 10 according to the present invention. The polyester container 10 includes a mouth portion 11, a neck portion 12, a shoulder portion 13, a body portion 14, and a bottom portion 15, as shown in FIG.

In one embodiment, the spout 11 comprises a threaded portion 16 to which the cap is screwed, a turnip 17 below the threaded portion 16, and a support ring 18 below the turnip 17, as shown in FIG.

In one embodiment, neck 12 is located between support ring 18 and shoulder 13 and has a generally cylindrical shape with a generally uniform diameter, as shown in FIG. Moreover, in one embodiment, the shoulder portion 13 has a cylindrical shape whose diameter gradually increases from the neck portion 12 side toward the body portion 14 side.

In one embodiment, body 14 is located between shoulder 13 and bottom 15, as shown in FIG. In one embodiment, the body 14 also includes a panel portion 21 into which the body 14 is recessed, as shown in FIG. With such a configuration, deformation of the polyester container due to increase or decrease in internal pressure can be prevented in the case of filling the polyester container with heated contents or in the case of a polyester container which is heated after being filled with the contents.

In one embodiment, as shown in FIG. 1, the bottom portion 15 includes a centrally-located recessed portion 19 and a ground portion 20 provided around the recessed portion 19. At this ground portion 20, the trunk portion 14 are connected. With such a configuration, deformation of the polyester container due to increase or decrease in internal pressure can be prevented when the polyester container is filled with heated contents or when the polyester is heated after being filled with the contents.
In one embodiment, the "bottom part" means the inner part from the ground part when the polyester container is made to stand on its own.

Since the polyester container according to the present invention has reduced yellowness, the thickness of the polyester container can be increased. This is because even if the thickness of the polyester container is increased, the color of the contents hardly changes when the contents are viewed from the outside of the polyester container. Therefore, the polyester container according to the present invention can improve the strength of the polyester container while suppressing the influence of color on the contents. The cross-sectional thickness of the body of the polyester container is preferably 0.05 mm or more, more preferably 0.1 mm or more.
On the other hand, from the viewpoint of reducing the amount of polyester container used, the cross-sectional thickness of the body of the polyester container is preferably 0.54 mm or less, more preferably 0.5 mm or less.
In addition, the thickness of the cross section in the trunk|drum of a polyester container means the location where thickness becomes the thinnest.

In the polyester container according to the present invention, the ratio of capacity to mass (volume/mass) is preferably 5 mL/g or more, more preferably 8 mL/g or more, from the viewpoint of moldability of the polyester container.
On the other hand, the volume/mass ratio is preferably 50 mL/g or less, more preferably 45 mL/g or less, from the viewpoint of the strength of the polyester container.

The polyester container according to the present invention may have a single-layer structure or a multi-layer structure of two or more layers. Moreover, when the polyester container has a multilayer structure, each layer may have the same composition or a different composition.

In one embodiment, the polyester container may be provided with a vapor-deposited film on its surface. Thereby, the gas barrier property of the polyester container can be improved. The deposited film may be positioned on the inner surface or the outer surface of the polyester container, but is preferably positioned on the inner surface.

Examples of deposited films include metals such as aluminum, inorganic oxides such as aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, titanium oxide, boron oxide, hafnium oxide, and barium oxide, hexamethyldisiloxane, and the like. organic silicon compounds, and a hard carbon film such as a DLC (Diamond Like Carbon) film.
A hard carbon film made of a DLC film is a hard carbon film also called an i-carbon film or a hydrogenated amorphous carbon film (aC:H) ^, and is an amorphous carbon film mainly composed of SP3 bonds. is.

Also, the thickness of the deposited film is not particularly limited, and can be, for example, 1 nm or more and 150 nm or less.

Formation of the deposited film can be performed using a conventionally known method, for example, a physical vapor deposition method (physical vapor deposition method, PVD method) such as a vacuum deposition method, a sputtering method and an ion plating method, and a plasma A chemical vapor deposition method (Chemical Vapor Deposition method, CVD method) such as a chemical vapor deposition method, a thermal chemical vapor deposition method, and a photochemical vapor deposition method can be used.
The thickness of the deposited layer can be measured, for example, at the body portion of the polyester container, and means the point where the thickness is the thinnest.

[Polyester preform]
As used herein, a "polyester preform" is a preform prior to blow molding of a polyester container.
The polyester preform according to the invention is used for the production of the polyester container according to the invention. Accordingly, the polyester preform according to the invention contains mechanically recycled polyester and a bluing agent. The polyester container according to the present invention can be produced by configuring the polyester preform as described above.
The mechanically recycled polyester and bluing agent contained in the polyester preform according to the present invention can be the same as those used for the polyester container according to the present invention.

Hereinafter, one embodiment of the structure of the polyester preform according to the present invention will be described with reference to FIG.

FIG. 2 is a schematic half-sectional view showing one embodiment of the polyester preform 30 according to the present invention. The polyester preform 30 includes, as shown in FIG. Of these, the mouth portion 31 corresponds to the mouth portion 11 of the polyester container 10 and has substantially the same shape as the mouth portion 11 . The body portion 32 corresponds to the neck portion 12, the shoulder portion 13 and the body portion 14 of the polyester container 10, and has a substantially cylindrical shape. The bottom portion 33 corresponds to the bottom portion 15 of the polyester container 10 and has a substantially hemispherical shape.

The mouth portion 31 includes a threaded portion 34 corresponding to the threaded portion 16 of the polyester container 10 to which a cap (not shown) is screwed, a turnip 35 provided below the threaded portion 34 and corresponding to the turnip 17 of the polyester container 10, A support ring 36 is provided below the turnip 35 and corresponds to the support ring 18 of the polyester container 10 . The shape of the mouth portion 31 may be a conventionally known shape.

The cross-sectional thickness of the body of the polyester preform according to the present invention is preferably 1.3 mm or more, more preferably 1.7 mm or more. On the other hand, the cross-sectional thickness of the body portion of the polyester preform is preferably 4.7 mm or less, more preferably 4.0 mm or less.
The polyester container according to the present invention can be produced by setting the cross-sectional thickness of the body portion of the polyester preform within the above range.
The cross-sectional thickness of the body portion of the polyester preform means the thinnest portion.

The present invention includes the following embodiments.
[1] A polyester container containing mechanically recycled polyester and a bluing agent,
The content of the bluing agent with respect to the content of the mechanically recycled polyester is 0.0001% by mass or more and 0.00125% by mass or less,
A polyester container, wherein said bluing agent is a dye having a vaporization temperature of less than or equal to 230°C at 15 mbar.
[2] The polyester container of [1], wherein the bluing agent is an anthraquinone bluing agent.
[3] The polyester container according to [1] or [2], wherein the content of the mechanically recycled polyester with respect to the entire polyester constituting the polyester container is 95% by mass or more.
[4] comprising a mouth, a neck, a shoulder, a body and a bottom,
The polyester container according to any one of [1] to [3], wherein the body portion has a thickness of 0.05 mm or more and 0.54 mm or less.
[5] The polyester container according to any one of [1] to [4], wherein the content is a colorless and transparent liquid.
[6] The polyester container according to any one of [1] to [5], wherein the b ^* value in the L ^* a ^* b ^* color system of the mechanically recycled polyester is +3.0 or more.
[7] A polyester preform used for manufacturing the polyester container according to any one of [1] to [6].

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

[Example 1]
Pellets A made of mechanically recycled polyester and pellets B made of a polyethylene terephthalate masterbatch containing an anthraquinone bluing agent having the structure of formula (3) were prepared. The vaporization temperature of the bluing agent is 215° C. at 15 mbar.
First, 97 parts by mass of Pellets A and 3 parts by mass of Pellets B were dry-blended to obtain a mixture. The content of the bluing agent relative to the mechanically recycled polyester in the resulting mixture is 0.0005% by mass.
Next, the resulting mixture was melted and the melt was injected using an injection molding machine to produce a polyester preform shown in FIG. The thickness of the body portion of the polyester preform was 3.5 mm, and the basis weight was 22 g.

Next, the polyester preform was heated to 110° C. and subjected to biaxial stretching blow molding in a blow molding mold to produce a polyester container having an internal capacity of 500 mL as shown in FIG. The cross-sectional thickness of the body of the polyester container was 0.32 mm.

[Example 2]
A polyester preform shown in FIG. 2 was produced in the same manner as in Example 1, except that the pellets A and B were dry blended so that the bluing agent content relative to the mechanically recycled polyester was 0.00035% by mass. did. The thickness of the body portion of the polyester preform was 3.5 mm, and the basis weight was 22 g.

Next, in the same manner as in Example 1, a polyester container was produced from the polyester preform. The cross-sectional thickness of the body of the polyester container was 0.32 mm.

[Example 3]
A polyester preform shown in FIG. 2 was produced in the same manner as in Example 1, except that the pellets A and B were dry blended so that the content of the bluing agent relative to the mechanically recycled polyester was 0.0002% by mass. did. The thickness of the body portion of the polyester preform was 3.5 mm, and the basis weight was 22 g.

Next, in the same manner as in Example 1, a polyester container was produced from the polyester preform. The cross-sectional thickness of the body of the polyester container was 0.32 mm.

[Comparative Example 1]
A polyester preform shown in FIG. 2 was produced in the same manner as in Example 1, except that only pellet A was used. The thickness of the body portion of the polyester preform was 3.5 mm, and the basis weight was 22 g.

Next, in the same manner as in Example 1, a polyester container was produced from the polyester preform. The cross-sectional thickness of the body of the polyester container was 0.32 mm.

[Comparative Example 2]
A pellet C made of a polyethylene terephthalate masterbatch containing a cobalt-based pigment (cobalt blue) as a bluing agent was prepared.
A polyester preform shown in FIG. 2 was produced in the same manner as in Example 1, except that the pellets A and C were dry blended so that the content of the bluing agent relative to the mechanically recycled polyester was 0.0005% by mass. did. The thickness of the body portion of the polyester preform was 3.5 mm, and the basis weight was 22 g.

Next, in the same manner as in Example 1, a polyester container was produced from the polyester preform. The cross-sectional thickness of the body of the polyester container was 0.32 mm.

<<Measurement of color>>
A sample obtained by finely cutting only the mouth portion of the polyester container produced in Examples and Comparative Examples was precooled under liquid nitrogen for 10 minutes using a freeze crusher (manufactured by SPEX, Model 6870 Freezer/Mill). The powder was obtained by freeze-grinding for 10 minutes below. Then, this powder is measured with a spectrocolorimeter (CMS-35SP, manufactured by Murakami Color Research Laboratory Co., Ltd.) with reflected light to determine the L ^* value, a ^* value, and L* value in L ^* a ^* b ^* color system. b ^* values were measured. The measurement conditions were SCE (exclude specular reflection), 10° field of view, and D65 light source. In addition, the measurement was performed based on JISZ8722:2009. Table 1 shows the measurement results.

<< Content measurement of bluing agent >>
The polyester containers produced in Examples and Comparative Examples were pulverized to obtain flakes. The flakes were then treated at 230° C. and 15 mbar for 2 hours. The content of the bluing agent contained in the flakes after treatment was measured by LC-MS (manufactured by Bruker Japan Co., Ltd., maxis impact) in Examples, and ICP-AES (manufactured by Shimadzu Corporation) in Comparative Example 2. , ICPE-9820). Table 1 shows the measurement results.

It can be seen that the yellowness of the polyester container according to the present invention is reduced. In addition, it can be seen that the bluing agent was easily removed from the polyester container according to the present invention by the treatment under high temperature and reduced pressure that is carried out in mechanical recycling.

10: Polyester container 11: Mouth part 12: Neck part 13: Shoulder part 14: Body part 15: Bottom part 16: Screw part 17: Cover 18: Support ring 19: Depression part 20: Ground part 21: Panel part 30: Polyester preform 31: Mouth 32: Body 33: Bottom 34: Screw 35: Turnip 36: Support ring

Accordingly, the present invention is a polyester container comprising a mouth, a neck, a shoulder, a body and a bottom, comprising:
including mechanically recycled polyester and a bluing agent,
The content of the bluing agent with respect to the content of the mechanically recycled polyester is 0.0001% by mass or more and 0.00125% by mass or less,
The bluing agent is a dye having a vaporization temperature of 230° C. or less at 1500 Pa ,
The polyester container, wherein the b ^* value in the L ^* a ^* b ^* color system of the mechanically recycled polyester is +3.0 or more.

The bluing agent contained in the polyester container according to the invention is a dye having a vaporization temperature of 230° C. or less at 1500 Pa . By using such a dye as a bluing agent, the bluing agent can be easily removed when the polyester container is mechanically recycled. This is because, in mechanical recycling, the bluing agent can be easily removed together with contaminants inside the resin when the flakes or pellets are treated under high temperature and reduced pressure for a certain period of time.
From the viewpoint that the bluing agent can be more easily removed from the flakes or pellets, the vaporization temperature of the dye used as the bluing agent is preferably 225° C. or less, more preferably 220° C. or less at 1500 Pa . .
On the other hand, the vaporization temperature of the dye used as the bluing agent is preferably 300° C. or higher, more preferably 350° C. or higher at 1013 25 Pa (atmospheric pressure). By using such a dye having a vaporization temperature or higher, it is possible to reduce the amount of dye released into the atmosphere during the production of the polyester container, and it is possible to easily adjust the content of the bluing agent in the polyester container after molding. .

The present invention includes the following embodiments.
[1] A polyester container containing mechanically recycled polyester and a bluing agent,
The content of the bluing agent with respect to the content of the mechanically recycled polyester is 0.0001% by mass or more and 0.00125% by mass or less,
A polyester container, wherein the bluing agent is a dye having a vaporization temperature of 230° C. or less at 1500 Pa .
[2] The polyester container of [1], wherein the bluing agent is an anthraquinone bluing agent.
[3] The polyester container according to [1] or [2], wherein the content of the mechanically recycled polyester with respect to the entire polyester constituting the polyester container is 95% by mass or more.
[4] comprising a mouth, a neck, a shoulder, a body and a bottom,
The polyester container according to any one of [1] to [3], wherein the body portion has a thickness of 0.05 mm or more and 0.54 mm or less.
[5] The polyester container according to any one of [1] to [4], wherein the content is a colorless and transparent liquid.
[6] The polyester container according to any one of [1] to [5], wherein the b ^* value in the L ^* a ^* b ^* color system of the mechanically recycled polyester is +3.0 or more.
[7] A polyester preform used for manufacturing the polyester container according to any one of [1] to [6].

[Example 1]
Pellets A made of mechanically recycled polyester and pellets B made of a polyethylene terephthalate masterbatch containing an anthraquinone bluing agent having the structure of formula (3) were prepared. The vaporization temperature of the bluing agent is 215° C. at 1500 Pa.
First, 97 parts by mass of Pellets A and 3 parts by mass of Pellets B were dry-blended to obtain a mixture. The content of the bluing agent relative to the mechanically recycled polyester in the resulting mixture is 0.0005% by mass.
Next, the resulting mixture was melted and the melt was injected using an injection molding machine to produce a polyester preform shown in FIG. The thickness of the body portion of the polyester preform was 3.5 mm, and the basis weight was 22 g.

<< Content measurement of bluing agent >>
The polyester containers produced in Examples and Comparative Examples were pulverized to obtain flakes. The flakes were then treated at 230° C. and 1500 Pa for 2 hours. The content of the bluing agent contained in the flakes after treatment was measured by LC-MS (manufactured by Bruker Japan Co., Ltd., maxis impact) in Examples, and ICP-AES (manufactured by Shimadzu Corporation) in Comparative Example 2. , ICPE-9820). Table 1 shows the measurement results.

Claims (6)

A polyester container comprising a mouth, a neck, a shoulder, a body and a bottom, comprising:
including mechanically recycled polyester and a bluing agent,
The content of the bluing agent with respect to the content of the mechanically recycled polyester is 0.0001% by mass or more and 0.00125% by mass or less,
The bluing agent is a dye having a vaporization temperature of 230° C. or less at 15 mbar;
A polyester container, wherein the b ^* value in the L ^* a ^* b ^* color system of the mechanically recycled polyester is +3.0 or more. The polyester container according to Claim 1, wherein the bluing agent is an anthraquinone bluing agent. The polyester container according to claim 1 or 2, wherein the content of said mechanically recycled polyester is 95% by mass or more with respect to the entire polyester constituting said polyester container. The polyester container according to any one of claims 1 to 3, wherein the thickness of the body portion is 0.05 mm or more and 0.54 mm or less. The polyester container according to any one of claims 1 to 4, wherein the content is a colorless and transparent liquid. A polyester preform used for manufacturing the polyester container according to any one of claims 1 to 5.

Images