JP2006103744A - Polyester resin container containing reduced aldehydic substance and manufacturing method for its container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that aldehydic substances, a byproduct from a polyester resin container, has a negative effect on the original taste or aroma of drinking water, such as natural mineral water, by a simple method, and also meet a social demand for energy saving and natural resource saving with regard to an environmental protection issue. <P>SOLUTION: A polyester resin multilayer container is provided with an inorganic thin film layer as an inner surface layer, and employs a reclaimed material from a recovered polyester resin container to have the function of reducing the ingress of aldehydic substances to the inside of the container. In a preform molding process for the container, a compression molding method with a low thermal load is employed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a polyester resin container having reduced aldehydes and a method for producing the same, and more particularly, to a by-product of aldehydes such as acetaldehyde, which is by-produced as a small amount of impurities in a polyester resin and adversely affects the contents stored in the container. It relates to a polyester resin container with an inorganic thin film layer provided on the inner surface that has reduced life and does not enter the container. Further, the preform is preformed by compression molding, the preform is blow molded, and the inorganic thin film layer It relates to a method of manufacturing the container by forming the film by vapor deposition.

  Plastic containers are widely used in daily life or for industrial use due to their light weight, economy, ease of molding, excellent physical properties, transparency, adaptability to environmental problems, and the like. In particular, polyester resin containers represented by so-called PET bottles (polyethylene terephthalate containers) are containers for food and drink due to their excellent mechanical strength, cleanliness, high gas shielding properties and non-polluting properties. However, in recent years, PET bottles have been especially favored by consumers as portable beverage small containers, and in addition, two-stage blow molding methods, etc. The development has led to sufficient stretching and crystallization of polyethylene terephthalate preforms (parisons), significantly improved heat resistance and pressure resistance of PET bottles, requiring high-temperature beverages and high-temperature sterilization for winter. As it is also used for beverages, the importance and demand of PET bottles are increasing.

And, due to the recent increase in interest in the nature and health of consumer foods and beverages, soft drinks are strongly intended for use in containers such as PET bottles, especially in natural water. It seems that the taste (flavor) and fragrance due to the minerals, etc., as well as the refreshing and healthy feelings are particularly favored.
However, in polyester resins, which are the main raw materials such as PET bottles, the generation of impurities such as acetaldehyde and formaldehyde as a by-product is avoided by thermal decomposition and hydrolysis of the resin during polymerization and molding of the resin. (Usually around 10 ppm), the trace amount of aldehydes elutes from the container wall into the drinking water, adversely affects the unique flavor and aroma of drinking water such as natural mineral water, The problem of altering the taste and fragrance has been derived, and due to the recent consumer's strong commitment to the natural taste and fragrance, it has become a serious problem in polyester resin containers.
Naturally, it is desirable that the amount of this by-product impurity is small. Particularly, natural water has a larger influence on the flavor than other beverages such as fruit juice beverages. Therefore, in the technical field of polyester resin containers such as PET bottles, There has been a strong demand for an improved technique for reducing the effects of such substances as small as possible.

These aldehydes are produced from components such as ethylene glycol by cleavage of the ester bond due to thermal decomposition or hydrolysis at high temperature during polymerization or molding of polyester resin, and the amount depends on the polymerization conditions such as polymerization temperature and polymerization time. Although it can be reduced considerably by controlling the mold, it occurs again during molding of preforms, etc., and the amount is affected by the molding temperature and mold residence time. It is also a considerable burden.
In this way, the amount of aldehydes generated depends on the polymerization conditions such as the polymerization temperature and polymerization time of the polyester, or sufficient drying of the resin, as well as the molding temperature and mold residence time when molding preforms and containers. However, since it is an indirect countermeasure, there is a limit to the amount of reduction, and complicated precise management of the polymerization and molding processes is required, resulting in poor economic efficiency.

A direct and effective countermeasure to this problem is already known, and the generation of acetaldehyde is reduced by a simple means of blending a small amount of polyamide resin into a polyester resin. A polyester resin container having a composition in which 0.05 parts by weight or more and less than 1 part by weight of a metaxylylene group-containing polyamide resin is added to a terephthalate resin is disclosed and can be applied to injection molding and extrusion molding (see Patent Document 1).
This countermeasure is the simplest method, and is excellent in reducing the amount of acetaldehyde by-products, but the metaxylylene group-containing polyamide resin used is quite expensive, and the polyester resin container is colored yellow. The transparency of the polyester resin container may be lowered, and the injection molding method receives a considerably high temperature heat history, so that the performance of the metaxylylene group-containing polyamide resin is deteriorated due to thermal deterioration.

A number of direct improvements without using polyamide resins have also been disclosed. As a typical example, a polyethylene terephthalate resin obtained by melt polymerization is solidified under an inert gas containing hydrogen in the absence of oxygen. A method of suppressing the aldehyde content and the regenerated amount by phase polymerization (see Patent Document 2), and when using a specific screw type plasticizer when molding a mixture of polyethylene naphthalate and polyethylene terephthalate. A method of suppressing the formation of acetaldehyde by advancing the transesterification reaction (see Patent Document 3), a method of reducing acetaldehyde by incorporating an active oxidation catalyst that oxidizes acetaldehyde to acetic acid, and the like are disclosed (Patent Document). 4).
However, in the method in Patent Document 2, aldehydes are again produced as a by-product in the molding step, and the method in Patent Document 3 targets a specific resin, and the method in Patent Document 4 requires an additional catalyst. However, it cannot be said that the by-product of aldehydes is sufficiently reduced.

  Furthermore, as another improvement method, a container in which a protective layer such as an ethylene vinyl alcohol copolymer is provided on the inner surface layer of the container in order to prevent the acetaldehyde harmful substance in the polyester resin container from moving into the container is disclosed. (Patent Document 5), a protective layer of another type of resin must be provided, and the acetaldehyde exudation cannot be completely prevented.

  In addition to the above-mentioned problem of reducing aldehydes, as a further second technical request, in the polyester resin container, there is also a technical request for imparting high functionality such as high barrier performance to various gases, Although it can be said to be the third technical requirement, recently, in the production of polyester resin containers as the plastic industry, social demands from other aspects such as energy saving and resource saving in environmental protection issues have also become stronger. Reduce the energy consumption of the molding machine in the production of container products, the heating process, the drying process, etc., reduce the environmental impact of carbon dioxide gas through energy savings, and collect and reuse used containers, especially collecting containers It is required to save resources by reusing directly used for manufacturing containers and to reduce consumption of fossil resources. Technical deal with the contribution to the request are also become inevitable situation in research and development.

JP-A-62-50328 (Claims, page 1, lower left column, line 18 to lower right column, line 19) JP-A-9-3179 (summary) JP 2001-179733 A (summary) Japanese translation of PCT publication No. 2003-512831 (abstract, claim 1) Japanese National Patent Publication No. 11-513952 (summary and second page)

As described above in paragraphs 0003 to 0008, the problem of by-products of aldehydes has been solved to a considerable degree by the various improved methods described above, but aldehydes can be easily and sufficiently reduced by a universal method. In recent years, especially in polyester resin containers such as PET bottles, it is important to say that the above-mentioned first to third requests are the demands of consumers or the demands of the social era. Problems are presented.
Therefore, trace amounts of by-product aldehydes generated during polymerization and molding of polyester resin have an adverse effect on the unique flavor and aroma of drinking water such as natural mineral water, and the taste and aroma of natural water are eliminated. The polyester resin container is also provided with high functionality as a high barrier performance against various gases, and at the same time energy saving and energy saving in environmental protection problems. In order to respond to social demands from other aspects such as resources, the energy used in the production of container products is reduced, the environmental impact of carbon dioxide gas is reduced by energy conservation, and the collection and reuse of used containers are In particular, the present invention solves the problem of saving resources by reducing the consumption of fossil resources by reusing the collection container directly for manufacturing the container. It is an issue come.

In order to solve such a problem, the inventors of the present application, as a by-product of aldehydes during polymerization or molding of a polyester resin material (in the present invention, polyester resin means a thermoplastic polyester resin). Control method, preform material and acetaldehyde reducing agent and blending ratio thereof, molding conditions and molding equipment in preform compression molding, molding conditions and molding equipment in blow molding, and each layer configuration of polyester resin container, In particular, with regard to the gas barrier layer, etc., various considerations were made from various perspectives and continued to be experimentally examined and examined.
As a result, in order to reduce the aldehydes and suppress the adverse effects on the drinking water stored in the container, basically, a method of suppressing the by-product of aldehydes at the time of molding the polyester resin, or drinking water Can be used to prevent aldehydes from entering the container and dissolving in the stored liquid during storage or consumption of the container. Adopting a compression molding method that receives a relatively low thermal history as compared to the injection molding method as a preform molding method, suppressing the by-product reaction of aldehydes by suppressing the thermal load, or A specific shielding layer that prevents the invasion of aldehydes is provided on the inner surface of the container in contact with the stored liquid, and an appropriate combination of aldehydes by-product inhibitors is also adopted. It was.
An inorganic thin film layer is used as a specific shielding layer that suppresses intrusion of aldehydes, and typically a silicon oxide film (indicated by SiOx) layer is employed, which is a gas barrier layer of oxygen and carbon dioxide gas. And a film layer is formed by vapor deposition of a silicon oxide compound. As other inorganic thin film blocking layers, various carbon films such as diamond-like carbon films and modified carbon films, titanium oxide films, aluminum oxide (alumina) films, ceramic films, silicon carbide films, silicon nitride films, etc. should also be used. Can do.
Furthermore, by using a polyester resin multilayer container in which a gas barrier layer such as a specific oxygen shielding layer or oxygen absorption layer is formed, it is possible to provide high functionality as a high barrier performance against various gases such as oxygen. In addition, by adopting a compression molding method that can be molded under relatively mild conditions as compared to the injection molding method as a molding method, by reducing the thermal energy required for heating the molding device and molding material during molding, Reduces environmental impact of carbon dioxide gas by reducing energy consumption in environmental protection problems, reduces the by-product of aldehydes by reducing heat load, and reuses used collection containers directly for the production of containers It was also possible to save resources and reduce consumption of fossil resources.

As a result of these, the entire invention of the present application was created, and as described above in paragraph 0008, the first to third requests as demands from consumers or social times in polyester resin containers It is not an exaggeration to say that all the important problems that should be solved can be solved together by a novel combination of the above-mentioned methods.
By-products during molding of aldehydes or intrusion into the inside of the container is sufficiently suppressed, and it has a high functionality of shielding various gases, and the used collection container can be reused directly to the container, reducing production energy and fossil It can be said that the polyester resin container having such a composite function that reduces the consumption of resources should be referred to as a next-generation polyester bottle.

In order to increase the adhesion between the silicon oxide thin film layer and the polyester resin layer and the flexibility of the laminated structure, an organic silicon polymer film layer is provided as an intermediate layer between the polyester resin layer and the silicon oxide thin film layer. .
The recycled material from the used collection container is used in the form of a single layer, blended with an unused polyester resin, or a combination layer with an unused polyester resin layer.
Plasticizing conditions for compression molding also affect the reduction of aldehydes, especially under low heat load conditions, and the aldehydes are reduced, and the yellowing of the container material (transparency deterioration) is also suppressed, and a soft drink container As a function is retained.

Here, even in view of the prior art, a polyester resin container provided with an inorganic thin film layer is known (claim 4 of Japanese Patent Application Laid-Open No. 2003-20023), but the present invention is based on a technique such as molding conditions with low heat load. This is a container with reduced aldehydes, and this configuration differs from the prior art.
Further, although the used collection container is directly reused for forming the container (paragraph 0021 of the above publication, claim 2 and paragraph 0009 of JP-A-2003-39531), the inorganic thin film layer is also used. The above-described configuration such as adoption is different from the present invention. Although JP-A-2003-39531 describes the migration rate of acetaldehyde into a container (paragraph 0006), it does not inhibit the migration of acetaldehyde by a special configuration.
Furthermore, when forming a preform by compression molding, there is also known a preform in which aldehydes are suppressed by the provision of the maximum value of the calorific value of isothermal crystallization in polyester. It is a different technology that requires a collection container reuse resin.
In addition, as described above in paragraph 0007, there is also disclosed a container in which a protective layer such as an ethylene vinyl alcohol copolymer is provided on the inner surface layer of the container in order to prevent the acetaldehyde harmful substance in the polyester resin container from moving into the container. (Patent Document 5), however, a protective layer of another type of resin has to be provided, and leaching of acetaldehyde cannot be completely prevented.
In any other prior literature, the description suggesting the basic configuration of the present invention and the characteristics as the next-generation polyester resin container described in paragraphs 0011 to 0012 cannot be found.

  In the above, the background of the creation of the present invention and the basic components and features of the present invention have been described in an overview. Here, when overviewing the present invention, the present invention has the following invention unit group: The invention of [1] is a basic invention, and other inventions embody the basic invention or form an embodiment. (The entire invention group is collectively referred to as “the present invention”.)

[1] A polyester resin multilayer container in which an inorganic thin film layer is provided in an inner layer of a polyester resin layer and has a function of reducing aldehydes.
[2] The polyester resin multilayer container according to [1], wherein the inorganic thin film layer is a silicon oxide thin film layer.
[3] The polyester resin multilayer container according to [2], wherein an organic silicon polymer film layer is provided as an intermediate layer between the polyester resin layer and the silicon oxide thin film layer.
[4] The polyester resin multilayer container according to [2], wherein a polyester resin layer-organosilicon polymer film layer-silicon oxide thin film layer-organosilicon polymer film layer is provided.
[5] The polyester resin layer is a used polyester resin container recycled material, or the polyester resin layer is mixed with a used polyester resin container recycled material, or a multilayer including a used polyester resin container recycled material is provided. The polyester resin multilayer container according to any one of [1] to [4].
[6] The polyester resin multilayer container according to [5], wherein the recycled material of the used polyester resin container is a recycled resin material obtained by pulverizing a polyester resin container collected after use and washing with alkali.
[7] The polyester resin multilayer container according to any one of [1] to [6], further comprising a gas shielding layer and / or a gas absorbing layer.
[8] The polyester resin multilayer container according to any one of [1] to [7], wherein the shielding or absorbing gas is oxygen and / or carbon dioxide.
[9] The polyester resin is plasticized and compression molded to form a preform, then the preform is blow molded to form a container, and then an inorganic thin film layer is deposited on the inner layer of the polyester resin layer. A polyester resin multilayer container according to any one of [1] to [8], and a method for producing the multilayer container.

In the present invention, acetaldehyde and formaldehyde in the polyester resin container can be remarkably reduced, so that particularly in a soft drink container, a trace amount of aldehydes can be found in the unique flavor of drinking water such as natural mineral water. The problem of adversely affecting the scent, erasing its flavor and altering the taste and scent of natural water, etc. is sufficiently solved.
In addition, in the polyester resin container, high functionality as a high barrier performance against various gases is also given, and at the same time, the energy used in the manufacture of container products is reduced, and the environmental impact of carbon dioxide gas is reduced by energy saving. In addition, it is possible to conserve resources by collecting and reusing used containers, in particular, reusing the collected containers directly for the production of containers, thereby reducing the consumption of fossil resources.

  The invention of the present application has been described in accordance with the basic configuration of the invention of the present application as means for solving the problem. However, in the following, the embodiments of the invention of the invention group of the present application described above will be described in detail. explain.

1. Polyester resin multi-layer container provided with an inorganic thin film layer (1) Basic configuration The first basic invention of the present application is that the amount of aldehydes such as acetaldehyde as an impurity is unavoidable during polymerization (usually about 0.5 to 10 ppm) In a polyester resin container using a normal polyester resin such as polyethylene terephthalate, which is produced as a by-product in), an inorganic thin film layer is provided as an inner layer of the polyester resin layer, thereby having a function of reducing aldehydes. This is a polyester resin multilayer container. The container of the present invention is preferably manufactured by biaxial stretching blow molding or biaxial stretching two-stage blow molding.

(2) Polyester resin The main component of the molding material used in the present invention is a polyester resin, and ordinary polyethylene terephthalate (commonly known as PET) is mainly used.
Preferably, polyethylene terephthalate uses a crystalline resin in which the main repeating unit is ethylene terephthalate, 90 mol% or more of the acid component is terephthalic acid, and 90 mol% or more of the glycol component is ethylene glycol. Examples of other acid components of this PET include isophthalic acid and naphthalene dicarboxylic acid, and examples of other glycol components include diethylene glycol, 1,4-butanediol, cyclohexanedimethanol and propylene glycol.
A resin having a glass transition point (Tg) of 50 to 90 ° C. and a melting point (Tm) of about 200 to 275 ° C. is used, and a small amount (about 5 to 25%) of polyethylene naphthalate or polycarbonate can be blended.

(3) Inorganic thin film An inorganic thin film layer is formed in the inner surface layer by the side of the container in a polyester resin container employ | adopted as a specific shielding layer which suppresses the penetration | invasion into the container inside of aldehydes. This also functions as a gas barrier layer of oxygen and carbon dioxide, and a film layer is formed by vapor deposition of a silicon oxide compound.
In the inorganic thin film, an inorganic compound such as silicon oxide SiOx is formed by vapor deposition. The vapor-deposited film needs to be flexible, and it is preferable that the film thickness be sufficiently thin so that it does not peel or crack due to deformation of the container. Particularly preferred is 5 to 30 nm in combination with the following organosilicon polymer layer film. The thickness of other layers other than those is not particularly limited.
The vapor deposition is performed by a high frequency plasma CVD method, a microwave plasma CVD method, or the like. In order to avoid thermal deformation of the substrate during the treatment, a method of coating at a low temperature such as plasma CVD or sol-gel method is preferable.
As other inorganic thin film blocking layers, various carbon films such as diamond-like carbon films and modified carbon films, titanium oxide films, aluminum oxide (alumina) films, ceramic films, silicon carbide films, silicon nitride films, etc. should also be used. Can do.

As a typical example of the inorganic thin film, a silicon oxide film (SiOx) will be described in detail below.
As an organic compound used as a silicon source and a carbon source, any compound can be used as long as it reacts with an oxidizing gas to form a silicon oxide. Silane compounds such as disilane, vinyltrimethylsilane, methylsilane, dimethylsilane, trimethylsilane, diethylsilane, propylsilane, phenylsilane, methyltriethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane Alkoxysilane compounds such as phenyltrimethoxysilane, methyltrimethoxysilane, and methyltriethoxysilane, and octamethylcyclotetrasiloxane, 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane, etc. Machine siloxane compound is used. In addition to these materials, aminosilane, silazane, and the like can also be used.
Such organosilicon compounds can be used alone or in combination of two or more. In the present invention, hexamethyldisiloxane (HMDSO) is most preferably used.
Moreover, monosilane (SiH ₄ ) or silicon tetrachloride can be used in combination with the above-described organosilicon compound. Furthermore, hydrocarbons such as CH ₄ , C ₂ H ₄ , C ₂ H ₆ can be used in combination with the organosilicon compound as a carbon source.
Oxygen or NOx is used as the oxidizing gas, and argon or helium is used as the carrier gas.

As a method for forming a thin film, a pre-deposition step and a main deposition step, and a post-deposition step performed thereafter will be described below.
[Pre-deposition process]
In the pre-deposition step at the start of deposition, a certain amount of organosilicon compound gas (and carrier gas and hydrocarbon gas as necessary) is supplied to the plasma processing chamber in which the plastic substrate to be treated is held.
The amount of organosilicon compound introduced varies depending on the surface area of the plastic substrate to be treated and the type of organosilicon compound. For example, when the substrate is a plastic container, the silicon raw material is in a standard state per container. Therefore, it is desirable to supply at a relatively small flow rate of 0.5 to 50 cc / min, particularly 1 to 20 cc / min (hereinafter sometimes simply referred to as sccm). In order to form a vapor deposition film having a stable composition with no variation, it is preferable that the flow rate is always set to a constant flow rate without being changed in the main vapor deposition step described later.
In this pre-deposition step, an oxidizing gas is not supplied, so that an organosilicon layer is formed. Therefore, the plasma-generated glow discharge can be generated by either microwaves or high-frequency electric fields, as long as it does not cause thermal deformation of the substrate beyond the output required to cause the reaction of the organosilicon compound. In the case of microwaves, the output is 30 W to 1500 W, and in the case of high frequencies, the output is 50 W to 2000 W, although it varies depending on the chamber size.
Furthermore, the plasma treatment time in this pre-deposition process differs depending on the surface area of the plastic substrate to be treated, the thickness of the deposited film to be formed, and the type of the organometallic compound, and cannot be generally defined. The plasma treatment of a plastic container using the above will be explained. An organic silicon film having a thickness of about 0.1 to 10 nm is formed per container for about 0.05 to 5 seconds. Is preferred. In this pre-deposition step, depending on the case, it is possible to supply a trace amount of oxidizing gas that does not impair the flexibility of the organosilicon layer.
In addition, performing the pre-deposition step without supplying the oxidizing gas in this way also achieves an additional advantage that alteration due to etching of the plastic substrate surface due to the oxidizing gas can be effectively avoided. Is done. That is, in the next main vapor deposition step in which the oxidizing gas is supplied, since the organosilicon layer is already formed on the surface of the substrate, etching of the substrate surface with the oxidizing gas is effectively prevented. Become. As a result, for example, when applied to the present invention using a plastic container as a base material, the flavor characteristics are further improved.

[Main deposition process]
In the main vapor deposition step performed subsequent to the pre-deposition step, silicon is formed by glow discharge by supplying an oxidizing gas (and carrier gas and hydrocarbon gas if necessary) to the plasma processing chamber in addition to a certain amount of organosilicon compound gas. An oxide layer is formed.
At this time, the introduction amount of the oxidizing gas varies depending on the kind of the organosilicon compound gas, the surface area of the substrate to be treated, etc., but generally 5 to 500 sccm, particularly 10 to 300 sccm per container. It is preferable to supply at a large flow rate.
Moreover, in this main vapor deposition process, it is preferable to generate plasma-generated glow discharge while changing from a low output region to a high output region.
Therefore, for example, in the case of glow discharge using microwaves, it is preferable to change the output from the range of 30 W to 300 W to 100 W to 1500 W, and in the case of high frequency, the output is changed from the range of 50 W to 350 W to 150 W to 2000 W. Is good.
The plasma treatment time in the main vapor deposition process also differs depending on the surface area of the substrate to be treated, the thickness of the vapor deposition film to be formed, and the type of the organosilicon compound, and cannot be specified in general. It is preferable that a silicon oxide layer having a thickness of about 3 to 300 nm is formed per container for 1.5 seconds or longer.
In addition, although the transition from the above-described pre-deposition to the main deposition may be performed continuously or sequentially, it is preferable to perform the transition continuously. From the viewpoint of continuously changing the elemental composition from the organosilicon layer to the silicon oxide layer, without forming an interface between the layers, and integrating the vapor deposition films, it is preferable to make the transition continuously. Further, from the organosilicon layer to the silicon oxide layer, the silicon binding energy in the photoelectron spectroscopic analysis is continuously changed from about 101 to 102 eV derived from the organosilicon material to about 103 to 104 eV derived from the silicon oxide bond. Is preferable.

[Post-deposition process]
After the pre-deposition and the main vapor deposition are performed as described above to form the organosilicon layer and the silicon oxide layer, the organosilicon layer is formed.

(4) Organosilicon polymer film layer In order to improve the adhesion between the silicon oxide thin film layer and the polyester resin layer and the flexibility of the laminated structure, an organosilicon polymer is used as an intermediate layer between the polyester resin layer and the silicon oxide thin film layer. A membrane layer is provided.

2. Multi-layer container using used polyester resin container recycled material (1) Basic structure It is a container characterized by using used polyester resin container recycled material, preform molding is performed by compression molding, low temperature By-product formation of aldehydes is reduced by reducing the thermal load by molding.
In this container, i) polyester resin is a recycled material for used polyester resin containers, and ii) or used polyester resin containers for polyester resins (unused polyester resins, commonly referred to as “virgin resins”). Three modes are employed in which a recycled material is blended and iii) or a multilayer including a used polyester resin container recycled material is provided.

Here, as an example of a typical layer structure, FIG. 1 illustrates a four-layer / five-layer stacked structure in which the above-described inorganic thin film layer and organic silicon polymer layer film are provided in the mode iii). In the laminated structure 10 of FIG. 1, the silicon oxide thin film layer 11, the organic silicon polymer film layer 12, the polyester resin layer 13, the used polyester resin container recycled material layer 14, and the polyester resin outer layer 15 are arranged from the inside of the container. It is composed of
In addition, from the inside of the container, five layers and seven layers comprising an inorganic thin film layer, an organic silicon polymer film layer, a polyester resin layer, an oxygen absorbing layer, a used polyester resin container recycled material layer, an oxygen absorbing layer, and a polyester resin outer layer. This layer configuration is also exemplified, and in this layer configuration, if the used polyester resin container recycled material layer is a polyester resin layer, a four-layer / seven-layer configuration is obtained.

(2) Recycled material for used polyester resin containers In the present invention, resource consumption is reduced by collecting and reusing used containers, especially by using the collected containers directly in the manufacture of containers, thereby reducing the consumption of fossil resources. Make.
Since the recovered polyester in the used container has a thermal history applied to thermoforming, the intrinsic viscosity is reduced and the mechanical properties are deteriorated. If it is contained, and it is thermoformed again to form a container as it is, it tends to cause a decrease in various properties of the container and a decrease in flavor retention due to the transfer of aldehydes in the container wall to the contents. Containers collected after use are naturally washed, but they may be contaminated with substances that cannot be removed by washing. Not acceptable in terms of mechanical properties. Therefore, the polyester in the collection container is usually only reused for fibers, and when it is reused in a polyester resin container, special measures are required to cope with viscosity reduction, residual aldehydes, and sanitary treatment. It becomes.

In the invention of the present application, the countermeasure against the decrease in the intrinsic viscosity and the deterioration of the mechanical properties is to mix the used polyester resin with the virgin polyester resin, or the used polyester resin container for the virgin polyester resin layer. A layer made of recycled material is added, and the deterioration of mechanical properties is compensated by virgin polyester resin.
For the remaining aldehydes, the inorganic thin film layer prevents the aldehydes from entering the container.
The sanitary treatment of the container is a recycled resin material obtained by crushing a polyester resin container collected after use and washing it with alkali.

  In addition, in the polyester resin container of this invention, you may mix | blend various additives, such as a normal colorant, a ultraviolet absorber, antioxidant, and an antibacterial agent suitably.

3. Gas-shielding layer and / or gas-absorbing layer In the polyester resin container of the present invention, preferably a gas-shielding layer and / or a gas-absorbing layer are further provided, and the high-functionality is also contributed by the inorganic thin film layer. Is granted.
The shielding or absorbing gas is oxygen and / or carbon dioxide. Oxygen gas deteriorates the flavor and odor by chemically changing the contents stored in the container by oxidation. When the soft drink contains carbon dioxide, it is necessary not to let the carbon dioxide escape from the container.
As the gas shielding layer, a resin having gas shielding properties such as an ethylene-vinyl alcohol copolymer and a cyclic olefin copolymer is used, and as the gas (oxygen) absorbing layer, a resin containing an oxygen scavenger, Alternatively, a polyamide-based resin or an oxidizable polyolefin-based resin is used. Specific examples of the ethylene-vinyl alcohol copolymer include a saponified copolymer obtained by saponifying an ethylene-vinyl acetate copolymer so that the saponification degree is 96 mol% or more, particularly 99 mol% or more. used. As the oxygen scavenger (oxygen absorber), iron-based oxygen scavengers excellent in oxygen absorption and economy are typically used. The iron-based oxygen absorber provides a strong oxygen absorbing action due to its excellent reducibility (deoxygenation from surrounding substances).

4). Molding of the polyester resin container The molding of the polyester resin container of the present invention is basically performed by plasticizing the polyester resin with an extruder or the like, compressing the molten resin to form a preform, and then blowing the preform. The container is formed, and then, if necessary, an inorganic thin film layer is deposited on the inner layer of the polyester resin layer.

(1) About plasticization method Polyester resin molding material is plasticized (fluidization of molding material composition for preforming by warming kneading), compression molding for preforming is performed, and preform (existing) When forming the bottom cylindrical parison), preferably, the molding material is dried to reduce the production of aldehydes by hydrolysis at the time of plasticization, and the plasticization is performed by a single-screw or multi-screw extruder. Perform at as low a temperature as possible. The meaning of the low temperature is a temperature lower than the plasticizing temperature of preform molding by ordinary injection molding or the like, and is preferably in a range of 265 to 280 ° C. slightly exceeding the melting point of polyethylene terephthalate.
By implementing under low temperature conditions, a heat load is suppressed and the by-production of aldehydes is suppressed. Furthermore, the energy consumption can be reduced and the environmental impact of carbon dioxide gas can be reduced by saving energy.

(2) Compression molding In compression molding, a heated molding resin material is inserted into a female cavity of a male and female mold, and the resin material is compressed in cooperation with the male and female molds to a desired shape. This is a method of forming by flowing. From the viewpoint of production efficiency, rotary-type continuous compression molding using a large number of molds is suitable for preforming preform production. A thermoplastic molding material melt is continuously extruded and supplied. After the molten mass is cut into molten masses and placed in a number of molds to be moved, the molten mass is compression molded, and the compression molded product is cooled and solidified and discharged out of the mold. Is called. When manufacturing a multilayer container, multilayer extrusion is performed by a plurality of extruders to form a multilayer preform.
Unlike injection molding, compression molding is small in size and inexpensive, enables processing at a relatively low temperature, suppresses by-products of aldehydes, and can produce a high-density molded product with no gate residue. Therefore, it is preferable to reduce the thermal load by suppressing the molding temperature as much as possible.
The plasticized molding material is compression-molded by a normal compression molding method, and preformed into a preform (bottomed cylindrical parison) for molding a container.

(3) Blow molding A preform that has been preformed is conveyed to a blow molding die and subjected to normal blow molding by feeding a pressure fluid into the preform, and the product has a shape along the mold cavity. Molded into a container. Blow molding is preferably biaxial stretch blow, and if necessary, two-stage blow may be performed. In addition, it is preferable to crystallize a mouth neck part by heat processing different from shaping | molding as usual.
Also in blow molding, for the same reason as in compression molding, it is preferable to reduce the thermal load by suppressing the molding temperature as much as possible.

In the following, the present invention will be described in more detail with reference to comparative examples, but the examples are for demonstrating the significance and rationality of each component of the present invention.
[Data measurement method]
Air space and acetaldehyde content: The inside of the molded container is sufficiently replaced with nitrogen gas, sealed, and stored in an atmosphere at 22 ° C. for 24 hours, and then the amount of acetaldehyde in the gas phase in the container is determined by a normal gas chromatograph. Measured (GC-6A type manufactured by Shimadzu Corporation was used).

[Example-1]
In the co-injection molding machine, a commercially available polyester resin (inherent viscosity: 0.80 dl / g) was supplied to the inner layer and outer layer injection machines, and at the same time, the used recovered polyester resin container recycled material was supplied to the intermediate layer injection machine. The injection nozzles of these injection machines were co-injected into an injection mold under the conditions of an injection nozzle temperature of 280 ° C. and a resin pressure of 24.5 MPa at a ratio of 15 g of polyester resin and 10 g of used recovered polyester resin container recycled material. A three-layer preform (weight 25 g) was molded. Further, this preform was heated to 100 ° C., then biaxially stretched and blown at a stretching ratio of 2.4 times in length and 2.9 times in width using a normal temperature blow mold, and the inner volume was 500 ml. A multi-layer bottle of layers was obtained. Next, a silicon oxide thin film layer having a thickness of 30 nm was formed on the inner layer surface of the bottle by a microwave plasma CVD method to obtain an inner surface-deposited bottle.
The results of measuring the amount of acetaldehyde present in the air space in the bottle (μg / L) are shown in Table 1.

[Example-2]
A commercially available polyester resin (inherent viscosity: 0.80 dl / g) was plasticized at an in-machine temperature of 275 ° C. and 280 ° C. using a single-screw extruder and a used recovered polyester resin container recycled material as an intermediate layer, respectively. A two- and three-layer preform (weight: 25 g) composed of 15 g of a polyester resin and 10 g of a used recovered polyester resin container recycled material was molded by a compression molding machine using a 20 ° C. mold. Thereafter, the same procedure as in Example-1 was performed. The measurement results are shown in Table 1.

[Example-3]
In the co-injection molding machine, a commercially available polyester resin (inherent viscosity: 0.80 dl / g) was supplied to the inner layer, outer layer and intermediate layer injection machines, and MXD-6 nylon was supplied to the gas cutoff injection machine. The injection nozzle temperature of these injection machines was 280 ° C. and the resin pressure was 24.5 MPa. In the injection mold, 24.25 g of polyester resin and MXD-6 nylon were co-injection molded at a ratio of 0.75 g, and the inner layer A two-type five-layer preform (weight 25 g) made of a polyester resin for the outer layer and the intermediate layer, and an oxygen-barrier barrier material between the inner layer and the intermediate layer and between the outer layer and the intermediate layer was molded. Thereafter, the same procedure as in Example-1 was performed. The measurement results are shown in Table 1.

[Example-4]
In the co-injection molding machine, a commercially available polyester resin (inherent viscosity: 0.80 dl / g) is supplied to the inner and outer layer injection machines, and at the same time, the used recovered polyester resin container recycled material is supplied to the intermediate layer injection machine, and MXD-6. Nylon (manufactured by Toyobo Co., Ltd.) was supplied to each gas shutoff injector. 15 g of polyester resin, 9.25 g of used recovered polyester resin container recycled material, and 0.75 g of MXD-6 nylon in the injection mold under the conditions of the injection nozzle temperature of 280 ° C. and the resin pressure of 24.5 MPa. Co-injection molding at the ratio of the inner layer and the outer layer are polyester resin, the intermediate layer is a used recycled polyester resin container recycled material, the inner layer and the intermediate layer, and the oxygen blocking barrier material between the outer layer and the intermediate layer A preform (weight 25 g) was molded. Thereafter, the same procedure as in Example-1 was performed. The measurement results are shown in Table 1.

[Comparative Example-1]
In an injection molding machine, a commercially available polyester resin (inherent viscosity: 0.80 dl / g) is injection-molded into an injection mold under the conditions of an injection nozzle temperature of 280 ° C. and a resin pressure of 24.5 MPa. A preform (weight 25 g) was obtained. Further, this preform was heated to 100 ° C. and then subjected to biaxial stretch blow molding at a stretch ratio of 2.4 times in length and 2.9 times in width using a blow mold at room temperature to obtain a bottle having an internal volume of 500 ml. It was. The measurement results are shown in Table 1.

[Comparative Example-2]
The comparative example of Example-2 is shown, Comprising: The silicon oxide thin film was not formed. The measurement results are shown in Table 1.

[Comparative Example-3]
The comparative example of Example-3 is shown, Comprising: The silicon oxide thin film was not formed. The measurement results are shown in Table 1.
(In the table, ND means the detection limit (0.1 μg / L) or less)

Furthermore, the sensory test (flavor test) by a paneler was performed on the preform of each example and each comparative example.
Repacked with commercially available mineral water containing glass and sealed mouth, 22 ° C 60% R
After storage for 2 weeks in a constant temperature and humidity (dark place) of H, a comparison with glassy mineral water was performed by a sensory (flavor) test.
Flavor test score: ◎ No significant difference ○ Slight feel △ Slightly inferior × Inferior

[Consideration of results of Examples and Comparative Examples]
Examples 1-4 show the general form of the preform molding method and layer structure in the present invention. From the results of measuring the amount of acetaldehyde (μg / L) in the air space in the bottle, Even if it takes such a form, it turns out that the byproduct of aldehydes is reduced in the forming container by forming an inorganic thin film in the innermost layer.
In Example 2, since the compression molding method having a lower thermal load than that of the injection molding method is used, it is shown by the flavor test that the amount of aldehydes is further reduced as compared with Example 1.
In Comparative Examples 1 to 3, since the inorganic thin film layer is not provided, the amount of acetaldehyde present in the molded container is not reduced as compared with each Example. Moreover, the flavor test in the preform also shows that aldehydes are not reduced.

It is sectional drawing which illustrates the layer structure of the polyester resin container in this invention.

Explanation of symbols

10: Laminated structure 11: Inorganic thin film layer 12: Organosilicon polymer film layer 13 Polyester resin layer 14: Used polyester resin container recycled material layer 15: Polyester resin outer layer

Claims (9)

A polyester resin multilayer container, wherein an inorganic thin film layer is provided in an inner layer of the polyester resin layer and has a function of reducing aldehydes. The polyester resin multilayer container according to claim 1, wherein the inorganic thin film layer is a silicon oxide thin film layer. The polyester resin multilayer container according to claim 2, wherein an organic silicon polymer film layer is provided as an intermediate layer between the polyester resin layer and the silicon oxide thin film layer. The polyester resin multilayer container according to claim 2, wherein a polyester resin layer-organosilicon polymer film layer-silicon oxide thin film layer-organosilicon polymer film layer is provided. The polyester resin layer is a used polyester resin container recycled material, or the polyester resin layer is mixed with a used polyester resin container recycled material, or a multilayer including a used polyester resin container recycled material layer is provided. The polyester resin multilayer container as described in any one of Claims 1-4. 6. The polyester resin multilayer container according to claim 5, wherein the recycled material of the used polyester resin container is a recycled resin material obtained by pulverizing a polyester resin container collected after use and washing with alkali. The polyester resin multilayer container according to any one of claims 1 to 6, further comprising a gas shielding layer and / or a gas absorbing layer. The polyester resin multilayer container according to any one of claims 1 to 7, wherein the gas to be shielded or absorbed is oxygen and / or carbon dioxide gas. Polyester resin is plasticized and compression molded to form a preform, then preform is blow molded to form a container, and then an inorganic thin film layer is deposited on the inner layer of the polyester resin layer. The polyester resin multilayer container as described in any one of Claims 1-8 and the manufacturing method of the container.

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