Recycled resin compositions, molded containers, bottles, and tubes

Abstract

To provide molded containers with excellent color, moldability, and drop strength using recycled resin compositions made from PET bottle caps, and to expand the applications of recycling using PET bottle caps. [Solution] The problem is solved by a recycled resin composition containing recycled resin (X1) obtained using PET bottle caps, a resin other than the recycled resin (X1) (X2), and a white pigment (Y1), wherein the recycled resin composition has a melt mass flow rate (MFR) of 0.1 to 5 g / 10 min at 190°C, the recycled resin (X1) contains polyethylene and polypropylene, with a polyethylene content:polypropylene content of 70:30 to 95:5, and the white pigment (Y1) is titanium oxide that has undergone one of the surface treatments selected from the group consisting of aluminum oxide, silicon dioxide, and siloxane.

Description

Technical Field

[0001] Embodiments of the present invention relate to a recycled resin composition, a formed container, a bottle, a tube, and a method for manufacturing a formed container.

Background Art

[0002] Polyester bottles have characteristics such as transparency, design, light weight, and safety, and are therefore used in many fields such as food, healthcare, cosmetics, and medicine, and the usage amount is increasing. In recent years, in the promotion of a recycling-oriented society, polyester, which is the material of the polyester bottle body, is recycled and used for bottles, daily necessities, clothing, etc., and a high recycling rate has been achieved.

[0003] For example, Patent Document 1 describes a biaxially oriented polyester film roll formed by winding a biaxially oriented polyester film composed of a polyester resin using recycled PET bottles and a polyester resin composition containing particles.

[0004] On the other hand, polyolefin resins are often used for the caps of polyester bottles because they have high resistance to the contents and are easy to mold. In addition, in order to enhance the design of the cap, various colorings are performed on the polyolefin resin using pigments. Therefore, currently, as a recycled application of PET bottle caps, they are mostly used only for applications where hue is not important, such as pallets and building materials.

[0005] Regarding the recycling of PET bottle caps, for example, Patent Document 2 describes a method for manufacturing a recycled building material characterized by melt-kneading waste plastic, crushed shells, and polypropylene and extruding them by an extruder.

[0006] To expand the uses of recycled PET bottle caps, one could consider separating them by color after collection, or separating and removing the colorants during recycling. However, due to the complexity and cost involved, practical implementation is difficult.

[0007] Furthermore, in the recycling of PET bottle caps, the collected caps are crushed and washed to form resin flakes, which are then melted and kneaded in an extruder or similar machine to create granules. However, residual impurities such as ink on the top surface of the caps, as well as the thermal history of the thermoplastic resin, can cause problems when the resulting molded product is formed, such as uneven film thickness and reduced drop strength. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 2022 / 049998 [Patent Document 2] Japanese Patent Publication No. 2000-308869 [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, an embodiment of the present invention is a recycled resin composition using collected PET bottle caps, and the objective is to provide a molded container with excellent moldability, color, and drop strength using this recycled resin composition. The recycled resin composition of the present invention can expand the applications of recycling using PET bottle caps. [Means for solving the problem]

[0010] The present invention includes, but is not limited to, the following embodiments. (1) A recycled resin composition containing recycled resin (X1) obtained using PET bottle caps, a resin other than the recycled resin (X1) (X2), and a white pigment (Y1), The recycled resin composition has a melt mass flow rate (MFR) of 0.1 to 5 g / 10 min at 190°C. The recycled resin (X1) contains polyethylene and polypropylene, and the polyethylene content (parts by mass) : polypropylene content (parts by mass) is 70:30 to 95:5. A recycled resin composition in which the white pigment (Y1) is titanium dioxide that has undergone one of the surface treatments selected from the group consisting of aluminum oxide, silicon dioxide, and siloxane. (2) The recycled resin composition according to (2), wherein the recycled resin (X1) has a melt mass flow rate (MFR) of 0.1 to 10 g / 10 min at 190°C. (3) The recycled resin composition according to (1) or (2), further comprising at least one pigment (Y2) selected from the group consisting of monoazo yellow, disazo yellow, monoazo orange, quinacridone red, diketopyrrolopyrrole red, phthalocyanine green, phthalocyanine blue, and quinacridone violet. (4) The recycled resin composition according to any one of (1) to (3), wherein the content of the white pigment (Y1) is 0.5 to 25% by mass, based on 100% by mass of the recycled resin composition. (5) A molded container manufactured using any of the recycled resin compositions described in (1) to (4). (6) The molded container according to (5), wherein the brightness (L* value) of at least some of the surfaces is 60.0 or higher. (7) A bottle, which is a molded container as described in (5). (8)(5) A molded container, a tube. (9) A method for manufacturing a molded container, comprising the step of molding it by blow molding or extrusion molding using any of the recycled resin compositions described in (1) to (4). [Effects of the Invention]

[0011] According to one embodiment of the present invention, a molded container with excellent moldability, color, and drop strength is provided as a new application for recycled resin obtained from PET bottle caps. Furthermore, according to another embodiment of the present invention, a recycled resin composition suitable for molded containers is provided. Moreover, according to another embodiment of the present invention, a method for manufacturing molded containers is provided as a new application for recycled resin obtained from PET bottle caps. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will now be described. Embodiments of the present invention are not limited to those described below. In this specification, numerical ranges specified using "~" include the numerical values ​​before and after "~" as the lower and upper limits. Unless otherwise noted, each component may be used independently or in combination of two or more. It should be noted that "PET bottle cap" is sometimes simply referred to as "cap," and "pigment derived from PET bottle cap" refers to the pigment that was contained in the PET bottle cap. Furthermore, "CI" as used below refers to the Color Index (CI). The meltmass flow rate (MFR) can be determined in accordance with JIS K 7210-1:2014. The numerical values ​​described herein refer to the values ​​obtained by the method described in the [Examples] section below.

[0013] Recycled resin composition In embodiments of the present invention, the recycled resin composition contains a recycled resin (X1) obtained using PET bottle caps, a resin other than the recycled resin (X2) (X2), and a white pigment (Y1), and has a melt mass flow rate (MFR) of 0.1 to 5 g / 10 min at 190°C. Furthermore, the recycled resin (X1) contains polyethylene and polypropylene, with a polyethylene content (parts by mass) and polypropylene content (parts by mass) of 70:30 to 95:5, and the white pigment (Y1) is titanium oxide that has undergone one of the surface treatments selected from the group consisting of aluminum oxide, silicon dioxide, and siloxane.

[0014] PET bottle caps are formed of a resin composition that has a unique color for each product from the viewpoints of design and distinctiveness, and contains a corresponding colorant. When various used PET bottle caps are collected to obtain a recycled resin composition, the recycled resin composition contains multiple types of colorants and recycled resin. Due to the colors exhibited by the colorants, such recycled resin compositions have limited recycling applications.

[0015] In contrast, embodiments of the present invention can provide a recycled resin composition that is excellent in moldability, hue, and drop strength even when the collected PET bottle caps are used without being sorted or separated by adopting a specific composition. Thus, new recycling applications for PET bottle caps have been found. According to the embodiments of the present invention, it is possible to reduce PET bottle cap waste, reduce the environmental load, and contribute to the realization of a resource recycling-oriented society. Also, from the perspective of manufacturing molded containers, in addition to being able to manufacture containers at a low cost by suppressing raw material costs, it has the effect of being excellent in design.

[0016] The melt mass flow rate (MFR) of the recycled resin composition is 0.1 to 5 g / 10 min, preferably 0.2 to 4.5 g / 10 min, more preferably 0.3 to 4.0 g / 10 min. It is preferable that the melt mass flow rate (MFR) is within this range because it enables the production of molded containers that are more excellent in moldability and drop strength.

[0017] The melt mass flow rate of the recycled resin composition can be controlled by factors such as the type of PET bottle cap used, the resin (X2), the type and blending amount of the pigment (Y1) and other pigments, and the kneading conditions of the recycled resin composition.

[0018] The type of resin used for bottle caps varies depending on the season, region, and other collection conditions for used PET bottles. For example, caps for cold beverages are often made of polyethylene, while caps for hot beverages are often made of polypropylene. In addition, PET bottle caps are sometimes sorted by color using color sorting equipment. By combining these caps for recycling, it is possible to select them so that the polyethylene and polypropylene content ratio and the melt mass flow rate (MFR) in the recycled resin fall within the aforementioned range.

[0019] The mass ratio (PE / PP) of polyethylene / polypropylene content in the recycled resin composition is preferably 0.5 to 300, more preferably 1 to 100, and even more preferably 3 to 30. Being within this range allows for superior moldability and drop strength.

[0020] <Resin (X)> The recycled resin composition of this embodiment includes recycled resin (X1) and resin (X2) obtained using PET bottle caps. The recycled resin (X1) is a resin containing polyethylene and polypropylene, with a polyethylene content (parts by mass) and polypropylene content (parts by mass) of 70:30 to 95:5. Resin (X2) is a resin other than recycled resin (X1). By including an additional resin (X2) in addition to the recycled resin (X1), it is possible to provide a recycled resin composition with excellent drop strength while maintaining a high recycling rate and good moldability.

[0021] [Recycled resin (X1)] The recycled resin (X1) is a resin obtained using PET bottle caps. The material used for PET bottle caps is generally polyolefin resin, mainly polyethylene (PE) and / or polypropylene (PP). Polyethylene can be high-density polyethylene (HDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), etc., with high-density polyethylene being preferred. The recycled resin (X1) includes polyethylene and polypropylene, preferably high-density polyethylene and polypropylene. This tends to result in molded containers with superior drop resistance.

[0022] The ratio of polyethylene to polypropylene in the recycled resin (X1) is polyethylene content (parts by mass): polypropylene content (parts by mass) = 70:30 to 95:5. More preferably, the ratio is 75:25 to 92.5:7.5, and even more preferably, 80:20 to 90:10. Within this range, it is possible to provide molded containers with superior moldability and drop strength while increasing the recycling rate of the recycled resin composition. The mass ratio of polyethylene to polypropylene in the recycled resin (X1) can be determined by heat-pressing the cap or recycled material at 200°C for 30 seconds to form a thin film, and then measuring it by transmission using an infrared spectrophotometer (FT / IR-4100, manufactured by JASCO Corporation). 719cm derived from PE -1 The peak and PP originate from 841cm -1 By comparing the peak heights, a calibration curve can be created, and the polyethylene to polypropylene content ratio (PP:PE) can be calculated.

[0023] Furthermore, the recycled resin (X1) is preferably a resin with a melt mass flow rate (MFR) of 0.1 to 10 g / 10 min at 190°C. More preferably, it is 0.2 to 9 g / 10 min, and even more preferably 0.3 to 8 g / 10 min. The MFR of the recycled resin (X1) is a value obtained by measuring at 190°C and a 2.16 kg load in accordance with JIS K 7210-1:2014, using resin flakes obtained by crushing and washing collected PET bottle caps, or a resin composition obtained by melting and kneading these into pellets. Specifically, it can be obtained by the method described in the examples. By having the melt mass flow rate (MFR) of the recycled resin (X1) within this range, it is possible to provide molded containers with superior moldability and drop strength while increasing the recycling ratio of the recycled resin composition.

[0024] The content of recycled resin (X1) may be, for example, 5 to 95% by mass, 10 to 95% by mass, or 50 to 70% by mass, based on the recycled resin composition (100% by mass). If it is 95% by mass or less, better moldability can be maintained in blow molding or extrusion molding. If it is 50% by mass or more, the proportion of recycled resin can be increased, which is preferable.

[0025] [Resin (X2)] Resin (X2) is a resin other than recycled resin (X1). The resin (X2) may be a resin used for molding the container, and is preferably a thermoplastic resin. It may also be a recycled resin other than the recycled resin (X1), or a virgin resin derived from petroleum resources. Being a virgin resin is preferable in terms of moldability.

[0026] The resin (X2) may be a resin compatible with the recycled resin (X1), and examples of compatible resins include polyester, polystyrene, polyolefin, aromatic nylon, etc. Examples of polyolefins include polyethylene such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), polypropylene, ethylene-vinyl acetate copolymer, ethylene-α-olefin random copolymer, and ionomer resin. The resin (X2) preferably contains polyolefin, more preferably contains polyethylene, polypropylene, or both, and even more preferably contains polyethylene. High-density polyethylene is preferred because it allows for the provision of molded containers with excellent drop strength.

[0027] The melt mass flow rate (MFR) of the resin (X2) is preferably, for example, 0.01 to 50 g / 10 min, and more preferably 0.1 to 10 g / 10 min. Having the melt mass flow rate (MFR) within this range allows for the provision of molded containers with superior moldability and drop strength.

[0028] The content of resin (X2) may be, for example, 2 to 900 parts by mass, 5 to 250 parts by mass, or 10 to 100 parts by mass per 100 parts by mass of recycled resin (X1). A content of 2 parts by mass or more allows for better moldability in blow molding or extrusion molding. A content of 100 parts by mass or less is preferable because it allows for a higher proportion of recycled resin.

[0029] <Pigment (Y)> The recycled resin composition of this embodiment contains a white pigment (Y1). It may also contain other pigments.

[0030] [White pigment (Y1)] The white pigment (Y1) is titanium dioxide that has undergone one of the surface treatments selected from the group consisting of aluminum oxide, silicon dioxide, and siloxane. By including such a white pigment (Y1), the material offers excellent hue and opacity, expanding its applications to molded containers and other uses, and enabling recycling. Furthermore, it suppresses outgassing from the resin composition, thus providing molded containers with superior moldability and drop strength.

[0031] The white pigment (Y1) may be a pigment derived from PET bottle caps contained in the recycled resin composition. The white pigment (Y1) derived from PET bottle caps may be referred to as "pigment (Y1a)," and pigments other than the pigment (Y1a) derived from PET bottle caps may be referred to as "pigment (Y1b)."

[0032] Surface treatments for titanium dioxide can be broadly classified into treatments using inorganic compounds or organic compounds. Examples of inorganic compounds include aluminum oxide, silicon dioxide, and zirconium oxide. Examples of organic compounds include siloxanes, silane coupling agents, polyhydric alcohols, titanium coupling agents, alkanolamines or their derivatives, and higher fatty acids or their metal salts.

[0033] The recycled resin composition of the present invention is characterized by containing a white pigment (Y1), which is titanium oxide that has undergone a surface treatment selected from the group consisting of aluminum oxide, silicon dioxide, and siloxane. The surface treatment of aluminum oxide, silicon dioxide, and siloxane may be a combination of multiple treatments, but it is preferable that at least aluminum oxide surface treatment is performed. By including such a white pigment (Y1), a molded container with excellent moldability, hue, and drop strength can be provided.

[0034] Aluminum oxide is an oxide of aluminum, and water-soluble aluminum salts are preferred. Specifically, examples include aluminum chloride, aluminum sulfate, and sodium aluminum aluminate nitrate. Titanium oxide can also be coated with alumina (Al2O3) by adding sulfuric acid or chlorine. Examples of silicon dioxide include sodium silicate and silicon tetrachloride. Examples of siloxanes include dimethylpolysiloxane, methylhydrogenpolysiloxane, and alkyl-modified polysiloxane.

[0035] Furthermore, the white pigment (Y1) may be further surface-treated with a compound other than one selected from the group consisting of aluminum oxide, silicon dioxide, and siloxane. Other compounds include inorganic compounds such as zirconium oxide, or organic compounds such as silane coupling agents.

[0036] The content of the white pigment (Y1) is preferably 0.25 to 30% by mass, more preferably 0.5 to 25% by mass, and even more preferably 1 to 10% by mass, based on the recycled resin composition (100% by mass). When it is 0.25% by mass or more, the hue and opacity are better, and the contents of the container tend to be sufficiently concealed. When it is 30% by mass or less, the drop impact strength of the molded container can be maintained better. In this case, the white pigment (Y1) refers to the total amount of white pigment derived from the PET bottle cap (pigment (Y1a)) and pigments other than those derived from the PET bottle cap (Y1b).

[0037] [Other pigments] The recycled resin composition of the present invention may contain other pigments. These other pigments are pigments other than the white pigment (Y1), and may be pigments derived from PET bottle caps, and may further contain pigments other than those derived from PET bottle caps.

[0038] Other pigments include organic pigments such as azo pigments, quinacridone pigments, perylene pigments, isoindolinone pigments, diketopyrrolopyrrole pigments, and phthalocyanine pigments, as well as inorganic pigments.

[0039] Examples of azo pigments include monoazo yellow, monoazo red, monoazo orange, disazo yellow, and disazo orange. Examples of quinacridone pigments include quinacridone red, quinacridone violet, and quinacridone magenta. Examples of perylene pigments include perylene red and perylene orange. Examples of isoindolinone pigments include isoindolinone orange and isoindolinone yellow. Examples of diketopyrrolopyrrole pigments include diketopyrrolopyrrole red and diketopyrrolopyrrole orange. Examples of phthalocyanine pigments include phthalocyanine blue and phthalocyanine green.

[0040] Examples of inorganic pigments include calcium carbonate, barium sulfate, zinc sulfide, iron oxide, ultramarine, cobalt blue, nickel titanium yellow, bismuth yellow, carbon black, and pearl pigments.

[0041] Specific examples of azo pigments include CI Pigment Yellow 93, 95, 150, 151, 168, 169, 180, 181, CI Pigment Red 144, 208, 214, etc. Specific examples of quinacridone pigments include CI Pigment Red 122, 207, CI Pigment Violet 19, etc. Specific examples of perylene pigments include CI Pigment Red 149, 178, etc. Specific examples of isoindolinone pigments include CI Pigment Yellow 109, 110, 139, CI Pigment Orange 61, etc. Specific examples of diketopyrropyrrole pigments include CI Pigment Red 254, 264, and CI Pigment Orange 71. These are some examples.

[0042] Examples of pigment yellow 93 include Chromophthal Yellow 3GNP (BASF), examples of pigment yellow 95 include Chromophthal Yellow GRP (BASF), examples of pigment yellow 150 include Vinamon Yellow 115002 (Heubach), examples of pigment yellow 151 include PV Fast Yellow H4G (Clariant), and examples of pigment yellow 168 include Lionol Yellow K5G (Toyoca). Examples of pigment yellow 169 (manufactured by Lahmi), Lionol Yellow K2R (manufactured by Toyo Color), examples of pigment yellow 180, PV Fast Yellow HG (manufactured by Clariant), examples of pigment yellow 181, PV Fast Yellow H3R (manufactured by Clariant), examples of pigment red 144, Chromophthal Red BRN (manufactured by BASF), examples of pigment red 208, Graftol Red HF2B (B Examples of pigments include: Pigment Red 214 (manufactured by ASF), Chromophthal Red BN (manufactured by BASF), Pigment Red 122, Fastogen Super Magenta RE03 (manufactured by DIC), Vinamon Red 312201 (manufactured by Heubach), Pigment Red 207, Fastogen Super Scarlet GK (manufactured by DIC), Pigment Violet 19, Chromophthal Red 2020 (manufactured by BASF), Pigment Red Examples of pigments include Paliogen Red K3580 (BASF), Pigment Red 178 is Paliogen Red K3911HD (BASF), Pigment Red 254 is Chromophthal Red 2028 (BASF), Pigment Red 264 is Irgazine DPP Rubin TR (BASF), and Pigment Orange 71 is Chromophthal DPP Orange TRP (BASF).

[0043] Other pigments may include at least one pigment (Y2) selected from the group consisting of monoazo yellow, disazo yellow, monoazo orange, quinacridone red, diketopyrrolopyrrolopyrrole red, phthalocyanine green, phthalocyanine blue, and quinacridone violet, which are commonly used in PET bottle caps. Pigment (Y2) may be a pigment derived from a PET bottle cap, and may further contain pigments other than those derived from PET bottle caps. Pigment (Y2) derived from a PET bottle cap may be referred to as "pigment (Y2a)", and pigment (Y2) other than pigment (Y2a) derived from a PET bottle cap may be referred to as "pigment (Y2b)".

[0044] For example, blue caps mainly use phthalocyanine blue, green caps mainly use phthalocyanine green, yellow caps mainly use monoazo yellow, disazo yellow, or monoazo orange, and red caps mainly use quinacridone red, diketopyrrolopyrrole red, or quinacridone violet. Pigment (Y2a) typically contains two or more pigments, for example, five or more, or ten or more. Pigment (Y2a) and pigment (Y2b) may contain the same pigment or not. Examples of pigment (Y2a) include organic pigments and inorganic pigments. Because the present invention uses a recycled resin composition, even collected PET bottles containing these pigments (Y2) can be recycled and used in molded containers, thereby expanding the range of recycling applications.

[0045] The pigment (Y2) content is preferably 0 to 15% by mass, more preferably 0 to 10% by mass, and even more preferably 0 to 5% by mass, based on the recycled resin composition (100% by mass). A content of 15% by mass or less allows for better maintenance of hue. It may also be 0.01% by mass or more.

[0046] If the other pigment is an organic pigment, its content may be, for example, 0-15% by mass, 0-10% by mass, 0-5% by mass, 0-4% by mass, or 0-3% by mass, based on the recycled resin composition (100% by mass). A content of 15% by mass or less tends to result in a better appearance of the molded container.

[0047] If the other pigments are inorganic pigments, their content is, for example, 0-25% by mass, 0-20% by mass, 0-10% by mass, 0-8% by mass, or 0-6% by mass, based on the recycled resin composition (100% by mass). Within this range, the drop impact strength of the bottle can be maintained more effectively.

[0048] <Optional ingredients> The recycled resin composition may contain any components, such as additives, as needed. Examples of additives include metal soaps such as alkali metals, alkaline earth metals, and zinc; antioxidants; ultraviolet absorbers; light stabilizers; metal deactivators; surfactants such as nonionic surfactants, cationic surfactants, anionic surfactants, and amphoteric surfactants; antistatic agents; and flame retardants such as halogenated, phosphorusated, and metal oxides.

[0049] Examples of metallic soaps include calcium stearate, magnesium stearate, barium stearate, zinc stearate, aluminum stearate, lithium stearate, calcium lauryl stearate, zinc lauryl stearate, and magnesium lauryl stearate.

[0050] Examples of antioxidants include phenolic and phosphite-based antioxidants. Phosphite-based antioxidants include diethyl[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphonate and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate. Phosphite-based antioxidants include tris(2,4-di-tert-butylphenyl)phosphite and bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol-di-phosphite.

[0051] Examples of UV-blocking agents include benzotriazole-based and triazine-based agents. Examples of benzotriazole-based agents include 2,2-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6[(2H-benzotriazole-2-yl)phenol]], 2-(2H-benzotriazole-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, and 2-[5-chloro(2H)-benzotriazole-2-yl]-4-methyl-6-(tert-butyl)phenol. An example of a triazine-based agent is 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-[(hexyl)oxy]-phenol.

[0052] Examples of light stabilizers include hindered amines. Examples of hindered amines include bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl)imino}], and polycondensates of dibutylamine·1,3,5-triazine·N,N-bis(2,2,6,6-tetramethyl-4-piperidyl-1,6-hexamethylenediamine·N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine.

[0053] Examples of metal deactivators include 2,3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide.

[0054] The content of optional components is, for example, 0.01 to 5% by mass, preferably 0.05 to 3% by mass, and more preferably 0.1 to 1% by mass, based on the recycled resin composition (100% by mass). If it is 0.01% by mass or more, the effect of the added material can be fully exerted. If it is 5% by mass or less, molding can be performed while suppressing migration such as bleed-out.

[0055] <Method for producing recycled tree composition> A recycled resin composition can be obtained, for example, by a manufacturing method that includes crushing PET bottle caps to obtain crushed material (crushing step), and melting and kneading the crushed material to obtain a kneaded material (kneading step). The manufacturing method may further include optional steps such as washing the PET bottle caps, drying the washed PET bottle caps, washing the crushed material, drying the washed crushed material, separating the crushed material, adding optional components, and molding the kneaded material into a shape such as pellets.

[0056] The method for crushing the packaging material in the crushing process is not particularly limited, and examples include using a jaw crusher, impact crusher, cutter mill, stamp mill, ring mill, roller mill, jet mill, or hammer mill.

[0057] In the mixing process, any components such as additives may be added as needed. The melt mixing method is not particularly limited, and examples include mixing with a Henschel mixer, tumbler, disper, etc., followed by melt mixing with a batch mixer such as a kneader, roll mill, super mixer, Henschel mixer, Shugi mixer, vertical granulator, high-speed mixer, fur matrix, ball mill, steel mill, sand mill, vibratory mill, attritor, Banbury mixer, twin-screw extruder, single-screw extruder, rotor-type twin-screw mixer, etc. When granulating the mixed material into pellets or the like, a twin-screw extruder or single-screw extruder can be preferably used.

[0058] In this way, PET bottle caps are crushed and washed, and the resulting recycled material containing recycled resin (X1) and pigment (Ya) can be used as recycled resin pellets or the like. Using such recycled material and resin (X2), a recycled resin composition containing recycled resin (X1), resin (X2), and white pigment (Y1) can be produced by melt-kneading them using a twin-screw extruder or a single-screw extruder, for example, by the following manufacturing method (i), manufacturing method (ii), or a combination thereof.

[0059] From the viewpoint of moldability and recycling ratio, the amount of resin (X2) blended per 100 parts by mass of recycled material is preferably 2 to 900 parts by mass, more preferably 5 to 250 parts by mass, and even more preferably 10 to 100 parts by mass.

[0060] [Manufacturing method (i)] The process includes melting and kneading recycled material obtained from PET bottle caps with resin (X2) and white pigment (Y1b), The recycled material includes recycled resin (X1) and pigment (Ya). A method for producing a recycled resin composition, wherein the white pigment (Y1b) is titanium dioxide that has undergone one of the surface treatments selected from the group consisting of aluminum oxide, silicon dioxide, and siloxane.

[0061] In this case, from the viewpoint of hue and drop strength, the amount of white pigment (Y1b) blended per 100 parts by mass of recycled material is preferably 0.5 to 50 parts by mass, and more preferably 1 to 20 parts by mass.

[0062] [Manufacturing method (ii)] The process includes a step of melting and kneading recycled material obtained using PET bottle caps with resin (X2), The recycled material includes recycled resin (X1) and pigment (Ya). The pigment (Ya) contains white pigment (Y1a), A method for producing a recycled resin composition, wherein the white pigment (Y1a) is titanium dioxide that has undergone one of the surface treatments selected from the group consisting of aluminum oxide, silicon dioxide, and siloxane.

[0063] The content of the white pigment (Y1a) may be 0 to 10% by mass, based on the recycled resin composition.

[0064] ≪Molded container≫ The molded container comprises a recycled resin layer formed from the recycled resin composition of the present invention, and may have a single-layer structure of recycled resin layers as shown below, or a multi-layer structure. • Recycled resin layer • Resin layer L1 / Recycled resin layer • Resin layer L1 / Adhesive layer / Recycled resin layer • Resin layer L1 / Resin layer L2 / Recycled resin layer • Resin layer L1 / Adhesive layer / Resin layer L2 / Adhesive layer / Recycled resin layer

[0065] An adhesive layer is a layer used to bond two or more layers together. For example, it is used to bond two layers that have different melting points. Known adhesive layers include those formed using adhesives containing acid-modified polyolefins, ethylene-acrylic acid copolymer resins, ethylene-vinyl acetate copolymer resins, etc. Commercially available adhesives include Nucrel (manufactured by Mitsui DuPont Polychemicals), Admer (manufactured by Mitsui Chemicals), and Mersen (manufactured by Tosoh Corporation).

[0066] Resin layers L1 and L2 are layers with various functions, such as an innermost layer to prevent direct contact between the contents and the recycled resin layer containing recycled material, a barrier layer, or an outermost layer placed outside the outer layer to improve the smoothness of the container surface and further enhance its design. For example, resin layers L1 and L2 may each be layers with the same composition as the inner or outer layer, independently of each other.

[0067] <Shape, usage, etc.> The shape of the molded container may be any shape, such as a bottle, tube, cylinder, prism, or sphere. Preferably, it is in the shape of a bottle or tube. According to embodiments of the present invention, a bottle or tube that is a single-layer or multi-layer molded container can be obtained. The capacity of the molded container is not particularly limited and may be any capacity, such as 350 mL, 500 mL, 1000 mL, 1500 mL, or 2000 mL. The overall thickness of the molded container may be uniform or non-uniform. For example, if the molded container is a bottle, the thickness of the mouth, shoulder, body, bottom, etc. of the bottle may differ from one another.

[0068] Molded containers are suitable for a variety of applications, including detergents, cosmetics, pharmaceuticals, food products, and medical supplies. Preferably, the molded container is a detergent bottle or detergent tube.

[0069] <Brightness and Yellowness> The lightness (L* value) of at least a portion of the surface of the molded container may be 60.0 or higher. The lightness (L* value) is the L* value in the L*a*b* color system defined by the International Commission on Illumination (CIE) and can be measured using a colorimeter. Preferably, the lightness (L* value) is 70.0 or higher, or 75.0 or higher. This can be adjusted by the thickness of the recycled resin layer, etc. If the molded container is a bottle or tube, it is preferable that at least the lightness of the body portion satisfies the above range, and more preferably that the lightness of the entire bottle or tube satisfies the above range. It may be 99.9 or lower.

[0070] The molded container may have a yellowness (YI value) of at least a portion of its surface between -15.0 and 15.0. The yellowness (YI value) is determined according to JIS K 7373:2006 based on the XYZ color system defined by the International Commission on Illumination (CIE), and can be measured using a colorimeter. Preferably, the yellowness (YI value) is between -10.0 and 10.0, or between -5.0 and 5.0. The yellowness (YI value) can be adjusted by the thickness of the recycled resin layer, etc. If the molded container is a bottle or tube, it is preferable that at least the yellowness of the body satisfies the above range, and more preferably that the yellowness of the entire bottle or tube satisfies the above range.

[0071] <Total light transmittance> The molded container may have a total light transmittance of 10.0% or less in at least a portion of it. The total light transmittance is preferably 5.0% or less, or 1.0% or less. The total light transmittance can be adjusted by the total light transmittance, thickness, etc., of the outer and inner layers. If the molded container is a bottle or tube, it is preferable that the total light transmittance of at least the body portion satisfies the above range, and it is more preferable that the total light transmittance of the entire bottle or tube satisfies the above range.

[0072] <thickness> If the molded container is a bottle, the thickness of the recycled resin layer may preferably be 500 to 3,000 μm, more preferably 700 to 2,500 μm, and even more preferably 900 to 1,500 μm. A thickness of 500 μm or more allows the strength of the bottle to be maintained. A thickness of 3,000 μm or less is preferable because it allows for uniform blow molding. For tubes, the thickness is preferably 100 to 1,000 μm, more preferably 150 to 800 μm, and even more preferably 200 to 600 μm. A thickness of 100 μm or more allows the tube to maintain its strength. A thickness of 1,000 μm or less is preferable because it allows for the construction of a lightweight tube.

[0073] For bottles, a thickness of 500-3,000 μm allows for a balance between blow molding properties and strength. For tubes, a thickness of 100-1,000 μm allows for a balance between lightness and strength.

[0074] The thickness of the adhesive layer is, for example, 10 to 100 μm. The thickness of the resin layer L1 may be a thickness suitable for the function and material of the resin layer L1, for example, 50 to 1,000 μm. The thickness of the resin layer L2 may be a thickness suitable for the function and material of the resin layer L2, for example, 50 to 1,000 μm.

[0075] ≪Method for manufacturing molded containers≫ An embodiment of the present invention relates to a method for manufacturing a molded container, which involves using a recycled resin composition containing recycled resin (X1), resin (X2), and white pigment (Y1) obtained from PET bottle caps, and molding it by blow molding or extrusion molding. The blow molding method may be, for example, injection blow molding, and the extrusion molding method may be, for example, co-extrusion molding.

[0076] Brightness, yellowness, and total light transmittance can be adjusted by changing the thickness of the recycled resin layer, etc.

[0077] MFR can be determined in accordance with JIS K 7210:-1:2014. Total light transmittance can be measured in accordance with JIS K 7375:2008. Lightness (L* value) is the L* value in the L*a*b* color system defined by the International Commission on Illumination (CIE), and can be measured using a colorimeter. The yellowness (YI value) is determined according to JIS K 7373:2006, based on the XYZ color system defined by the International Commission on Illumination (CIE), and can be measured using a colorimeter.

[0078] <Brightness and Yellowness> The lightness (L* value) of at least a portion of the surface of the molded container may be 60.0 or higher. The lightness (L* value) is the L* value in the L*a*b* color system defined by the International Commission on Illumination (CIE) and can be measured using a colorimeter. Preferably, the lightness (L* value) is 70.0 or higher, or 75.0 or higher. If the molded container is a bottle or tube, it is preferable that at least the lightness of the body satisfies the above range in terms of hue, and more preferably that the lightness of the entire bottle or tube satisfies the above range. The molded container may have a yellowness (YI value) of at least a portion of its surface between -15.0 and 15.0. The yellowness (YI value) is determined according to JIS K 7373:2006 based on the XYZ color system defined by the International Commission on Illumination (CIE), and can be measured using a colorimeter. Preferably, the yellowness (YI value) is between -10.0 and 10.0, or between -5.0 and 5.0. If the molded container is a bottle or tube, it is preferable that at least the yellowness of the body satisfies the above range in terms of hue, and more preferably that the yellowness of the entire bottle or tube satisfies the above range.

[0079] <Total light transmittance> The molded container may have a total light transmittance of 10.0% or less in at least a portion of it. The total light transmittance is preferably 5.0% or less, or 1.0% or less. If the molded container is a bottle or tube, it is preferable from the viewpoint of design that the total light transmittance of at least the body portion meets the above range, and it is more preferable that the total light transmittance of the entire bottle or tube meets the above range.

[0080] The amount of recycled resin (X1), resin (X2), white pigment (Y1), and pigment (Y2) obtained using PET bottle caps used may be the amount corresponding to the content of the molded container in the above embodiment. [Examples]

[0081] Embodiments of the present invention will be described by reference to examples. Embodiments of the present invention are not limited to the following examples. In the examples, "parts" means "parts by mass" and "%" means "percentage by mass".

[0082] The methods for measuring the melt mass flow rate (MFR) of recycled resin compositions, the average particle size of pigments, and the PE / PP ratio of recycled resin compositions are as follows. <Method for measuring meltmass flow rate (MFR)> The melt mass flow rate was determined at 190°C and a load of 2.16 kg in accordance with JIS K 7210-1:2014.

[0083] <Average particle size of pigments> Samples were prepared by dispersing pigments with isopropyl alcohol. The resulting dispersion was irradiated with laser light using a Nikkiso Microtrac HRA particle size analyzer, and the particle size distribution was obtained by measuring the distribution pattern of the intensity of the light scattered as the laser light passed through the dispersion. Furthermore, the median diameter (50% diameter) on a volume basis was determined from the above particle size distribution values ​​and was used as the average particle size.

[0084] <Recycled resin composition PE / PP> The recycled resin composition was heat-pressed at 200°C for 30 seconds to form a thin film, which was then measured by transmission using an infrared spectrophotometer (FT / IR-4100, manufactured by JASCO Corporation). 719cm derived from PE -1 The peak and PP originate from 841cm -1 A calibration curve was created by comparing the peak heights, and the polyethylene content / polypropylene content (PE / PP) was calculated.

[0085] <Recycled material 1> PET bottle caps containing the following pigment (Y2a) were mixed and crushed. The resulting pulverized material was fed into a twin-screw extruder (manufactured by Japan Steel Works) and melt-kneaded at 220°C to obtain recycled material 1. The composition of recycled material 1 and the MFR of the contained recycled resin (X1) were as follows. [Recycled resin (X1)] Polyethylene content (parts by mass): Polypropylene content (parts by mass) = 95:5 Recycled resin (X1) MFR: 1.5g / 10 min [Pigment (Y2a)] Monoazo yellow, disazo yellow, monoazo orange, quinacridone red, diketopyrropyrrole red, phthalocyanine green, phthalocyanine blue, quinacridone violet

[0086] <Recycled materials 2-19> Depending on the type of PET bottle cap used as material, the process was modified as shown in Table 1. In addition, recycled materials 2-19 derived from PET bottle caps were manufactured in the same manner as recycled material 1. Furthermore, a mix of cap colors refers to the use of caps of various colors, including blue, green, yellow, red, white, and blue, without sorting them.

[0087] <Recycled material 20> White PET bottle caps containing 1.0% by mass of white pigment (Y1a) were crushed, and the resulting pulverized material was fed into a twin-screw extruder (manufactured by Japan Steel Works) and melt-kneaded at 220°C to obtain recycled material 20. The composition of recycled material 20 and the MFR of the contained recycled resin (X1) were as follows. [Recycled resin (X1)] Polyethylene content (parts by mass): Polypropylene content (parts by mass) = 85:15 Recycled resin (X1) MFR: 1.5g / 10 min [Pigment (Y1a)] Titanium oxide that has undergone one of the surface treatments selected from the group consisting of aluminum oxide, silicon dioxide, and siloxane.

[0088] Table 1 shows the MFR of the recycled resin (X1) contained in the recycled material, and the mass ratio (PE:PP ratio) of polyethylene content (parts by mass) to polypropylene content (parts by mass).

[0089] [Table 1]

[0090] The raw materials used in the examples are as follows: <Resin (X2)> (X2-1) HDPE1 (Hyzex 6203B, manufactured by Prime Polymer Co., Ltd., MFR: 0.36g / 10 min) (X2-2) HDPE2 (Hyzex 8200B, manufactured by Prime Polymer Co., Ltd., MFR: 0.03g / 10 min) (X2-3) LLDPE (Neozex 2006H, manufactured by Prime Polymer Co., Ltd., MFR: 0.63g / 10 min) (X2-4) LDPE (Tosoh Corporation Petrocene 170K MFR: 1.0g / 10 min) (X2-5) PP (Novatec PP EA9, manufactured by Nippon Polypropylene Co., Ltd., MFR: 0.5g / 10 mins)

[0091] <White pigment (Y1), etc.> (Y1-1) Titanium dioxide (Venatar Chronos 2230, average particle size: 0.37 μm, surface treatment: aluminum oxide, silicon dioxide, siloxane) (Y1-2) Titanium dioxide (manufactured by Ishihara Sangyo Co., Ltd., CR-80, average particle size: 0.25 μm, surface treatment: aluminum oxide, silicon dioxide) (Y1-3) Titanium dioxide (Sakai Chemical Industry Co., Ltd., D-962, average particle size: 0.26 μm, surface treatment: aluminum oxide, siloxane) (Y1-4) Titanium dioxide (Typake CR-95 manufactured by Ishihara Sangyo Co., Ltd., average particle size: 0.28 μm, surface treatment: aluminum oxide, polyol) (Y1'-5) Titanium dioxide (manufactured by Teika Co., Ltd., JR, average particle size: 0.27 μm, surface treatment: none) (Y1'-6) Titanium dioxide. See synthesis example 1 below (average particle size: 0.25 μm, surface treatment: polyol).

[0092] [Synthesis Example 1] Rutile-type titanium dioxide particles with an average particle size of 0.25 μm were crushed using a jet mill, and 0.5% by mass of trimethylolpropane was added and mixed to coat the titanium dioxide particles to obtain Y1'-6.

[0093] [Example 1] Fifty parts of recycled material 1, forty-seven parts of resin (X2-1) "HDPE1 (Hyzex 6203B MFR: 0.36 g / 10 min)" manufactured by Prime Polymer Co., Ltd., and three parts of white pigment (Y1-1) "Titanium dioxide (Kronos 2220 manufactured by Benatar, average particle size: 0.25 μm, surface treatment: aluminum oxide, silicon dioxide, siloxane)" were fed into a twin-screw extruder (manufactured by Japan Steel Works) and melt-kneaded at 220°C to obtain pelletized recycled resin composition 1.

[0094] Using recycled resin composition 1, a blow-molded bottle consisting of a single layer of recycled resin was manufactured by direct blow molding at a temperature of 220°C using a direct multilayer blow molding machine (manufactured by Nissei ASB Co., Ltd.). The blow-molded container was a cylindrical bottle with a capacity of 500 mL and a body diameter of 70 mm, and was molded so that the total thickness at the center of the body (near the midpoint between the shoulder and bottom of the container) was 1,000 μm.

[0095] [Examples 2-35, Comparative Examples 1-8] Except for changing the types and amounts (parts by mass) of recycled material, resin (X2), and pigment (Y1), respectively, as shown in Tables 2 and 3, recycled resin compositions 2 to 43 were manufactured in the same manner as recycled resin composition 1, and blow-molded bottles consisting of a single layer of recycled resin were manufactured in the same manner as in Example 1.

[0096] The titanium dioxide content (mass%) in the resin compositions of Examples 34, 35, and Comparative Example 8 was calculated by firing the obtained recycled resin compositions at 700°C for 20 minutes and performing elemental analysis of the residue using a Shimadzu EDX-7000 energy-dispersive X-ray fluorescence analyzer.

[0097] [Example 42] A blow-molded bottle with a multilayer structure of resin layer L1 / adhesive layer / recycled resin layer was manufactured by direct blow molding at a temperature of 220°C using a direct multilayer blow molding machine (manufactured by Nissei ASB Co., Ltd.) so that the thickness at the center of the body (near the center between the shoulder and bottom of the container) was 475 μm for the resin layer L1 and recycled resin layer, and 50 μm for the adhesive layer. HDPE (Hyzex 6008B, manufactured by Prime Polymer Co., Ltd.) was used for the resin layer L1, recycled resin composition 3 was used for the recycled resin layer, and modified polyolefin (Admer NF518, manufactured by Mitsui Chemicals, Inc.) was used for the adhesive layer.

[0098] [Example 43] A blow-molded bottle with a multilayer structure of resin layer L1 / recycled resin layer was manufactured by direct blow molding at a temperature of 220°C using a direct multilayer blow molding machine (manufactured by Nissei ASB Co., Ltd.) so that the thickness of the resin layer L1 and recycled resin layer in the center of the body (near the center of the shoulder and bottom of the container) was 500 μm. HDPE (Hyzex 6008B, manufactured by Prime Polymer Co., Ltd.) was used for the resin layer L1, and recycled resin composition 3 was used for the recycled resin layer.

[0099] In recycled resin compositions 1 to 40, the total content of pigment Ya was 0.1 to 5% by mass, based on the recycled resin composition.

[0100] Evaluation of molded containers The molded containers obtained in the examples and comparative examples were evaluated according to the following criteria. The evaluation results are shown in Tables 2 to 4. The evaluation was done on a three-point scale: ○, △, and ×, with ○ and △ indicating practical usability.

[0101] [Moldability] Three 3cm square sections were cut from the center of the molded container's body, and the thickness was measured with calipers. The difference between the maximum and minimum values ​​was used as the film thickness variation, and it was judged according to the following criteria. "Evaluation Criteria" ○: Film thickness variation is less than 50 μm △: Film thickness variation of 50 μm or more but less than 100 μm ×: Film thickness unevenness of 100 μm or more

[0102] [Hue] A 3cm square section was cut from the center of the molded container's body, and the L* and YI values ​​were measured using a colorimeter (SpectroColorMeterSE2000, manufactured by Nippon Denshoku Industries Co., Ltd.). The hue as seen from the appearance was determined according to the following criteria. "Evaluation Criteria" (L* value) ○: 70.0 or higher △: 60.0 or higher and less than 70.0 ×: Less than 60.0 (YI value) ○: Less than 10.0 △: 10.0 or higher, less than 15.0 ×: 15.0 or higher

[0103] [Concealing properties] A 3cm square section was cut from the center of the body of the molded container, and the total light transmittance was measured using a haze meter (BYK, HazeGuard Plus), and judged according to the following criteria. "Evaluation Criteria" ○: Less than 1.0% △: 1.0% or more and less than 10.0% ×: 10.0% or more

[0104] [Drop strength] The molded container was filled with water, sealed tightly, and dropped twice from a height of 1 meter onto a concrete floor: once with the bottom surface in contact and once with the body surface in contact. The results were then judged according to the following criteria. "Evaluation Criteria" ○: No cracks or breaks occurred, and no leakage of contents was observed. △: No leakage of contents was observed, but cracks or breaks occurred. ×: Cracks and breaks occurred, and leakage of contents was observed.

[0105] . [Recycled material content] The recycled material content (mass %) in the recycled resin layer was determined according to the following formula and judged according to the following criteria. Percentage of recycled material (by mass) = (Mass of recycled material (g) / Mass of recycled resin composition (g)) × 100 "Evaluation Criteria" ○: 50% by mass or more △: 10% by mass or more and less than 50% by mass ×: Less than 10% by mass

[0106] [Table 2-1]

[0107] [Table 2-2]

[0108] [Table 2-3]

[0109] [Table 2-4]

[0110] [Table 3]

[0111] [Table 4]

[0112] The results shown in Tables 2-4 confirm that the recycled resin composition of the present invention can be used to obtain molded containers with excellent moldability, color, and drop strength.

[0113] By using the recycled resin composition of the present invention, it is possible to provide a recycled resin composition with excellent moldability, color, and drop strength even when collected PET bottle caps are used without sorting or separating them, thereby expanding new recycling applications for PET bottle caps. Furthermore, when recycling was performed using only white caps through color sorting, the hue was at a level that was practical even with conventional recycled compositions, but the moldability and drop strength were poor. In contrast, it was confirmed that using the recycled resin composition of the present invention improved both moldability and drop strength. Furthermore, it has been confirmed that the recycled resin composition of the present invention can be suitably applied to molded containers such as bottles and tubes, whether it is a single-layer structure or a multi-layer structure of recycled resin layers.

Claims

1. A recycled resin composition containing recycled resin (X1) obtained using PET bottle caps, a resin other than the recycled resin (X1) (X2), and a white pigment (Y1), The recycled resin composition has a melt mass flow rate (MFR) of 0.1 to 5 g / 10 min at 190°C. The recycled resin (X1) contains polyethylene and polypropylene, and the polyethylene content (parts by mass) : polypropylene content (parts by mass) is 70:30 to 95:

5. The recycled resin composition is characterized by a white pigment (Y1) being titanium dioxide that has undergone one of the surface treatments selected from the group consisting of aluminum oxide, silicon dioxide, and siloxane.

2. The recycled resin composition according to claim 1, wherein the recycled resin (X1) has a melt mass flow rate (MFR) of 0.1 to 10 g / 10 min at 190°C.

3. The recycled resin composition according to claim 1, further comprising at least one pigment (Y2) selected from the group consisting of monoazo yellow, disazo yellow, monoazo orange, quinacridone red, diketopyrrolopyrrole red, phthalocyanine green, phthalocyanine blue, and quinacridone violet.

4. The recycled resin composition according to claim 1, wherein the content of the white pigment (Y1) is 0.5 to 25% by mass, based on 100% by mass of the recycled resin composition.

5. A molded container manufactured using the recycled resin composition described in any one of claims 1 to 4.

6. The molded container according to claim 5, wherein the brightness (L* value) of at least a portion of the surface is 60.0 or higher.

7. A bottle, which is a molded container according to claim 5.

8. A tube, which is a molded container according to claim 5.

9. A method for manufacturing a molded container, comprising the step of molding it by blow molding or extrusion molding using a recycled resin composition according to any one of claims 1 to 4.

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