Heat-resistant polyethylene terephthalate tray and method for manufacturing the same

Abstract

To provide a heat-resistant PET tray that is composed of recycled material including collected polyethylene terephthalate and features guaranteed safety for the human body and high added value.SOLUTION: A heat-resistant polyethylene terephthalate tray is composed of a resin composition including recycled material. The recycled material is composed of decontaminated, collected polyethylene terephthalate.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a heat-resistant polyethylene terephthalate tray and a method for manufacturing the same, using a recycled material made from recycled polyethylene terephthalate.

Background Art

[0002] In recent years, the concept of "realizing a circular society" represented by SDGs has become mainstream, and recycling has been promoted for food containers and the like. For example, plastic bottles used for beverages are mainly made of polyethylene terephthalate (PET), and since it is relatively easy to collect those that have once been on the market, efforts have been made to manufacture plastic bottles again from the collected plastic bottles (post-consumer materials of plastic bottles) (see, for example, Patent Document 1). On the other hand, the consumption of plastic trays in the country is about 800,000 t per year, but the collection work is complicated and the cost for reuse is high, so they are not collected and reused except for very few exceptions.

[0003] That is, while most plastic bottles are made of PET, the materials of plastic trays are diverse, including PET, polystyrene (PS), polypropylene (PP), polyvinyl chloride (PVC), polylactic acid (PLA), and composites thereof. Therefore, it is difficult to efficiently separate them by material, which is one of the reasons why the recycling of plastic trays has not progressed.

[0004] However, it is predicted that the concept of extended producer responsibility (EPR) will become mainstream in the future, and since the market mindset is also permeated with the idea of prioritizing ecology over economy, it is strongly desired to manufacture plastic trays from post-consumer materials not only for plastic bottles but also for plastic trays. Furthermore, with the enforcement of the Plastic Resource Recycling Law on April 1, 2022, there is growing momentum to promote the recycling of plastic trays by using monomaterials.

[0005] On the other hand, because the history of the plastic trays is unknown, even if their original use was for food, there is a problem in that plastic trays made from recycled materials cannot be guaranteed to be safe for human health.

[0006] To address this issue, the current practice is to ensure safety by applying a new plastic film (virgin film) to the surface of plastic trays made from post-consumer materials, thereby preventing direct contact between the food and the plastic tray. However, while the aforementioned method can reassure consumers, it is difficult to clearly meet the safety standards set forth in the FDA guidelines, which have now become an international standard. Furthermore, the aforementioned method introduces a new problem: the addition of a virgin film application process complicates the manufacturing line, and the cost of the film material increases. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] International Publication No. 2017 / 183048 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] This invention has been made in view of these circumstances, and aims to provide a high-value-added heat-resistant PET tray and a method for manufacturing the same, which uses recycled material made from recovered PET and ensures safety for the human body. [Means for solving the problem]

[0009] The inventors of the present invention have found that the above problem can be solved by manufacturing a heat-resistant PET tray using a resin composition containing recycled material that has been decontaminated to a level that ensures safety for the human body, even if harmful substances are mixed into the recovered PET material, and have completed the present invention.

[0010] However, the gist of the present invention is as follows: [1] to

[13] . [1] A heat-resistant PET tray made of a resin composition containing recycled material, wherein the recycled material is made of decontaminated PET recovery material. [2] A heat-resistant PET tray as described in [1], having a true specific gravity of 1.35 or higher. [3] The heat-resistant PET tray according to [1] or [2], wherein the resin composition contains a crystal nucleating agent. [4] The heat-resistant PET tray according to [3], wherein the nucleating agent is at least one selected from the group consisting of organometallic salts, metal hydrates, and metal hydroxides. [5] The heat-resistant PET tray according to any one of [1] to [4], wherein the resin composition contains a crosslinking agent. A method for manufacturing a heat-resistant PET tray as described in any of [6] [1] to [5], A method for manufacturing a heat-resistant PET tray, comprising: a grinding step for grinding recovered PET material; a decontamination step for decontaminating the pulverized material obtained in the grinding step or pellets obtained from the pulverized material; and a manufacturing step for manufacturing a heat-resistant PET tray from a resin composition containing recycled material obtained via the decontamination step. [7] The method for manufacturing a heat-resistant PET tray according to [6], wherein the recycled material has a total residual amount of surrogate contaminants of 220 ppb or less and / or a total elution amount of surrogate contaminants of 10 ppb or less when subjected to a surrogate contamination test. [8] The method for manufacturing a heat-resistant PET tray according to [7], wherein the substitute contaminant is at least one substance selected from each of the following groups (I) to (IV). (I) Chloroform, chlorobenzene, trichloroethane, diethyl ketone. (II) Toluene. (III) Benzophenone, methyl salicylate. (IV) Tetracosan, methyl stearate, phenylcyclohexane, 1-phenyldecane. [9] A method for manufacturing a heat-resistant PET tray according to any one of [6] to [8], wherein the decontamination treatment is at least one selected from the group consisting of vacuum heating treatment, infrared heating treatment, and nitrogen gas flow heating treatment.

[10] A method for producing a heat-resistant PET tray according to any one of [6] to [9], wherein the resin composition comprises a crystal nucleating agent.

[11] A method for producing a heat-resistant PET tray according to any one of [6] to

[10] , wherein the resin composition comprises a crosslinking agent.

[12] A method for producing a heat-resistant PET tray according to any one of [6] to

[11] , wherein the resin composition comprises a thermoplastic resin other than PET.

[13] A method for manufacturing a heat-resistant PET tray according to any one of [6] to

[12] , comprising a washing step of washing the pulverized material. [Effects of the Invention]

[0011] The heat-resistant PET tray of the present invention is made of a resin composition containing recycled material derived from recovered PET, exhibiting heat resistance, and even if harmful substances (specific chemical substances that adversely affect the human body) are mixed in, their amount is kept to a minimum through decontamination. Therefore, recovered PET can be effectively utilized, and furthermore, it can exhibit excellent performance as a high-value-added heat-resistant PET tray that ensures heat resistance and safety for the human body, such as a container for reheating cooked food in a microwave oven. Furthermore, the heat-resistant PET tray of the present invention also exhibits excellent oil resistance, moldability, and chemical resistance. Moreover, it is possible to reproduce trays with comparable performance through remelting or other means, making it highly recyclable. Moreover, the heat-resistant PET tray of the present invention eliminates the need to coat the tray surface with virgin film to prevent direct contact with food, and can also reduce manufacturing costs.

Embodiments for Carrying Out the Invention

[0012] Next, the embodiments for carrying out the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the present invention, when expressed as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it includes the meaning of "X or more and Y or less", and also the meaning of "preferably greater than X" or "preferably less than Y". Also, "X and / or Y" (X and Y are arbitrary components) means at least one of X and Y, and includes three cases: only X, only Y, and X and Y. And in the present invention, when expressed as "X or more" (X is an arbitrary number) or "Y or less" (Y is an arbitrary number), it also includes the intention of "preferably greater than X" or "preferably less than Y".

[0013] A heat-resistant PET tray according to an example of an embodiment of the present invention (hereinafter sometimes referred to as "this tray") is a heat-resistant PET tray made of a resin composition containing a recycled material, and the recycled material is composed of a recovered product of decontaminated PET. Hereinafter, the manufacturing method for obtaining this tray will be described in detail.

[0014] <Manufacturing Method of This Tray> This tray is manufactured by a method comprising a pulverizing step of pulverizing a recovered product of PET, a decontaminating step of decontaminating the pulverized product obtained by the pulverizing step or pellets obtained from the pulverized product, and a manufacturing step of manufacturing a heat-resistant PET tray from a resin composition containing the recycled material obtained via the decontaminating step. Hereinafter, each step will be described.

[0015] [Pulverizing Step] There are no particular restrictions on the types of PET materials that can be collected; for example, post-consumer materials and post-industrial materials are examples. The aforementioned post-consumer materials refer to items that have been put on the market and then collected by consumers after use. Examples include PET bottles and food trays collected by supermarkets and other mass retailers, local governments, schools, etc. This also includes compressed and baled packaging of these materials. Furthermore, the post-industrial materials mentioned above refer to materials generated during the product manufacturing process before they reach the market, such as PET film used as release film, and are typically discarded after being used in product manufacturing without ever being released to the general market.

[0016] There are no particular restrictions on the type of PET used; either amorphous PET (A-PET) or crystalline PET (C-PET) is acceptable.

[0017] The method for crushing the recovered PET material is not particularly limited; for example, it can be crushed using a cutting machine such as a slitter or shredder, or a crusher. Alternatively, it may be crushed in stages using multiple cutting machines or crushers. Furthermore, it may be crushed while being washed by water washing, alkaline washing, alkaline friction washing, etc.

[0018] The pulverized material obtained by crushing the recovered PET is preferably in the form of flakes, as this facilitates the decontamination process described later. Furthermore, from the standpoint of workability, the length of each side of the flakes is usually 1 to 100 mm, preferably 5 to 20 mm.

[0019] Furthermore, in the manufacturing method of this tray, it is also preferable to include a cleaning step in which the pulverized material is cleaned by water washing, alkaline washing, alkaline friction washing, or the like.

[0020] The pulverized material may be subjected to the next decontamination process as is, but in order to further increase its added value, it is preferable to separate it into two parts: a colorless and transparent product and the other (hereinafter referred to as "colored product"). PET is usually colorless and transparent, but depending on the application, there are also colored PET products with pigments mixed in, printed PET products, PET products with labels attached, PET products with paper or plastic stickers attached, and PET products that have lost their transparency due to crystallization. Separating these by color is desirable from a recycling standpoint, but accurately separating them by color is difficult. Therefore, from the perspective of balancing the effort required for color sorting with the quality of the recycled material obtained, it is preferable to separate the crushed material into two categories: colorless and transparent products and colored products.

[0021] The aforementioned sorting process involves, for example, placing the crushed material on a conveyor belt and transporting it while photographing the material with a CCD camera installed above it. Based on the photographic data and established criteria, the material is then sorted into colorless and transparent materials. For example, by differentiating the amount and direction of airflow for the colorless and transparent materials and changing the direction and distance they are blown, the materials can be separated into colorless and transparent materials and colored materials. The separated colorless and transparent crushed materials and colored crushed materials then undergo a decontamination process and a manufacturing process, respectively, to become heat-resistant PET trays.

[0022] Furthermore, the pulverized material may be made into pellets by a known method before the next decontamination process. If the shape is flake, it is preferable in terms of decontamination efficiency, which will be described later, and if the shape is pellet, it is preferable in terms of product stability during molding.

[0023] [Decontamination Process] Because the aforementioned PET materials are collected through various processes, there is a possibility that they may contain substances harmful to human health. For example, in the case of PET bottles, due to the characteristics of PET resin such as being transparent, having a lid, and being unbreakable, they are sometimes used to store things other than beverages, such as insecticides, pesticides, and fertilizers. Furthermore, since these chemicals penetrate PET, simply washing the collected materials will not remove the harmful substances remaining inside the resin. Therefore, when recycling collected PET materials, it is necessary to decontaminate them until they meet international safety standards.

[0024] The decontamination method is preferably at least one selected from the group consisting of vacuum heating, infrared heating, and nitrogen gas flow heating, in order to efficiently perform decontamination.

[0025] The conditions for the vacuum heat treatment are, for example, a pressure of 0.1 to 200 mbar, a temperature of 130 to 210°C, preferably 150 to 180°C or higher, and a duration of 30 minutes or more.

[0026] The conditions for the infrared heating treatment are, for example, infrared radiation (near-infrared radiation) with a wavelength of 0.78 to 3 μm, a temperature of 130°C or higher, preferably 160°C or higher, and a duration of 0.3 to 3 hours, preferably 0.4 to 0.8 hours.

[0027] The conditions for the nitrogen gas flow heating treatment are, for example, a nitrogen gas flow adjusted to 50 mb to atmospheric pressure, and a nitrogen gas flow temperature of 130°C or higher, preferably 160°C or higher.

[0028] Among these decontamination methods, vacuum heating is preferred. This is because the recovered PET, which is the raw material for the pulverized material, has been molded at least once, and therefore has undergone a thermal history, resulting in a lower degree of polymerization compared to virgin PET, and consequently a decrease in strength. Normally, solid-phase polymerization is performed to increase the degree of polymerization of PET, and the conditions for this solid-phase polymerization are almost the same as those for the vacuum heat treatment described above. Therefore, by performing vacuum heat treatment, the degree of polymerization of PET with a reduced degree of polymerization can be made the same as that of virgin PET.

[0029] The degree of polymerization of the recycled material obtained through the decontamination process is typically 100 to 180, preferably 130 to 160. When the degree of polymerization of the recycled material is within this range, it tends to achieve strength equivalent to that of virgin PET.

[0030] Furthermore, the degree of polymerization can also be determined by its intrinsic viscosity, which is typically 0.60 to 0.80, preferably 0.65 to 0.80, of the recycled material. When the intrinsic viscosity of the recycled material is within the above range, it tends to achieve strength equivalent to that of virgin PET. The above intrinsic viscosity can be measured in accordance with JIS K 7390-1.

[0031] Furthermore, it is preferable that the recycled material has a total residual amount of surrogate contaminants of 220 ppb or less and / or a total elution amount of surrogate contaminants of 10 ppb or less when a surrogate contaminant test is performed. The aforementioned surrogate contamination test is a test to confirm whether, even if hazardous substances are mixed in the recovered PET material, the decontamination process removes the hazardous substances to a concentration that does not affect the human body. In other words, even if hazardous substances are mixed in the pulverized material before decontamination, the decontamination process removes the hazardous substances to a concentration that ensures safety for the human body. The total residual amount and total leaching amount of the aforementioned substitute contaminants are obtained using a method in accordance with the "Guidelines for Direct Contact of Recycled Plastics with Food" created by the U.S. FDA.

[0032] Furthermore, it is preferable to use at least one substance selected from each of the following groups (I) to (IV) as the substitute contaminant, as this allows for obtaining more reliable indicators and simplifies the assessment of safety. (I) Chloroform, chlorobenzene, trichloroethane, diethyl ketone. (II) Toluene. (III) Benzophenone, methyl salicylate. (IV) Tetracosan, methyl stearate, phenylcyclohexane, 1-phenyldecane.

[0033] [Manufacturing process] The recycled material obtained through the aforementioned decontamination process may be used in the manufacturing process as flakes, or it may be used in the manufacturing process as pellets by known methods. If the recycled material is in flake form, the pelletizing process can be avoided, thus reducing manufacturing costs. Furthermore, if the recycled material is in pellet form, foreign matter can be removed during the pellet manufacturing process, and the consistent shape allows for stable production.

[0034] Furthermore, the recycled material may be used as is in the resin composition for the manufacture of heat-resistant PET trays, or virgin PET may be added to it.

[0035] When virgin PET is used, the mass content ratio of recycled material to virgin PET (recycled material / virgin PET) is usually 1 / 99 to 99 / 1, preferably 5 / 95 to 80 / 20, and more preferably 25 / 75 to 50 / 50.

[0036] The aforementioned resin composition is mainly composed of PET, and preferably also contains a nucleating agent, a crosslinking agent, and other thermoplastic resins other than PET.

[0037] Examples of the nucleating agent include aliphatic polymers, organometallic salts, inorganic compounds, natural mineral particles, metal hydrates, and metal hydroxides. These may be used individually or in combination of two or more. Among these, at least one selected from the group consisting of organometallic salts, metal hydrates, and metal hydroxides is preferred, with metal hydrates being particularly preferred, due to its excellent crystallization rate of PET. The inclusion of a nucleating agent in the resin composition tends to promote crystallization during molding.

[0038] Examples of the aliphatic polymers include low-density polyethylene, linear low-density polyethylene, high-density polyethylene, polypropylene, polybutene, polypentene, and polymethylpentene. Examples of the aforementioned organometallic salts include alkali metal or alkaline earth metal salts of organic carboxylic acids such as sodium benzoate, potassium benzoate, calcium benzoate, sodium p-butylbenzoate, potassium p-butylbenzoate, calcium p-butylbenzoate, sodium stearate, potassium stearate, calcium stearate, sodium montana, potassium montana, calcium montana, sodium palmitate, potassium palmitate, calcium palmitate, sodium salt of ethylene-methacrylic acid copolymer, potassium salt of ethylene-methacrylic acid copolymer, calcium salt of ethylene-methacrylic acid copolymer, sodium terephthalate, and lithium terephthalate. Examples of the inorganic compounds include graphite, carbon black, magnesium oxide, calcium silicate, magnesium silicate, calcium carbonate, and magnesium carbonate. Examples of the aforementioned mineral particles include talc and kaolin. Examples of the aforementioned metal hydrates include Mg4Al2(OH) 12 Examples include CO3·3H2O. Examples of the aforementioned metal hydroxide include Mg3Si4(OH)2.

[0039] When the aforementioned nucleating agent is used, its content is usually 0.02% by mass or more relative to the resin composition, preferably 0.1 to 1.5% by mass, and more preferably 0.2 to 1.0% by mass.

[0040] Examples of the crosslinking agent include anhydrous aromatic compounds having two or more functional groups, aliphatic anhydrides having two or more functional groups, polyolefins having two or more functional groups, and aromatic compounds having two or more functional groups. These may be used individually or in combination of two or more. The inclusion of a crosslinking agent in the resin composition tends to increase the physical strength of the tray.

[0041] Examples of aromatic anhydrides having two or more functional groups include phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, and the like. Examples of aliphatic anhydrides having two or more functional groups include maleic anhydride, hexahydrophthalic anhydride, 3-methyl-hexahydrophthalic anhydride, 4-methyl-hexahydrophthalic anhydride, tetrahydrophthalic anhydride, nadic anhydride, and methylnadic anhydride. Examples of polyolefins having two or more functional groups include acrylonitrile, ethylene propylene rubber, and styrene copolymer. Examples of aromatic compounds having two or more functional groups include salicylic acid.

[0042] When the aforementioned crosslinking agent is used, its content is typically 0.1 to 20% by mass, preferably 0.3 to 10% by mass, and more preferably 0.5 to 1% by mass, relative to the resin composition.

[0043] Other thermoplastic resins besides PET include, for example, polyolefins (excluding those listed as crosslinking agents). The inclusion of other thermoplastic resins in the resin composition tends to increase the impact strength of this tray.

[0044] Examples of the polyolefins include high-density polyethylene, low-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ultra-high molecular weight polyethylene. These may be used individually or in combination of two or more. Among these, linear low-density polyethylene is preferred.

[0045] When using thermoplastic resins other than PET, their content is typically 0.1 to 20% by mass, preferably 0.5 to 10% by mass, and more preferably 1 to 5% by mass, relative to the resin composition.

[0046] Furthermore, the resin composition may contain additives such as stabilizers, colorants, acid value inhibitors, ultraviolet absorbers, plasticizers, lubricants, antistatic agents, and bulking agents, to the extent that they do not impair the effects of the present invention. These may be used individually or in combination of two or more. In particular, when using the pulverized colored material as recycled material, since the pulverized colored material contains a mixture of various colors, it is preferable from an aesthetic standpoint to color it using a coloring agent to make it a single color.

[0047] The aforementioned nucleating agent, crosslinking agent, other thermoplastic resins other than PET, and additives may be incorporated, for example, when the recycled material is made into pellets, or when it is formed into the film described below.

[0048] A heat-resistant PET sheet can be manufactured by putting a resin composition containing these materials into an extruder, melt-extruding it, and forming it into a sheet using known methods such as T-die molding.

[0049] Subsequently, the heat-resistant PET sheet is heated to a temperature range from its glass transition temperature to its crystallization temperature (e.g., 80 to 130°C), then molded into a tray shape by a known method, such as vacuum, compressed air, or hot plate molding. After that, the tray is obtained by holding it at a temperature range from its crystallization temperature to its melting point (e.g., 130 to 220°C, preferably 200°C or higher) to allow it to heat-set (crystallize). It should be noted that a higher degree of polymerization and intrinsic viscosity of the PET is preferable because it results in a higher crystallization temperature and thus superior moldability.

[0050] In addition to the methods described above, the tray may also be molded by melting the resin composition and pouring it directly into a mold, and then heat-setting it.

[0051] <Book Tray> The tray obtained in this manner exhibits heat resistance and does not deform even above the glass transition temperature of PET (approximately 70°C). The thermal deformation temperature of this tray is typically 180°C or higher, preferably 190°C or higher. The upper limit is typically 250°C. The thermal deformation temperature is measured by differential scanning calorimetry (DSC).

[0052] Furthermore, the true specific gravity of this tray is preferably 1.35 or higher, and more preferably 1.38 or higher. The upper limit is 1.44. When the true specific gravity of this tray is 1.35 or higher, the PET is sufficiently crystallized, and sufficient heat resistance tends to be obtained.

[0053] This tray is made from recycled material obtained by decontaminating recovered PET, and as mentioned above, it is preferable that the recycled material has a total residual amount of surrogate contaminants of 220 ppb or less and / or a total elution amount of surrogate contaminants of 10 ppb or less when a surrogate contamination test is performed.

[0054] Thus, despite being made from recycled PET waste, this tray minimizes the use of substances harmful to human health, resulting in superior safety. Therefore, even when used as a food tray, it is no longer necessary to cover the surface with virgin film to prevent direct contact with food, as was done conventionally, thus reducing manufacturing costs. [Examples]

[0055] Next, examples will be described together with comparative examples. However, the present invention is not limited to the following examples.

[0056] <Example 1> Virgin heat-resistant PET trays were crushed using a pulverizer with a 10mm mesh to obtain approximately 20kg of flake-like pulverized material. This pulverized material was then contaminated with the following surrogate contaminants to create a pseudo-post-consumer material of PET trays.

[0057] As substitute contaminants, chlorobenzene, toluene, benzophenone, and phenylcyclohexane were prepared. Chlorobenzene is a volatile polar substance, toluene is a volatile nonpolar substance, benzophenone is a nonvolatile polar substance, and phenylcyclohexane is a nonvolatile nonpolar substance. In other words, the substitute contaminants were selected as chemical substances that represent the physicochemical properties of each substance.

[0058] Next, a polyethylene bag was placed inside a stainless steel (SUS) container, and the pulverized material was placed inside. The four types of pre-mixed substitute contaminants were then added dropwise to the pulverized material in the amounts specified below relative to its mass. The polyethylene bag and the SUS container were then sealed and left to stand at 40°C for two weeks to allow the pulverized material to be impregnated with the substitute contaminants at the concentrations specified below, thereby obtaining a pseudo-post-consumer material. During the standing period, the material was stirred three times a day. Chlorobenzene 1500 ppm Toluene 1000 ppm Benzophenone 150 ppm Phenylecyclohexane 500 ppm

[0059] Using the pseudo-post-consumer material obtained in this way, a heat-resistant PET tray was manufactured.

[0060] [Decontamination process] The pseudo-post-consumer material obtained above was decontaminated using a small vacuum heater (manufactured by Onoda Kiki Co., Ltd.) with a capacity of 400mm x 400mm x 250mm under the following conditions to obtain recycled material. The decontamination process was carried out in batches. [Decontamination conditions] Vacuum degree 1~2torr(1.33~2.66mbar) Vacuum type, Oil type Heating temperature 200℃ Duration of stay: 60 minutes

[0061] [Measurement of residual levels of surrogate contaminants] The residual amount of surrogate contaminants was calculated by performing gas chromatography analysis under the following measurement conditions and creating a calibration curve from the obtained peak areas. As a result, the total content (residual amount) of surrogate contaminants was 220 ppb or less. [Measurement conditions] • Device: Headspace sampler HP7694 Gas Chromatography / Mass Spectrometer (GC / MS) HP6890 • Headspace sampler operating conditions Heating temperature: Oven 125℃ Sample loop 130℃ Transfer line 135℃ Heating time: 45 minutes Injection time: 0.5 minutes Headspace introduction volume: 1 mL ·GC / MS measurement conditions Column DB-VRX (30m x 0.25mm inner diameter, 1.4μm film thickness, manufactured by J&W Scientific) Column temperature 40°C (4 minutes) → Increase temperature by 20°C / min to 240°C Injection temperature 250℃ Inlet temperature: 280℃ Carrier gas He, 130kPa (0.5 min) → 50kPa Ionization voltage 70 eV Ion acceleration voltage • Measurement method 1.0 g of the sample (pulverized material) was placed in a 10 mL vial, sealed, and then measured using a headspace sampler / GC / MS.

[0062] Furthermore, the amount of surrogate contaminants leached out was also measured in accordance with the aforementioned guidelines [Guidelines for direct contact of recycled plastics with food]. As a result, the amount of surrogate contaminants leached out was 10 ppb or less.

[0063] To 100 parts by mass of the obtained recycled material, Mg4Al2(OH) was used as a crystal nucleating agent. 12A resin composition was prepared by mixing 0.25 parts by mass of CO3·3H2O on a pure content basis. This composition was then fed into an extruder (manufactured by Viscotec, with a 90mm extruder bore, a 400KW motor rating, and a 200KW heater) to produce heat-resistant PET tray sheets. The intrinsic viscosity of the recycled material was 0.73.

[0064] Next, a heat-resistant PET tray was manufactured using the heat-resistant PET tray sheet described above under the following conditions. The resulting heat-distortion temperature of the heat-resistant PET tray, determined by DSC, was 198°C, and its true specific gravity was 1.38. [Molding conditions] Equipment manufacturing company Kiefel Model KMD78.1 Sheet width: 600mm Sheet thickness: 0.4mm Molded size: L70mm x W60mm x H35mm Vacuum air-cooled Heating ceramic heater Station 3 Molding cycle: 3.6 seconds

[0065] <Example 2> In Example 1, Mg4Al2(OH) was used as a crystal nucleating agent in 100 parts by mass of recycled material. 12 A heat-resistant PET tray was manufactured in the same manner as described above, except that 0.25 parts by mass of CO3·3H2O (on a purity basis) and 2 parts by mass of ethylene alkyl acrylate (as a crosslinking agent) were mixed to form a resin composition. The heat distortion temperature of the obtained heat-resistant PET tray by DSC method was 195°C, and the true specific gravity was 1.38. Furthermore, a free-fall test conducted in accordance with JIS Z 0200 showed that the heat-resistant PET tray met Level I and possessed high strength.

[0066] Thus, despite being made from recycled PET waste, this PET tray offers sufficient safety and high quality. [Industrial applicability]

[0067] This invention allows for the manufacture of highly safe, heat-resistant PET trays from recycled PET waste, making it widely applicable to food packaging and other uses.

Claims

1. A method for manufacturing a heat-resistant polyethylene terephthalate tray made of a resin composition containing recycled material, The resin composition contains a nucleating agent, and the nucleating agent contains Mg 4 Al 2 (OH) 12 CO 3 ・3H 2 O, The recycled material consists of recovered decontaminated polyethylene terephthalate. The process comprises a grinding step for grinding recovered polyethylene terephthalate, a decontamination step for decontaminating the pulverized material obtained in the grinding step or pellets obtained from the pulverized material, and a manufacturing step for manufacturing a heat-resistant polyethylene terephthalate tray from a resin composition containing recycled material obtained via the decontamination step. The decontamination treatment includes vacuum heating treatment, A method for manufacturing a heat-resistant polyethylene terephthalate tray, wherein the recycled material obtained through the decontamination process has an intrinsic viscosity of 0.60 to 0.

80.

2. The method for manufacturing a heat-resistant polyethylene terephthalate tray according to claim 1, wherein the true specific gravity of the heat-resistant polyethylene terephthalate tray is 1.35 or more.

3. A method for producing a heat-resistant polyethylene terephthalate tray according to claim 1 or 2, wherein the resin composition contains a crosslinking agent.

4. A method for producing a heat-resistant polyethylene terephthalate tray according to claim 1 or 2, wherein the recycled material has a total residual amount of surrogate contaminants of 220 ppb or less and / or a total elution amount of surrogate contaminants of 10 ppb or less when subjected to a surrogate contamination test.

5. The method for producing a heat-resistant polyethylene terephthalate tray according to claim 4, wherein the substitute contaminant is at least one substance selected from each of the following groups (I) to (IV). (I) Chloroform, chlorobenzene, trichloroethane, diethyl ketone. (II) Toluene. (III) Benzophenone, methyl salicylate. (IV) Tetracosan, methyl stearate, phenylcyclohexane, 1-phenyldecane.

6. A method for producing a heat-resistant polyethylene terephthalate tray according to claim 1 or 2, wherein the resin composition comprises a thermoplastic resin other than polyethylene terephthalate.

7. A method for manufacturing a heat-resistant polyethylene terephthalate tray according to claim 1 or 2, comprising a washing step of washing the pulverized material.