PET container and method for manufacturing the same

Abstract

To provide a container having a good visibility even when directly printed.SOLUTION: A PET container includes a transparent container body molded from polyethylene terephthalate (PET) capable of holding a content, an opaque region provided on a part of an outer surface or an inner surface of the container body, and a printed layer including a colorant provided on at least a part of the opaque region. A manufacturing method of the PET container includes a molding step of molding the transparent container body capable of holding the content using polyethylene terephthalate (PET), an opacifying step of at least partially opacifying the outer surface or the inner surface of the container body, and a printing step of forming a print layer on an opacified part of the container body by an inkjet method.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a PET container and a method for manufacturing the same.

Background Art

[0002] Containers having a printing layer provided on the surface of the container body are known (Patent Document 1). However, printing applied to a transparent container has poor visibility, and printed characters, codes, etc. are difficult to recognize. When printing characters, etc. on a label provided on the outside of the container, visibility is improved, but it is necessary to peel off the label during recycling, etc., and there are cases where it is necessary to separate the label. [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-52607

Summary of the Invention

[0003] In a first aspect of the present invention, there is provided a PET container comprising: a transparent container body formed of polyethylene terephthalate (PET) and capable of holding contents; an opaque region provided on a part of an outer surface or an inner surface of the container body; and a printing layer containing a coloring agent provided on at least a part of the opaque region.

[0004] Further, in a second aspect, there is provided a method for manufacturing a PET container, comprising: a molding step of molding a transparent container body capable of holding contents using polyethylene terephthalate (PET); an opaque step of at least partially opaqueifying an outer surface or an inner surface of the container body; and a printing step of forming a printing layer on the opaque portion of the container body by an inkjet method.

[0005] Note that the above summary of the invention does not list all the necessary features of the present invention. Also, sub-combinations of these feature groups can also be inventions.

Brief Description of the Drawings

[0006] [Figure 1] An example of the appearance of the container 100 in the present embodiment is shown. [Figure 2]An example of the layer configuration of the container 100 in this embodiment is shown. [Figure 3] Another example of the layer configuration of the container 100 in this embodiment is shown. [Figure 4] Another example of the layer configuration of the container 100 in this embodiment is shown. [Figure 5] Another example of the appearance of the container 100 in this embodiment is shown. [Figure 6] Another example of the appearance of the container 100 in this embodiment is shown. [Figure 7] Another example of the appearance of the container 100 in this embodiment is shown. [Figure 8] An example of the manufacturing flow of the container 100 of this embodiment is shown. [Modes for carrying out the invention]

[0007] The present invention will be described below through embodiments, but these embodiments are not intended to limit the invention as defined in the claims. Furthermore, not all combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0008] Figure 1 shows an example of a container 100 in this embodiment. The container 100 has a transparent appearance and is printed on at least a portion of it. The container 100 has a container body 10, an opaque area 20, a printed layer 30, and a transparent area 35.

[0009] The container body 10 is a structure capable of holding its contents. The container body 10 is molded from a recyclable transparent material such as resin or glass. For example, the container body 10 is molded from polyethylene terephthalate (PET), in which case the container 100 becomes a PET container and is referred to as a PET bottle, etc. The contents held in the container body 10 may be beverages, food, medicine, or industrial products, etc. Details of the container body 10 will be described later.

[0010] The opaque area 20 is an opaque area provided on a part of the outer or inner surface of the container body 10, for example, an area where a part of the outer or inner surface of the container body 10 is whitened. The opaque area 20 may be provided in a part of the container 100 other than the mouth portion (i.e., the part to which a cap or other lid is attached). For example, the opaque area 20 may be provided on a part or all of the body portion, bottom portion, and / or shoulder portion of the container 100.

[0011] The opaque region 20 may be provided so as to surround the entire area where the printed layer 30 is provided, as shown in the figure. The opaque region 20 may not be provided outside the area where the printed layer 30 is provided, or if it is provided, it may be only in a part of the area, so as not to impede the visibility of the contents of the container 100 or the aesthetic appearance of the container 100. For example, the opaque region 20 may be provided in 1 to 95% of the outer surface area of ​​the container 100 excluding the lid, preferably in 3 to 60%, and more preferably in 5 to 30%.

[0012] The printing layer 30 is a layer containing a coloring agent, provided in at least a portion of the opaque area 20. The printing layer 30 imparts letters or patterns to the container 100.

[0013] The transparent area 35 is a transparent area of ​​the container body 10. The transparent area 35 may be an area of ​​the container body 10 other than the opaque area 20. In the transparent area 35, the contents may be at least partially observable from the outside, but it does not need to be completely transparent and may be semi-transparent. In addition, the transparent area 35 may be an area that is colored with a coloring agent or the like to the extent that transparency is maintained.

[0014] As shown in Figure 1, the printed layer 30 of the container 100 is formed on top of the opaque area 20. Therefore, compared to the case where the printed layer 30 is provided only in the transparent area 35, the printed content of the printed layer 30 is easier to see. For example, if the contents are a dark-colored beverage and the printed layer 30 contains black letters or codes, the absence of the opaque area 20 would result in a weak contrast between the printed layer 30 and the contents, significantly worsening visibility. Even if the contents are a transparent beverage such as water, a similar visibility problem may occur depending on the background. On the other hand, the presence of the opaque area 20 ensures contrast between the printed layer 30 and the contents, improving visibility.

[0015] Figure 2 shows an example of the layered structure of the container 100 in this embodiment. In Figure 2, the upper side is the outer surface of the container 100 (i.e., the surface that comes into contact with the outside air), and the lower side is the inner surface (i.e., the surface that comes into contact with the contents).

[0016] A transparent material can be used as the material for the container body 10, for example, glass or resin. When an opaque region 20 is formed by whitening, it is desirable that the material be a crystallizable resin. As the material, one or more materials selected from polyester resins, polyolefin resins, polystyrene resins, polyamide resins, acrylic resins, polyvinyl chloride resins, polyacrylonitrile resins, polyvinyl alcohol resins, and biodegradable resins may be used.

[0017] As the polyester resin, thermoplastic polyesters such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate are preferably used. As the polyolefin resin, low-density / high-density polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, and random / block copolymers of any linear or cyclic olefin may be used. As the polystyrene resin, polystyrene, acrylonitrile / styrene copolymer, ABS, or α-methylstyrene / styrene copolymer may be used. Examples of the polyamide resin include nylon 6, nylon 6-6, nylon 6 / 6-6 copolymer, metaxylylene diadipamide, nylon 6-10, nylon 11, nylon 12, and nylon 13. Examples of the acrylic resin include acrylic ester and methacrylic ester. Examples of the polyvinyl chloride resin include polyvinyl chloride and polyvinylidene chloride.

[0018] The container body 10 may contain various additives. For example, the container body 10 may contain a plasticizer, a UV absorber, a flame retardant, an antistatic agent, an antioxidant, a weathering agent, a deodorant, a matting agent, a mold release agent, an ion exchanger, a colorant, and other additives.

[0019] At least a part of the container body 10 (for example, the region including the opaque region 20) or the entire outer surface may be subjected to a surface treatment. For example, the container body 10 may be subjected to a plasma treatment, a corona treatment, an ozone treatment, a primer coating treatment, or the like. Thereby, the adhesion between the container body 10 and the printing layer 30 can be improved. Also, a surface treatment may be performed on the inner surface of the container body 10, or another layer may be formed. For example, an oxygen barrier film (for example, a SiOx film) may be formed on the inner surface of the container body 10. The thickness of the container body 10 is arbitrary, but for example, it is preferably in the range of 0.1 to 1.0 mm.

[0020] In the embodiment of FIG. 2, the opaque region 20 is formed on a part of the outer surface of the container body 10. For example, a part of the outer surface of the container body 10 is processed to be opaque, thereby forming the opaque region 20. The opaque region 20 is not formed by laminating another opaque layer on the container body 10, but is a part of the container body 10. Therefore, when the container 100 is recycled, separate peeling treatment or the like is not required. Note that, unlike FIG. 2, the opaque region 20 may be formed on a part of the inner surface of the container body 10, may be formed throughout the thickness direction from the inner surface to the outer surface of the container body 10, or the opaque region 20 may be formed on both the outer surface and the inner surface.

[0021] The opaque region 20 blocks at least a part of the visible light passing between the inside and the outside of the container 100. For example, the total light transmittance of the opaque region 20 may be 85% or less. Preferably, the total light transmittance of the opaque region 20 is 45% or less, and more preferably 25% or less. The total light transmittance may be calculated based on the average of the transmittances of light with wavelengths of 400 to 700 nm. For example, the total light transmittance may be calculated by the method of JIS K7376-1 or a method equivalent thereto.

[0022] The opaque region 20 may be realized by various methods. For example, the opaque region 20 may be a region where the resin (e.g., PET) of the container body is whitened. As an example, the opaque region 20 may be a region where the resin is at least partially crystallized by heating or the like.

[0023] In this case, the opaque region 20 is formed by utilizing the fact that the resin turns white during crystallization. The opaque region 20 formed by crystallization diffuses at least a part of the visible light passing between the inside and the outside of the container 100.

[0024] The thickness of the opaque region 20 due to crystallization can be any value, but it is preferable that it be in the range of 0.05 to 1 mm. If it is less than 0.05 mm, the opacity may be insufficient and visibility may be poor, and if it is more than 1 mm, the degree of crystallization may be high, which may cause the resin to become brittle and prone to cracking. The haze value of the crystallized opaque region 20 may be between 0.5 and 100. If it is less than 0.5, the visibility of the image on the printed layer 30 will be reduced.

[0025] The thermal induction crystallinity of the crystallized opaque region 20 may be 15-80%, preferably 45-80%, and more preferably 55-80%. The thermal induction crystallinity may be calculated using the gradient between the density of the uncrystallized resin and the crystalline density of the resin, based on the measured resin density. The resin density may be measured at room temperature (e.g., 25°C) using a method compliant with ASTM 1505. The crystalline density of the resin may be a known value and can also be calculated from the unit cell parameter.

[0026] For example, the density (dam) of uncrystallized PET is 1.335 g / cm³. 3 The density (dcr) of crystallized PET is 1.455 g / cm³. 3 It is known that, in heat-resistant PET, the value of thermal induction crystallinity is a major factor determining heat resistance. Crystallination does not occur throughout the entire PET, but rather in the presence of regular crystals at various points along the molecular chain, and the ratio of these crystals is called the thermal induction crystallinity. The density of uncrystallized PET resin is dam = 1.335 g / cm³. 3 Crystalline PET with dcr = 1.455 g / cm³ 3 The degree of crystallinity X is determined by measuring the density d of the molded product and using the following formula. 1 / d = X / dcr + (1-X) / dam X = dcr(dam-d) / d(dam-dcr) As an example, the measured resin density (d) of PET was 1.394 g / cm³. 3 In this case, X is calculated to be 51.32%. The degree of thermal induction crystallinity may be determined by the method described in Japanese Patent Publication No. 2005-531445.

[0027] Furthermore, if the container body 10 contains a coloring agent or otherwise has a unique color, it will not necessarily turn white, but rather change to a state where the unique color becomes cloudy. For example, if the container body 10 contains a red coloring agent, it is expected to change to a light pink color due to crystallization, but such cases are also referred to here as "whitening."

[0028] Instead of whitening, the opaque region 20 may be a region where the resin of the container body is partially foamed. In this case, the container body 10 contains many fine bubble cells in the opaque region 20, and the opaque region 20 is formed by the diffusion of light passing through the bubble cells. The haze value of the opaque region 20 due to partial foaming may be between 0.5 and 100. If it is less than 0.5, the visibility of the image on the printed layer 30 will decrease.

[0029] The printed layer 30 is formed adjacent to the upper side of the opaque region 20. If the opaque region 20 is formed on the inner surface of the container body 10, the printed layer 30 is formed on the outer surface of the container body 10 in the area corresponding to the opaque region 20 (the area facing the opaque region 20 through the container body 10). The printed layer 30 may also be formed in the transparent region 35 as well as the opaque region 20.

[0030] The printed layer 30 displays various characters, identification codes, symbols, pictures, patterns, etc. (hereinafter collectively referred to as "pictures, etc.") formed by printing. Examples of characters include the product name and description of the container 100 (for example, the taste of the contents, ingredients, manufacturer, and expiration date, etc.) and a description of the container body 10 (the material of the container body 10, whether it is recyclable, and how to recycle it, etc.). Examples of identification codes include barcodes and 2D codes, which may represent the product name, description, description of the container body 10, and links to websites displaying this information instead of characters.

[0031] The printed layer 30 is a cured product of the ink composition formed by printing. The printed layer 30 may contain a binder resin, a colorant, and other additives.

[0032] The binder resin may contain an alkali-soluble resin. For example, the binder resin may be an alkali-soluble thermoplastic resin or an alkali-soluble photocurable resin. Being alkali-soluble allows the printed layer 30 to be easily peeled off and dissolved later with an alkaline solution, facilitating the recycling of the container 100. The binder resin may further contain resins other than alkali-soluble resins.

[0033] The coloring agent may contain pigments or dyes that can be used for printing. The color of the coloring agent is not particularly limited, but it is desirable to include colors that provide high contrast against a white background, such as black, blue, or brown. The content of the coloring agent may be 1 to 20% by weight, preferably 3 to 15% by weight, relative to the entire printed layer 30. Since the printed layer 30 is provided on top of the opaque area 20, visibility is better compared to when there is no opaque area 20. Therefore, the content of the coloring agent can be reduced compared to when there is no opaque area 20.

[0034] Figure 3 shows another example of the layer configuration of the container 100 in this embodiment. In the embodiment shown in Figure 3, the opaque region 20 is a region on the outer surface of the container body 10 that has been roughened. Unlike in Figure 3, the opaque region 20 may be a region on the inner surface of the container body 10 that has been roughened, or it may be a region on both the inner and outer surfaces that have been roughened.

[0035] The arithmetic mean roughness (Ra) of the roughened surface of the opaque region 20 may be between 0.05 and 20 μm. The average length (RSm) of the roughened opaque region 20 may be between 50 and 1000 μm. The haze value of the roughened opaque region 20 may be between 0.5 and 100. If it is less than 0.5, the visibility of the image on the printed layer 30 will be reduced.

[0036] Furthermore, Ra / RSm is preferably 0.001 or higher, and more preferably 0.002 or higher. By satisfying the above requirements for Ra / RSm value, the haze can be further improved, and the visibility of the printed layer 30 can be enhanced.

[0037] Figure 4 shows another example of the layer configuration of the container 100 in this embodiment. As shown in the figure, the container body 10 may include multiple layers. For example, the container body 10 may have an intermediate layer 14 and PET layers 12 and 16 made of polyethylene terephthalate that sandwich the intermediate layer 14.

[0038] The PET layer 12 and PET layer 16 may have the same configuration as the container body 10 described in Figure 2. Instead of the PET layer 12 and PET layer 16, a layer of a resin different from PET, which was listed as the material for the container body 10, may be provided.

[0039] The intermediate layer 14 provides various functions and added value to the container 100. For example, the intermediate layer 14 may be a layer having oxygen barrier properties. In this case, the intermediate layer 14 may be a polyamide resin such as nylon (e.g., nylon 6, nylon 6-6, nylon 6 / 6-6 copolymer, metaxylylenediadipamide, nylon 6-10, nylon 11, nylon 12, and nylon 13), or an ethylene-vinyl alcohol copolymer (e.g., ethylene-vinyl acetate copolymer), and preferably nylon. By using these materials, the preservation of the contents can be improved.

[0040] Furthermore, for example, the intermediate layer 14 may be a layer made of recycled materials. For example, the intermediate layer 14 may be a recycled resin such as recycled PET. As an example, the intermediate layer 14 may be mechanically recycled PET or chemically recycled PET. By using recycled materials, the environmental burden incurred in the manufacture of the container 100 can be reduced.

[0041] When the container 100 consists of multiple layers, the haze value of the opaque region 20 may be between 1 and 100. If it is less than 1, the visibility of the design on the printed layer 30 will be reduced.

[0042] The container 100 may have further layers. For example, an adhesive layer or another functional layer may be provided between the PET layer 12, the intermediate layer 14, and the PET layer 16.

[0043] In Figure 4, an opaque region 20 is provided in the PET layer 12, but instead of this, or in addition, the opaque region 20 may be provided in another layer. For example, the opaque region 20 may be provided in the intermediate layer 14 and / or the PET layer 16.

[0044] Figure 5 shows another example of the appearance of the container 100 in this embodiment. Unlike Figure 1, the opaque area 20 is not provided to surround the entire area of ​​the printed layer 30, but may be provided to outline the contour of the pattern or design on the printed layer 30. For example, if the printed layer 30 includes printed characters, the opaque area 20 is provided at least on the edges of the characters included in the pattern or design. If the pattern or design includes a code such as a two-dimensional code or a barcode, the opaque area 20 may be provided to surround the outer periphery of the code (i.e., on the inside of the code and on the outer edge). As an example, the opaque area 20 may be provided only on the edges of the contour of the pattern or design.

[0045] For example, the opaque area 20 may be provided such that its area is 105-400%, preferably 110-200%, of the area of ​​independent characters, codes, symbols, etc. of the printed layer 30. 2 If the letter "W" is printed on an area of ​​2cm², then 200% of that area is 2cm². 2 An opaque region 20 may be formed inside and around the letter "W" with an area such that it outlines the letter "W". However, since the letter "W" is formed on the opaque region 20, only 200%-100%=100% of the opaque region 20 can be observed from above the letter.

[0046] Figure 6 shows another example of the appearance of the container 100 in this embodiment. The opaque region 20 may have portions in which the opacity changes in steps. For example, as shown in Figure 6, the portion of the printed layer 30 that is close to the pattern or design may have the highest opacity (for example, be the most strongly whitened), and the opacity may decrease as the distance from the pattern or design increases.

[0047] Figure 7 shows another example of the appearance of the container 100 in this embodiment. The container 100 has recesses 40 formed on the outer or inner surface of the container body 10, separate from the printed layer 30. The recesses 40 may be formed to represent letters, symbols, identification codes, pictures, patterns, etc. The recesses 40 may be formed by a mold or the like during or after the blow molding of the container 100.

[0048] For example, the container 100 may have recesses representing letters or symbols, where these recesses represent information about the material of the container body 10, and the printed layer 30 may represent information specific to the product sold using the container 100. As an example, the letters "PET," meaning polyethylene terephthalate, may be formed as a recess 40 on the outer surface of the container body 10, and the product name of the contents of the container 100 (for example, the product name of a specific soft drink), and / or information about the product (for example, the raw materials of the soft drink) or a two-dimensional code for the URL of a website providing such information may be formed as the printed layer 30 on the opaque area 20. This allows for the mass production of containers 100 with information independent of the contents using a mold, and then the addition of different information on demand later by digital printing or the like, depending on the contents.

[0049] Next, a method for manufacturing the container 100 will be described. The method for manufacturing the container 100 may include at least a molding step, an opacification step, and a printing step.

[0050] In the molding stage, a transparent container body 10 capable of holding contents is formed by molding a transparent material. The molding stage may include a preform molding stage and a blow molding stage.

[0051] In the opacification step, the outer or inner surface of the container body 10 is made opaque at least partially, forming an opaque region 20. The opacification step may be performed separately from the molding step and after the molding step. Alternatively / in addition, the opacification step may be performed in the middle of the molding step.

[0052] During the printing stage, a printed layer 30 is formed on at least the opaque region 20 of the container body 10.

[0053] Figure 8 shows an example of a flow chart for manufacturing the container 100 of this embodiment. The container 100 of this embodiment can be manufactured by performing the processes S100 to S500 in Figure 8. For the sake of explanation, the processes S100 to S500 will be described in order, but at least some of these processes may be performed in parallel, or the steps may be rearranged without departing from the spirit of the present invention. In addition, some steps may be omitted.

[0054] First, in S100, a preform is molded. For example, a transparent material such as resin, which will be the material for the container body 10, may be melted at high temperature and pressure, injected into a mold, and then cooled and solidified to form a preform in the shape of the mold. The temperature during melting and injection may be in the range of 200°C to 300°C, for example. The pressure during injection may be set appropriately according to the shape of the container, etc., but may be in the range of 10 to 40 MPa, for example. The preform may be rapidly cooled after injection. This prevents the entire preform from crystallizing and becoming opaque.

[0055] In S100, a single-layer preform may be formed by injecting a single layer of resin, or a multi-layer preform may be formed by co-injecting multiple layers of resin into the mold. Alternatively, a multi-layer preform may be formed by co-compression molding, sequential injection, etc., instead of or in addition to co-injection.

[0056] When a multilayer preform is formed, a container 100 as shown in Figure 4 can be obtained. When forming a multilayer preform, co-injection may be performed so that a resin with a specific function (for example, a resin with oxygen barrier properties such as nylon or a recycled resin) is positioned between the base resin (for example, PET).

[0057] The lid portion of the injection-molded preform may be heat-treated to induce crystallization. Crystallization of the lid portion of the preform can impart heat resistance. The heat treatment temperature should be such that the material crystallizes, for example, in the range of 140°C to 200°C.

[0058] Next, in S200, the preform is blow-molded. For example, biaxial stretch blow molding may be performed. As an example, the preform may be heated and then inserted into a mold, stretched in the longitudinal direction of the preform with a stretching rod (i.e., longitudinal stretching), and then pressurized air may be blown into the preform to expand its radius (i.e., transverse stretching) to form the container body 10.

[0059] Blow molding may be performed while heating the preform at a temperature above the glass transition temperature (Tg) of the material but below its crystallization temperature. For example, if the material of the container body 10 is PET, it may be heated to 100-130°C. Known heating methods such as infrared, high-frequency induction, and hot air can be used. After the molding of the container body 10 is complete, the pressurized air may be switched to cooling air (e.g., air, carbon dioxide, nitrogen gas, or liquefied forms thereof) and sent into the interior of the container body 10 to cool it.

[0060] The recess 40 may be formed during blow molding. For example, the recess 40 described in Figure 7 may be provided by placing a mold with a pattern or the like pre-formed in a convex shape on the outside of the preform and performing blow molding.

[0061] Next, in S300, an opaque region 20 is formed in the container body 10. The opaque region 20 may be formed by at least partially whitening the resin such as PET of the container body 10. Whitening may be achieved by at least partially crystallizing the resin such as PET of the container body 10.

[0062] For example, the heated portion may be crystallized by heating part or all of the body, bottom, and / or shoulder portion of the container body 10. The temperature of the heated portion should be such that the material crystallizes, and may be in the range of 140°C to 200°C, for example.

[0063] The heating method can be achieved by pressing a heated heating element, such as a heated mold, against the portion of the container body 10 that is to be made opaque 20, irradiating it with infrared light, or irradiating it with a laser. For example, if a rectangular heated heating element is pressed against the body of the container body 10 and crystallization occurs, a certain area of ​​opaque region 20 will be formed as shown in Figure 1.

[0064] Furthermore, when heating is performed using a laser or the like to match the outline of the pattern on the printed layer 30, a bordered opaque region 20 as shown in Figure 5 is formed. In addition, by adjusting the amount of heating with a laser according to the distance from the outline of the pattern, a stepped opaque region 20 as shown in Figure 6 is formed.

[0065] When forming an opaque region 20 by crystallization, heating may be performed so that the degree of thermal induction crystallization of the opaque region 20 is 15-80%, preferably 45-80%, and more preferably 55-80%. The same applies when crystallization is performed during the preform molding stage described later.

[0066] The opaque region 20 is preferably provided on the outer surface of the container body 10, but it may also be formed on the inner surface of the container body 10. For example, the opaque region 20 may be formed on the inner surface by irradiating the portion corresponding to the opaque region 20 from the inside of the container body 10 with a laser or infrared light.

[0067] Instead of whitening due to crystallization, the opaque region 20 may be formed by roughening the outer or inner surface of the container body 10. For example, the outer surface of the container body 10 may be roughened by mechanical means (e.g., mechanical polishing or sandblasting), chemical means (e.g., ozone treatment), or physical means (e.g., laser treatment). When using sandblasting, the opaque region 20 may be formed by directly sandblasting the container body 10, or by sandblasting the surface of the mold to form a rough surface, and then transferring the rough surface of the mold to the surface of the preform during blow molding. When using sandblasting, glass beads, glass powder, alumina particles, etc., can be used as the sandblasting material.

[0068] Next, in S400, a printed layer 30 is formed on the outer surface of the container body 10. The printed layer 30 is provided at least in the opaque area 20 of the container body 10, but may also be provided in the transparent area 35. By forming the printed layer 30 on both, the visibility of important information can be improved, as well as the decorative aspect of the container 100.

[0069] The method for forming the printed layer 30 is not particularly limited, but examples include various printing methods such as inkjet printing, offset printing, gravure printing, and electrophotographic printing, or coatings such as roll coating. An inkjet method that allows on-demand printing is particularly preferred. After printing or coating, a process of drying and curing the ink may be performed. Curing may be performed by heat curing or ultraviolet curing.

[0070] A known ink composition can be used to form the printed layer 30. For example, a composition with appropriate solvents and additives added to the material described above for the printed layer 30 can be used. Particularly from the viewpoint of reducing environmental impact, it is desirable to use an ink composition that contains an alkali-soluble resin. The content of the colorant in the ink composition is preferably 1 to 20% by weight, and more preferably 3 to 15% by weight, relative to the weight of the solids. As described above, the printed layer 30 has excellent visibility due to the opaque region 20, so the content of the colorant in the ink composition can be reduced compared to when there is no opaque region 20.

[0071] The printing layer 30 may be a single layer or a multilayer layer. Furthermore, additional layers may be provided on top of the printing layer 30 as needed. For example, a protective layer may be provided on top of the printing layer 30 to protect it from physical / chemical damage.

[0072] Next, in S500, the container 100, after the formation of the printed layer, is inspected. For example, the outer or inner surface of the container 100 is inspected for dents, holes, scratches, and stains. For example, the opacity of the opaque area 20 formed on the container 100 is inspected. Also, for example, the pattern formed on the container 100 is inspected for sufficient clarity, and for any printing misalignment, chipping, or blurring. The inspection may be performed by an inspection device or by visual inspection by a person.

[0073] In the above example, the formation of the opaque region 20 (S300) was performed after blow molding (S200), but it may be done by other methods. For example, the formation of the opaque region 20 may be performed in parallel with blow molding and / or in parallel with preform molding.

[0074] When forming the opaque region 20 in parallel with blow molding, a portion of the container body 10 may be heated to a temperature above the crystallization temperature at the same time as blow molding. For example, while blow molding, a heated mold or other heating element, or a mold roughened by sandblasting, may be pressed against the portion of the container body 10 that is to be made into the opaque region 20, or infrared light may be irradiated, or a laser may be irradiated.

[0075] When forming a multilayer preform in S100, one, more, or all of the layers may be foamed. For example, in the case of a three-layer structure as shown in Figure 4, only the intermediate layer corresponding to the intermediate layer 14 of the preform may be foamed. In this case, the foaming agent may be contained only in the intermediate layer.

[0076] When the formation of the opaque region 20 is carried out in parallel with preform molding, the portion of the mold from which the resin is injected that comes into contact with the region of the preform where the opaque region will be formed may be cooled slowly after injection, rather than rapidly, to promote crystallization (i.e., opacity). Alternatively, the region of the preform where the opaque region will be formed may be injected at a higher temperature than other parts of the mold.

[0077] Alternatively, in addition to the slow cooling method, the resin forming the intermediate layer (e.g., nylon or recycled PET) may be under-mixed to facilitate the formation of nuclei that serve as starting points for crystallization within the resin, thereby promoting crystallization (i.e., opacity). For example, under-mixing can be induced by lowering the temperature during plasticization of the resin forming the intermediate layer, and by reducing the back pressure and rotational speed of the screw. As an example, if the intermediate layer resin is nylon or recycled PET, the temperature during plasticization may be set to 120-140°C.

[0078] Alternatively, the opaque region 20 may be formed by partially foaming the PET or other resin of the container body 10. For example, the material of the container body 10 may be pre-mixed with a foaming agent, and preform molding as described in S100 may be performed. Then, only the portion of the preform corresponding to the opaque region 20 may be heated under conditions that cause the foaming agent to foam, thereby forming foam cells in the preform. Subsequently, the opaque region 20 can be formed by blow molding while maintaining the foam cells in S200.

[0079] The foaming agent can be any agent capable of forming fine, uniform foam cells within the container body 10, such as sodium carbonate or an inert gas. A known method, such as the method described in Japanese Patent Application Publication No. 2009-262366, can be used for forming the foam cells.

[0080] When using a multilayer preform, all layers or only some of the layers may be whitened to form an opaque region 20. For example, in the three-layer configuration shown in Figure 4, if the intermediate layer 14 is nylon, the intermediate layer 14 can be whitened by partially heating the multilayer preform at a temperature above the crystallization temperature of nylon and below the crystallization temperature of PET (e.g., 120-140°C). If the intermediate layer 14 is recycled PET, the intermediate layer 14 can be whitened by partially heating the multilayer preform at a temperature above the crystallization temperature of recycled PET and below the crystallization temperature of PET (e.g., 120-140°C).

[0081] Alternatively, instead of partially heating the preform, whitening may be promoted by keeping the moisture content of the intermediate layer 14 material (e.g., nylon or recycled PET) higher than that of the inner and outer PET layers (i.e., PET layer 12 and PET layer 16).

[0082] Furthermore, in addition to / instead of the method described above, the opacification step S300 in Figure 8 may be performed within each of the molding steps S100 to S200. That is, in these molding steps, a container may be molded using polyethylene terephthalate (PET) and an opaque material, having a transparent container body 10 capable of holding contents and an opaque region 20 provided on at least a part of the outer or inner surface of the container body 10. For example, the opacification step may be performed together with the molding step using methods such as two-color molding, compression molding, or integral film molding.

[0083] When using two-color molding (also called double molding), primary injection molding is performed using PET as the material to first form a single-layer preform corresponding to the container body 10. Then, secondary injection molding is performed using an opaque material so that the outer or inner surface of the single-layer preform is covered with an opaque material. This results in a two-layer preform with PET as the base material and a portion of it being two-layered.

[0084] Subsequently, the two-layer preform is blow-molded to obtain a container having a transparent container body and an opaque region 20 provided on at least a portion of the outer or inner surface of the container body. In the preform, the region covered with the opaque material later becomes the opaque region 20.

[0085] When using compression molding, an opaque material may be molded together with the container body 10 to form a container having an opaque region 20 provided on at least a part of the outer or inner surface of the container body 10. When integrally molding a film, a heat-shrinkable material such as a partially opaque film may be placed around the preform and heat-shrinked to integrally mold the film that forms the opaque region 20 with the preform.

[0086] Examples 1 and 3-26 shown below involve performing steps S200 and S300 in parallel as shown in Figure 8. That is, the opaque region 20 is formed during blow molding. Example 2 involves performing step S300 after step S200 as shown in Figure 8. That is, the opaque region 20 is formed after blow molding. [Example 1] A single-layer preform was molded using commercially available polyethylene terephthalate resin material, and then a PET bottle-shaped container was manufactured by biaxially stretching blow molding of the preform. An opaque region was formed by pressing a mold heated to 160°C against a portion of the body of this PET bottle container. The haze value of the opaque region was 20.

[0087] [Example 2] In Example 1, an opaque region was formed using laser irradiation instead of a heated mold. Specifically, a single-layer preform was molded using a commercially available polyethylene terephthalate resin material, and then a PET bottle-shaped container was manufactured by biaxially stretching blow molding of the preform. An opaque region was formed on a part of the body of this PET bottle container using laser irradiation (wavelength 9.3 μm, output 30 W). The haze value of the opaque region was 90.

[0088] [Example 3] In Example 1, instead of using a heated mold, a mold roughened by sandblasting was used to roughen a portion of the outside of the container, thereby creating an opaque region. Glass beads with a particle size of F400 according to JIS R6001 were used as the sandblasting agent, and the blasting pressure was 3 kgf / cm². 2 Sandblasting was performed.

[0089] [Example 4] The procedure was the same as in Example 3, except that glass beads with a particle size of F320 were used as the sandblasting agent.

[0090] [Example 5] The procedure was the same as in Example 3, except that glass beads with a particle size of F100 were used as the sandblasting agent.

[0091] [Example 6] The procedure was the same as in Example 3, except that glass beads with a particle size of F80 were used as the sandblasting agent.

[0092] [Example 7] The procedure was the same as in Example 3, except that alumina particles with a particle size of F100 were used as the sandblasting agent.

[0093] [Example 8] The procedure was the same as in Example 3, except that glass beads with a particle size of F70 were used as the sandblasting agent.

[0094] [Example 9] The procedure was the same as in Example 3, except that glass powder with a particle size of F54 was used as the sandblasting agent.

[0095] [Example 10] The procedure was the same as in Example 3, except that corundum with a particle size of F60 was used as the sandblasting agent.

[0096] [Example 11] The procedure was the same as in Example 3, except that alumina particles with a particle size of F46 were used as the sandblasting agent.

[0097] [Example 12] The procedure was the same as in Example 3, except that corundum with a particle size of F24 was used as the sandblasting agent.

[0098] [Example 13] The procedure was the same as in Example 3, except that corundum with a particle size of F36 was used as the sandblasting agent.

[0099] [Example 14] The procedure was the same as in Example 3, except that corundum with a particle size of F16 was used as the sandblasting agent.

[0100] [Example 15] A single-layer preform was molded using commercially available polyethylene terephthalate resin material. A low-density polyethylene was then coated onto the outside of the single-layer preform, and secondary injection molding was performed to obtain a two-layer preform. Biaxially stretched blow molding was performed on the two-layer preform to produce a PET bottle-shaped container. Under the same conditions as in Example 3, an opaque region was formed on a portion of the outside of the container using a sandblasted mold. [Example 16] The procedure was the same as in Example 15, except that glass beads with a particle size of F80 were used as the sandblasting agent.

[0101] [Example 17] The procedure was the same as in Example 15, except that glass beads with a particle size of F100 were used as the sandblasting agent.

[0102] [Example 18] The procedure was the same as in Example 15, except that glass beads with a particle size of F320 were used as the sandblasting agent.

[0103] [Example 19] The procedure was the same as in Example 15, except that glass beads with a particle size of F70 were used as the sandblasting agent.

[0104] [Example 20] The procedure was the same as in Example 15, except that alumina particles with a particle size of F100 were used as the sandblasting agent. [Example 21] The procedure was the same as in Example 15, except that corundum with a particle size of F60 was used as the sandblasting agent.

[0105] [Example 22] The procedure was the same as in Example 15, except that glass powder with a particle size of F54 was used as the sandblasting agent.

[0106] [Example 23] The procedure was the same as in Example 15, except that alumina particles with a particle size of F46 were used as the sandblasting agent.

[0107] [Example 24] The procedure was the same as in Example 15, except that corundum with a particle size of F16 was used as the sandblasting agent.

[0108] [Example 25] The procedure was the same as in Example 15, except that corundum with a particle size of F24 was used as the sandblasting agent.

[0109] [Example 26] The procedure was the same as in Example 15, except that corundum with a particle size of F36 was used as the sandblasting agent.

[0110] The arithmetic mean height (Ra), mean length (RSm), and haze of the opaque region of the containers manufactured in Examples 3 to 26 were measured. The measurement results are shown in Table 1 below. The units for Ra and RSm are μm. [Table 1] [Table 1]

[0111] As shown in Table 1, Examples 5-8, where the Ra / RSm ratio was greater than 0.001 and less than 0.002 in the single-layer preform, showed higher haze compared to Examples 3-4, where the Ra / RSm ratio was less than 0.001. Examples 9-14, where the Ra / RSm ratio was greater than 0.002, showed even higher haze compared to Examples 5-8. Furthermore, it was shown that in single-layer preforms, a good haze was generally achieved when the Ra ratio exceeded 0.8 μm.

[0112] Examples 18-20, with an Ra / RSm ratio greater than 0.01 and less than 0.02 in the two-layer preform, showed higher haze compared to Examples 15-17, with an Ra / RSm ratio of less than 0.01. Examples 21-26, with an Ra / RSm ratio greater than 0.02, showed even higher haze compared to Examples 18-20. Furthermore, it was shown that in the two-layer preform, a good haze is generally achieved when the Ra ratio exceeds 1.8 μm.

[0113] Although the present invention has been described above using embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various modifications or improvements can be made to the above embodiments. It will be clear from the claims that such modified or improved forms may also be included in the technical scope of the present invention.

[0114] It should be noted that the execution order of operations, procedures, steps, and stages in the methods described in the claims, specification, and drawings is not explicitly stated as "before" or "prior to," and that they can be implemented in any order unless the results of a previous process are used in a later process. Even if the operation flow in the claims, specification, and drawings is described using phrases such as "first," "next," etc. for convenience, it does not mean that it is essential to perform them in that order. An example of an embodiment of the present invention is shown as an item. [Item 1] A transparent container body molded from polyethylene terephthalate (PET) capable of holding its contents, An opaque area provided on the outer surface or a part of the inner surface of the container body, A printed layer containing a coloring agent is provided in at least a portion of the opaque area, Equipped with, PET container. [Item 2] The opaque areas are the whitened regions of the PET material on the container body. PET container as described in item 1. [Item 3] The opaque region is a region where the PET of the container body has been at least partially crystallized. PET containers as described in item 2. [Item 4] The opaque area is a region on the outer or inner surface of the container body that has been roughened. PET containers as described in item 2. [Item 5] The arithmetic mean roughness (Ra) of the roughened region is between 0.05 and 20 μm. PET containers as described in item 4. [Item 6] The Ra / RSm value, calculated from the arithmetic mean roughness (Ra) and mean length (RSm) of the roughened region, is 0.001 or greater. PET containers as described in item 4 or 5. [Item 7] The opaque areas are regions where the PET material of the container body has been partially foamed. PET containers as described in item 2. [Item 8] The container itself is The middle class, It consists of polyethylene terephthalate, with a PET layer sandwiching an intermediate layer, A PET container as described in any one of items 1 through 7, including the item described in item 1. [Item 9] The intermediate layer contains nylon or recycled PET. PET containers as described in item 8. [Item 10] The haze in the opaque region is 0.5 to 100. A PET container as described in any one of items 1 through 9. [Item 11] The thermally induced crystallinity of PET in the opaque region is 15% to 80%. A PET container as described in any one of items 1 through 10. [Item 12] The total light transmittance in the opaque region is 85% or less. Total light transmittance is the average transmittance for light with wavelengths of 400-700 nm. A PET container as described in any one of items 1 through 11. [Item 13] The printed layer contains printed characters, The opaque area is provided at least around the edges of the characters. A PET container as described in any one of items 1 through 12. [Item 14] The container body further comprises recesses formed on the outer surface representing letters or symbols. A PET container as described in any one of items 1 through 13. [Item 15] The letters or symbols in the recesses represent information about the material of the container body. The printed layer represents information specific to the product sold in the PET container. PET containers as described in item 14. [Item 16] A molding step in which a transparent container body capable of holding contents is formed using polyethylene terephthalate (PET), An opacification step in which the outer or inner surface of the container body is made opaque, A printing step in which a printed layer is formed on the opaque portion of the container body using an inkjet method, A method for manufacturing a PET container equipped with [the necessary features]. [Item 17] The opacification step includes at least partially whitening the PET of the container body. A method for manufacturing a PET container as described in item 16. [Item 18] The opacification step includes at least partially crystallizing the PET of the container body. A method for manufacturing a PET container as described in item 17. [Item 19] The opacification step includes roughening the outer or inner surface of the container body. A method for manufacturing a PET container as described in item 17. [Item 20] The arithmetic mean roughness (Ra) of the roughened surface of the container body is between 0.05 and 20 μm. A method for manufacturing a PET container as described in item 19. [Item 21] The Ra / RSm value, calculated from the arithmetic mean roughness (Ra) and mean length (RSm) of the roughened surface, is 0.001 or greater. A method for manufacturing a PET container as described in item 19 or 20. [Item 22] The opacification step includes partially foaming the PET of the container body. A method for manufacturing a PET container as described in item 17. [Item 23] A molding step of forming a container using polyethylene terephthalate (PET) and an opaque material, the container having a transparent container body capable of holding contents and an opaque region provided on at least a part of the outer or inner surface of the container body, A printing step in which a printed layer is formed on the opaque area of ​​the container using an inkjet method, A method for manufacturing a PET container equipped with [the necessary features]. [Item 24] The molding process is carried out using double-mold molding, in which an opaque material is injected to cover the outer or inner surface of the container body. A method for manufacturing a PET container as described in item 23. [Explanation of Symbols]

[0115] 10 Container body 12 PET layers 14. Middle Class 16 PET layers 20 Opaque area 30 printing layer 35 Transparent area 40 recess 100 containers

Claims

1. A transparent container body molded from polyethylene terephthalate (PET) that can hold its contents, An opaque region provided on a part of the outer or inner surface of the container body other than the lid, A printing layer containing a coloring agent is provided in at least a portion of the opaque region, Equipped with, The opaque region is a region that has been whitened by at least partially crystallizing the PET of the container body. The haze of the opaque region is 0.5 to 100. The thermal induction crystallinity of the PET in the opaque region is 15% to 80%. PET container.

2. The thickness of the opaque region is 0.05 to 1 mm. The PET container according to claim 1.

3. The container body is The middle class, It consists of polyethylene terephthalate, with a PET layer sandwiching the aforementioned intermediate layer, A PET container according to claim 1, comprising

4. The aforementioned intermediate layer includes nylon or recycled PET. The PET container according to claim 3.

5. The total light transmittance of the opaque region is 85% or less. The aforementioned total light transmittance is the average transmittance for light with wavelengths of 400 to 700 nm. A PET container according to any one of claims 1 to 4.

6. The aforementioned printing layer includes printed characters, The opaque region is provided at least on the edge portion of the character. A PET container according to any one of claims 1 to 5.

7. The container body further comprises recesses formed on its outer surface that represent letters or symbols. A PET container according to any one of claims 1 to 6.

8. The letters or symbols in the recess represent information about the material of the container body, The printed layer represents information specific to the product sold using the PET container. The PET container according to claim 7.

9. A molding step in which a transparent container body capable of holding contents is formed using polyethylene terephthalate (PET), An opacification step to form an opaque region by making at least a portion of the outer or inner surface of the container body other than the lid opaque, A printing step in which a printed layer is formed on the opaque portion of the container body using an inkjet method, Equipped with, The opacification step includes whitening the PET of the container body by at least partially crystallizing it. The haze of the opaque region is 0.5 to 100. The thermal induction crystallinity of the PET in the opaque region is 15% to 80%. A method for manufacturing PET containers.

10. The thickness of the opaque region is 0.05 to 1 mm. A method for manufacturing a PET container according to claim 9.

Images